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24-100901-Technical Info Report-3.13.24 TECHNICAL INFORMATION REPORT Penwell Property South End of 2nd Ave SW Federal Way, Washington Prepared for: Chris Penwell 696 Moss Farm Road Cheshire, Ct 06410 September 6, 2023 Our Job No. 7708 9/6/2023 7708.016-TIR FINL TABLE OF CONTENTS 1.0 PROJECT OVERVIEW Figure 1.0.1 – Technical Information Report (TIR) Worksheet Figure 1.0.2 – Vicinity Map Figure 1.0.3 – Predeveloped Drainage Basin Map Figure 1.0.4 – Soil Survey Map Figure 1.0.5 – Assessor Map Figure 1.0.6 – FEMA Map Figure 1.0.7 – Sensitive Area Map Figure 1.0.8 – Developed Drainage Basin Map Figure 1.0.9 – Downstream Basin Map 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Analysis of the Core Requirements and Special Requirements 3.0 OFF-SITE ANALYSIS 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.1 Existing Site Hydrology 4.2 Developed Site Hydrology 4.3 Performance Standards 4.4 Flow Control System Figure 4.4.1 – Detention System Calculations Figure 4.4.2 – Stormbrixx Detention System Detail 4.5 Water Quality System Figure 4.5.1 – Modular Wetland Detail Figure 4.5.2 – CDS Pre-Settling Unit Detail Figure 4.5.3 - Modular Wetland and CDS Unit GULD Approval 4.5 On-site BMP’s 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN Figure 5.0.1 – 100-year 24-hour Isopluvials 6.0 SPECIAL REPORTS AND STUDIES 6.1 Geotechnical Engineering Study prepared by Earth Solutions NW, LLC. Dated September 1, 2023 6.2 SWPPP prepared by Barghausen Consulting Engineers, Inc., dated August 3, 2023 7708.016-TIR FINL 7.0 OTHER PERMITS 8.0 ESC ANALYSIS AND DESIGN Figure 8.0.1 – TESC Plan 9.0 BOND QUANTITIES AND FACILITY SUMMARIES 9.1 Erosion Control Bond Quantity Worksheet 9.2 Stormwater Facility Summary Sheet 10.0 OPERATIONS AND MAINTENANCE MANUAL Tab 1.0 7708.016-TIR FINL 1.0 PROJECT OVERVIEW This section contains the following information: Figure 1.0.1 – Technical Information Report (TIR) Worksheet Figure 1.0.2 – Vicinity Map Figure 1.0.3 – Predeveloped Drainage Basin Map Figure 1.0.4 – Soil Survey Map Figure 1.0.5 – Assessor's Map Figure 1.0.6 – FEMA Map Figure 1.0.7 – Sensitive Area Map Figure 1.0.8 – Developed Drainage Basin Map Figure 1.0.9 – Downstream Basin Map 7708.016-TIR FINL 1.0 PROJECT OVERVIEW The Penwell Property project consists of the development of an existing parcel in Federal Way by re- constructing a shared access road and single-family residence. The project site consists of approximately 0.94 acres of parcel area at the south end of 2nd Ave SW. The project site is located within a portion of Section 6, Township 21 North, Range 4 East, Willamette Meridian, in the City of Federal Way, Washington. The tax parcel number for the property is 199600-3800. The site contains an existing shared access road that connects to 2nd Ave SW at the northeast corner of the site and to the neighbor property at the southwest property corner. The remaining portion of the site consists of largely forested area with an unnamed stream bisecting the site on the east side. Elevations range from 136 to 202 feet across the site sloping down to the unnamed stream. The low point of the site is located at the centerline of the stream as it leaves the site to the north. A portion of the slopes on-site exceed 40% in grade and may be considered a potential landslide hazard area. This area was shown on the King County iMap as an erosion hazard area. Further detail on the landslide hazard area is discussed in the Geotechnical Engineering Study prepared by Earth Solutions NW, LLC included in Section 6.0 of this report. The USDA Web Soil Survey for this area shown in Figure 1.0.4 of this section indicates that the on- site soils are considered Indianola loamy sand, Alderwood and Kitsap soils and Alderwood gravelly sandy loam with 0 to 30 percent slopes. According to the Geotechnical Engineering Study prepared by Earth Solutions NW, LLC the underlying native soil for the site consists of course to fine grained deposits. The study also concluded that infilitration facilities are infeasible for this project due to the steep grades and groundwater seepage encountered in the property. In addition to the shared access road and single-family residence, the project will construct stormwater pipes and catch basins, a stormwater detention system, sewer facilities and water facilities to serve the property. Stormwater runoff generated by new impervious and pervious surfaces will be routed to a Stormbrixx detention system before discharging to the unnamed stream near the north property line. Prior to entering the detention system, runoff will flow through a Contech CDS pre-settling unit and a Contech Modular Wetland water quality unit for enhanced water quality treatment. The storm drainage design is based on the 2021 King County Surface Water Design Manual (2021 KCSWDM) and the City of Federal Way Addendum to The King County Surface Water Design Manual. Please refer to Section 4.0 of this TIR for further details regarding the design of the drainage facilities. KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner Phone _____ Address Project Engineer Company ____ Phone _______ Part 2 PROJECT LOCATION AND DESCRIPTION Project Name _ DLS-Permitting Permit #_____ Location Township Range _ Section _ Site Address _______ Part 3 TYPE OF PERMIT APPLICATION □ Land use (e.g.,Subdivision / Short Subd. / UPD) □ Building (e.g.,M/F / Commercial / SFR) □ Clearing and Grading □ Right-of-Way Use □ Other ___________________________ Part 4 OTHER REVIEWS AND PERMITS1 □ DFW HPA □ COE CWA 404 □ ECY Dam Safety □ FEMA Floodplain □ COE Wetlands □ Other _________ □ Shoreline Management □ Structural Rockery/Vault/______ □ ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Type of Drainage Review (check one): Date (include revision dates): Date of Final: □ □ □ □ □ Full Targeted Simplified Large Project Directed Site Improvement Plan (Engr. Plans) Plan Type (check one): Date (include revision dates): Date of Final: □ Full □ Modified □ Simplified Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Experimental /Blanket Description: (include conditions in TIR Section 2) Approved Adjustment No._ _ Date of Approval: __________________________ 1 DFW: WA State Dept. of Fish and Wildlife. HPA: hydraulic project approval. COE: (Army) Corps of Engineers. CWA: Clean Water Act. ECY: WA State Dept. of Ecology. FEMA: Federal Emergency Management Agency. ESA: Endangered Species Act. 2021 Surface Water Design Manual 1 Last revised 7/23/2021 Chris Penwell (206) 651-9323 696 Moss Farm Road Cheshire, CT 06410 Barry Talkington Barghausen Consulting Engineers (425) 251-6222 Penwell Residence 21 4 East 6 West of the intersection at Fay Road NE and NE 110th ST X 8/3/2023 X 8/3/2023 X X Figure 1.0.1 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: Describe: Completion Date:Re: KCSWDM Adjustment No. Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan :________________________________ Special District Overlays:_________________________ Drainage Basin:__________________________________ Stormwater Requirements: _______________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS □ River/Stream □Steep Slope □ Lake □Erosion Hazard □ Wetlands □Landslide Hazard □ Closed Depression □Coal Mine Hazard □ Floodplain □Seismic Hazard □ Other □Habitat Protection □ Part 10 SOILS Soil Type Slopes Erosion Potential □ High Groundwater Table (within 5 feet) □ Sole Source Aquifer □ Other ______________ _______________________ □ Seeps/Springs □ Additional Sheets Attached 2021 Surface Water Design Manual 2 Last revised 7/23/2021 Lower Puget Sound 2021 King County Surface Water Design Manual with City of Federal Way Addendum X X Indianola loamy sand Indianola loamy sand Alderwood and Kitsap soils very steep Alderwood gravelly sandy loam 5-15% N/A 15-30% 8-15% Low Moderate Moderate Low X X KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE LIMITATION / SITE CONSTRAINT □ Core 2 - Offsite Analysis____________________ _________________________________ □ Sensitive/Critical Areas _____________________ _________________________________ □ SEPA _____________________________________ _________________________________ □ LID Infeasibility____________________________ _________________________________ □ Other _____________________________________ _________________________________ □ □ Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Core Requirements (all 8 apply): Discharge at Natural Location Number of Natural Discharge Locations: Offsite Analysis Level: 1 / 2 / 3 dated: Flow Control (include facility Level: 1 / 2 / 3 or Exemption Number ______________ summary sheet)Flow Control BMPs Conveyance System Spill containment located at: Erosion and Sediment Control /CSWPP/CESCL/ESC Site Supervisor: Construction Stormwater Pollution Prevention Contact Phone: After Hours Phone: Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality (include facility Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog summary sheet)or Exemption No. Landscape Management Plan: Yes / No For Entire Project:Total Replaced Impervious surfaces on the site % of Target Impervious that had a feasible FCBMP Total New Pervious Surfaces on the site Repl. Imp. on site mitigated w/flow control facility implemented Repl. Imp. on site mitigated w/water quality facility Repl. Imp. on site mitigated with FCBMP 2021 Surface Water Design Manual 3 Last revised 7/23/2021 X Onsite wetland, stream and steep slope areas Developed Basin 1 7/28/2023 N/A TBD TBD TBD Reduced Impervious Surface Credit 2,434 SF 4,520 SF 2,434 SF 2,434 SF 0 SF 29% KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Special Requirements (as applicable): Area Specific Drainage Requirements Type: CDA / SDO / MDP / BP / LMP / Shared Fac. / None Name: Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: Source Control (commercial / industrial land use) Describe land use: Describe any structural controls: Oil Control High-use Site: Yes / No Treatment BMP: Maintenance Agreement: Yes / No with whom? Other Drainage Structures Describe: Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION ^ Clearing Limits ^ Cover Measures ^ Perimeter Protection ^ Traffic Area Stabilization ^ Sediment Retention ^ Surface Water Collection ^ Dewatering Control ^ Dust Control ^ Flow Control ^ Protection of Flow Control BMP Facilities (existing and proposed) ^ Maintain BMPs / Manage Project MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION ^ Stabilize exposed surfaces ^ Remove and restore Temporary ESC Facilities ^ Clean and remove all silt and debris, ensure operation of Permanent Facilities, restore operation of Flow Control BMP Facilities as necessary ^ Flag limits of SAO and open space preservation areas ^ Other 2021 Surface Water Design Manual 4 Last revised 7/23/2021 X X X X X X X X X X X X X X X KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Type/Description Water Quality Type/Description □ Detention □Vegetated Flowpath □ Infiltration □Wetpool □ Regional Facility □Filtration □ Shared Facility □Oil Control □ Flow Control BMPs □Spill Control □ Other □Flow Control BMPs □Other Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS □ Drainage Easement □ Cast in Place Vault □ Covenant □ Retaining Wall □ Native Growth Protection Covenant □ Rockery > 4’ High □ Tract □ Structural on Steep Slope □ Other □ Other Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. Signed/Date 2021 Surface Water Design Manual 5 Last revised 7/23/2021 X X Stormbrixx System X Modular Wetland X Reduced Impervious Surface Credit 9/6/2023 Horizontal: Scale: Vertical: For: Title: V I C I N I T Y M A P Job Number N.T.S.N/A 7708 D AT E: 07/18/23 Penwell Residence Federal Way, Washington P:\7000s\7708\exhibit\graphics\7708 vmap.cdr RE FER ENC E: MapQuest (2023) SITE Figure 1.0.2 Title:For: 1 7708 CHRIS PENWELL 696 MOSS FARM ROAD CHESHIRE, CT 06410 PENWELL PROPERTYCITY OF FEDERAL WAY, KING COUNTY, WASHINGTONPTN. OF THE SE 1/4, OF THE NE 1/4, SEC. 06, TWP 21 N., RGE 04 E., W.M.FOR PENWELL PROPERTY1 PREDEVELOPED BASIN MAP OFPREDEVELOPED BASIN MAPPREDEVELOPED BASINSCALE: 1"=20'Figure 1.0.3 Horizontal: Scale: Vertical: For: Title: S O I L S U RV E Y M A P Job Number N.T.S.N/A 7708 D AT E: 07/18/23 Penwell Residence Federal Way, Washington P:\7000s\7708\exhibit\graphics\7708 soil.cdr H SG A A B B RE FER ENCE: US DA, Natural Resources Conservation Service LE GEN D: SITE InC = Indianola loamy sand, 5-15% slopes InD = Indianola loamy sand, 15-30% slopes AkF = Alderwood and Kitsap soils, very steep AgC = Alderwood gravelly sandy loam, 8-15% slopes Figure 1.0.4 Horizontal: Scale: Vertical: For: Title: A S S E S S O R M A P Job Number N.T.S.N/A 7708 D AT E: 07/18/23 Penwell Residence Federal Way, Washington P:\7000s\7708\exhibit\graphics\7708 amap.cdr SITE RE FER ENC E: King County Department of Assessments (Oct. 2020) Figure 1.0.5 Horizontal: Scale: Vertical: For: Title: F E M A M A P Job Number N.T.S.N/A 7708 D AT E: 07/18/23 Penwell Residence Federal Way, Washington P:\7000s\7708\exhibit\graphics\7708 fema.cdr REFER EN CE: Federal Emergency Management Agency (Portion of Map 53033C1230G, Aug. 2020) Areas determined to be outside the 0.2% annual chance floodplain. ZONE X OTHER AREAS L E G E N D SITE Figure 1.0.6 Horizontal: Scale: Vertical: For: Title: S E N S I T I V E A R E A S M A P Job Number N.T.S.N/A 7708 D AT E: 07/18/23 Penwell Residence Federal Way, Washington P:\7000s\7708\exhibit\graphics\7708 sens.cdr SITE RE FER ENC E: King County iM AP (2023) Figure 1.0.7 Title:For: 1 7708 CHRIS PENWELL 696 MOSS FARM ROAD CHESHIRE, CT 06410 PENWELL PROPERTYCITY OF FEDERAL WAY, KING COUNTY, WASHINGTONPTN. OF THE SE 1/4, OF THE NE 1/4, SEC. 06, TWP 21 N., RGE 04 E., W.M.FOR PENWELL PROPERTY1 DEVELOPED BASIN MAP OFDEVELOPED BASIN MAPDEVELOPED BASINSCALE: 1"=20'Figure 1.0.8 Title:For: 1 7708 CHRIS PENWELL 696 MOSS FARM ROAD CHESHIRE, CT 06410 PENWELL PROPERTYCITY OF FEDERAL WAY, KING COUNTY, WASHINGTONPTN. OF THE SE 1/4, OF THE NE 1/4, SEC. 06, TWP 21 N., RGE 04 E., W.M.FOR PENWELL PROPERTY1 DOWNSTREAM BASIN MAP OFDOWNSTREAM BASIN MAP2ND AVE SW FLOWPATH LEGENDSPECIAL NOTE1/4 MILE DOWNSTREAMFROM SITEUNNAMED TRIBUTARYSCALE 1"=150'PROJECT SITE3RD AVE SW SW 293RD ST3RD AVE SW 6TH AVE SW SW 292ND STSW 297TH STPUGET SOUNDFigure 1.0.9 Tab 2.0 7708.016-TIR FINL 2.0 CONDITIONS AND REQUIREMENTS SUMMARY This section contains the following information: 2.1 Analysis of the Core Requirements and Special Requirements 7708.016-TIR FINL 2.1 Analysis of the Core Requirements and Special Requirements CORE REQUIREMENTS HOW PROJECT HAS ADDRESSED REQUIREMENT No. 1: Discharge at Natural Location Runoff from the existing site sheetflows towards the unnamed stream flowing northwest and leaves the site near the north boundary line. Stormwater runoff tributary to the proposed improvements will be collected by a tightlined conveyance system and discharged to the unnamed stream near the north boundary line after detention and water quality treatment, thus maintaining the natural discharge location of the site. No. 2: Off-Site Analysis The off-site analysis has been included within Section 3.0 of this Technical Information Report. No. 3: Flow Control Runoff from all target surfaces in the developed site is designed to be collected and detained per the Conservation Flow Control standard. No. 4: Conveyance System The conveyance system has been designed per the 2021 King County Surface Water Design Manual. The conveyance calculations are included in Section 5.0 of this report. No. 5: Erosion and Sediment Control Temporary erosion control measures for this project will include: stabilized construction entrance, perimeter runoff control, cover practices, and construction sequencing. No. 6: Maintenance and Operations An Operations and Maintenance Manual is provided in Section 10.0 of this report. No. 7: Bonds and Liability Bonding will be completed using the City of Federal Way Bond Quantity Worksheet. No. 8: Water Quality The project is required to provide Enhanced Basic Water Quality Treatment and will do so via a Contech Modular Wetland water quality unit upstream of the detention system. No. 9: Flow Control BMPs According to the Geotechnical Engineering Study in Section 6.1, infiltration should not be applied for this project due to the steep hillside characteristics of the site and the observed presence of various groundwater seepage zones. Because of this, the following BMP’s are infeasible: Full Infiltration, Limited Infiltration, Bioretention, Permeable Pavement and Perforated Stub-Out Connections. Full Dispersion and Basic Dispersion are also infeasible due the steep characteristics of the existing and proposed site. As such, the Reduced Impervious Surface Credit BMP will be implemented to the maximum extent feasible for the impervious areas constructed outside the existing shared access and utility easement extending through the site. All pervious surfaces will incorporate soil amendment as detailed in the 2021 KCSWDM. 7708.016-TIR FINL SPECIAL REQUIREMENTS HOW PROJECT HAS ADDRESSED REQUIREMENT No. 1: Other Adopted Area Specific Requirements This special requirement does not apply to this project. No. 2: Floodplain/Floodway Delineation The proposed development is not located within the 100-year floodplain. No. 3: Flood Protection Facilities This project does not rely on an existing flood protection facility nor propose to modify or construct a new flood protection facility, therefore this special requirement does not apply. No. 4: Source Controls This project is a single-family residential project and is not subject to this special requirement. No. 5: Oil Control This site is not classified as a high-use site given the criteria found in the 2021 KCSWDM, therefore no special oil control treatment is necessary. Tab 3.0 7708.016-TIR FINL 3.0 OFF-SITE ANALYSIS This section contains the following information: Task 1 – Study Area Definitions and Maps Task 2 – Resource Review Task 3 – Field Inspection 3.1 Conveyance System Nuisance Problems (Type 1) 3.2 Severe Erosion Problems (Type 2) 3.3 Severe Flooding Problems (Type 3) 3.4 Downstream Water Quality Problems Task 4 – Drainage System Description and Problem Descriptions 7708.016-TIR FINL TASK 1 – STUDY AREA DEFINITION AND MAPS The Penwell Property project consists of the development of an existing parcel in Federal Way by constructing a shared access road and single-family residence. The project site consists of approximately 0.94 acres of parcel area at the south end of 2nd Ave SW. The project site is located within a portion of Section 6, Township 21 North, Range 4 East, Willamette Meridian, in the City of Federal Way, Washington. The site is bounded to the east and south by single-family residences which discharge runoff to their respective street conveyance systems along their frontage. The site is bounded to the west by a single-family residence and access road which discharges runoff to the northeast towards the unnamed stream flowing through the site. Finally, the site is bounded to the north by forested land and the portion of the unnamed stream located downgradient of the site. Because of the reasons stated above, no upstream runoff is expected to flow towards the project site. Stormwater runoff generated by new impervious and pervious surfaces will be routed to a Stormbrixx detention system before to discharging to the unnamed stream near the north property line. Prior to entering the detention system, runoff will flow through a Contech CDS pre-settling unit and a Contech Modular Wetland water quality unit for enhanced water quality treatment. Once entering the unnamed stream, runoff will flow offsite to the northwest per the flowpath detailed in Task 3 of this section. 7708.016-TIR FINL TASK 2 – RESOURCE REVIEW · Adopted Basin Plans: The site is tributary to the Lower Puget Sound Basin which is a tributary to the Puget Sound. · Floodplain and Floodway FEMA Maps: The project site is not located in a floodplain area, therefore this is not applicable. · Other Off-Site Analysis Reports: A site investigation was conducted as a Level 1 Off-Site Drainage Analysis. · Critical and Sensitive Area maps: The King County iMap and City of Federal Way Sensitive Areas map show the existing unnamed stream flowing across the site. The maps also show an erosion hazard area along the western portion of the site. The Geotechnical Engineering Study included in Section 6.1 concurs with the online maps due to potential erosion hazard areas observed near the western side of the site. · Drainage Complaints and Studies: A review of the King County iMap did not show any drainage complaints within one mile downstream of the project site. · Road Drainage Problems: There were no Road Drainage issues determined downstream of the project site. · United States Department of Agriculture Web Soil Survey: Based on the Soils Map for this area (see Figure 1.0.4 – Soil Survey Map in Section 1.0), the site is located on Alderwood gravelly sandy loam, Alderwood and Kitsap soils and Indianola loamy sand. This soils type is confirmed by the Geotechnical Engineering Study prepared for the project. · Wetland Inventory Map: The City of Federal Way Sensitive Areas Map and King County iMap do not show any wetlands located within the project site. A critical area assessment conducted by Habitat Technologies concluded that there is an existing wetland onsite located adjacent to the unnamed stream on the north portion of the site. 7708.016-TIR FINL TASK 3 – FIELD INSPECTION Level 1 Off-Site Drainage Analysis: The field reconnaissance for the Level 1 Off-Site Drainage Analysis was conducted on July 28, 2023. On the day of the site visit, conditions were sunny and dry. As mentioned earlier in this report, most of the stormwater from the predeveloped site naturally discharges to the existing unnamed stream crossing the site and flows off-site to the northwest. A series of photos taken during the site visit with a detailed description of the downstream flowpath are shown below: Photo #1 – Looking North Photo #2 – Looking Northwest Photo #1 shows the upstream end of the 36-inch culvert on the east side of the existing on-site access road. The existing unnamed stream crossing the site flows through this culvert and outlets to the northwest of the access road. Photo #2 was obtained near the outlet location of the existing culvert. Due to the summer conditions, the stream corridor consists of small flows and thick brushes shown in the picture above. This stream continues to flow northwest before exiting the site at the north boundary. 7708.016-TIR FINL Photo #3 – Looking Southeast Photo #4 – Looking Northwest Photo #3 was taken from 3rd Ave SW approximately 520 feet downstream of the project site. Photo #4 was taken from SW 293rd St approximately 900 feet from the project site. As shown in the photos, the finished grade of both roadways sits considerably higher than the stream. Due to the steep slopes and thick brushes in the vicinity, photos were unable to be obtained along at the current water surface elevation of the stream. From visual observation at both locations, the characteristics of the stream were similar to the on-site location where the stream corridor consists of low flows and thick brushes. The stream eventually discharges to the Puget Sound approximately one-quarter mile downstream of the project site. Please refer to the Downstream Basin Map (Figure 1.0.9) for a map location of the photos obtained during the downstream analysis and a visual representation of the downstream flowpath. 7708.016-TIR FINL TASK 4 – DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS DOWNSTREAM DRAINAGE ANALYSIS After the field inspection was conducted on the conveyance system downstream of the project site, each of the potential drainage problems outlined below was evaluated for the system. 3.1 Conveyance System Nuisance Problems (Type 1) Conveyance system nuisance problems are minor but not chronic flooding or erosion problems that result from the overflow of a constructed conveyance system that is substandard or has become too small as a result of upstream development. Such problems warrant additional attention because of their chronic nature and because they result from the failure of a conveyance system to provide a minimum acceptable level of protection. There were no conveyance system nuisance problems observed during the July 28, 2023 site visit. 3.2 Severe Erosion Problems (Type 2) Severe erosion problems can be caused by conveyance system overflows or the concentration of runoff into erosion-sensitive open drainage features. Severe erosion problems warrant additional attention because they pose a significant threat either to health and safety, or to public or private property. The only open drainage features within one mile of the project site is the Puget Sound which the unnamed stream discharges to approximately one-quarter mile downstream of the site. Runoff from the developed site will be detained per the Level 2 Conservation Flow Control standard, therefore no future erosion control problems will occur downstream. 3.3 Severe Flooding Problems (Type 3) Severe flooding problems can be caused by conveyance system overflows or the elevated water surfaces of ponds, lakes, wetlands, or closed depressions. Severe flooding problems are defined as follows: · Flooding of the finished area of a habitable building for runoff events less than or equal to the 100-year event. Examples include flooding of finished floors of homes and commercial or industrial buildings. Flooding in electrical/heating systems and components in the crawlspace or garage of a home. Such problems are referred to as "severe building flooding problems." · Flooding over all lanes of a roadway or severely impacting a sole access driveway for runoff events less than or equal to the 100-year event. Such problems are referred to as "severe roadway flooding problems." Based on a review of the FEMA Map (Section 1.0) the proposed site is not located in any floodplain areas therefore no severe flooding problems are expected. 3.4 Downstream Water Quality Problems After reviewing the Washington State Department of Ecology Water Quality Atlas, there are no Category 5, 4 or 2 Waterbodies located within one mile downstream of the project site therefore no water quality problems are expected from this development. Tab 4.0 7708.016-TIR FINL 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN This section contains the following information: 4.1 Existing Site Hydrology 4.2 Developed Site Hydrology 4.3 Performance Standards 4.4 Flow Control System 4.5 Water Quality System 4.6 On-Site BMP’s 7708.016-TIR FINL 4.1 Existing Site Hydrology The existing conditions of the project site consist of largely forested land with an unnamed stream entering the site near the southeast corner and exiting near the north property line. A critical area assessment conducted by Habitat Technologies identified an on-site wetland adjacent to the unnamed stream on the north portion of the site. An existing shared access road located within a 30-foot-wide private road and utility easement crosses the site starting at 2nd Ave SW at the northeast property corner and ending at the southwest property corner. The majority of the site slopes northeast with stormwater runoff sheet flowing in that direction and entering the unnamed stream. Once entering the stream, runoff begins to flow northwest before leaving the site. Please refer to the Predeveloped Basin Map (Figure 1.0.3) for further detail on the existing on-site drainage conditions. The Soil Survey Map identified the on-site soils as Indianola loamy sand, Alderwood and Kitsap soils, and Alderwood gravelly sandy loam. Although these soils are classified as Type A and B soils, the Geotechnical Engineering Study prepared by Earth Solutions NW concluded that the soils should be modeled as Type C when sizing the on-site detention facility. 7708.016-TIR FINL 4.2 Developed Site Hydrology The Developed Basin for the project site consists of all on-site stormwater tributary to the new/replaced impervious and pervious surfaces associated with this project. New and replaced impervious surfaces constructed with this project consist of the re-constructed shared access road and single-family residence footprint. New pervious surfaces constructed with this project will consist of any disturbed area outside the shared access road and house footprint and lawn area located above the Stormbrixx detention system. A conveyance system consisting of catch basins and storm pipes will be constructed in the shared access road to collect stormwater runoff and route it to the on-site detention system. As previously stated, the Geotechnical Engineering Study included in Section 6.1 concluded that infiltration should not be applied for this project due to the steep hillside characteristics of the site and the observed presence of various groundwater seepage zones. Please refer to the Developed Basin Map (Figure 1.0.8) for further detail on the on-site drainage conditions of the developed site. A breakdown of the impervious and pervious areas in the developed basin is shown in the tables below. A more detailed breakdown is shown in the Developed Basin Map in Section 1.0: Developed Basin Impervious Road Impervious Roof Pervious Lawn Total Area 0.15 Ac 0.06 Ac 0.10 Ac(1) 0.31 Ac Notes: 1. Modeled as till grass For the Stormbrixx detention system design and WWHM sizing calculations, please refer to Section 4.4. 7708.016-TIR FINL 4.3 Performance Standards According to the Flow Control Applications Map for the City of Federal Way, this project shall conform to the Conservation Flow Control standards. This standard requires developed discharge durations to match predeveloped durations for the range of predeveloped discharge rates from 50% of the 2-year peak flow to the full 50-year peal flow. Also, developed peak discharge rates shall match predeveloped peak discharge rates for the 2- and 10-year return periods. The project is also required to provide Enhanced Basic Water Quality and will do via a Modular Wetland System. See Section 4.5 for more detail. 7708.016-TIR FINL 4.4 Flow Control System The Stormbrixx detention system was sized per the Conservation Flow Control requirements based on the 2021 KCSWDM. As outlined earlier, this standard requires that discharges be designed to match developed discharge durations to predeveloped durations for the range of 50 percent of the 2-year peak flow up to the 50-year peak flow. This standard also requires that the 2-year and 10- year predeveloped peak flows be matched in the developed condition. After sizing the detention system for these standards using WWHM, it was determined that the live storage volume required for the system is 3,659 cubic feet. The live storage volume provided by the detention system is 3,704 cubic feet as shown in the Stormbrixx Detention System Detail (Figure 4.4.2). For further detail on the WWHM calculations please see Figure 4.4.1 included in this section. WWHM2012 PROJECT REPORT Figure 4.4.1 Detention Vault 8/3/2023 8:56:30 AM Page 2 General Model Information WWHM2012 Project Name:Detention Vault Site Name: Site Address: City: Report Date:8/3/2023 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2023/01/27 Version:4.2.19 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Detention Vault 8/3/2023 8:56:30 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Steep 0.31 Pervious Total 0.31 Impervious Land Use acre Impervious Total 0 Basin Total 0.31 Detention Vault 8/3/2023 8:56:30 AM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Steep 0.1 Pervious Total 0.1 Impervious Land Use acre ROADS STEEP 0.15 ROOF TOPS FLAT 0.06 Impervious Total 0.21 Basin Total 0.31 Detention Vault 8/3/2023 8:56:30 AM Page 6 Mitigated Routing Vault 1 Width:21 ft. Length:20.6 ft. Depth:9 ft. Discharge Structure Riser Height:8.5 ft. Riser Diameter:18 in. Orifice 1 Diameter:0.360 in.Elevation:0 ft. Orifice 2 Diameter:0.400 in.Elevation:4.1 ft. Orifice 3 Diameter:0.430 in.Elevation:6.2 ft. Element Flows To: Outlet 1 Outlet 2 Vault Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.009 0.000 0.000 0.000 0.1000 0.009 0.001 0.001 0.000 0.2000 0.009 0.002 0.001 0.000 0.3000 0.009 0.003 0.001 0.000 0.4000 0.009 0.004 0.002 0.000 0.5000 0.009 0.005 0.002 0.000 0.6000 0.009 0.006 0.002 0.000 0.7000 0.009 0.007 0.002 0.000 0.8000 0.009 0.007 0.003 0.000 0.9000 0.009 0.008 0.003 0.000 1.0000 0.009 0.009 0.003 0.000 1.1000 0.009 0.010 0.003 0.000 1.2000 0.009 0.011 0.003 0.000 1.3000 0.009 0.012 0.004 0.000 1.4000 0.009 0.013 0.004 0.000 1.5000 0.009 0.014 0.004 0.000 1.6000 0.009 0.015 0.004 0.000 1.7000 0.009 0.016 0.004 0.000 1.8000 0.009 0.017 0.004 0.000 1.9000 0.009 0.018 0.004 0.000 2.0000 0.009 0.019 0.005 0.000 2.1000 0.009 0.020 0.005 0.000 2.2000 0.009 0.021 0.005 0.000 2.3000 0.009 0.022 0.005 0.000 2.4000 0.009 0.023 0.005 0.000 2.5000 0.009 0.024 0.005 0.000 2.6000 0.009 0.025 0.005 0.000 2.7000 0.009 0.026 0.005 0.000 2.8000 0.009 0.027 0.005 0.000 2.9000 0.009 0.028 0.006 0.000 3.0000 0.009 0.029 0.006 0.000 3.1000 0.009 0.030 0.006 0.000 3.2000 0.009 0.031 0.006 0.000 3.3000 0.009 0.032 0.006 0.000 3.4000 0.009 0.033 0.006 0.000 3.5000 0.009 0.034 0.006 0.000 3.6000 0.009 0.035 0.006 0.000 3.7000 0.009 0.036 0.006 0.000 Detention Volume Required = 3,659 CF Detention Vault 8/3/2023 8:56:30 AM Page 7 3.8000 0.009 0.037 0.006 0.000 3.9000 0.009 0.038 0.006 0.000 4.0000 0.009 0.039 0.007 0.000 4.1000 0.009 0.040 0.007 0.000 4.2000 0.009 0.041 0.008 0.000 4.3000 0.009 0.042 0.009 0.000 4.4000 0.009 0.043 0.009 0.000 4.5000 0.009 0.044 0.010 0.000 4.6000 0.009 0.045 0.010 0.000 4.7000 0.009 0.046 0.011 0.000 4.8000 0.009 0.047 0.011 0.000 4.9000 0.009 0.048 0.011 0.000 5.0000 0.009 0.049 0.012 0.000 5.1000 0.009 0.050 0.012 0.000 5.2000 0.009 0.051 0.012 0.000 5.3000 0.009 0.052 0.012 0.000 5.4000 0.009 0.053 0.013 0.000 5.5000 0.009 0.054 0.013 0.000 5.6000 0.009 0.055 0.013 0.000 5.7000 0.009 0.056 0.013 0.000 5.8000 0.009 0.057 0.014 0.000 5.9000 0.009 0.058 0.014 0.000 6.0000 0.009 0.059 0.014 0.000 6.1000 0.009 0.060 0.014 0.000 6.2000 0.009 0.061 0.015 0.000 6.3000 0.009 0.062 0.016 0.000 6.4000 0.009 0.063 0.017 0.000 6.5000 0.009 0.064 0.018 0.000 6.6000 0.009 0.065 0.019 0.000 6.7000 0.009 0.066 0.019 0.000 6.8000 0.009 0.067 0.020 0.000 6.9000 0.009 0.068 0.020 0.000 7.0000 0.009 0.069 0.021 0.000 7.1000 0.009 0.070 0.021 0.000 7.2000 0.009 0.071 0.022 0.000 7.3000 0.009 0.072 0.022 0.000 7.4000 0.009 0.073 0.023 0.000 7.5000 0.009 0.074 0.023 0.000 7.6000 0.009 0.075 0.023 0.000 7.7000 0.009 0.076 0.024 0.000 7.8000 0.009 0.077 0.024 0.000 7.9000 0.009 0.078 0.024 0.000 8.0000 0.009 0.079 0.025 0.000 8.1000 0.009 0.080 0.025 0.000 8.2000 0.009 0.081 0.026 0.000 8.3000 0.009 0.082 0.026 0.000 8.4000 0.009 0.083 0.026 0.000 8.5000 0.009 0.084 0.027 0.000 8.6000 0.009 0.085 0.529 0.000 8.7000 0.009 0.086 1.432 0.000 8.8000 0.009 0.087 2.529 0.000 8.9000 0.009 0.088 3.660 0.000 9.0000 0.009 0.089 4.667 0.000 9.1000 0.009 0.090 5.430 0.000 9.2000 0.000 0.000 5.921 0.000 Detention Vault 8/3/2023 8:56:30 AM Page 8 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.31 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.1 Total Impervious Area:0.21 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.013872 5 year 0.022097 10 year 0.027437 25 year 0.033895 50 year 0.038456 100 year 0.042794 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.009174 5 year 0.014728 10 year 0.01956 25 year 0.027239 50 year 0.034282 100 year 0.042627 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.016 0.006 1950 0.017 0.010 1951 0.027 0.023 1952 0.010 0.005 1953 0.008 0.006 1954 0.011 0.009 1955 0.020 0.010 1956 0.015 0.012 1957 0.014 0.007 1958 0.013 0.009 Detention Vault 8/3/2023 8:56:51 AM Page 9 1959 0.011 0.006 1960 0.020 0.021 1961 0.011 0.007 1962 0.008 0.005 1963 0.010 0.007 1964 0.013 0.007 1965 0.010 0.010 1966 0.009 0.006 1967 0.020 0.010 1968 0.011 0.007 1969 0.012 0.006 1970 0.011 0.007 1971 0.011 0.010 1972 0.022 0.014 1973 0.011 0.008 1974 0.011 0.009 1975 0.017 0.009 1976 0.011 0.009 1977 0.002 0.006 1978 0.011 0.007 1979 0.006 0.005 1980 0.025 0.014 1981 0.008 0.006 1982 0.021 0.018 1983 0.014 0.010 1984 0.010 0.006 1985 0.006 0.006 1986 0.024 0.014 1987 0.021 0.019 1988 0.009 0.006 1989 0.006 0.006 1990 0.046 0.021 1991 0.027 0.021 1992 0.012 0.007 1993 0.011 0.006 1994 0.004 0.005 1995 0.013 0.011 1996 0.030 0.023 1997 0.027 0.020 1998 0.009 0.006 1999 0.024 0.015 2000 0.011 0.010 2001 0.003 0.005 2002 0.013 0.015 2003 0.017 0.006 2004 0.025 0.025 2005 0.016 0.010 2006 0.016 0.009 2007 0.035 0.061 2008 0.046 0.026 2009 0.021 0.014 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0459 0.0605 2 0.0458 0.0260 3 0.0346 0.0255 Detention Vault 8/3/2023 8:56:51 AM Page 10 4 0.0305 0.0231 5 0.0271 0.0229 6 0.0271 0.0212 7 0.0266 0.0209 8 0.0255 0.0209 9 0.0251 0.0199 10 0.0244 0.0189 11 0.0240 0.0176 12 0.0217 0.0150 13 0.0214 0.0147 14 0.0211 0.0144 15 0.0208 0.0142 16 0.0204 0.0139 17 0.0200 0.0136 18 0.0199 0.0117 19 0.0171 0.0110 20 0.0171 0.0105 21 0.0167 0.0104 22 0.0161 0.0104 23 0.0160 0.0100 24 0.0156 0.0100 25 0.0150 0.0100 26 0.0143 0.0099 27 0.0142 0.0098 28 0.0134 0.0094 29 0.0133 0.0093 30 0.0131 0.0090 31 0.0126 0.0090 32 0.0121 0.0086 33 0.0115 0.0085 34 0.0115 0.0080 35 0.0115 0.0075 36 0.0114 0.0073 37 0.0110 0.0071 38 0.0110 0.0071 39 0.0109 0.0070 40 0.0109 0.0066 41 0.0108 0.0065 42 0.0108 0.0065 43 0.0107 0.0065 44 0.0107 0.0065 45 0.0107 0.0065 46 0.0101 0.0064 47 0.0101 0.0064 48 0.0099 0.0064 49 0.0096 0.0063 50 0.0092 0.0063 51 0.0087 0.0063 52 0.0086 0.0062 53 0.0083 0.0061 54 0.0078 0.0060 55 0.0077 0.0059 56 0.0056 0.0059 57 0.0055 0.0055 58 0.0055 0.0053 59 0.0037 0.0053 60 0.0026 0.0052 61 0.0020 0.0050 Detention Vault 8/3/2023 8:56:51 AM Page 12 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0069 11407 9824 86 Pass 0.0073 10365 7253 69 Pass 0.0076 9439 6992 74 Pass 0.0079 8628 6752 78 Pass 0.0082 7940 6543 82 Pass 0.0085 7274 6325 86 Pass 0.0088 6669 6019 90 Pass 0.0092 6098 5709 93 Pass 0.0095 5608 5324 94 Pass 0.0098 5150 4969 96 Pass 0.0101 4778 4603 96 Pass 0.0104 4417 4250 96 Pass 0.0108 4081 3948 96 Pass 0.0111 3773 3700 98 Pass 0.0114 3546 3480 98 Pass 0.0117 3287 3240 98 Pass 0.0120 3067 2988 97 Pass 0.0123 2866 2706 94 Pass 0.0127 2669 2502 93 Pass 0.0130 2481 2299 92 Pass 0.0133 2306 2085 90 Pass 0.0136 2158 1875 86 Pass 0.0139 1970 1651 83 Pass 0.0143 1830 1436 78 Pass 0.0146 1686 1210 71 Pass 0.0149 1573 991 63 Pass 0.0152 1460 906 62 Pass 0.0155 1362 887 65 Pass 0.0159 1268 872 68 Pass 0.0162 1175 851 72 Pass 0.0165 1103 837 75 Pass 0.0168 1030 812 78 Pass 0.0171 962 785 81 Pass 0.0174 905 752 83 Pass 0.0178 849 708 83 Pass 0.0181 803 673 83 Pass 0.0184 750 636 84 Pass 0.0187 715 595 83 Pass 0.0190 680 561 82 Pass 0.0194 638 530 83 Pass 0.0197 605 494 81 Pass 0.0200 572 461 80 Pass 0.0203 544 424 77 Pass 0.0206 504 380 75 Pass 0.0209 469 334 71 Pass 0.0213 435 305 70 Pass 0.0216 391 285 72 Pass 0.0219 351 266 75 Pass 0.0222 321 243 75 Pass 0.0225 293 222 75 Pass 0.0229 264 195 73 Pass 0.0232 230 164 71 Pass 0.0235 203 151 74 Pass Detention Vault 8/3/2023 8:56:51 AM Page 13 0.0238 177 135 76 Pass 0.0241 161 122 75 Pass 0.0244 142 111 78 Pass 0.0248 130 98 75 Pass 0.0251 116 86 74 Pass 0.0254 103 63 61 Pass 0.0257 95 49 51 Pass 0.0260 79 31 39 Pass 0.0264 71 23 32 Pass 0.0267 58 17 29 Pass 0.0270 49 5 10 Pass 0.0273 46 5 10 Pass 0.0276 44 5 11 Pass 0.0279 43 5 11 Pass 0.0283 42 5 11 Pass 0.0286 41 5 12 Pass 0.0289 40 5 12 Pass 0.0292 39 5 12 Pass 0.0295 36 5 13 Pass 0.0299 34 5 14 Pass 0.0302 34 5 14 Pass 0.0305 31 5 16 Pass 0.0308 28 5 17 Pass 0.0311 26 5 19 Pass 0.0315 25 5 20 Pass 0.0318 22 5 22 Pass 0.0321 20 5 25 Pass 0.0324 18 5 27 Pass 0.0327 14 5 35 Pass 0.0330 13 5 38 Pass 0.0334 11 5 45 Pass 0.0337 10 5 50 Pass 0.0340 10 5 50 Pass 0.0343 8 5 62 Pass 0.0346 6 5 83 Pass 0.0350 4 3 75 Pass 0.0353 4 3 75 Pass 0.0356 4 3 75 Pass 0.0359 3 3 100 Pass 0.0362 3 3 100 Pass 0.0365 3 3 100 Pass 0.0369 3 3 100 Pass 0.0372 3 3 100 Pass 0.0375 3 3 100 Pass 0.0378 3 3 100 Pass 0.0381 3 3 100 Pass 0.0385 3 3 100 Pass Detention Vault 8/3/2023 8:56:51 AM Page 14 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.0305 acre-feet On-line facility target flow:0.0377 cfs. Adjusted for 15 min:0.0377 cfs. Off-line facility target flow:0.0211 cfs. Adjusted for 15 min:0.0211 cfs. Detention Vault 8/3/2023 8:56:57 AM Page 16 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Detention Vault 8/3/2023 8:56:57 AM Page 17 Appendix Predeveloped Schematic Detention Vault 8/3/2023 8:56:58 AM Page 18 Mitigated Schematic Detention Vault 8/3/2023 8:56:58 AM Page 19 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Detention Vault.wdm MESSU 25 PreDetention Vault.MES 27 PreDetention Vault.L61 28 PreDetention Vault.L62 30 POCDetention Vault1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 12 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 12 C, Forest, Steep 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 12 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 12 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO Detention Vault 8/3/2023 8:56:58 AM Page 20 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 12 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 12 0 4.5 0.08 400 0.15 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 12 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 12 0.2 0.3 0.35 6 0.3 0.7 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 12 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATE1 Detention Vault 8/3/2023 8:56:58 AM Page 21 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 12 0.31 COPY 501 12 PERLND 12 0.31 COPY 501 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC Detention Vault 8/3/2023 8:56:58 AM Page 22 WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN Detention Vault 8/3/2023 8:56:58 AM Page 23 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Detention Vault.wdm MESSU 25 MitDetention Vault.MES 27 MitDetention Vault.L61 28 MitDetention Vault.L62 30 POCDetention Vault1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 18 IMPLND 3 IMPLND 4 RCHRES 1 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Vault 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 18 C, Lawn, Steep 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 18 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR Detention Vault 8/3/2023 8:56:58 AM Page 24 # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 18 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 18 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 18 0 4.5 0.03 400 0.15 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 18 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 18 0.1 0.15 0.25 6 0.3 0.25 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 18 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 3 ROADS/STEEP 1 1 1 27 0 4 ROOF TOPS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 3 0 0 1 0 0 0 4 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 3 0 0 4 0 0 4 1 9 4 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 3 0 0 0 0 0 4 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC Detention Vault 8/3/2023 8:56:58 AM Page 25 3 400 0.1 0.1 0.05 4 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 3 0 0 4 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 3 0 0 4 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 18 0.1 RCHRES 1 2 PERLND 18 0.1 RCHRES 1 3 IMPLND 3 0.15 RCHRES 1 5 IMPLND 4 0.06 RCHRES 1 5 ******Routing****** PERLND 18 0.1 COPY 1 12 IMPLND 3 0.15 COPY 1 15 IMPLND 4 0.06 COPY 1 15 PERLND 18 0.1 COPY 1 13 RCHRES 1 1 COPY 501 16 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** 1 Vault 1 1 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 Detention Vault 8/3/2023 8:56:58 AM Page 26 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 0 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.01 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 92 4 Depth Area Volume Outflow1 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (ft/sec) (Minutes)*** 0.000000 0.009931 0.000000 0.000000 0.100000 0.009931 0.000993 0.001112 0.200000 0.009931 0.001986 0.001573 0.300000 0.009931 0.002979 0.001926 0.400000 0.009931 0.003972 0.002224 0.500000 0.009931 0.004966 0.002487 0.600000 0.009931 0.005959 0.002724 0.700000 0.009931 0.006952 0.002942 0.800000 0.009931 0.007945 0.003146 0.900000 0.009931 0.008938 0.003336 1.000000 0.009931 0.009931 0.003517 1.100000 0.009931 0.010924 0.003689 1.200000 0.009931 0.011917 0.003853 1.300000 0.009931 0.012910 0.004010 1.400000 0.009931 0.013904 0.004161 1.500000 0.009931 0.014897 0.004307 1.600000 0.009931 0.015890 0.004449 1.700000 0.009931 0.016883 0.004586 1.800000 0.009931 0.017876 0.004718 1.900000 0.009931 0.018869 0.004848 2.000000 0.009931 0.019862 0.004974 2.100000 0.009931 0.020855 0.005097 2.200000 0.009931 0.021848 0.005216 2.300000 0.009931 0.022842 0.005334 2.400000 0.009931 0.023835 0.005448 2.500000 0.009931 0.024828 0.005561 2.600000 0.009931 0.025821 0.005671 2.700000 0.009931 0.026814 0.005779 2.800000 0.009931 0.027807 0.005885 2.900000 0.009931 0.028800 0.005989 3.000000 0.009931 0.029793 0.006092 3.100000 0.009931 0.030787 0.006192 3.200000 0.009931 0.031780 0.006291 3.300000 0.009931 0.032773 0.006389 3.400000 0.009931 0.033766 0.006485 3.500000 0.009931 0.034759 0.006580 3.600000 0.009931 0.035752 0.006673 3.700000 0.009931 0.036745 0.006765 3.800000 0.009931 0.037738 0.006856 3.900000 0.009931 0.038731 0.006945 4.000000 0.009931 0.039725 0.007034 4.100000 0.009931 0.040718 0.007121 Detention Vault 8/3/2023 8:56:58 AM Page 27 4.200000 0.009931 0.041711 0.008581 4.300000 0.009931 0.042704 0.009235 4.400000 0.009931 0.043697 0.009755 4.500000 0.009931 0.044690 0.010207 4.600000 0.009931 0.045683 0.010613 4.700000 0.009931 0.046676 0.010988 4.800000 0.009931 0.047669 0.011338 4.900000 0.009931 0.048663 0.011669 5.000000 0.009931 0.049656 0.011983 5.100000 0.009931 0.050649 0.012284 5.200000 0.009931 0.051642 0.012574 5.300000 0.009931 0.052635 0.012853 5.400000 0.009931 0.053628 0.013123 5.500000 0.009931 0.054621 0.013385 5.600000 0.009931 0.055614 0.013640 5.700000 0.009931 0.056607 0.013889 5.800000 0.009931 0.057601 0.014131 5.900000 0.009931 0.058594 0.014368 6.000000 0.009931 0.059587 0.014600 6.100000 0.009931 0.060580 0.014827 6.200000 0.009931 0.061573 0.015049 6.300000 0.009931 0.062566 0.016854 6.400000 0.009931 0.063559 0.017726 6.500000 0.009931 0.064552 0.018441 6.600000 0.009931 0.065545 0.019074 6.700000 0.009931 0.066539 0.019652 6.800000 0.009931 0.067532 0.020192 6.900000 0.009931 0.068525 0.020702 7.000000 0.009931 0.069518 0.021187 7.100000 0.009931 0.070511 0.021652 7.200000 0.009931 0.071504 0.022099 7.300000 0.009931 0.072497 0.022532 7.400000 0.009931 0.073490 0.022951 7.500000 0.009931 0.074483 0.023358 7.600000 0.009931 0.075477 0.023755 7.700000 0.009931 0.076470 0.024143 7.800000 0.009931 0.077463 0.024521 7.900000 0.009931 0.078456 0.024891 8.000000 0.009931 0.079449 0.025254 8.100000 0.009931 0.080442 0.025609 8.200000 0.009931 0.081435 0.025959 8.300000 0.009931 0.082428 0.026302 8.400000 0.009931 0.083421 0.026639 8.500000 0.009931 0.084415 0.026971 8.600000 0.009931 0.085408 0.529475 8.700000 0.009931 0.086401 1.432083 8.800000 0.009931 0.087394 2.529198 8.900000 0.009931 0.088387 3.660450 9.000000 0.009931 0.089380 4.667650 9.100000 0.009931 0.090373 5.430083 END FTABLE 1 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1001 STAG ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL Detention Vault 8/3/2023 8:56:58 AM Page 28 END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 16 RCHRES ROFLOW COPY INPUT MEAN END MASS-LINK 16 END MASS-LINK END RUN Detention Vault 8/3/2023 8:56:58 AM Page 31 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2023; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com CHECKED BY:-REVISIONSNO.DESCRIPTIONDATEBY---ABCDRAWN BY:EMAIL:7/7/20231230804CWEST SALES OFFICE825 W BEECHCRAFT ST.CASA GRANDE, AZ 85122Tel. (888) 490-9552Fax (520) 421-9899EAST SALES OFFICE9470 PINECONE DRIVEMENTOR, OH 44060Tel. (800) 543-4764Fax (440) 639-7235www.acousa.comSHEET NO.DATEDESIGN SERV. NO.SYSTEMLAYER(S)REV.SHEET OFACO, INC.SOUTHEAST SALES OFFICE4211 PLEASANT RD.FORT MILL, SC 29708Tel. (800)-543-4764Fax (803)-802-1063DRAWN BYEMAILCHECKED BYAAAaron.Adrovet@aco.comPENWELL RESIDENCEFEDERAL WAY, WANOTESSD312APPROVEDAPPROVED AS NOTEDREVISE AND RESUBMITREJECTEDSIGNED:DATE:COMMENTS:APPROVEDAPPROVED AS NOTEDALL DRAWINGS ARE AS ACCURATE AS THE INFORMATIONSUPPLIED. ALL REASONABLE CARE HAS BEEN TAKEN INCOMPILING THE INFORMATION WITHIN. PLEASE REVIEW THISINFORMATION FOR ACCURACY.GENERAL NOTES1.IT IS CUSTOMERS RESPONSIBILITY TO ENSURE THAT EACH PRODUCT IS FIT FOR ITS INTENDED PURPOSE AND THAT THE ACTUALCONDITIONS ARE SUITABLE.2.IT IS THE CUSTOMERS RESPONSIBILITY TO FOLLOW ACO, INC. INSTALLATION INSTRUCTIONS FOR EACH PRODUCT. SEEK ENGINEERINGADVICE FOR INSTALLATIONS NOT ILLUSTRATED IN THE INSTALLATION GUIDELINES.3.FOR FURTHER PRODUCT INFORMATION, CUT SHEETS, SPECIFICATIONS AND INSTALLATION INSTRUCTIONS, PLEASE VISIT US AT OURWEBSITE: ACOSTORMBRIXX.USSTORMBRIXX NOTES1.ALL FABRICATIONS TO BE COMPLETED BY INSTALLING CONTRACTOR. HE/SHE TO VERIFY THE ENTIRE SCOPE OF STORMBRIXX SD HAS BEENPROVIDED FOR THIS PROJECT.2.DIMENSIONS ARE FROM OUTSIDE TO OUTSIDE.3.LAYOUT IS BASED ON CORRESPONDENCE WITH BARGHAUSEN CONSULTING ENGINEERS, INC. PROVIDED TO THE ACO, INC. TECHNICALSERVICES DEPARTMENT.4.THIS PLAN VIEW REPRESENT ONE OF SIX STORMBRIXX SD HALF LAYER ORIENTATIONS REQUIRED FOR THIS TANK. FOR COMPLETE, BRICK -BONDABLE INSTALLATION DRAWINGS, PLEASE REQUEST THIS SERVICE FROM THE ACO, INC. SALES DEPARTMENT.5.THE NUMBER OF ACCESS/INSPECTION LOCATIONS DISPLAYED ARE RECOMMENDATIONS, AND MORE/LESS CAN BE ADDED WITH EASE VIAREVISION.6.ACCESS UNITS OCCUPY A PROFILE EQUIVALENT TO HALF OF ON HALF MODULE AND ALLOW FOR DIRECT ACCESS TO UP 15" PIPECONNECTIONS.7.ACCESS PLATES OCCUPY THE EQUIVALENT PROFILE OF HALF OF ONE HALF MODULE AND MUST BE SURROUNDED BY BRICK BONDEDMODULES. ACCESS PLATES CAN BE PLACED ANYWHERE BESIDES THE EDGE OF THE SYSTEM.8.HOLDING CAPACITY OF ONE FULLY ASSEMBLED STORMBRIXX SD MODULE = 22.54 CFINSTALLATION NOTES1.ALL FABRICATIONS TO BE COMPLETED BY INSTALLINGCONTRACTOR.2.EXCAVATE AWAY FROM TANK'S PROFILE PER OSHASTANDARDS.3.UP TO 18" PIPE CONNECTIONS CAN BE CORED DIRECTLYINTO STORMBRIXX SD SIDE PANELS.4.USE LAYER CONNECTORS TO RESTRICT SHEARINGMOVEMENT BETWEEN BRICK-BONDED LAYERS/HALFLAYERS.5.USE LAYER CONNECTORS TO ADHERE ACCESS UNITS TOBRICK-BONDED HALF MODULES.6.A VOID AREA EQUIVALENT TO HALF OF ONE HALF MODULEIS PRESENT UNDER EACH ACCESS PLATE.7.IRREGULAR TANKS - TRIM SIDE PANELS A CORNERJUNCTIONS FOR EXACT FIT.ALWAYS ARRANGE THE SAME4 PILLARS IN A SQUARESHEET INDEX1SHEET NO.DESCRIPTIONNOTES2STORMBRIXX PLAN VIEWFigure 4.4.2 ACO STORMBRIXX SD TANKTANK STRUCTURAL VOLUME 4,043 FT³TOTAL HOLDING VOLUME 3,922 FT³LIVE STORAGE VOLUME (8.5 FT) 3,704 FT³NUMBER OF LAYERS = 3 (9 FT)INLET PIPECONNECTIONOUTLET PIPECONNECTION21'-7 7/8" [6.60m]23'-7 1/2" [7.20m]ACO STORMBRIXX SD HALF MODULEPT# 314090TWO ACO STORMBRIXX SD TOP COVERS PERHALF MODULE PT# 314092STORMBRIXX SD ACCESS PLATE PT# 314075,EXTENSION SHAFTS PT# 314038,AND DUCTILE IRON COVER PT# 314043.PERIMETER OF STORMBRIXX SD SIDE PANELS; PT# 314091.IMPERMEABLE GEOMEMBRANE AND GEOTEXTILE FABRICAROUND ENTIRE SURFACE AREA OF TANK.CHECKED BY:-REVISIONSNO.DESCRIPTIONDATEBY---ABCDRAWN BY:EMAIL:7/7/20231230804CWEST SALES OFFICE825 W BEECHCRAFT ST.CASA GRANDE, AZ 85122Tel. (888) 490-9552Fax (520) 421-9899EAST SALES OFFICE9470 PINECONE DRIVEMENTOR, OH 44060Tel. (800) 543-4764Fax (440) 639-7235www.acousa.comSHEET NO.DATEDESIGN SERV. NO.SYSTEMLAYER(S)REV.SHEET OFACO, INC.SOUTHEAST SALES OFFICE4211 PLEASANT RD.FORT MILL, SC 29708Tel. (800)-543-4764Fax (803)-802-1063DRAWN BYEMAILCHECKED BYAAAaron.Adrovet@aco.comPENWELL RESIDENCEFEDERAL WAY, WASTORMBRIXX PLAN VIEWSD322 *All systems must be designed and installed to meet orexceed ACO StormBrixx minimum requirements. AlthoughACO StormBrixx offers support during the design, review,and construction phases of the module system, it is theultimate responsibility of the Engineer of Record to designthe system in full compliance with all applicableengineering practices, laws, and regulations.48" [1200mm]36" [914mm]24" [602.5mm]ACO StormBrixx SD Module48"x24"x36" [1200x602.5x914mm (H)]22.54cuft net volume per completed moduleBrick or Cross Bonded (where applicable)part# 314090Installation depths of ACO StormBrixx SDInstallation LocationMinimumcover depth(4) ft (m)Non-trafficked areas i.e. landscaping (2)1.65 (0.5)Parking lots, vehicles up to 5,512lbs gross mass (1)1.8 (0.55)Parking lots, occasional vehicles greater than5,512lbs gross mass (3)2.0 (0.6)Occasional heavy truck traffic up to HS-20loadingPlease consultwith ACO (1) Assumes 27 degree load distribution through fill materialand overlaying surface asphalt or block paving (2) Minimum cover depth to avoid accidental damage fromgardening/landscaping work (3) Occasional sanitation trucks or similar vehicles (typicallyone per week) (4) Please check minimum frost cover depths and water tableheights for geographical locationMaximum depth to invert of ACO StormBrixx SDthree layer system14.77 (4.5)NotesMaximum cover depth of ACO StormBrixx SD6.5 (2)GLSECTION PROFILEFinished road surface; bitumen,concrete, etc. (Surface anddepth to suit engineer's spec)6" [150mm] minimum of nativebackfill, 3/4" crushed stone, orpea gravel at 95% compactionStormbrixx Side Panel; part# 314091(typ. for all exterior sides)6" [150mm] minimum of nativebackfill, 3/4" crushed stone, orpea gravel at 95% compactionUndisturbed earth base of excavationor made ground with a minimum CBRof 5% and suitable for anticipated loadImpermeable Geomembrane (inner) 30milminimum/Geotextile fabric (outer) 6ozminimum around entire perimeter of tankConcrete load distributionplate (by others)Detention Outlet(location based on usage)Detention Inlet(location based on usage)12" (300mm) minimum of nativebackfill, 3/4" crushed stone, orpea gravel at 95% compactionSD Access Plate part#314075Extension Shaft part#314038Sub baseCover Depth(Refer to chart)108" (2,743mm)Vented cover and framepart#314053 or optional solidcover and frame part#314056PLANLength to SuitWidth to SuitDetention InletDetention OutletBrick-bonded modulesStormBrixx SD Top Cover part# 314092(typ. for top layer only)DETENTION - STORMBRIXX SD THREE LAYERS WITH ACCESS PLATESD-SD-3L-DVTDATE:07/31/20199470 Pinecone DriveMentor, OH 44060Tel: 440-639-7230Fax: 440-639-7235ACO, Inc.INSTALLATION DRAWING - ACO STORMBRIXX SD825 W. Beechcraft StCasa Grande, AZ 85122Tel: 520-421-9988Fax: 520-421-9899Arizona Tel: 888-490-9552 e-mail: info@acousa.com Ohio Tel: 800-543-4764 South Carolina Tel: 800-543-47644211 Pleasant Rd.Fort Mill, SC 29708Tel: 440-639-7230Fax: 803-802-1063ISSUE: DWWW.ACOSTORMBRIXX.US 7708.016-TIR FINL 4.5 Water Quality System This project is required to provide Enhanced Basic Water Quality as outlined by the City of Federal Way Water Quality Applications Map. Enhanced Water Quality Treatment will be provided by a Contech Modular Wetland System located upstream of the Stormbrixx detention system. The off- line water quality flow rate for this system is 0.021 cfs and was obtained by modeling the Developed Basin in the WWHM program. Any flows exceeding the water quality flow rate will be bypassed by an internal bypass unit within the Modular Wetland System up to the 100-year developed peak flow. For further detail on the WWHM water quality calculations please refer to Figure 4.4.1. Pre- settling prior to the Modular Wetland System will be provided by a Contech CDS Unit. Please refer to Figures 4.5.1 and 4.5.2 included in this section for details on the Modular Wetland System and CDS unit. Both units have GULD approval from the Washington State Department of Ecology. The GULD approval documents for both units are included as Figure 4.5.3 of this section. PLAN VIEW ELEVATION VIEW RIGHT END VIEW STANDARD DETAIL STORMWATER BIOFILTRATION SYSTEM MWS-L-4-4-V-UG FOR PATENT INFORMATION, GO TO www.ContechES.com/IP LEFT END VIEW INSTALLATION NOTES SITE SPECIFIC DATA Penwell Property Federal Way, WA MWS 0.021 2.0 ≤2.1 ≤1.0 0.23 154.10 CPEP 12" 153.60 CPEP 12" 158.58 158.58 158.58 Figure 4.5.1 CB#20.021-12"CPEP155.10155.10CPEP12"100 yr0.23158.66Figure 4.5.2 November 2022 GENERAL USE LEVEL DESIGNATION FOR BASIC (TSS) ENHANCED AND PHOSPHORUS TREATMENT For Contech Engineered Solutions, LLC (Contech) Modular Wetlands Linear Ecology’s Decision Based on Modular Wetland Systems, Inc, application submissions, including the Technical Evaluation Report, dated April 1, 2014, Ecology hereby issues the following use level designation: 1. General Use Level Designation (GULD) for the Modular Wetlands Linear Stormwater Treatment System for Basic, Phosphorus, and Enhanced treatment • Sized at a hydraulic loading rate of: • 1 gallon per minute (gpm) per square foot (sq ft) of Wetland Cell Surface Area • Prefilter box (approved at either 22 inches or 33 inches tall) • 3.0 gpm/sq ft of prefilter box surface area for moderate pollutant loading rates (low to medium density residential basins). • 2.1 gpm/sq ft of prefilter box surface area for high pollutant loading rates (commercial and industrial basins). 2. Ecology approves the Modular Wetlands Linear Stormwater Treatment System units for Basic, Phosphorus, and Enhanced treatment at the hydraulic loading rate listed above. Designers shall calculate the water quality design flow rates using the following procedures: • Western Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute water quality treatment design flow rate as calculated using the latest version of the Western Washington Hydrology Model or other Ecology- approved continuous runoff model. Figure 4.5.3 • Eastern Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute water quality treatment design flow rate as calculated using one of the three methods described in Chapter 2.7.6 of the Stormwater Management Manual for Eastern Washington (SWMMEW) or local manual. • Entire State: For treatment installed downstream of detention, the water quality treatment design flow rate is the full 2-year release rate of the detention facility. 3. These use level designations have no expiration date but may be amended or revoked by Ecology, and are subject to the conditions specified below. Ecology’s Conditions of Use Applicants shall comply with the following conditions: 1) Design, assemble, install, operate, and maintain the Modular Wetlands Linear Stormwater Treatment System units, in accordance with Contech’s. applicable manuals and documents and the Ecology Decision. 2) Each site plan must undergo Contech review and approval before site installation. This ensures that site grading and slope are appropriate for use of a Modular Wetlands Linear Stormwater Treatment System unit. 3) Modular Wetlands Linear Stormwater Treatment System media shall conform to the specifications submitted to and approved by Ecology. 4) The applicant tested the Modular Wetlands Linear Stormwater Treatment System with an external bypass weir. This weir limited the depth of water flowing through the media, and therefore the active treatment area, to below the root zone of the plants. This GULD applies to Modular Wetlands Linear Stormwater Treatment Systems whether plants are included in the final product or not. 5) Maintenance: The required maintenance interval for stormwater treatment devices is often dependent upon the degree of pollutant loading from a particular drainage basin. Therefore, Ecology does not endorse or recommend a “one size fits all” maintenance cycle for a particular model/size of stormwater treatment technology. • Typically, Contech designs Modular Wetland systems for a target prefilter media life of 6 to 12 months. • Indications of the need for maintenance include effluent flow decreasing to below the design flow rate or decrease in treatment below required levels. • Owners/operators must inspect Modular Wetland systems for a minimum of twelve months from the start of post-construction operation to determine site-specific maintenance schedules and requirements. You must conduct inspections monthly during the wet season, and every other month during the dry season (According to the SWMMWW, the wet season in western Washington is October 1 to April 30. According to the SWMMEW, the wet season in eastern Washington is October 1 to June 30). After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections. • Conduct inspections by qualified personnel, follow manufacturer’s guidelines, and use methods capable of determining either a decrease in treated effluent flowrate and/or a decrease in pollutant removal ability. • When inspections are performed, the following findings typically serve as maintenance triggers: • Standing water remains in the vault between rain events, or • Bypass occurs during storms smaller than the design storm. • If excessive floatables (trash and debris) are present (but no standing water or excessive sedimentation), perform a minor maintenance consisting of gross solids removal, not prefilter media replacement. • Additional data collection will be used to create a correlation between pretreatment chamber sediment depth and pre-filter clogging (see Issues to be Addressed by the Company section below) 6) Discharges from the Modular Wetlands Linear Stormwater Treatment System units shall not cause or contribute to water quality standards violations in receiving waters. Applicant: Contech Engineered Solutions, LLC Applicant’s Address: 11815 NE Glenn Widing Dr. Portland, OR 97220 Application Documents: Original Application for Conditional Use Level Designation, Modular Wetland System, Linear Stormwater Filtration System Modular Wetland Systems, Inc., January 2011 Quality Assurance Project Plan: Modular Wetland System – Linear Treatment System Performance Monitoring Project, draft, January 2011 Revised Application for Conditional Use Level Designation, Modular Wetland System, Linear Stormwater Filtration System Modular Wetland Systems, Inc., May 2011 Memorandum: Modular Wetland System-Linear GULD Application Supplementary Data, April 2014 Technical Evaluation Report: Modular Wetland System Stormwater Treatment System Performance Monitoring, April 2014 Applicant’s Use Level Request: • General Use Level Designation as a Basic, Enhanced, and Phosphorus treatment device in accordance with Ecology’s Guidance for Evaluating Emerging Stormwater Treatment Technologies Technology Assessment Protocol – Ecology (TAPE) January 2011 Revision. Applicant’s Performance Claims: • The Modular Wetlands Linear is capable of removing a minimum of 80-percent of TSS from stormwater with influent concentrations between 100 and 200 mg/L. • The Modular Wetlands Linear is capable of removing a minimum of 50-percent of total phosphorus from stormwater with influent concentrations between 0.1 and 0.5 mg/L. • The Modular Wetlands Linear is capable of removing a minimum 30-percent of dissolved copper from stormwater with influent concentrations between 0.005 and 0.020 mg/L. • The Modular Wetlands Linear is capable of removing a minimum 60-percent of dissolved zinc from stormwater with influent concentrations between 0.02 and 0.30 mg/L. Ecology’s Recommendations: • Contech has shown Ecology, through laboratory and field-testing, that the Modular Wetlands Linear Stormwater Treatment System filter system is capable of attaining Ecology’s Basic, Phosphorus, and Enhanced treatment goals. Findings of Fact: Laboratory Testing The Modular Wetlands Linear Stormwater Treatment System has the: • Capability to remove 99 percent of total suspended solids (using Sil-Co-Sil 106) in a quarter-scale model with influent concentrations of 270 mg/L. • Capability to remove 91 percent of total suspended solids (using Sil-Co-Sil 106) in laboratory conditions with influent concentrations of 84.6 mg/L at a flow rate of 3.0 gpm per square foot of media. • Capability to remove 93 percent of dissolved Copper in a quarter-scale model with influent concentrations of 0.757 mg/L. • Capability to remove 79 percent of dissolved Copper in laboratory conditions with influent concentrations of 0.567 mg/L at a flow rate of 3.0 gpm per square foot of media. • Capability to remove 80.5-percent of dissolved Zinc in a quarter-scale model with influent concentrations of 0.95 mg/L at a flow rate of 3.0 gpm per square foot of media. • Capability to remove 78-percent of dissolved Zinc in laboratory conditions with influent concentrations of 0.75 mg/L at a flow rate of 3.0 gpm per square foot of media. Field Testing • Modular Wetland Systems, Inc. conducted monitoring of an MWS-Linear (Model # MWS-L-4-13) from April 2012 through May 2013, at a transportation maintenance facility in Portland, Oregon. The manufacturer collected flow-weighted composite samples of the system’s influent and effluent during 28 separate storm events. The system treated approximately 75 percent of the runoff from 53.5 inches of rainfall during the monitoring period. The applicant sized the system at 1 gpm/sq ft. (wetland media) and 3gpm/sq ft. (prefilter). • Influent TSS concentrations for qualifying sampled storm events ranged from 20 to 339 mg/L. Average TSS removal for influent concentrations greater than 100 mg/L (n=7) averaged 85 percent. For influent concentrations in the range of 20-100 mg/L (n=18), the upper 95 percent confidence interval about the mean effluent concentration was 12.8 mg/L. • Total phosphorus removal for 17 events with influent TP concentrations in the range of 0.1 to 0.5 mg/L averaged 65 percent. A bootstrap estimate of the lower 95 percent confidence limit (LCL95) of the mean total phosphorus reduction was 58 percent. • The lower 95 percent confidence limit of the mean percent removal was 60.5 percent for dissolved zinc for influent concentrations in the range of 0.02 to 0.3 mg/L (n=11). The lower 95 percent confidence limit of the mean percent removal was 32.5 percent for dissolved copper for influent concentrations in the range of 0.005 to 0.02 mg/L (n=14) at flow rates up to 28 gpm (design flow rate 41 gpm). Laboratory test data augmented the data set, showing dissolved copper removal at the design flow rate of 41 gpm (93 percent reduction in influent dissolved copper of 0.757 mg/L). Issues to be addressed by the Company: 1. Contech should collect maintenance and inspection data for the first year on all installations in the Northwest in order to assess standard maintenance requirements for various land uses in the region. Contech should use these data to establish required maintenance cycles. 2. Contech should collect pre-treatment chamber sediment depth data for the first year of operation for all installations in the Northwest. Contech will use these data to create a correlation between sediment depth and pre-filter clogging. Technology Description: Download at https://www.conteches.com/modular-wetlands Contact Information: Applicant: Jeremiah Lehman Contech Engineered Solutions, LLC 11815 NE Glenn Widing Dr. Portland, OR 97220 Jeremiah.Lehman@ContechES.com Applicant website: http://www.conteches.com Ecology web link: http://www.ecy.wa.gov/programs/wg/stormwater/newtech/index.html Ecology: Douglas C. Howie, P.E. Department of Ecology Water Quality Program (360) 870-0983 douglas.howie@ecy.wa.gov Revision History Date Revision June 2011 Original use-level-designation document September 2012 Revised dates for TER and expiration January 2013 Modified Design Storm Description, added Revision Table, added maintenance discussion, modified format in accordance with Ecology standard December 2013 Updated name of Applicant April 2014 Approved GULD designation for Basic, Phosphorus, and Enhanced treatment December 2015 Updated GULD to document the acceptance of MWS – Linear Modular Wetland installations with or without the inclusion of plants July 2017 Revised Manufacturer Contact Information (name, address, and email) December 2019 Revised Manufacturer Contact Address July 2021 Added additional prefilter sized at 33 inches August 2021 Changed “Prefilter” to “Prefilter box” November 2022 Changed Contacts to Contech ES August 2018 GENERAL USE LEVEL DESIGNATION FOR PRETREATMENT (TSS) For CONTECH Engineered Solutions CDS® System Ecology’s Decision: Based on the CONTECH Engineered Solutions (CONTECH) application submissions for the CDS® System, Ecology hereby issues the following use designations for the CDS storm water treatment system: 1. General Use Level Designation (GULD) for pretreatment use, as defined in Ecology’s 2011 Technical Guidance Manual for Evaluating Emerging Stormwater Treatment Technologies Technology Assessment Protocol – Ecology (TAPE) Table 2, (a) ahead of infiltration treatment, or (b) to protect and extend the maintenance cycle of a basic, enhanced, or phosphorus treatment device (e.g., sand or media filter). This GULD applies to 2,400 micron screen CDS® units sized per the table below. 2. The following table shows flowrates associated with various CDS models: CDS Model Water Quality Flow cfs L/s Precast** Inline or Offline CDS 2015-4 0.7 19.8 CDS 2015-5 0.7 19.8 CDS 2020-5 1.1 31.2 CDS2025-5 1.6 45.3 CDS3020-6 2 56.6 CDS3030-6 3 85.0 CDS3035-6 3.8 106.2 CDS4030-8 4.5 127.4 CDS4040-8 6 169.9 CDS4045-8 7.5 212.4 CDS5640-10 9 254.9 CDS5653-10 14 396.5 CDS5668-10 19 538.1 CDS5678-10 25 7.08 Offline Only CDS3030-V 3 85 Precast** CDS4030-7 4.5 127.4 CDS4040-7 6 169.9 CDS4045-7 7.5 212.4 CDS5640-8 9 254.9 CDS5653-8 14 396.5 CDS5668-8 19 538.1 CDS5678-8 25 708 CDS5042 9 254.9 CDS5050 11 311.5 CDS7070 26 736.3 CDS10060 30 849.6 CDS10080 50 1416 CDS100100 64 1812.5 Cast In Place CDS150134-22 148 4191.4 CDS200164-26 270 7646.6 CDS240160-32 300 8496.2 *Specially Designed CDS Units may be approved by Ecology on a on a site-by-site basis. **Contact Contech for updated model numbers if PMIU, PMSU, PSW, PSWC are specified. 3. The water quality design flow rates are calculated using the following procedures:  Western Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using the latest version of the Western Washington Hydrology Model or other Ecology- approved continuous runoff model.  Eastern Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using one of the three methods described in Chapter 2.2.5 of the Stormwater Management Manual for Eastern Washington (SWMMEW) or local manual.  Entire State: For treatment installed downstream of detention, the water quality design flow rate is the full 2-year release rate of the detention facility. 4. The pretreatment GULD has no expiration date; however, Ecology may amend or revoke the designation. 5. All designations are subject to the conditions specified below. 6. Properly designed and operated CDS systems may also have applicability in other situations (example: low-head situations such as bridges or ferry docks), for TSS where, on a case-by-case basis, it is found to be infeasible or impracticable to use any other approved practice. Jurisdictions covered under the Phase I or II municipal stormwater permits should use variance/exception procedures and criteria as required by their NPDES permit. 7. Ecology finds that the CDS, sized according to the table above, could also provide water quality benefits in retrofit situations. Ecology’s Conditions of Use: CDS systems shall comply with these conditions: 1. Design, assemble, install, operate, and maintain CDS Systems in accordance with Contech’s applicable manuals and documents and the Ecology decision and conditions specified herein. Ecology recommends use of the inspection and maintenance schedule included as Attachment 1. 2. Maintenance: The required inspection/maintenance interval for stormwater treatment devices is often dependent upon the efficiency of the device and the degree of pollutant loading from a particular drainage basin. Therefore, Ecology does not endorse or recommend a “one size fits all” maintenance cycle for a particular model/size of manufactured treatment device.  Owners/operators must inspect the CDS™ System for a minimum of twelve months from the start of post-construction operation to determine site-specific maintenance schedules and requirements. You must conduct inspections monthly during the wet season, and every other month during the dry season. (According to SWMMWW, the wet season for western Washington is October 1 to April 30. According to SWMMEW, the wet season in eastern Washington is October 1 to June 30). After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections.  Conduct inspections by qualified personnel, follow manufacturer’s guidelines, and use methods capable of determining either a decrease in treated effluent flow rate and/or a decrease in pollutant removal ability. 3. Discharges from the CDS System shall not cause or contribute to water quality standards violations in receiving waters. Applicant: Contech Engineered Solutions Applicant’s Address: 11835 NE Glen Widing Drive Portland, OR 97220 Application Documents:  Contech Stormwater Solutions Application to: Washington State Department of Ecology Water Quality Program for General Use Level Designation – Pretreatment Applications and Conditional Use Level Designation – Oil Treatment of the Continuous Deflective Separation (CDS™) Technology (June 2007)  Strynchuk, Royal, and England, The Use of a CDS Unit for Sediment Control in Brevard County.  Walker, Allison, Wong, and Wootton, Removal of Suspended Solids and Associated Pollutants by a CDS Gross Pollutant Trap, Cooperative Research Centre for Catchment Hydrology, Report 99/2, February 1999  Allison, Walker, Chiew, O’Neill, McMahon, From Roads to Rivers Gross Pollutant Removal from Urban Waterways, Cooperative Research Centre for Catchment Hydrology, Report 98/6, May 1998 Applicant’s Use Level Request:  General use level designation as a pretreatment device and conditional use level designation as an oil and grease device in accordance with Ecology’s Stormwater Management Manual for Western Washington. Applicant’s Performance Claims: Based on laboratory trials, the CDS™ System will achieve 50% removal of total suspended solids with d50 of 50-μm and 80% removal of total suspended solids with d50 of 125-μm at 100% design flowrate with typical influent concentration of 200-mg/L. Ecology’s Recommendation: Ecology finds that:  The CDS™ system, sized per the table above, should provide, at a minimum, equivalent performance to a presettling basin as defined in the most recent Stormwater Management Manual for Western Washington, Volume V, Chapter 6. Findings of Fact: 1. Laboratory testing was completed on a CDS 2020 unit equipped with 2400-m screen using OK-110 sand (d50 of 106-μm) at flowrates ranging from 100 to 125% of the design flowrate (1.1 cfs) with a target influent of 200 mg/L. Laboratory results for the OK-110 sand showed removal rates from about 65% to 99% removal with 80% removal occurring near 70% of the design flowrate. 2. Laboratory testing was completed on a CDS 2020 unit equipped with 2400-m screen using “UF” sediment (d50 of 20 to 30-μm) at flowrates ranging from 100 to 125% of the design flowrate (1.1 cfs) with a target influent of 200 mg/L. Laboratory results for the “UF” sediment showed removal rates from about 42% to 94% removal with 80% removal occurring at 5% of the design flowrate. 3. Laboratory testing was completed on a CDS 2020 unit equipped with 4700-m screen using OK-110 sand (d50 of 106-μm) at flowrates ranging from 100 to 125% of the design flowrate (1.1 cfs) with a target influent of 200 mg/L. Laboratory results for the OK-110 sand showed removal rates from about 45% to 99% removal with an average removal of 83.1%. 4. Laboratory testing was completed on a CDS 2020 unit equipped with 4700-m screen using “UF” sediment (d50 of 20 to 30-μm) at flowrates ranging from 100 to 125% of the design flowrate (1.1 cfs) with a target influent of 200 mg/L. Laboratory results for the “UF” sediment showed removal rates from about 39% to 88% removal with an average removal of 56.1%. 5. Contech completed laboratory testing on a CDS2020 unit using motor oil at flowrates ranging from 25% to 75% of the design flowrate (1.1 cfs) with influents ranging from 7 to 47 mg/L. Laboratory results showed removal rates from 27% to 92% removal. A spill test was also run at 10% of the design flowrate with an influent of 82,000 mg/L with an average percent capture of 94.5% 6. Independent parties in California, Florida, and Australia completed various field studies. Field studies showed the potential for the unit to remove oils and grease and total suspended solids, and capture 100% gross solids greater than the aperture size of the screen under treatment flow rate. 7. CDS Technology has been widely accepted with over 6,200 installations in the United States and Canada. There are over 1,380 installations in Washington and Oregon. Technology Description: Engineers can download a technology description from the company’s website. www.conteches.com Recommended Research and Development: Ecology encourages Contech to pursue continuous improvements to the CDS system. To that end, Ecology makes the following recommendations: 1. Conduct testing to quantify the flowrate at which resuspension occurs. 2. Conduct testing on various sized CDS units to verify the sizing technique is appropriate. 3. Test the system under normal operating conditions, pollutants partially filling the swirl concentrator. Results obtained for “clean” systems may not be representative of typical performance. Contact Information: Applicant Contact: Jeremiah Lehman Contech Engineered Solutions (503) 258-3136 jlehman@conteches.com Applicant website: http://www.conteches.com/ Ecology web link: http://www.ecy.wa.gov/programs/wq/stormwater/newtech/index.html Ecology: Douglas C. Howie. P.E. Department of Ecology Water Quality Program (360) 407-6444 douglas.howie@ecy.wa.gov Revision History Date Revision July 2008 Original use-level-designation document February 2010 Reinstate Contech’s Oil Control PULD August 2012 Revised design storm criteria, revised oil control QAPP, TER, and Expiration dates December 2012 Revised Contech Engineered Solutions Contact Information; Added QAPP for Oil Treatment May 2013 Revised model numbers in Attachment 1 April 2014 Revised Due dates for QAPP and TER and changed Expiration date August 2014 Revised Due dates for QAPP and TER and changed Expiration date July 2016 Updated Oil Control PULD to a CULD based on preliminary field monitoring results November 2016 Revised Contech Contact person August 2018 Removed CULD for Oil from document Attachment 1 CDS Stormwater Treatment Unit Checklist Frequency Drainage System Feature Problem Conditions to Check For Recommended Action Date Inspected* J F M A M J J A S O N D M & S Inlet Chamber Accumulation of trash, debris and sediment Trash blocking inlet throat opening & sediment accumulation exceeds 2 inches Remove trash, debris, and sediments. Inlet throat opening should not be blocked by any materials. A Screen Blockage/Damage Biological growth on the surface of the screen; broken screen or loose screen Powerwash screen to clean the surface and Contact CSS for screen repair (broken or loose) M Separation Chamber Trash and floatable debris accumulation Excessive trash and floatable debris accumulation on the surface in separation chamber Remove trash or other floatable debris in separation chamber to minimum level A Oil Baffle** Damaged Baffles corroding, cracking, warping, and/or showing signs of failure as determined by maintenance/inspection person. Baffles repaired or replaced to design specifications. M & S Oil sorbent** Consumed Change of color in sorbents (fresh sorbents typically appears to be white or light yellow) Remove spent oil sorbent and replace with new sorbent M Sediment Depth in the Sump Sediment accumulation Sediment accumulation exceeds 75-85% sump depth (varies depending on the Model, see attached Table) Sediment in sump should be removed using vactor truck. M Sediment Depth behind the screen Sediment accumulation Sediment accumulation exceeds 2 inches behind the screen Sediment behind the screen should be removed using vactor truck. Frequency Drainage System Feature Problem Conditions to Check For Recommended Action Date Inspected* J F M A M J J A S O N D M Access Cover (MH, Grate, cleanout) Access cover Damaged/ Not working One maintenance person cannot remove lid after applying 80 pounds of lift, corrosion of deformation of cover. Cover repaired to proper working specifications or replaced. A Inlet and Outlet Piping Damaged Piping/Leaking Any part of the pipes are crushed or damaged due to corrosion and/or settlement. Pipe repaired or replaced. A Concrete Structure Concrete structure (MH or diversion vault) has cracks in wall, bottom, and damage to frame and/or top slab. Cracks wider than ½ inch or evidence of soil particles entering the structure through the cracks, or maintenance/inspection personnel determine that the structure is not structurally sound. Structure repaired so that no cracks exist wider than 0.25 inch at the joint of inlet/outlet pipe. A Access Ladder Ladder rungs unsafe Maintenance person judges that ladder is unsafe due to missing rungs, misalignment, rust, or cracks. Ladder must be fixed or secured immediately. Ladder meets design standards and allows maintenance persons safe access. *Note dates when maintenance was performed and type of maintenance performed in notes section below. **May not be present on all units. (M) Monthly from November through April. (A) Once in late summer (preferable September) (S) After any major storm (use 1-inch in 24 hours as a guideline). If you are unsure whether a problem exists, please contact a Professional Engineer. Notes: Maintenance of CDS stormwater treatment unit typically does not require confined space entry. Visual inspections should be performed above ground. If entry is required, it should be performed by qualified personnel. Refer to CDS Unit Operation & Maintenance Guideline for maintenance details. Typically the CDS unit needs to be inspected before and after the rainfall seasons (November to April), after any major storms (>1-inch within 24 hour) and in the event of chemical spills. Contact Contech Engineered Solutions (CSS) (800-548-4667) if there is any damage to the internal components of CDS Unit. CDS Maintenance Indicators and Sediment Storage Capacities CDS Model Diameter Distance from Water Surface to Top of Sediment Pile Sediment Storage Capacity ft m ft m yd 3 m3 CDS2015 5 1.5 3.0 0.9 1.3 1.0 CDS2020 5 1.5 3.5 1.1 1.3 1.0 CDS2025 5 1.5 4.0 1.2 1.3 1.0 CDS3020 6 1.8 4.0 1.2 2.1 1.6 CDS3030 6 1.8 4.6 1.4 2.1 1.6 CDS3035 6 1.8 5.0 1.5 2.1 1.6 CDS4030 8 2.4 4.6 1.4 5.6 4.3 CDS4040 8 2.4 5.7 1.7 5.6 4.3 CDS4045 8 2.4 6.2 1.9 5.6 4.3 7708.016-TIR FINL 4.6 On-site BMP’s The 2021 KCSWDM states that all projects must apply all feasible BMP’s to both individual lots and road improvements. As mentioned earlier, the Geotechnical Engineering Study prepared by Earth Solutions NW concluded that infiltration should not be applied for this project due to the steep hillside characteristics of the site and the observed presence of various groundwater seepage zones. Because of this, the following BMP’s are infeasible: Full Infiltration, Limited Infiltration, Bioretention, Permeable Pavement and Perforated Stub-Out Connections. Full Dispersion and Basic Dispersion are also infeasible due the steep characteristics of the existing and proposed site. As such, the Reduced Impervious Surface Credit BMP will be implemented to the maximum extent feasible for the impervious areas constructed outside the existing shared access and utility easement extending through the site. All pervious surfaces will incorporate soil amendment as detailed in the 2021 KCSWDM. Reduced Impervious Surface Credit BMP In addition, Section C.2.9.2 (2021 KCSWDM) of the Restricted Footprint BMP states that for sites between 22,000 square feet and 250,000 square feet, any recorded limit on total impervious surface less than the norm of 4,000 square feet or 4% of the site area, whichever is greater, qualifies for a restricted footprint credit equal to the difference in square footage. The total area of the project site is 40,805 square feet, therefore 4% of the total site area is 1,632 square feet. This means that any area of impervious lot coverage less than 4,000 square feet qualifies for a restricted footprint credit. Section 19.110.020 of the City of Federal Way Code states that a vehicular access easement will not be used in determining compliance with the maximum lot coverage requirements. This means the impervious area tributary to the single-family residence will be the only impervious area counting towards the lot coverage requirement. The footprint area of the single-family residence is 2,817 square feet, which means 1,183 square feet of area are credited as restricted footprint area. Tab 5.0 7708.016-TIR FINL 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN The on-site conveyance system was designed in accordance with the 2021 KCSWDM. The proposed conveyance system for this project consists of thickened edge asphalt curb, catch basins, and storm drainage pipe. Conveyance Calculations 100-year conveyance calculations for the pipes were completed using the rational method. The design intent of the conveyance system is to fully convey the 100-year storm event flowing at full condition. The following parameters were used in the design of the conveyance storm pipes. 1. A runoff coefficient – “C” value was calculated for the project site according to Table 3.2.1.A found in the 2021 KCSWDM. 2. A 100-year/24-hour precipitation of 4.3 inches in accordance with Figure 3.2.1.D. 3. A starting time of concentration of 6.3 minutes. 4. An “n” factor of 0.014 per table 4.2.1.D of the 2016 KCSWDM was used for the conveyance pipes. Rational Method Equation = = 0.9 ( !) = (#)() = (4.3)(0.82) = 3.53 (#) ! 100 ! !) = 0.31 ! (+!,! !) = (0.9)(3.53)(0.31) = -../ 012 3 (4567 89:; <615) Manning’s equation was used to verify the capacity of the proposed 12-inch pipe conveyance system. The roughness coefficient used for the storm drainage pipe was 0.014 assuming a smooth- walled corrugated polyethylene pipe. A minimum slope of 0.5% was used for the pipe to calculate a worst-case scenario. Manning’s’ Equation (Pipe): =1.49 (#)=/?√A 7708.016-TIR FINL = 0.79 = (CD !) # = 3.14 (E #!!) = 0.014 ( ℎ ) A = 0.005 (ℎ A) = ( 1.49 0.014)(0.79)(0.79 3.14)=/?√0.005 = G.2H 012 3 (89:; <615) Based on the results from the calculations above, the pipe conveyance system has a maximum flow capacity of 2.37 cfs. This means that the pipe system will adequately convey the peak 100- year storm event flow rate of 0.98 cfs. 3.2.1 RATIONAL METHOD 2021 Surface Water Design Manual 7/23/2021 3-19 FIGURE 3.2.1.D 100-YEAR 24-HOUR ISOPLUVIALS Figure 5.0.1 Project site Tab 6.0 7708.016-TIR FINL 6.0 SPECIAL REPORTS AND STUDIES 6.1 Geotechnical Engineering Study prepared by Earth Solutions NW, LLC., dated September 1, 2023 6.2 SWPPP prepared by Barghausen Consulting Engineers, Inc., dated August 3, 2023 EarthSolutionsNWLLC EarthSolutions NW LLC Geotechnical Engineering Construction Observation/Testing Environmental Services 15365 N.E.90th Street,Suite 100 Redmond,WA 98052 (425)449-4704 Fax (425)449-4711 www.earthsolutionsnw.com GEOTECHNICAL ENGINEERING STUDY PROPOSED SINGLE-FAMILY RESIDENCE SOUTHWEST 296 STREET AND 2 PLACE SOUTHWEST FEDERAL WAY,WASHINGTON ES-8670 TH ND PREPARED FOR CHRISTOPHER PENWELL September 1, 2023 _________________________ Chase G. Halsen, L.G., L.E.G. Senior Project Geologist _________________________ Henry T. Wright, P.E. Associate Principal Engineer GEOTECHNICAL ENGINEERING STUDY PROPOSED SINGLE-FAMILY RESIDENCE SOUTHWEST 296TH STREET AND 2ND PLACE SOUTHWEST FEDERAL WAY, WASHINGTON ES-8670 Earth Solutions NW, LLC 15365 Northeast 90th Street, Suite 100 Redmond, Washington 98052 Phone: 425-449-4704 | Fax: 425-449-4711 www.earthsolutionsnw.com 09/01/2023 09/01/2023 Geotechnical-Engineering Report Important Information about This Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help. The Geoprofessional Business Association (GBA) has prepared this advisory to help you – assumedly a client representative – interpret and apply this geotechnical-engineering report as effectively as possible. In that way, you can benefit from a lowered exposure to problems associated with subsurface conditions at project sites and development of them that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed herein, contact your GBA-member geotechnical engineer. Active engagement in GBA exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Understand the Geotechnical-Engineering Services Provided for this Report Geotechnical-engineering services typically include the planning, collection, interpretation, and analysis of exploratory data from widely spaced borings and/or test pits. Field data are combined with results from laboratory tests of soil and rock samples obtained from field exploration (if applicable), observations made during site reconnaissance, and historical information to form one or more models of the expected subsurface conditions beneath the site. Local geology and alterations of the site surface and subsurface by previous and proposed construction are also important considerations. Geotechnical engineers apply their engineering training, experience, and judgment to adapt the requirements of the prospective project to the subsurface model(s). Estimates are made of the subsurface conditions that will likely be exposed during construction as well as the expected performance of foundations and other structures being planned and/or affected by construction activities. The culmination of these geotechnical-engineering services is typically a geotechnical-engineering report providing the data obtained, a discussion of the subsurface model(s), the engineering and geologic engineering assessments and analyses made, and the recommendations developed to satisfy the given requirements of the project. These reports may be titled investigations, explorations, studies, assessments, or evaluations. Regardless of the title used, the geotechnical-engineering report is an engineering interpretation of the subsurface conditions within the context of the project and does not represent a close examination, systematic inquiry, or thorough investigation of all site and subsurface conditions. Geotechnical-Engineering Services are Performed for Specific Purposes, Persons, and Projects, and At Specific Times Geotechnical engineers structure their services to meet the specific needs, goals, and risk management preferences of their clients. A geotechnical-engineering study conducted for a given civil engineer will not likely meet the needs of a civil-works constructor or even a different civil engineer. Because each geotechnical-engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. Likewise, geotechnical-engineering services are performed for a specific project and purpose. For example, it is unlikely that a geotechnical- engineering study for a refrigerated warehouse will be the same as one prepared for a parking garage; and a few borings drilled during a preliminary study to evaluate site feasibility will not be adequate to develop geotechnical design recommendations for the project. Do not rely on this report if your geotechnical engineer prepared it: • for a different client; • for a different project or purpose; • for a different site (that may or may not include all or a portion of the original site); or • before important events occurred at the site or adjacent to it; e.g., man-made events like construction or environmental remediation, or natural events like floods, droughts, earthquakes, or groundwater fluctuations. Note, too, the reliability of a geotechnical-engineering report can be affected by the passage of time, because of factors like changed subsurface conditions; new or modified codes, standards, or regulations; or new techniques or tools. If you are the least bit uncertain about the continued reliability of this report, contact your geotechnical engineer before applying the recommendations in it. A minor amount of additional testing or analysis after the passage of time – if any is required at all – could prevent major problems. Read this Report in Full Costly problems have occurred because those relying on a geotechnical- engineering report did not read the report in its entirety. Do not rely on an executive summary. Do not read selective elements only. Read and refer to the report in full. You Need to Inform Your Geotechnical Engineer About Change Your geotechnical engineer considered unique, project-specific factors when developing the scope of study behind this report and developing the confirmation-dependent recommendations the report conveys. Typical changes that could erode the reliability of this report include those that affect: • the site’s size or shape; • the elevation, configuration, location, orientation, function or weight of the proposed structure and the desired performance criteria; • the composition of the design team; or • project ownership. As a general rule, always inform your geotechnical engineer of project or site changes – even minor ones – and request an assessment of their impact. The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered. Most of the “Findings” Related in This Report Are Professional Opinions Before construction begins, geotechnical engineers explore a site’s subsurface using various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing is performed. The data derived from that sampling and testing were reviewed by your geotechnical engineer, who then applied professional judgement to form opinions about subsurface conditions throughout the site. Actual sitewide-subsurface conditions may differ – maybe significantly – from those indicated in this report. Confront that risk by retaining your geotechnical engineer to serve on the design team through project completion to obtain informed guidance quickly, whenever needed. This Report’s Recommendations Are Confirmation-Dependent The recommendations included in this report – including any options or alternatives – are confirmation-dependent. In other words, they are not final, because the geotechnical engineer who developed them relied heavily on judgement and opinion to do so. Your geotechnical engineer can finalize the recommendations only after observing actual subsurface conditions exposed during construction. If through observation your geotechnical engineer confirms that the conditions assumed to exist actually do exist, the recommendations can be relied upon, assuming no other changes have occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation-dependent recommendations if you fail to retain that engineer to perform construction observation. This Report Could Be Misinterpreted Other design professionals’ misinterpretation of geotechnical- engineering reports has resulted in costly problems. Confront that risk by having your geotechnical engineer serve as a continuing member of the design team, to: • confer with other design-team members; • help develop specifications; • review pertinent elements of other design professionals’ plans and specifications; and • be available whenever geotechnical-engineering guidance is needed. You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction- phase observations. Give Constructors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can shift unanticipated-subsurface-conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note conspicuously that you’ve included the material for information purposes only. To avoid misunderstanding, you may also want to note that “informational purposes” means constructors have no right to rely on the interpretations, opinions, conclusions, or recommendations in the report. Be certain that constructors know they may learn about specific project requirements, including options selected from the report, only from the design drawings and specifications. Remind constructors that they may perform their own studies if they want to, and be sure to allow enough time to permit them to do so. Only then might you be in a position to give constructors the information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Conducting prebid and preconstruction conferences can also be valuable in this respect. Read Responsibility Provisions Closely Some client representatives, design professionals, and constructors do not realize that geotechnical engineering is far less exact than other engineering disciplines. This happens in part because soil and rock on project sites are typically heterogeneous and not manufactured materials with well-defined engineering properties like steel and concrete. That lack of understanding has nurtured unrealistic expectations that have resulted in disappointments, delays, cost overruns, claims, and disputes. To confront that risk, geotechnical engineers commonly include explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The personnel, equipment, and techniques used to perform an environmental study – e.g., a “phase-one” or “phase-two” environmental site assessment – differ significantly from those used to perform a geotechnical-engineering study. For that reason, a geotechnical-engineering report does not usually provide environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not obtained your own environmental information about the project site, ask your geotechnical consultant for a recommendation on how to find environmental risk-management guidance. Obtain Professional Assistance to Deal with Moisture Infiltration and Mold While your geotechnical engineer may have addressed groundwater, water infiltration, or similar issues in this report, the engineer’s services were not designed, conducted, or intended to prevent migration of moisture – including water vapor – from the soil through building slabs and walls and into the building interior, where it can cause mold growth and material-performance deficiencies. Accordingly, proper implementation of the geotechnical engineer’s recommendations will not of itself be sufficient to prevent moisture infiltration. Confront the risk of moisture infiltration by including building-envelope or mold specialists on the design team. Geotechnical engineers are not building-envelope or mold specialists. Copyright 2019 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent or intentional (fraudulent) misrepresentation. Telephone: 301/565-2733 e-mail: info@geoprofessional.org www.geoprofessional.org September 1, 2023 ES-8670 Christopher Penwell 696 Moss Farms Road Cheshire, Connecticut 06410 Greetings: Earth Solutions NW, LLC (ESNW) is pleased to present this geotechnical report to support the proposed project. Based on the results of our investigation, the construction of a single-family residence is feasible from a geotechnical standpoint. Our study indicates the site is underlain by sequenced coarse- to fine-grained, pre-Olympia glacial deposits. Based on the observed soil and groundwater conditions, visual observations, and results of preliminary slope stability analyses, it is our opinion that the slope which comprises the majority of the site area has a moderate to high landslide potential. As such, the proposed structure will need to be supported on deep foundation elements. A further discussion of our slope stability analyses, foundation support recommendations, and considerations are provided in this report. From a geotechnical standpoint, infiltration should not be pursued for the project. The site is located on a fairly steep hillside and the introduction of additional water (via infiltration) could potentially reduce stability of the slope. Furthermore, the observed presence of various groundwater seepage zones, particularly during the summer months, indicates unfavorable site infiltration characteristics. Pertinent geotechnical recommendations are provided in this study. We appreciate the opportunity to be of service to you on this project. If you have any questions regarding the content of this geotechnical engineering study, please call. Sincerely, EARTH SOLUTIONS NW, LLC Chase G. Halsen, L.G., L.E.G. Senior Project Geologist cc: Barghausen Consulting Engineers, Inc. Attention: Ivana Halvorsen Vicente Varas, P.E. 15365 N.E. 90th Street, Suite 100 • Redmond, WA 98052 •(425) 449-4704 • FAX (425) 449-4711 Earth Solutions NW LLC Geotechnical Engineering, Construction Observation/Testing and Environmental Services Earth Solutions NW, LLC Table of Contents ES-8670 PAGE INTRODUCTION ................................................................................. 1 General .................................................................................... 1 Project Description ................................................................. 1 SITE CONDITIONS ............................................................................. 2 Surface ..................................................................................... 2 Subsurface .............................................................................. 2 Topsoil .......................................................................... 2 Fill .................................................................................. 2 Native Soil and Geologic Setting ................................ 3 Groundwater ................................................................. 3 Geologically Hazardous Areas .............................................. 3 Landslide Hazard Areas ............................................... 4 Deep Foundation Support ................................... 4 Erosion Hazard ............................................................. 5 DISCUSSION AND RECOMMENDATIONS ....................................... 5 General .................................................................................... 5 Site Preparation and Earthwork ............................................. 5 Temporary Erosion Control ......................................... 5 Stripping ....................................................................... 6 Excavations and Slopes .............................................. 6 In-situ and Imported Soil ............................................. 7 Structural Fill ................................................................ 7 Site Modifications ......................................................... 7 Foundations ............................................................................ 8 Axial Load Capacity and Pipe Pile Installation ........... 8 Lateral Load Capacity ................................................... 8 Seismic Design ....................................................................... 9 Slab-on-Grade Floors ............................................................. 9 Retaining Walls ....................................................................... 10 Drainage................................................................................... 10 Infiltration Feasibility ................................................... 11 Utility Support and Trench Backfill ....................................... 11 LIMITATIONS ...................................................................................... 11 Additional Services ................................................................. 11 REFERENCES .................................................................................... 12 Earth Solutions NW, LLC Table of Contents Cont’d ES-8670 GRAPHICS Plate 1 Vicinity Map Plate 2 Subsurface Exploration Plan Plate 3 Retaining Wall Drainage Detail Plate 4 Footing Drain Detail APPENDICES Appendix A Subsurface Exploration Logs Appendix B Laboratory Test Results Appendix C Slope/W Output Earth Solutions NW, LLC GEOTECHNICAL ENGINEERING STUDY PROPOSED SINGLE-FAMILY RESIDENCE SOUTHWEST 296TH STREET AND 2ND PLACE SOUTHWEST FEDERAL WAY, WASHINGTON ES-8670 INTRODUCTION General This geotechnical engineering study was prepared for the proposed single-family residence to be constructed near the intersection of Southwest 296th Street and 2nd Place Southwest, in Federal Way, Washington. This study was prepared to provide geotechnical recommendations for currently proposed development plans and included the following geotechnical services:  Test pit and boring explorations to characterize soil and groundwater conditions.  Laboratory testing of representative soil samples collected at the test locations.  Geotechnical engineering analyses. Project Description The proposed project is currently pursuing the construction of a single-family residence and associated infrastructure improvements, which will be targeted at the southwest corner of the site area. To our understanding, this location was chosen due to various site constraints relating to identified critical areas and the associated buffers. We understand that stormwater runoff will likely be managed via a detention structure to be located adjacent to the access driveway. We understand that the proposed residential structure will be three stories and constructed using relatively lightly loaded wood framing. Perimeter footing loads will likely be about 2 to 3 kips per linear foot. Slab-on-grade loading is anticipated to be approximately 150 pounds per square foot (psf). We anticipate a series of bench cuts will be utilized across the building envelope to minimize disturbances to the existing slope. If the above design assumptions either change or are incorrect, ESNW should be contacted to review the recommendations provided in this report. ESNW should review the final designs to confirm that appropriate geotechnical recommendations have been incorporated into the plans. Christopher Penwell ES-8670 September 1, 2023 Page 2 Earth Solutions NW, LLC SITE CONDITIONS Surface The subject site is located near the Southwest 296th Street and 2nd Place Southwest intersection in Federal Way, Washington. The approximate site location is depicted on Plate 1 (Vicinity Map) and consists of King County parcel number 119600-3800, totaling a gross site area of about 0.94 acres. The site is undeveloped and heavily forested. The only exception is a local access road along the eastern and southern property edge that provides access to the adjacent residence. Topography generally descends to the northeast towards a drainage features that trends in a northwest-to-southeast fashion. Limited topography descends to the southwest on the opposite side of this feature. In total, about 75 to 80 feet of elevation change occurs across the site. The referenced site plan packet indicates that the majority of site slopes possess a gradient of less than 40 percent. However, gradients over 40 percent are present within the west-central site area and other isolated pockets across the property. Subsurface An ESNW representative observed, logged, and sampled the excavation of one test pit on July 15, 2022, and two soil borings on July 19, 2022. The test pit was extended to a depth of about 9.5 feet below the ground surface (bgs) while the borings were advanced to depths of about 31.5 and 51 feet bgs. All subsurface explorations were completed with exploratory equipment and operators retained by ESNW. The approximate locations of the explorations are depicted on Plate 2 (Subsurface Exploration Plan). Please refer to the soil logs provided in Appendix A for a more detailed description of the encountered subsurface conditions. Representative soil samples collected at the exploration locations were analyzed following Unified Soil Classification System (USCS) and United States Department of Agriculture (USDA) methods and procedures. Topsoil Topsoil was encountered in approximately the upper six inches of existing grades at the test pit location. The topsoil was characterized by a dark brown color, the presence of fine organic material, and small root intrusions. Based on our observations, a similar topsoil condition can be expected across the building envelope. Fill Existing fill was not interpreted at the boring locations, but rather, the notation of fill in the attached soil logs represents material placed to establish a level drilling pad. These pads were constructed at the time of our test pit exploration. Christopher Penwell ES-8670 September 1, 2023 Page 3 Earth Solutions NW, LLC Native Soil and Geologic Setting Native soils were classified primarily as layered silty sand and silt with variable sand percentages (USCS: SM and ML, respectively). In general, soils within the upper approximate 10 to 15 feet of existing grades were characterized as being loose to medium dense. Thereafter (at the boring locations), native soils were encountered in a dense to very dense condition and extended to the terminus of each boring location, which occurred at depths between about 31.5 and 51.0 feet bgs. Medium dense soils were encountered at the terminus of the test pit location which occurred at a depth of about nine-and-one-half feet bgs. At the time of the July 2022 exploration, native soils were observed in a moist to wet condition. The referenced geologic map indicates that the site is underlain by pre-Olympia age course- grained deposits (Qpogc). Surface exposures of pre-Olympia age fine-grained deposits are mapped directly downgradient of the site. The referenced Web Soil Survey indicates the site area is primarily underlain by Indianola loamy sand and Alderwood Kitsap soils (Map Unit Symbols: InD and AkF, respectively). The Indianola series is derived from sandy glacial outwash while the Alderwood/Kitsap soils are derived from basal till. Based on the conditions encountered during the subsurface exploration, native soils are generally considered representative of sequenced course- to fine-grained deposits that are pre-Olympia in age. For stormwater runoff design characterizations, the native site soil may be considered at Type C soil. Groundwater Perched groundwater seepage was encountered at both boring locations during the July 2022 fieldwork. In general, the seepage was first exposed at a depth of about seven-and-one-half to eight-and-one-half feet bgs, extending to the termination depth of each location, and characterized with variable degrees of flow rate. Perched groundwater was not encountered within the test pit location. Groundwater seeps are common within glacial deposits, and the elevations and/or flow volumes of seepages can fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater elevations are higher during the winter, spring, and early summer months. Geologically Hazardous Areas The Federal Way Revised Code (FWRC) 19.145.220 recognizes and defines geologically hazardous areas as landslide, erosion, and seismic hazards. Based on our review of the FWRC definitions (19.05.070), the site is considered to possess a landslide and erosion hazard due to the current slope gradients and identified soil units within the site area. A discussion of the identified hazard areas and applicable mitigation recommendations are provided in the following sections. Please note that it is our opinion that any seismic-related instability coincides with any potential site landslide hazard. As such, a specific seismic hazard discussion is not provided. Christopher Penwell ES-8670 September 1, 2023 Page 4 Earth Solutions NW, LLC Landslide Hazard Areas Based on a review of the critical areas impact plan sheet, the majority of site gradients are between 15 percent and 39.99 percent. However, slope areas of 40 percent gradient or more over at least a 10-foot elevation chare are present within the west-central site area and extend into the proposed footprint of the residence. As such, these sloping areas may be considered a potential landslide hazard per the FWRC definitions. The standard buffer associated with landslide hazard areas is 50 feet per the FWRC. However, we understand that a reduced buffer and/or development within a landslide hazard area may be considered provided it will not lead to or create any increased landslide hazard or be at risk of landslide hazard damages. To further evaluate the potential landslide hazard, a slope stability analysis was performed for the subject site to represent the current (pre-construction) and post-construction site configuration. Please note that general assumptions about the foundation excavation configuration were made in the development of the stability analyses. Two models were produced for each condition; one represented slope performance under static site conditions while the other represented slope performance under seismic conditions. Soil strength parameters were chosen based on our experience with similar deposits and the WSDOT Geotechnical manual. A seismic coefficient (Kh) of 0.343 was used in the model. The following table depicts the minimum factor- of-safety associated with each condition and model: Pre-Existing Condition FOS Post-Construction Condition FOS Static 1.63 Static 1.58 Seismic 1.00 Seismic 1.08 Based on the modeling, slope stability is interpreted to be stable under static conditions and are generally unchanged between the two conditions. However, the seismic analysis results in safety factors that are below acceptable standards. Due to lower than acceptable slope stability safety factors, it is our opinion that the residence will need to be supported on deep foundation elements. Deep Foundation Support In our opinion, the proposed foundation can be supported on a pipe pile system in which each pile is driven into the dense to very dense native soils at depth. Although some lateral resistance can be derived from the pipe pile system, the implementation is not considered to be landslide hazard mitigation and was not modeled as such in our slope stability analyses. The deep foundation elements would provide continued foundation support should soil movement occur and result in the loss of soil beneath or adjacent to footing elements. It must be noted that this approach would not mitigate the potential for soil movement, and as such, the residence may not be habitable if a landslide occurs. It is our opinion that this approach will not decrease slope stability characteristics or increase the potential for impacts to neighboring properties. Foundation design recommendations and pipe pile considerations are provided in this report. Christopher Penwell ES-8670 September 1, 2023 Page 5 Earth Solutions NW, LLC Erosion Hazard Per the FWRC 19.145.240, there is no standard buffer associated with erosion hazard areas. However, the project should follow the recommendations of the critical area report to minimize the adverse effects of the potential hazard on the proposed project. In our opinion, erosion can be successfully managed and mitigated both during and post-construction provided typical site BMPs are utilized and managed and permanent landscaping is installed following the completion of the project. DISCUSSION AND RECOMMENDATIONS General Based on the results of our investigation, the construction of the proposed single-family residence is feasible from a geotechnical standpoint. The primary geotechnical considerations for the proposed development concern temporary excavation support, foundation support recommendations, geologically hazardous area mitigation, and stormwater management design. Site Preparation and Earthwork Initial site preparation activities will consist of installing temporary erosion control measures, establishing grading limits, and site clearing and stripping activities. Subsequent earthwork activities will involve excavation for the building, building pad preparation, and installation of infrastructure and stormwater management improvements. Temporary Erosion Control The following temporary erosion and sediment control Best Management Practices (TESC BMPs) are offered:  Temporary construction entrances and drive lanes should be constructed with at least six inches of quarry spalls to both minimize off-site soil tracking and provide a stable access entrance surface. A woven geotextile fabric can be placed beneath the quarry spalls to provide greater stability if needed.  Silt fencing should be placed around the site perimeter.  When not in use, soil stockpiles should be covered or otherwise protected. Stockpiles should not be placed on or directly adjacent to slopes.  Temporary measures for controlling surface water runoff, such as interceptor trenches, sumps, or interceptor swales, should be installed before beginning earthwork activities.  Based on limited site space and sloped topography, a stormwater collection tank may be necessary. Christopher Penwell ES-8670 September 1, 2023 Page 6 Earth Solutions NW, LLC  Dry soils disturbed during construction should be wetted to reduce dust.  When appropriate, permanent planting or hydroseeding will help to stabilize site soils.  Based on the site soils and sloped topography, we recommend completing earthwork during the dry season. Additional TESC BMPs, as specified by the project civil engineer on the plans, should be incorporated into construction activities. TESC measures will require upkeep and potential modification during construction to ensure proper function; such upkeep should be coordinated with the site erosion control lead, where applicable. Stripping Topsoil was generally encountered in the upper approximately six inches of existing grades at the test pit location. For stripping estimations, an average topsoil thickness of about six inches can be assumed, based on our field observations. Where encountered, organic-rich topsoil should be stripped and segregated into a stockpile for later use on site or to be exported. Excavations and Slopes Based on the soil conditions observed at the test pit locations, the following allowable temporary slope inclinations, as a function of horizontal to vertical (H:V) inclination, may be used. The applicable Federal Occupation Safety and Health Administration (OSHA) and Washington Industrial Safety and Health Act (WISHA) soil classifications are also provided:  Loose to medium dense soil 1.5H:1V (Type C)  Areas exposing groundwater seepage 1.5H:1V (Type C)  Dense to very dense, undisturbed native soil 0.75H:1V (Type A) Steeper temporary slope inclinations within undisturbed, very dense native soil may be feasible based on the soil and groundwater conditions exposed within the excavations. ESNW can evaluate the feasibility of utilizing steeper temporary slopes on a case-by-case basis at the time of construction. In any case, an ESNW representative should observe temporary slopes to confirm inclinations are suitable for the exposed soil conditions and to provide additional excavation and slope stability recommendations, as necessary. If the recommended temporary slope inclinations cannot be achieved, temporary shoring may be necessary to support excavations. Permanent slopes should be graded to 2H:1V (or flatter) and planted with vegetation to enhance stability and minimize erosion potential. Permanent slopes should be observed by ESNW before vegetation and landscaping. ESNW must review the proposed grading plans to assist in evaluating suitable temporary slope inclinations and/or the necessity of temporary shoring designs. Christopher Penwell ES-8670 September 1, 2023 Page 7 Earth Solutions NW, LLC In-situ and Imported Soil Successful use of the on-site soil as structural fill will largely be dictated by the moisture content at the time of placement and compaction. Based on the conditions observed during the subsurface exploration, the native soils are considered to possess a moderate to high moisture sensitivity. Depending on the time of year construction occurs, remedial measures (such as soil aeration) may be necessary as part of site grading and earthwork activities. If the on-site soil cannot be successfully compacted, the use of imported soil may be necessary. In our opinion, a contingency should be provided in the project budget for the export of soil that cannot be successfully compacted as structural fill, particularly if grading activities take place during periods of extended rainfall activity. In general, soils with fine contents greater than 5 percent typically degrade rapidly when exposed to periods of rainfall. Imported structural fill soil should consist of well-graded, granular soil that can achieve a suitable working moisture content. During wet weather conditions, imported soil intended for use as structural fill should consist of a well-graded, granular soil with a fines content of 5 percent or less (where the fines content is defined as the percent passing the Number 200 sieve, based on the minus three-quarter-inch fraction). Structural Fill Structural fill is defined as compacted soil placed in foundation, slab-on-grade, roadway, permanent slope, retaining wall, and utility trench backfill areas. The following recommendations are provided for soils intended for use as structural fill:  Moisture content At or slightly above optimum  Relative compaction (minimum) 95 percent (per ASTM D1557)  Loose lift thickness (maximum) 12 inches Existing site soil may only be considered suitable for use as structural fill if a suitable moisture content is achieved at the time of placement and compaction. If the on-site soil cannot achieve the above specifications, the use of imported structural fill material will likely be necessary. Concerning underground utility installations and backfill, local jurisdictions will likely dictate soil type(s) and compaction requirements. Site Modifications From a geotechnical standpoint, the project should strive to minimize the amount of proposed grade fills, to the extent possible. ESNW should review grading plans to evaluate any potential impacts resulting from the placement and compaction of fill material. Christopher Penwell ES-8670 September 1, 2023 Page 8 Earth Solutions NW, LLC Foundations As discussed in the Geologically Hazardous Areas section of this report, it is our opinion that the proposed residence be supported on deep foundation elements in attempt to provide continued foundation support should a landslide occur. Design recommendations relating to pile capacities is provided in this section. From a geotechnical standpoint, 4-inch diameter pipe piles (or larger) should be considered for this project. Based on the conditions encountered during our subsurface explorations, we anticipate dense to very dense native soils to be encountered at depths of about 20 to 30 feet bgs; however, ultimate pipe pile lengths will be dictated by achieving adequate refusal in dense soil. In our opinion, the contractor should consider ultimate pile lengths in excess of about 30 feet. Due to the encountered groundwater conditions and overall soil characteristics, the pipe piles should consist of galvanized steel to reduce the potential for corrosion. Axial Load Capacity and Pipe Pile Installation Provided the pipe piles are driven to refusal, the following allowable axial load capacities may be used for the design: Pile Diameter (in.) Load Capacity (kips) Refusal Criteria (seconds/inch) Minimum Hammer Size (lb.) 4 20 16 850 With structural loading as expected, total settlement in the range of one inch and differential settlement of about one-half inch is anticipated. Most settlement should occur during construction, as dead loads are applied. If modified installation methods or equipment are used during construction, ESNW should be notified to review the recommendations provided in this report. Typically, piles are alternatively driven with respect to other piles in a row to minimize the temporary loss of soil strength during installation (which may affect subsequent pile installations). An ESNW representative should observe the pipe pile installations to verify the achievement of adequate refusal. In addition, we recommend a pipe pile load testing program be incorporated into the final plans. Load testing on at least 3 percent of the installed piles should be completed. The testing program would ideally also include one or two verification tests on the driven pipe piles to 200 percent of the design load. Lateral Load Capacity The lateral load capacity of pipe piles is minimal and should be neglected for design purposes. If lateral load capacity is required, ESNW can review the pile design and provide batter pile recommendations. Limited lateral load capacity can be provided by the passive resistance developed by grade beams, if applicable. Christopher Penwell ES-8670 September 1, 2023 Page 9 Earth Solutions NW, LLC Seismic Design The 2018 International Building Code (2018 IBC) recognizes the most recent edition of the Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic design, specifically concerning earthquake loads. Based on the soil conditions encountered at the test locations, the parameters and values provided below are recommended for seismic design per the 2018 IBC. Parameter Value Site Class C* Mapped short-period spectral response acceleration, SS (g) 1.352 Mapped 1-second period spectral response acceleration, S1 (g) 0.464 Short period site coefficient, Fa 1.2 Long-period site coefficient, Fv 1.5 Adjusted short-period spectral response acceleration, SMS (g) 1.623 Adjusted 1-second period spectral response acceleration, SM1 (g) 0.697 Design short-period spectral response acceleration, SDS (g) 1.082 Design 1-second period spectral response acceleration, SD1 (g) 0.464 * Assumes very dense soil conditions, encountered to a maximum depth of 51 feet bgs during the July 2022 field exploration, remain very dense to at least 100 feet bgs. Slab-on-Grade Floors Slab-on-grade floors for the proposed residential structures should be supported by competent, firm, and unyielding subgrades. Unstable or yielding subgrade areas should be recompacted or overexcavated and replaced with suitable structural fill before slab construction. A capillary break consisting of at least four inches of free-draining crushed rock or gravel should be placed below each slab. The free-draining material should have a fines content of 5 percent or less (where the fines content is defined as the percent passing the Number 200 sieve, based on the minus three- quarter-inch fraction). In areas where slab moisture is undesirable, the installation of a vapor barrier below the slab should be considered. Vapor barriers should be made from material specifically designed for use as a vapor barrier and should be installed by the manufacturer’s recommendations. Christopher Penwell ES-8670 September 1, 2023 Page 10 Earth Solutions NW, LLC Retaining Walls Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The following parameters may be used for the design:  Active earth pressure (unrestrained condition) 35 pcf (equivalent fluid)  Active earth pressure (backslope) 55 pcf  At-rest earth pressure (restrained condition) 55 pcf  At-rest earth pressure (backslope) 75 pcf  Traffic surcharge* (passenger vehicles) 70 psf (rectangular distribution)  Passive earth pressure 300 pcf (equivalent fluid)  Coefficient of friction 0.40  Seismic surcharge 8H psf** * Where applicable. ** Where H equals the retained height (in feet). The above passive earth pressure and coefficient of friction values include a FOS of 1.5 and are based on a level backfill condition and level grade at the wall toe. Revised design values will be necessary if sloping grades are to be used above or below retaining walls. Additional surcharge loading from adjacent foundations, sloped backfill, or other relevant loads should be included in the retaining wall design. Retaining walls should be backfilled with free-draining material that extends along with the height of the wall and a distance of at least 18 inches behind the wall. The upper 12 inches of the wall backfill may consist of less permeable soil if desired. A sheet drain may be considered instead of using free-draining backfill. A perforated drainpipe should be placed along the base of the wall and connected to an approved discharge location. A typical retaining wall drainage detail is provided on Plate 3. If drainage is not provided, hydrostatic pressures should be included in the wall design. Drainage Zones of perched groundwater seepage could develop in site excavations depending on the time of year grading operations take place, particularly within deeper excavations. Temporary measures to control surface water runoff and groundwater during construction would likely involve interceptor trenches, interceptor swales, and sumps; however, stormwater collection tanks may also be necessary. ESNW should be consulted during preliminary grading to both identify areas of seepage and provide recommendations to reduce the potential for seepage-related instability. Christopher Penwell ES-8670 September 1, 2023 Page 11 Earth Solutions NW, LLC Finish grades must be designed to direct surface drain water away from structures and slopes where feasible. Water must not be allowed to pond adjacent to structures or slopes. In our opinion, foundation drains should be installed along building perimeter footings. A typical foundation drain detail is provided on Plate 4. Infiltration Feasibility From a geotechnical standpoint, infiltration should not be pursued for the project. The site is located on a steep hillside and the introduction of additional water (via infiltration, perforated stub outs, etc.) could potentially reduce slope stability and increase erosion. Furthermore, the observed presence of various groundwater seepage zones, particularly during the summer months, indicates unfavorable site infiltration characteristics. Utility Support and Trench Backfill In our opinion, the native soil will generally be suitable for the support of utilities. Remedial measures may be necessary for some areas to provide support for utilities, such as overexcavation and replacement with structural fill and/or placement of geotextile fabric. Groundwater seepage may be encountered within utility excavations, and caving of trench walls may occur where groundwater is encountered. Depending on the time of year and conditions encountered, dewatering or temporary trench shoring may be necessary during utility excavation and installation. The on-site soil is not considered suitable for use as structural backfill throughout the utility trench excavations unless the soil is at (or slightly above) the optimum moisture content at the time of placement and compaction. Moisture conditioning of the soil may be necessary at some locations before use as structural fill. Each section of the utility lines must be adequately supported by the bedding material. Utility trench backfill should be placed and compacted to the structural fill specifications previously detailed in this report or to the applicable specifications of the presiding jurisdiction. LIMITATIONS This study has been prepared for the exclusive use of Christopher Penwell and his representatives. The recommendations and conclusions provided in this study are professional opinions consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. No warranty, express or implied, is made. Variations in the soil and groundwater conditions observed at the test locations may exist and may not become evident until construction. ESNW should reevaluate the conclusions provided in this study if variations are encountered. Additional Services ESNW should have an opportunity to review the final project plans concerning the geotechnical recommendations provided in this report. ESNW should also be retained to provide testing and consultation services during construction. Christopher Penwell ES-8670 September 1, 2023 Page 12 Earth Solutions NW, LLC REFERENCES  WSS, maintained by the Natural Resources Conservation Service under the USDA  Lidar-Revised Geologic Map of the Poverty Bay 7.5’ Quadrangle, King and Pierce Counties, Washington, prepared by R.W. Tabor, D.B. Booth, and K.G. Troost, 2014  Penwell Property Plan Set, prepared by Barghausen Consulting Engineers, Inc., dated August 3, 2023. Geotechnical Engineering,Construction Observation/Testing and Environmental Services Drwn.MRS Checked CGH Date Aug.2022 Date 08/09/2022 Proj.No.8670 Plate 1 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC Vicinity Map Redondo Bay Lot 35 Federal Way,Washington Reference: King County,Washington OpenStreetMap.org NORTH NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. SITE Federal Way Plate Proj.No. Date Checked DrawnEarthSolutionsNWLLC GeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCMRS NORTH NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. NOTE:The graphics shown on this plate are not intended for design purposes or precise scale measurements,but only to illustrate the approximate test locations relative to the approximate locations of existing and /or proposed site features.The information illustrated is largely based on data provided by the client at the time of our study.ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. LEGEND Approximate Location of ESNW Boring,Proj.No. ES-8670,July 2022 Approximate Location of ESNW Test Pit,Proj.No. ES-8670,July 2022 Subject Site Cross Section 0 4 0 8 0 1 6 0 Sc ale in Feet1"=8 0 ' CGH 08/31/2023 8670 2SubsurfaceExplorationPlan RedondoBayLot35FederalWay,WashingtonTP-1 B-1 TP-1 B-1 B-2 S.W.296TH STREET 2ND PLACE S.W.200 190 180 170 160 150 140 200 190 180 170 160 150140 Geotechnical Engineering,Construction Observation/Testing and Environmental Services Drawn CAM Checked HTW Date May 2023 Date 05/08/2023 Proj.No.8670 Plate 3 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC NOTES: Free-draining Backfill should consist of soil having less than 5 percent fines. Percent passing No.4 sieve should be 25 to 75 percent. Sheet Drain may be feasible in lieu of Free-draining Backfill,per ESNW recommendations. Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1-inch Drain Rock. LEGEND: Free-draining Structural Backfill 1-inch Drain Rock 18"Min. Structural Fill Perforated Rigid Drain Pipe (Surround in Drain Rock) SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAW ING Retaining Wall Drainage Detail Redondo Bay Lot 35 Federal Way,Washington Geotechnical Engineering,Construction Observation/Testing and Environmental Services Drawn CAM Checked HTW Date May 2023 Date 05/08/2023 Proj.No.8670 Plate 4 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC Slope Perforated Rigid Drain Pipe (Surround in Drain Rock) 18"Min. NOTES: Do NOT tie roof downspouts to Footing Drain. Surface Seal to consist of 12"of less permeable,suitable soil.Slope away from building. LEGEND: Surface Seal:native soil or other low-permeability material. 1-inch Drain Rock SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAW ING Footing Drain Detail Redondo Bay Lot 35 Federal Way,Washington Earth Solutions NW, LLC Appendix A Subsurface Exploration Logs ES-8670 Subsurface conditions at the subject site were explored on July 15, 2022, and July 19, 2022, where one test pit was excavated and two soil borings were advanced. The machinery and operators used to perform each exploration were retained by ESNW. The approximate locations of the explorations are illustrated on Plate 2 of this study. The exploration logs are provided in this Appendix. The test pit was excavated to a maximum depth of approximately 9.5 feet bgs while the borings were advanced to 31.5 and 51.0 feet bgs. The final logs represent the interpretations of the field logs and the results of laboratory analyses. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. >12%Fines<5%FinesHighlyOrganicSoilsSiltsandClaysLiquidLimit50orMoreSiltsandClaysLiquidLimitLessThan50Fine-GrainedSoils-50%orMorePassesNo.200SieveCoarse-GrainedSoils-MoreThan50%RetainedonNo.200SieveSands-50%orMoreofCoarseFractionPassesNo.4SieveGravels-MoreThan50%ofCoarseFractionRetainedonNo.4Sieve>12%Fines<5%FinesGW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Well-graded gravel with or without sand,little to no fines Poorly graded gravel with or without sand,little to no fines Silty gravel with or without sand Clayey gravel with or without sand Well-graded sand with or without gravel,little to no fines Poorly graded sand with or without gravel,little to no fines Silty sand with or without gravel Clayey sand with or without gravel Silt with or without sand or gravel;sandy or gravelly silt Clay of low to medium plasticity;lean clay with or without sand or gravel; sandy or gravelly lean clay Organic clay or silt of low plasticity Elastic silt with or without sand or gravel;sandy or gravelly elastic silt Clay of high plasticity; fat clay with or without sand or gravel;sandy or gravelly fat clay Organic clay or silt of medium to high plasticity Peat,muck,and other highly organic soils EEaarrtthh SSoolluuttiioonnss NNWW LLC Geotechnical Engineering,Construction Observation/Testing and Environmental Services EXPLORATION LOG KEYFillFILLMadeGround Classifications of soils in this geotechnical report and as shown on the exploration logs are based on visual field and/or laboratory observations,which include density/consistency,moisture condition,grain size,and plasticity estimates,and should not be construed to imply field or laboratory testing unless presented herein. Visual-manual and/or laboratory classification methods of ASTM D2487 and D2488 were used as an identification guide for the Unified Soil Classification System. Terms Describing Relative Density and Consistency Coarse-Grained Soils: Fine-Grained Soils: SPT blows/foot SPT blows/foot Test Symbols &Units Fines =Fines Content (%) MC =Moisture Content (%) DD =Dry Density (pcf) Str =Shear Strength (tsf) PID =Photoionization Detector (ppm) OC =Organic Content (%) CEC =Cation Exchange Capacity (meq/100 g) LL =Liquid Limit (%) PL =Plastic Limit (%) PI =Plasticity Index (%) Component Definitions Descriptive Term Size Range and Sieve Number Smaller than No.200 (0.075 mm) Boulders Modifier Definitions Percentage by Weight (Approx.) <5 5 to 14 15 to 29 >30_ Modifier Trace (sand,silt,clay,gravel) Slightly (sandy,silty,clayey,gravelly) Sandy,silty,clayey,gravelly Very (sandy,silty,clayey,gravelly) Moisture Content Dry -Absence of moisture,dusty,dry to the touch Damp -Perceptible moisture,likely below optimum MC Moist -Damp but no visible water,likely at/near optimum MC Wet -Water visible but not free draining, likely above optimum MC Saturated/Water Bearing -Visible free water,typically below groundwater table Symbols Cement grout surface seal Bentonite chips Grout seal Filter pack with blank casing section Screened casing or Hydrotip with filter pack End cap ATD =At time of drilling Static water level (date) _>50 Density Very Loose Loose Medium Dense Dense Very Dense Consistency Very Soft Soft Medium Stiff Stiff Very Stiff Hard <4 4 to 9 10 to 29 30 to 49 <2 2 to 3 4 to 7 8 to 14 15 to 29 _>30 LLC EarthSolutions NW LLC Cobbles Gravel Coarse Gravel Fine Gravel Sand Coarse Sand Medium Sand Fine Sand Silt and Clay Larger than 12" 3"to 12" 3"to No.4 (4.75 mm) 3"to 3/4" 3/4"to No.4 (4.75 mm) No.4 (4.75 mm)to No.200 (0.075 mm) No.4 (4.75 mm)to No.10 (2.00 mm) No.10 (2.00 mm)to No.40 (0.425 mm) No.40 (0.425 mm)to No.200 (0.075 mm) 187.5 184.5 176.0 SS SS SS SS 67 100 100 100 14-10-11 (21) 8-11-13 (24) 6-8-11 (19) 9-14-20 (34) MC = 18.6 Fines = 26.5 MC = 31.8 MC = 30.4 Fines = 99.1 MC = 30.5 SP- SM SM ML SM Brown poorly graded SAND with silt, medium dense, moist (Drill Pad Fill) Gray silty SAND, medium dense, moist to wet -moderate iron oxide staining, [USDA Classification: slightly gravelly sandy LOAM] Brown sandy SILT, medium dense, wet -increased texture, gray layers -trace wood debris -becomes silt [USDA Classification: LOAM] -moderate iron oxide staining layers (1") -light perched groundwater seepage -becomes dense -layered moderate iron oxide staining (<1") Gray silty SAND, very dense, wet 2.5 5.5 14.0 (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 15.0 PAGE 1 OF 4 BORING NUMBER B-1 CHECKED BY HTW NOTES SURFACE CONDITIONS Brush AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING DRILLING CONTRACTOR Geologic Drill Partners DATE STARTED 7/19/22 COMPLETED 7/19/22 GROUND WATER LEVEL: GROUND ELEVATION 190 ft LOGGED BY CGH LATITUDE 47.33696 LONGITUDE -122.33791 PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GENERAL BH / TP / WELL - 8670.GPJ - GINT US.GDT - 8/30/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 161.0 SS SS SS 100 67 100 13-28-31 (59) 21-34-40 (74) 20-30-44 (74) MC = 29.5 MC = 14.0 Fines = 12.4 MC = 27.8 SM ML Gray silty SAND, very dense, wet (continued) -heavy iron oxide staining, light perched groundwater seepage [USDA Classification: slightly gravelly SAND] -heavy iron oxide staining -moderate to heavy perched groundwater seepage Gray SILT with sand, very dense, wet 29.0 (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)15.0 17.5 20.0 22.5 25.0 27.5 30.0 PAGE 2 OF 4 BORING NUMBER B-1 CHECKED BY HTW NOTES SURFACE CONDITIONS Brush AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING DRILLING CONTRACTOR Geologic Drill Partners DATE STARTED 7/19/22 COMPLETED 7/19/22 GROUND WATER LEVEL: GROUND ELEVATION 190 ft LOGGED BY CGH LATITUDE 47.33696 LONGITUDE -122.33791 PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GENERAL BH / TP / WELL - 8670.GPJ - GINT US.GDT - 8/30/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 150.0 SS SS SS 100 71 100 23-50/6" 27-34- 50/5" 27-34- 50/5" MC = 25.6 Fines = 83.7 MC = 28.9 MC = 28.9 ML SM Gray SILT with sand, very dense, wet (continued) -heavy perched groundwater seepage [USDA Classification: LOAM] -heavy iron oxide staining -sand lens (unknown thickness) -heavy perched groundwater seepage Gray silty SAND, very dense, wet -sand lens at top 5' of sample -moderately cemented, perched groundwater seepage 40.0 (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)30.0 32.5 35.0 37.5 40.0 42.5 45.0 PAGE 3 OF 4 BORING NUMBER B-1 CHECKED BY HTW NOTES SURFACE CONDITIONS Brush AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING DRILLING CONTRACTOR Geologic Drill Partners DATE STARTED 7/19/22 COMPLETED 7/19/22 GROUND WATER LEVEL: GROUND ELEVATION 190 ft LOGGED BY CGH LATITUDE 47.33696 LONGITUDE -122.33791 PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GENERAL BH / TP / WELL - 8670.GPJ - GINT US.GDT - 8/30/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 141.0 139.0 SS SS 100 100 27-33- 50/6" 28-50/6" MC = 27.2 MC = 27.3 Fines = 94.7 SM ML Gray silty SAND, very dense, wet (continued) -heavy perched groundwater seepage Gray SILT, very dense, wet -sands lens (unknown thickness) -heavy perched groundwater seepage [USDA Classification: LOAM] Boring terminated at 51. feet become below existing grade. Groundwater seepage encountered at 8.5 to BOH during drilling. LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on this test log as a standalone document. Refer to the text of the geotechnical report for a complete understanding of subsurface conditions. 49.0 51.0SAMPLE TYPENUMBERDEPTH(ft)45.0 47.5 50.0 PAGE 4 OF 4 BORING NUMBER B-1 CHECKED BY HTW NOTES SURFACE CONDITIONS Brush AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING DRILLING CONTRACTOR Geologic Drill Partners DATE STARTED 7/19/22 COMPLETED 7/19/22 GROUND WATER LEVEL: GROUND ELEVATION 190 ft LOGGED BY CGH LATITUDE 47.33696 LONGITUDE -122.33791 PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GENERAL BH / TP / WELL - 8670.GPJ - GINT US.GDT - 8/30/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 166.0 155.0 SS SS SS SS 17 100 100 100 8-4-2 (6) 1-1-5 (6) 6-7-11 (18) 9-11-15 (26) MC = 23.8 MC = 21.8 Fines = 29.1 MC = 28.1 MC = 25.9 Fines = 12.3 SM SM Brown silty SAND, loose, moist to wet (Drill Pad Fill) Gray silty SAND, loose, wet [USDA Classification: slightly gravelly sandy LOAM] -becomes medium dense -moderate perched groundwater seepage -heavy iron oxide staining [USDA Classification: slightly gravelly SAND] -moderate iron oxide staining -moderate perched groundwater seepage 4.0 15.0 (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 15.0 PAGE 1 OF 3 BORING NUMBER B-2 CHECKED BY HTW NOTES SURFACE CONDITIONS Bush AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING DRILLING CONTRACTOR Geologic Drill Partners DATE STARTED 7/19/22 COMPLETED 7/19/22 GROUND WATER LEVEL: GROUND ELEVATION 170 ft LOGGED BY CGH LATITUDE 47.33705 LONGITUDE -122.33748 PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GENERAL BH / TP / WELL - 8670.GPJ - GINT US.GDT - 8/30/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 144.0 141.0 SS SS SS 100 100 100 23-29-40 (69) 14-50/6" 18-20-30 (50) MC = 31.7 MC = 26.7 Fines = 34.5 MC = 28.8 SM ML SM Gray silty SAND, very dense, wet -moderate perched groundwater seepage [USDA Classification: very fine sandy LOAM], light perched groundwater seepage -heavy perched groundwater seepage -becomes saturated Gray SILT, very dense, wet Gray silty SAND, very dense, wet 26.0 29.0 (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)15.0 17.5 20.0 22.5 25.0 27.5 30.0 PAGE 2 OF 3 BORING NUMBER B-2 CHECKED BY HTW NOTES SURFACE CONDITIONS Bush AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING DRILLING CONTRACTOR Geologic Drill Partners DATE STARTED 7/19/22 COMPLETED 7/19/22 GROUND WATER LEVEL: GROUND ELEVATION 170 ft LOGGED BY CGH LATITUDE 47.33705 LONGITUDE -122.33748 PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GENERAL BH / TP / WELL - 8670.GPJ - GINT US.GDT - 8/30/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 138.5 SS 100 16-24- 50/5"MC = 30.9 SM Gray silty SAND, very dense, wet (continued) -heavy perched groundwater seepage Boring terminated at 31.5 feet below existing grade. Groundwater seepage encountered at 7.5 feet to BOH during drilling. LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on this test log as a standalone document. Refer to the text of the geotechnical report for a complete understanding of subsurface conditions. 31.5SAMPLE TYPENUMBERDEPTH(ft)30.0 PAGE 3 OF 3 BORING NUMBER B-2 CHECKED BY HTW NOTES SURFACE CONDITIONS Bush AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING DRILLING CONTRACTOR Geologic Drill Partners DATE STARTED 7/19/22 COMPLETED 7/19/22 GROUND WATER LEVEL: GROUND ELEVATION 170 ft LOGGED BY CGH LATITUDE 47.33705 LONGITUDE -122.33748 PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GENERAL BH / TP / WELL - 8670.GPJ - GINT US.GDT - 8/30/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 174.5 172.0 170.5 168.0 165.5 MC = 32.0 MC = 20.8 Fines = 38.3 MC = 20.0 MC = 21.7 TPSL SM ML SM SP- SM Dark brown TOPSOIL, roots to 7' Brown silty SAND, loose to medium dense, moist to wet Gray sandy SILT, medium dense, wet Gray silty SAND, medium dense, wet [USDA Classification: slightly gravelly fine sandy LOAM] Brown poorly graded SAND with silt, medium dense, wet -oxidized Test pit terminated at 9.5 feet below existing grade. No groundwater encountered during excavation. No caving observed. LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on this test log as a standalone document. Refer to the text of the geotechnical report for a complete understanding of subsurface conditions. 0.5 3.0 4.5 7.0 9.5SAMPLE TYPENUMBERDEPTH(ft)0.0 2.5 5.0 7.5 PAGE 1 OF 1 TEST PIT NUMBER TP-1 CHECKED BY HTW NOTES SURFACE CONDITIONS Brush AT TIME OF EXCAVATIONAT TIME OF EXCAVATION AFTER EXCAVATION EXCAVATION CONTRACTOR NW Excavating DATE STARTED 7/15/22 COMPLETED 7/15/22 GROUND WATER LEVEL: GROUND ELEVATION 175 ft LOGGED BY CGH LATITUDE 47.33703 LONGITUDE -122.33776 PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GENERAL BH / TP / WELL - 8670.GPJ - GINT US.GDT - 8/30/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG Earth Solutions NW, LLC Appendix B Laboratory Test Results ES-8670 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 0.0010.010.1110100 3 D100 140 Specimen Identification 1 fine 6 HYDROMETER 304 26.5 99.1 12.4 83.7 94.7 101/2 COBBLES Specimen Identification 4 coarse 20 401.5 8 14 USDA: Gray Slightly Gravelly Sandy Loam. USCS: SM. USDA: Brown Loam. USCS: ML. USDA: Gray Slightly Gravelly Sand. USCS: SM. USDA: Gray Loam. USCS: ML with Sand. USDA: Gray Loam. USCS: ML. 6 60 PERCENT FINER BY WEIGHTD10 0.099 0.191 0.329 0.338 GRAIN SIZE DISTRIBUTION 100 5.46 LL B-01 B-01 B-01 B-01 B-01 3/4 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS GRAVEL SAND 37.5 1.18 4.75 1.18 2 %Silt 1.75 B-01 B-01 B-01 B-01 B-01 2 2003 Cc CuClassification %Clay 16 PID60 D30 coarse SILT OR CLAYfinemedium GRAIN SIZE IN MILLIMETERS 3/8 50 2.5ft. 7.5ft. 20.0ft. 30.0ft. 50.0ft. 2.50ft. 7.50ft. 20.00ft. 30.00ft. 50.00ft. PL PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GRAIN SIZE USDA ES-8670 REDONDO BAY LOT 35.GPJ GINT US LAB.GDT 7/22/22Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 0.0010.010.1110100 3 D100 140 Specimen Identification 1 fine 6 HYDROMETER 304 29.1 12.3 34.5 38.3 101/2 COBBLES Specimen Identification 4 coarse 20 401.5 8 14 USDA: Gray Slightly Gravelly Sandy Loam. USCS: SM. USDA: Gray Slightly Gravelly Sand. USCS: SM. USDA: Gray Very Fine Sandy Loam. USCS: SM. USDA: Gray Slightly Gravelly Fine Sandy Loam. USCS: SM. 6 60 PERCENT FINER BY WEIGHTD10 0.08 0.197 0.225 0.339 0.126 0.13 GRAIN SIZE DISTRIBUTION 100 5.60 LL B-02 B-02 B-02 TP-01 3/4 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS GRAVEL SAND 9.5 4.75 2 4.75 %Silt 1.89 B-02 B-02 B-02 TP-01 2 2003 Cc CuClassification %Clay 16 PID60 D30 coarse SILT OR CLAYfinemedium GRAIN SIZE IN MILLIMETERS 3/8 50 5.0ft. 10.0ft. 20.0ft. 4.5ft. 5.00ft. 10.00ft. 20.00ft. 4.50ft. PL PROJECT NUMBER ES-8670 PROJECT NAME Redondo Bay Lot 35 GRAIN SIZE USDA ES-8670 REDONDO BAY LOT 35.GPJ GINT US LAB.GDT 7/22/22Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 Earth Solutions NW, LLC Appendix C Slope/W Output ES-8670 1.63 Distance 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200Elevation100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 Color Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Piezometric Surface Medium Dense Silty Sand 125 25 32 Medium Dense to Dense Sandy Silt 125 100 32 Very Dense Silt 120 250 32 2 Very Dense Silty Sand 125 125 36 1 Pre-Existing: Static Condition 8/21/23, 10:33 AM Pre-Existing - Static (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Static (2).html 1/7 P re -Exi sti ng - Static (2) Report generated using GeoStudio 2022.1. Copyright © 2022 Bentley Systems, Incorporated. File Informaon File Version: 11.04 Title: Penwell Property Created By: Chase Halsen Last Edited By: Chase Halsen Revision Number: 30 Date: 08/21/2023 Time: 10:32:51 AM Tool Version: 11.4.2.250 File Name: Updated Runs 08-18-23.gsz Directory: C:\Users\chase.halsen\Desktop\Project Files\8670\Slope Stability\ Last Solved Date: 08/21/2023 Last Solved Time: 10:32:53 AM Project Sengs Unit System: U.S. Customary Units Analysis Sengs Pre-Exisng - Stac (2) Kind: SLOPE/W Analysis Type: Morgenstern-Price Sengs Side Funcon Interslice force funcon opon: Half-Sine PWP Condions from: Piezometric Surfaces Apply Phreac Correcon: No Use Staged Rapid Drawdown: No Unit Weight of Water: 62.430189 pcf Slip Surface Direcon of movement: Le to Right Use Passive Mode: No Slip Surface Opon: Entry and Exit Crical slip surfaces saved: 1 Opmize Crical Slip Surface Locaon: No Tension Crack Opon: (none) Distribuon F of S Calculaon Opon: Constant Convergence Geometry Sengs Minimum Slip Surface Depth: 3 8/21/23, 10:33 AM Pre-Existing - Static (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Static (2).html 2/7 Number of Slices: 30 Factor of Safety Convergence Sengs Maximum Number of Iteraons: 100 Tolerable difference in F of S: 0.001 Under-Relaxaon Criteria Inial Rate: 1 Minimum Rate: 0.1 Rate Reducon Factor: 0.65 Reducon Frequency (iteraons): 50 Soluon Sengs Search Method: Root Finder Tolerable difference between starng and converged F of S: 3 Maximum iteraons to calculate converged lambda: 20 Max Absolute Lambda: 2 Materials Medium Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 25 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Medium Dense to Dense Sandy Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 100 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Very Dense Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 120 pcf Effecve Cohesion: 250 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Pore Water Pressure Piezometric Surface: 2 Very Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 125 psf Effecve Fricon Angle: 36 ° Phi-B: 0 ° Pore Water Pressure Piezometric Surface: 1 8/21/23, 10:33 AM Pre-Existing - Static (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Static (2).html 3/7 Slip Surface Entry and Exit Le Type: Range Le-Zone Le Coordinate: (0, 202) Le-Zone Right Coordinate: (99, 170.33679) Le-Zone Increment: 20 Right Type: Range Right-Zone Le Coordinate: (102.40444, 168.46976) Right-Zone Right Coordinate: (182.65, 136) Right-Zone Increment: 20 Radius Increments: 4 Slip Surface Limits Le Coordinate: (0, 202) Right Coordinate: (182.65, 136) Piezometric Surfaces Piezometric Surface 1 Coordinates X Y Coordinate 1 0 175 Coordinate 2 90 175 Piezometric Surface 2 Coordinates X Y Coordinate 1 0 160 Coordinate 2 117.65 160 Geometry Name: 2D Geometry (2) Sengs View: 2D Element Thickness: 1 Points X Y Point 1 0 202 Point 2 18 200 Point 3 26 198 8/21/23, 10:33 AM Pre-Existing - Static (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Static (2).html 4/7 Point 4 33 196 Point 5 40 194 Point 6 47 192 Point 7 53 190 Point 8 59 188 Point 9 64 186 Point 10 69 184 Point 11 75 182 Point 12 81 180 Point 13 85 178 Point 14 99.65 170 Point 15 117.65 160 Point 16 130.65 154 Point 17 136.65 152 Point 18 142.65 150 Point 19 146.65 148 Point 20 160.65 146 Point 21 171.65 142 Point 22 174.65 140 Point 23 182.65 136 Point 24 0 185 Point 25 66 185 Point 26 0 175 Point 27 90 175 Point 28 0 160 Point 29 0 150 Point 30 0 140 Point 31 182.65 100 Point 32 0 100 Regions Material Points Area Region 1 Medium Dense Silty Sand 1,24,25,9,8,7,6,5,4,3,2 681 ² Region 2 Medium Dense to Dense Sandy Silt 24,26,27,13,12,11,10,25 796 ² Region 3 Very Dense Silty Sand 26,28,15,14,27 1,560.6 ² Region 4 Very Dense Silt 28,29,18,17,16,15 1,291.5 ² Region 5 Very Dense Silty Sand 29,30,18 713.25 ² Region 6 Very Dense Silt 30,18,19,20,21,22,23,31,32 8,184.2 ² Slip Results Slip Surfaces Analysed: 1976 of 2205 converged Current Slip Surface Slip Surface: 1,303 8/21/23, 10:33 AM Pre-Existing - Static (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Static (2).html 5/7 Factor of Safety: 1.63 Volume: 742.90606 ³ Weight: 91,805.306 lbf Resisng Moment: 4,148,166.9 lbf· Acvang Moment: 2,538,313.3 lbf· Resisng Force: 53,193.605 lbf Acvang Force: 32,553.883 lbf Slip Rank: 1 of 2,205 slip surfaces Exit: (133.64053, 153.00316) Entry: (60.842715, 187.26291) Radius: 69.774632 Center: (121.51762, 221.71658) Slip Slices X Y PWP Base Normal Stress Friconal Strength Cohesive Strength Sucon Strength Base Material Slice 1 61.513722 186.13146 0 psf 49.09799 psf 30.679829 psf 25 psf 0 psf Medium Dense Silty Sand Slice 2 63.092364 183.60846 0 psf 152.43812 psf 95.25391 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 3 65 180.83447 0 psf 305.74949 psf 191.05348 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 4 67.5 177.61476 0 psf 485.89888 psf 303.62332 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 5 69.345202 175.38875 0 psf 620.24836 psf 387.57419 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 6 71.017803 173.60666 86.986399 psf 713.9727 psf 455.53221 psf 125 psf 0 psf Very Dense Silty Sand Slice 7 73.672601 170.96202 252.092 psf 902.86186 psf 472.81198 psf 125 psf 0 psf Very Dense 8/21/23, 10:33 AM Pre-Existing - Static (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Static (2).html 6/7 Silty Sand Slice 8 76.5 168.44317 409.34426 psf 1,074.5706 psf 483.31523 psf 125 psf 0 psf Very Dense Silty Sand Slice 9 79.5 166.04354 559.15339 psf 1,234.8535 psf 490.92486 psf 125 psf 0 psf Very Dense Silty Sand Slice 10 82 164.22411 672.74104 psf 1,342.3711 psf 486.51469 psf 125 psf 0 psf Very Dense Silty Sand Slice 11 84 162.89889 755.47451 psf 1,402.2566 psf 469.91467 psf 125 psf 0 psf Very Dense Silty Sand Slice 12 85.991673 161.67427 831.92763 psf 1,447.1421 psf 446.97944 psf 125 psf 0 psf Very Dense Silty Sand Slice 13 87.975018 160.54376 902.50584 psf 1,477.0148 psf 417.40519 psf 125 psf 0 psf Very Dense Silty Sand Slice 14 89.483346 159.73298 16.669898 psf 1,475.5216 psf 911.59172 psf 250 psf 0 psf Very Dense Silt Slice 15 91.20625 158.88405 69.66876 psf 1,515.941 psf 903.73122 psf 250 psf 0 psf Very Dense Silt Slice 16 93.61875 157.77582 138.8557 psf 1,571.1111 psf 894.97248 psf 250 psf 0 psf Very Dense Silt Slice 17 96.03125 156.77611 201.26824 psf 1,614.9824 psf 883.38662 psf 250 psf 0 psf Very Dense Silt Slice 18 98.44375 155.87995 257.21556 psf 1,646.2157 psf 867.94364 psf 250 psf 0 psf Very Dense Silt Slice 19 100.93571 155.06019 308.39298 psf 1,657.6042 psf 843.08076 psf 250 psf 0 psf Very Dense Silt Slice 20 103.50714 154.31962 354.62748 psf 1,645.2073 psf 806.44376 psf 250 psf 0 psf Very Dense Silt Slice 21 106.07857 153.68426 394.29295 psf 1,610.8379 psf 760.18165 psf 250 psf 0 psf Very Dense Silt 8/21/23, 10:33 AM Pre-Existing - Static (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Static (2).html 7/7 Slice 22 108.65 153.15119 427.57232 psf 1,552.123 psf 702.69725 psf 250 psf 0 psf Very Dense Silt Slice 23 111.22143 152.71805 454.61381 psf 1,467.1887 psf 632.72701 psf 250 psf 0 psf Very Dense Silt Slice 24 113.79286 152.38294 475.53452 psf 1,354.9915 psf 549.54572 psf 250 psf 0 psf Very Dense Silt Slice 25 116.36429 152.14446 490.42301 psf 1,215.604 psf 453.14335 psf 250 psf 0 psf Very Dense Silt Slice 26 118.95 152.00134 0 psf 1,115.2675 psf 696.89648 psf 250 psf 0 psf Very Dense Silt Slice 27 121.55 151.95407 0 psf 952.49222 psf 595.1832 psf 250 psf 0 psf Very Dense Silt Slice 28 124.15 152.00376 0 psf 766.72903 psf 479.10547 psf 250 psf 0 psf Very Dense Silt Slice 29 126.75 152.15063 0 psf 563.11485 psf 351.87321 psf 250 psf 0 psf Very Dense Silt Slice 30 129.35 152.39529 0 psf 347.3773 psf 217.06543 psf 250 psf 0 psf Very Dense Silt Slice 31 132.14526 152.77266 0 psf 132.5938 psf 82.853803 psf 250 psf 0 psf Very Dense Silt 1.00 Distance 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200Elevation100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 Color Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Piezometric Surface Medium Dense Silty Sand 125 25 32 Medium Dense to Dense Sandy Silt 125 100 32 Very Dense Silt 120 500 32 2 Very Dense Silty Sand 125 250 36 1 Color Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Piezometric Surface Medium Dense Silty Sand 125 25 32 Medium Dense to Dense Sandy Silt 125 100 32 Very Dense Silt 120 500 32 2 Very Dense Silty Sand 125 250 36 1 Pre-Existing: Seismic Condition 8/21/23, 10:37 AM Pre-Existing - Seismic (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Seismic (2).html 1/8 P re -Exi sti ng - Seismic (2) Report generated using GeoStudio 2022.1. Copyright © 2022 Bentley Systems, Incorporated. File Informaon File Version: 11.04 Title: Penwell Property Created By: Chase Halsen Last Edited By: Chase Halsen Revision Number: 31 Date: 08/21/2023 Time: 10:35:12 AM Tool Version: 11.4.2.250 File Name: Updated Runs 08-18-23.gsz Directory: C:\Users\chase.halsen\Desktop\Project Files\8670\Slope Stability\ Last Solved Date: 08/21/2023 Last Solved Time: 10:35:14 AM Project Sengs Unit System: U.S. Customary Units Analysis Sengs Pre-Exisng - Seismic (2) Kind: SLOPE/W Analysis Type: Morgenstern-Price Sengs Side Funcon Interslice force funcon opon: Half-Sine PWP Condions from: Piezometric Surfaces Apply Phreac Correcon: No Use Staged Rapid Drawdown: No Unit Weight of Water: 62.430189 pcf Slip Surface Direcon of movement: Le to Right Use Passive Mode: No Slip Surface Opon: Entry and Exit Crical slip surfaces saved: 1 Opmize Crical Slip Surface Locaon: No Tension Crack Opon: (none) Distribuon F of S Calculaon Opon: Constant Convergence Geometry Sengs Minimum Slip Surface Depth: 3 8/21/23, 10:37 AM Pre-Existing - Seismic (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Seismic (2).html 2/8 Number of Slices: 30 Factor of Safety Convergence Sengs Maximum Number of Iteraons: 100 Tolerable difference in F of S: 0.001 Under-Relaxaon Criteria Inial Rate: 1 Minimum Rate: 0.1 Rate Reducon Factor: 0.65 Reducon Frequency (iteraons): 50 Soluon Sengs Search Method: Root Finder Tolerable difference between starng and converged F of S: 3 Maximum iteraons to calculate converged lambda: 20 Max Absolute Lambda: 2 Materials Medium Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 25 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Medium Dense to Dense Sandy Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 100 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Very Dense Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 120 pcf Effecve Cohesion: 500 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Pore Water Pressure Piezometric Surface: 2 Very Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 250 psf Effecve Fricon Angle: 36 ° Phi-B: 0 ° Pore Water Pressure Piezometric Surface: 1 8/21/23, 10:37 AM Pre-Existing - Seismic (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Seismic (2).html 3/8 Slip Surface Entry and Exit Le Type: Range Le-Zone Le Coordinate: (0, 202) Le-Zone Right Coordinate: (99, 170.33679) Le-Zone Increment: 20 Right Type: Range Right-Zone Le Coordinate: (102.77214, 168.26548) Right-Zone Right Coordinate: (182.65, 136) Right-Zone Increment: 20 Radius Increments: 4 Slip Surface Limits Le Coordinate: (0, 202) Right Coordinate: (182.65, 136) Piezometric Surfaces Piezometric Surface 1 Coordinates X Y Coordinate 1 0 175 Coordinate 2 90 175 Piezometric Surface 2 Coordinates X Y Coordinate 1 0 160 Coordinate 2 117.65 160 Seismic Coefficients Horz Seismic Coef.: 0.343 Geometry Name: 2D Geometry (2) Sengs View: 2D Element Thickness: 1 8/21/23, 10:37 AM Pre-Existing - Seismic (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Seismic (2).html 4/8 Points X Y Point 1 0 202 Point 2 18 200 Point 3 26 198 Point 4 33 196 Point 5 40 194 Point 6 47 192 Point 7 53 190 Point 8 59 188 Point 9 64 186 Point 10 69 184 Point 11 75 182 Point 12 81 180 Point 13 85 178 Point 14 99.65 170 Point 15 117.65 160 Point 16 130.65 154 Point 17 136.65 152 Point 18 142.65 150 Point 19 146.65 148 Point 20 160.65 146 Point 21 171.65 142 Point 22 174.65 140 Point 23 182.65 136 Point 24 0 185 Point 25 66 185 Point 26 0 175 Point 27 90 175 Point 28 0 160 Point 29 0 150 Point 30 0 140 Point 31 182.65 100 Point 32 0 100 Regions Material Points Area Region 1 Medium Dense Silty Sand 1,24,25,9,8,7,6,5,4,3,2 681 ² Region 2 Medium Dense to Dense Sandy Silt 24,26,27,13,12,11,10,25 796 ² Region 3 Very Dense Silty Sand 26,28,15,14,27 1,560.6 ² Region 4 Very Dense Silt 28,29,18,17,16,15 1,291.5 ² Region 5 Very Dense Silty Sand 29,30,18 713.25 ² Region 6 Very Dense Silt 30,18,19,20,21,22,23,31,32 8,184.2 ² 8/21/23, 10:37 AM Pre-Existing - Seismic (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Seismic (2).html 5/8 Slip Results Slip Surfaces Analysed: 1974 of 2205 converged Current Slip Surface Slip Surface: 352 Factor of Safety: 1.00 Volume: 1,326.3536 ³ Weight: 165,216.42 lbf Resisng Moment: 18,769,043 lbf· Acvang Moment: 18,736,095 lbf· Resisng Force: 102,714.67 lbf Acvang Force: 102,577.27 lbf Slip Rank: 1 of 2,205 slip surfaces Exit: (129.79825, 154.39312) Entry: (15.611699, 200.26537) Radius: 171.21886 Center: (132.26756, 325.59417) Slip Slices X Y PWP Base Normal Stress Friconal Strength Cohesive Strength Sucon Strength Base Material Slice 1 16.805849 199.17472 0 psf 60.718503 psf 37.941132 psf 25 psf 0 psf Medium Dense Silty Sand Slice 2 20 196.34683 0 psf 226.40536 psf 141.47377 psf 25 psf 0 psf Medium Dense Silty Sand Slice 3 24 192.97679 0 psf 393.65937 psf 245.98568 psf 25 psf 0 psf Medium Dense Silty Sand Slice 4 27.75 189.99514 0 psf 524.75779 psf 327.90506 psf 25 psf 0 psf Medium Dense Silty Sand Slice 5 31.25 187.36735 0 psf 627.14129 psf 391.88137 psf 25 psf 0 psf Medium Dense Silty Sand Slice 6 33.773832 185.54422 0 psf 695.42604 psf 434.55042 psf 25 psf 0 psf Medium Dense Silty Sand Slice 7 37.273832 183.18156 0 psf 768.72969 psf 480.35562 psf 100 psf 0 psf Medium Dense to 8/21/23, 10:37 AM Pre-Existing - Seismic (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Seismic (2).html 6/8 Dense Sandy Silt Slice 8 41.75 180.27308 0 psf 883.22526 psf 551.90039 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 9 45.25 178.15024 0 psf 968.53782 psf 605.2096 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 10 48.898984 176.05872 0 psf 1,050.7445 psf 656.57802 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 11 51.898984 174.41469 36.541116 psf 1,136.6913 psf 799.30589 psf 250 psf 0 psf Very Dense Silty Sand Slice 12 54.5 173.0646 120.8275 psf 1,201.8902 psf 785.43804 psf 250 psf 0 psf Very Dense Silty Sand Slice 13 57.5 171.57167 214.03124 psf 1,273.147 psf 769.49264 psf 250 psf 0 psf Very Dense Silty Sand Slice 14 61.5 169.70859 330.34349 psf 1,349.2342 psf 740.26742 psf 250 psf 0 psf Very Dense Silty Sand Slice 15 65 168.14643 427.86976 psf 1,399.7872 psf 706.13934 psf 250 psf 0 psf Very Dense Silty Sand Slice 16 67.5 167.1062 492.81127 psf 1,440.6062 psf 688.6133 psf 250 psf 0 psf Very Dense Silty Sand Slice 17 70.5 165.91299 567.30395 psf 1,508.6398 psf 683.92052 psf 250 psf 0 psf Very Dense Silty Sand Slice 18 73.5 164.78459 637.75012 psf 1,579.1477 psf 683.96541 psf 250 psf 0 psf Very Dense 8/21/23, 10:37 AM Pre-Existing - Seismic (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Seismic (2).html 7/8 Silty Sand Slice 19 76.5 163.71965 704.23444 psf 1,652.4456 psf 688.91575 psf 250 psf 0 psf Very Dense Silty Sand Slice 20 79.5 162.71693 766.83466 psf 1,728.2989 psf 698.54463 psf 250 psf 0 psf Very Dense Silty Sand Slice 21 83 161.63001 834.69079 psf 1,784.0802 psf 689.77176 psf 250 psf 0 psf Very Dense Silty Sand Slice 22 86.87103 160.51453 904.33069 psf 1,793.5001 psf 646.01936 psf 250 psf 0 psf Very Dense Silty Sand Slice 23 89.37103 159.83723 10.161901 psf 2,113.2764 psf 1,314.1718 psf 500 psf 0 psf Very Dense Silt Slice 24 91.608333 159.28126 44.871106 psf 2,083.4999 psf 1,273.8766 psf 500 psf 0 psf Very Dense Silt Slice 25 94.825 158.52761 91.921735 psf 2,027.2833 psf 1,209.3481 psf 500 psf 0 psf Very Dense Silt Slice 26 98.041667 157.83901 134.9107 psf 1,943.052 psf 1,129.8521 psf 500 psf 0 psf Very Dense Silt Slice 27 101.45 157.1815 175.95954 psf 1,814.9284 psf 1,024.1414 psf 500 psf 0 psf Very Dense Silt Slice 28 105.05 156.56228 214.61728 psf 1,639.1737 psf 890.16166 psf 500 psf 0 psf Very Dense Silt Slice 29 108.65 156.02175 248.363 psf 1,432.2774 psf 739.79181 psf 500 psf 0 psf Very Dense Silt Slice 30 112.25 155.55914 277.24356 psf 1,199.1703 psf 576.0838 psf 500 psf 0 psf Very Dense Silt Slice 31 115.85 155.17383 301.29861 psf 945.79017 psf 402.72302 psf 500 psf 0 psf Very Dense Silt Slice 32 119.67471 154.8511 0 psf 708.77901 psf 442.89428 psf 500 psf 0 psf Very Dense Silt Slice 33 123.72412 154.60061 0 psf 424.23211 psf 265.08965 psf 500 psf 0 psf Very Dense Silt 8/21/23, 10:37 AM Pre-Existing - Seismic (2) file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Pre Existing/Updated Runs 08-18-23 - Pre-Existing - Seismic (2).html 8/8 Slice 34 127.77354 154.44628 0 psf 135.94436 psf 84.947464 psf 500 psf 0 psf Very Dense Silt 1.58 Distance 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200Elevation100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 Color Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Piezometric Surface Fill 125 0 32 Medium Dense Silty Sand 125 25 32 Medium Dense to Dense Sandy Silt 125 100 32 Very Dense Silt 120 250 32 2 Very Dense Silty Sand 125 125 36 1 Post-Construction: Static Condition 8/22/23, 11:56 AM Post-Construciton - Static file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Stat…1/8 Post-Con struci ton - Stat ic Report generated using GeoStudio 2022.1. Copyright © 2022 Bentley Systems, Incorporated. File Informaon File Version: 11.04 Title: Penwell Property Created By: Chase Halsen Last Edited By: Chase Halsen Revision Number: 33 Date: 08/22/2023 Time: 11:55:01 AM Tool Version: 11.4.2.250 File Name: Updated Runs 08-18-23.gsz Directory: C:\Users\chase.halsen\Desktop\Project Files\8670\Slope Stability\ Last Solved Date: 08/22/2023 Last Solved Time: 11:55:03 AM Project Sengs Unit System: U.S. Customary Units Analysis Sengs Post-Construciton - Stac Kind: SLOPE/W Analysis Type: Morgenstern-Price Sengs Side Funcon Interslice force funcon opon: Half-Sine PWP Condions from: Piezometric Surfaces Apply Phreac Correcon: No Use Staged Rapid Drawdown: No Unit Weight of Water: 62.430189 pcf Slip Surface Direcon of movement: Le to Right Use Passive Mode: No Slip Surface Opon: Entry and Exit Crical slip surfaces saved: 1 Opmize Crical Slip Surface Locaon: No Tension Crack Opon: (none) Distribuon F of S Calculaon Opon: Constant Convergence Geometry Sengs Minimum Slip Surface Depth: 3 8/22/23, 11:56 AM Post-Construciton - Static file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Stat…2/8 Number of Slices: 30 Factor of Safety Convergence Sengs Maximum Number of Iteraons: 100 Tolerable difference in F of S: 0.001 Under-Relaxaon Criteria Inial Rate: 1 Minimum Rate: 0.1 Rate Reducon Factor: 0.65 Reducon Frequency (iteraons): 50 Soluon Sengs Search Method: Root Finder Tolerable difference between starng and converged F of S: 3 Maximum iteraons to calculate converged lambda: 20 Max Absolute Lambda: 2 Materials Medium Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 25 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Medium Dense to Dense Sandy Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 100 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Very Dense Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 120 pcf Effecve Cohesion: 250 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Pore Water Pressure Piezometric Surface: 2 Very Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 125 psf Effecve Fricon Angle: 36 ° Phi-B: 0 ° Pore Water Pressure Piezometric Surface: 1 8/22/23, 11:56 AM Post-Construciton - Static file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Stat…3/8 Fill Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 0 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Slip Surface Entry and Exit Le Type: Range Le-Zone Le Coordinate: (0, 202) Le-Zone Right Coordinate: (75, 182) Le-Zone Increment: 20 Right Type: Range Right-Zone Le Coordinate: (77, 181.33333) Right-Zone Right Coordinate: (140, 151.0001) Right-Zone Increment: 20 Radius Increments: 4 Slip Surface Limits Le Coordinate: (0, 202) Right Coordinate: (183, 100) Piezometric Surfaces Piezometric Surface 1 Coordinates X Y Coordinate 1 0 175 Coordinate 2 90 175 Piezometric Surface 2 Coordinates X Y Coordinate 1 0 160 Coordinate 2 117.65 160 Surcharge Loads Surcharge Load 1 Surcharge (Unit Weight): 375 pcf Direcon: Vercal 8/22/23, 11:56 AM Post-Construciton - Static file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Stat…4/8 Coordinates X Y 6 194 40 194 Surcharge Load 2 Surcharge (Unit Weight): 375 pcf Direcon: Vercal Coordinates X Y 40 185 75 185 Geometry Name: 2D Geometry Sengs View: 2D Element Thickness: 1 Points X Y Point 1 0 202 Point 2 6 201 Point 3 6 192.5 Point 4 40 192.5 Point 5 40 184 Point 6 75 184 Point 7 75 182 Point 8 81 180 Point 9 85 178 Point 10 99.65 170 Point 11 117.65 160 Point 12 130.65 154 Point 13 136.65 152 Point 14 142.65 150 Point 15 146.65 148 Point 16 160.65 146 Point 17 166.65 144 Point 18 171.65 142 Point 19 174.65 140 Point 20 182.65 136 Point 21 0 185 Point 22 40 185 8/22/23, 11:56 AM Post-Construciton - Static file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Stat…5/8 Point 23 0 175 Point 24 90 175 Point 25 0 160 Point 26 0 150 Point 27 140.00035 151 Point 28 0 140 Point 29 0 100 Point 30 183 100 Point 31 67 184 Regions Material Points Area Region 1 Medium Dense Silty Sand 1,21,22,4,3,2 354 ² Region 2 Medium Dense to Dense Sandy Silt 21,23,24,9,8,7,31,5,22 766.5 ² Region 3 Very Dense Silty Sand 23,25,11,10,24 1,560.6 ² Region 4 Very Dense Silt 25,26,27,13,12,11 1,220.5 ² Region 5 Very Dense Silty Sand 26,28,27 700 ² Region 6 Very Dense Silt 28,29,30,20,19,18,17,16,15,14,27 8,276.1 ² Region 7 Fill 31,7,6 8 ² Slip Results Slip Surfaces Analysed: 1060 of 2205 converged Current Slip Surface Slip Surface: 1,983 Factor of Safety: 1.58 Volume: 622.90702 ³ Weight: 76,923.908 lbf Resisng Moment: 3,336,903.6 lbf· Acvang Moment: 2,114,081.3 lbf· Resisng Force: 46,809.216 lbf Acvang Force: 29,660.1 lbf Slip Rank: 1 of 2,205 slip surfaces Exit: (133.3147, 153.11177) Entry: (67.591724, 184) Radius: 62.948358 Center: (122.32471, 215.09334) Slip Slices X Y PWP Base Normal Stress Friconal Strength Cohesive Strength Sucon Strength Base Material Slice 1 67.640908 183.91374 0 psf 227.25273 psf 142.00327 psf 0 psf 0 psf Fill Slice 2 68.707772 182.17014 0 psf 293.90117 psf 183.64983 psf 100 psf 0 psf Medium Dense 8/22/23, 11:56 AM Post-Construciton - Static file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Stat…6/8 to Dense Sandy Silt Slice 3 70.743129 179.05616 0 psf 532.24551 psf 332.58391 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 4 72.778487 176.29975 0 psf 745.24048 psf 465.67794 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 5 74.398083 174.29295 44.141169 psf 872.31097 psf 601.70058 psf 125 psf 0 psf Very Dense Silty Sand Slice 6 76 172.49834 156.17904 psf 640.8637 psf 352.14402 psf 125 psf 0 psf Very Dense Silty Sand Slice 7 78 170.41861 286.01681 psf 785.97688 psf 363.24226 psf 125 psf 0 psf Very Dense Silty Sand Slice 8 80 168.51772 404.6901 psf 912.8924 psf 369.23058 psf 125 psf 0 psf Very Dense Silty Sand Slice 9 82 166.77443 513.52367 psf 1,012.6592 psf 362.64317 psf 125 psf 0 psf Very Dense Silty Sand Slice 10 84 165.17218 613.55294 psf 1,087.8964 psf 344.63072 psf 125 psf 0 psf Very Dense Silty Sand Slice 11 86.25 163.52995 716.07753 psf 1,150.9785 psf 315.97406 psf 125 psf 0 psf Very Dense Silty Sand Slice 12 88.75 161.86694 819.89964 psf 1,201.8483 psf 277.50196 psf 125 psf 0 psf Very Dense Silty Sand Slice 13 90.937217 160.53922 0 psf 1,222.2386 psf 888.00835 psf 125 psf 0 psf Very Dense Silty Sand 8/22/23, 11:56 AM Post-Construciton - Static file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Stat…7/8 Slice 14 92.84638 159.48477 32.166051 psf 1,288.6197 psf 785.11938 psf 250 psf 0 psf Very Dense Silt Slice 15 94.790272 158.49668 93.852488 psf 1,348.6994 psf 784.11539 psf 250 psf 0 psf Very Dense Silt Slice 16 96.734163 157.59127 150.37716 psf 1,401.9224 psf 782.05227 psf 250 psf 0 psf Very Dense Silt Slice 17 98.678054 156.76469 201.98085 psf 1,447.6825 psf 778.40078 psf 250 psf 0 psf Very Dense Silt Slice 18 100.775 155.96068 252.1756 psf 1,482.5534 psf 768.82538 psf 250 psf 0 psf Very Dense Silt Slice 19 103.025 155.18825 300.39833 psf 1,502.8109 psf 751.35075 psf 250 psf 0 psf Very Dense Silt Slice 20 105.275 154.50921 342.79109 psf 1,506.9294 psf 727.43436 psf 250 psf 0 psf Very Dense Silt Slice 21 107.525 153.92044 379.54835 psf 1,492.3234 psf 695.33903 psf 250 psf 0 psf Very Dense Silt Slice 22 109.775 153.41934 410.83175 psf 1,456.4356 psf 653.36583 psf 250 psf 0 psf Very Dense Silt Slice 23 112.025 153.0038 436.77402 psf 1,397.0443 psf 600.04344 psf 250 psf 0 psf Very Dense Silt Slice 24 114.275 152.6721 457.48199 psf 1,312.6028 psf 534.33876 psf 250 psf 0 psf Very Dense Silt Slice 25 116.525 152.42291 473.03887 psf 1,202.5647 psf 455.85836 psf 250 psf 0 psf Very Dense Silt Slice 26 118.73333 152.25689 0 psf 1,143.439 psf 714.49998 psf 250 psf 0 psf Very Dense Silt Slice 27 120.9 152.17044 0 psf 1,013.5131 psf 633.3133 psf 250 psf 0 psf Very Dense Silt Slice 28 123.06667 152.15868 0 psf 861.72266 psf 538.46408 psf 250 psf 0 psf Very Dense Silt Slice 29 125.23333 152.22157 0 psf 692.18643 psf 432.52609 psf 250 psf 0 psf Very Dense Silt Slice 30 127.4 152.35933 0 psf 509.78184 psf 318.54705 psf 250 psf 0 psf Very Dense Silt 8/22/23, 11:56 AM Post-Construciton - Static file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Stat…8/8 Slice 31 129.56667 152.57246 0 psf 319.65464 psf 199.74238 psf 250 psf 0 psf Very Dense Silt Slice 32 131.98235 152.90486 0 psf 126.13995 psf 78.820986 psf 250 psf 0 psf Very Dense Silt 1.08 Distance 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200Elevation100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 Factor of Safety ≤ 1.00 - 1.10 1.10 - 1.20 ≥ 1.20 Color Name Unit Weight (pcf) Effective Cohesion (psf) Effective Friction Angle (°) Piezometric Surface Fill 125 0 32 Medium Dense Silty Sand 125 25 32 Medium Dense to Dense Sandy Silt 125 100 32 Very Dense Silt 120 500 32 2 Very Dense Silty Sand 125 250 36 1 Post-Construction: Seismic Condition 8/21/23, 10:40 AM Post-Construciton - Seismic file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Sei…1/8 Post-Con struci ton - Sei smic Report generated using GeoStudio 2022.1. Copyright © 2022 Bentley Systems, Incorporated. File Informaon File Version: 11.04 Title: Penwell Property Created By: Chase Halsen Last Edited By: Chase Halsen Revision Number: 31 Date: 08/21/2023 Time: 10:35:12 AM Tool Version: 11.4.2.250 File Name: Updated Runs 08-18-23.gsz Directory: C:\Users\chase.halsen\Desktop\Project Files\8670\Slope Stability\ Last Solved Date: 08/21/2023 Last Solved Time: 10:35:13 AM Project Sengs Unit System: U.S. Customary Units Analysis Sengs Post-Construciton - Seismic Kind: SLOPE/W Analysis Type: Morgenstern-Price Sengs Side Funcon Interslice force funcon opon: Half-Sine PWP Condions from: Piezometric Surfaces Apply Phreac Correcon: No Use Staged Rapid Drawdown: No Unit Weight of Water: 62.430189 pcf Slip Surface Direcon of movement: Le to Right Use Passive Mode: No Slip Surface Opon: Entry and Exit Crical slip surfaces saved: 1 Opmize Crical Slip Surface Locaon: No Tension Crack Opon: (none) Distribuon F of S Calculaon Opon: Constant Convergence Geometry Sengs Minimum Slip Surface Depth: 3 8/21/23, 10:40 AM Post-Construciton - Seismic file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Sei…2/8 Number of Slices: 30 Factor of Safety Convergence Sengs Maximum Number of Iteraons: 100 Tolerable difference in F of S: 0.001 Under-Relaxaon Criteria Inial Rate: 1 Minimum Rate: 0.1 Rate Reducon Factor: 0.65 Reducon Frequency (iteraons): 50 Soluon Sengs Search Method: Root Finder Tolerable difference between starng and converged F of S: 3 Maximum iteraons to calculate converged lambda: 20 Max Absolute Lambda: 2 Materials Medium Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 25 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Medium Dense to Dense Sandy Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 100 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Very Dense Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 120 pcf Effecve Cohesion: 500 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Pore Water Pressure Piezometric Surface: 2 Very Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 250 psf Effecve Fricon Angle: 36 ° Phi-B: 0 ° Pore Water Pressure Piezometric Surface: 1 8/21/23, 10:40 AM Post-Construciton - Seismic file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Sei…3/8 Fill Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effecve Cohesion: 0 psf Effecve Fricon Angle: 32 ° Phi-B: 0 ° Slip Surface Entry and Exit Le Type: Range Le-Zone Le Coordinate: (0.12622, 201.97896) Le-Zone Right Coordinate: (75, 182) Le-Zone Increment: 20 Right Type: Range Right-Zone Le Coordinate: (77, 181.33333) Right-Zone Right Coordinate: (140, 151.0001) Right-Zone Increment: 20 Radius Increments: 4 Slip Surface Limits Le Coordinate: (0, 202) Right Coordinate: (183, 100) Piezometric Surfaces Piezometric Surface 1 Coordinates X Y Coordinate 1 0 175 Coordinate 2 90 175 Piezometric Surface 2 Coordinates X Y Coordinate 1 0 160 Coordinate 2 117.65 160 Seismic Coefficients Horz Seismic Coef.: 0.343 8/21/23, 10:40 AM Post-Construciton - Seismic file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Sei…4/8 Surcharge Loads Surcharge Load 1 Surcharge (Unit Weight): 375 pcf Direcon: Vercal Coordinates X Y 6 194 40 194 Surcharge Load 2 Surcharge (Unit Weight): 375 pcf Direcon: Vercal Coordinates X Y 40 185 75 185 Geometry Name: 2D Geometry Sengs View: 2D Element Thickness: 1 Points X Y Point 1 0 202 Point 2 6 201 Point 3 6 192.5 Point 4 40 192.5 Point 5 40 184 Point 6 75 184 Point 7 75 182 Point 8 81 180 Point 9 85 178 Point 10 99.65 170 Point 11 117.65 160 Point 12 130.65 154 Point 13 136.65 152 Point 14 142.65 150 Point 15 146.65 148 Point 16 160.65 146 8/21/23, 10:40 AM Post-Construciton - Seismic file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Sei…5/8 Point 17 166.65 144 Point 18 171.65 142 Point 19 174.65 140 Point 20 182.65 136 Point 21 0 185 Point 22 40 185 Point 23 0 175 Point 24 90 175 Point 25 0 160 Point 26 0 150 Point 27 140.00035 151 Point 28 0 140 Point 29 0 100 Point 30 183 100 Point 31 67 184 Regions Material Points Area Region 1 Medium Dense Silty Sand 1,21,22,4,3,2 354 ² Region 2 Medium Dense to Dense Sandy Silt 21,23,24,9,8,7,31,5,22 766.5 ² Region 3 Very Dense Silty Sand 23,25,11,10,24 1,560.6 ² Region 4 Very Dense Silt 25,26,27,13,12,11 1,220.5 ² Region 5 Very Dense Silty Sand 26,28,27 700 ² Region 6 Very Dense Silt 28,29,30,20,19,18,17,16,15,14,27 8,276.1 ² Region 7 Fill 31,7,6 8 ² Slip Results Slip Surfaces Analysed: 1062 of 2205 converged Current Slip Surface Slip Surface: 732 Factor of Safety: 1.08 Volume: 1,535.5402 ³ Weight: 190,371.02 lbf Resisng Moment: 23,990,785 lbf· Acvang Moment: 22,140,478 lbf· Resisng Force: 133,630.69 lbf Acvang Force: 123,389.77 lbf Slip Rank: 1 of 2,205 slip surfaces Exit: (140, 151.0001) Entry: (19.731639, 192.5) Radius: 168.49785 Center: (130.76035, 319.24444) 8/21/23, 10:40 AM Post-Construciton - Seismic file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Sei…6/8 Slip Slices X Y PWP Base Normal Stress Friconal Strength Cohesive Strength Sucon Strength Base Material Slice 1 22.030569 190.55759 0 psf 516.00535 psf 322.43593 psf 25 psf 0 psf Medium Dense Silty Sand Slice 2 26.628429 186.80759 0 psf 802.22872 psf 501.28814 psf 25 psf 0 psf Medium Dense Silty Sand Slice 3 30.772799 183.63928 0 psf 1,006.5365 psf 628.95381 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 4 34.46368 180.99314 0 psf 1,196.8009 psf 747.84419 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 5 38.15456 178.49354 0 psf 1,374.0408 psf 858.59596 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 6 41.834023 176.13968 0 psf 755.89776 psf 472.33735 psf 100 psf 0 psf Medium Dense to Dense Sandy Silt Slice 7 45.612376 173.86125 71.092635 psf 928.5263 psf 622.96202 psf 250 psf 0 psf Very Dense Silty Sand Slice 8 49.501035 171.65201 209.0156 psf 1,129.0128 psf 668.4171 psf 250 psf 0 psf Very Dense Silty Sand Slice 9 53.389694 169.57641 338.59564 psf 1,314.6199 psf 709.12315 psf 250 psf 0 psf Very Dense Silty Sand Slice 10 57.278353 167.62895 460.17576 psf 1,491.6581 psf 749.41576 psf 250 psf 0 psf Very Dense 8/21/23, 10:40 AM Post-Construciton - Seismic file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Sei…7/8 Silty Sand Slice 11 61.167012 165.80475 574.06088 psf 1,666.4331 psf 793.65486 psf 250 psf 0 psf Very Dense Silty Sand Slice 12 65.055671 164.09946 680.52269 psf 1,845.1744 psf 846.16898 psf 250 psf 0 psf Very Dense Silty Sand Slice 13 69 162.48805 781.12344 psf 2,036.62 psf 912.17165 psf 250 psf 0 psf Very Dense Silty Sand Slice 14 73 160.97019 875.88345 psf 2,246.9933 psf 996.16962 psf 250 psf 0 psf Very Dense Silty Sand Slice 15 75.345033 160.12016 928.95131 psf 1,802.093 psf 634.37459 psf 250 psf 0 psf Very Dense Silty Sand Slice 16 78.345033 159.13086 54.260498 psf 2,174.9541 psf 1,325.1565 psf 500 psf 0 psf Very Dense Silt Slice 17 83 157.67053 145.42903 psf 2,279.094 psf 1,333.2619 psf 500 psf 0 psf Very Dense Silt Slice 18 87.5 156.41515 223.80307 psf 2,295.6714 psf 1,294.647 psf 500 psf 0 psf Very Dense Silt Slice 19 92.4125 155.18704 300.47429 psf 2,280.2068 psf 1,237.0741 psf 500 psf 0 psf Very Dense Silt Slice 20 97.2375 154.13331 366.25875 psf 2,243.2219 psf 1,172.8568 psf 500 psf 0 psf Very Dense Silt Slice 21 101.9 153.25229 421.26054 psf 2,149.3678 psf 1,079.8413 psf 500 psf 0 psf Very Dense Silt Slice 22 106.4 152.53232 466.20859 psf 1,995.8799 psf 955.84475 psf 500 psf 0 psf Very Dense Silt Slice 23 110.9 151.93646 503.40837 psf 1,788.889 psf 803.25744 psf 500 psf 0 psf Very Dense Silt Slice 24 115.4 151.46338 532.9425 psf 1,531.3618 psf 623.88161 psf 500 psf 0 psf Very Dense Silt Slice 25 119.21931 151.14965 0 psf 1,416.1029 psf 884.87931 psf 500 psf 0 psf Very Dense 8/21/23, 10:40 AM Post-Construciton - Seismic file:///C:/Users/chase.halsen/Desktop/Project Files/8670/Slope Stability/Print outs/Post Construction/Updated Runs 08-18-23 - Post-Construciton - Sei…8/8 Silt Slice 26 122.35793 150.96355 0 psf 1,195.9893 psf 747.33709 psf 500 psf 0 psf Very Dense Silt Slice 27 125.60793 150.83377 0 psf 915.52615 psf 665.16868 psf 250 psf 0 psf Very Dense Silty Sand Slice 28 128.96931 150.76449 0 psf 667.22684 psf 484.76868 psf 250 psf 0 psf Very Dense Silty Sand Slice 29 133.65 150.79808 0 psf 365.43576 psf 265.50462 psf 250 psf 0 psf Very Dense Silty Sand Slice 30 138.32388 150.92476 0 psf 101.82714 psf 73.98175 psf 250 psf 0 psf Very Dense Silty Sand Slice 31 139.99889 151.00004 0 psf 26.229034 psf 16.389719 psf 500 psf 0 psf Very Dense Silt Construction Stormwater General Permit (CSWGP) Stormwater Pollution Prevention Plan (SWPPP) for Penwell Property Prepared for: Department of Ecology Northwest Regional Office Permittee / Owner Developer Operator / Contractor Chris Penwell Chris Penwell To be determined South end of 2nd Ave SW, Federal Way Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD TBD TBD SWPPP Prepared By Name Organization Contact Phone Number Vicente Varas Barghausen Consulting Engineers, Inc. (425) 251-6222 SWPPP Preparation Date August 03, 2023 Project Construction Dates Activity / Phase Start Date End Date Clear/Grade/Utilities/Building April / 01 / 2024 December / 01 / 2024 Table of Contents 1 Project Information ................................................................................................................. 4 1.1 Existing Conditions ......................................................................................................... 5 1.2 Proposed Construction Activities .................................................................................... 6 2 Construction Stormwater Best Management Practices (BMPs) ............................................ 7 2.1 The 13 Elements ............................................................................................................ 8 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits .......................................... 8 2.1.2 Element 2: Establish Construction Access .............................................................. 9 2.1.3 Element 3: Control Flow Rates .............................................................................. 10 2.1.4 Element 4: Install Sediment Controls .................................................................... 11 2.1.5 Element 5: Stabilize Soils ...................................................................................... 13 2.1.6 Element 6: Protect Slopes ..................................................................................... 15 2.1.7 Element 7: Protect Drain Inlets .............................................................................. 16 2.1.8 Element 8: Stabilize Channels and Outlets ........................................................... 17 2.1.9 Element 9: Control Pollutants ................................................................................ 18 2.1.10 Element 10: Control Dewatering ........................................................................... 25 2.1.11 Element 11: Maintain BMPs .................................................................................. 26 2.1.12 Element 12: Manage the Project ........................................................................... 27 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs .................................. 28 3 Pollution Prevention Team ................................................................................................... 29 4 Monitoring and Sampling Requirements .............................................................................. 30 4.1 Site Inspection .............................................................................................................. 30 4.2 Stormwater Quality Sampling ....................................................................................... 30 4.2.1 Turbidity Sampling ................................................................................................. 30 4.2.2 pH Sampling .......................................................................................................... 32 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies ......................... 33 5.1 303(d) Listed Waterbodies ........................................................................................... 33 5.2 TMDL Waterbodies ....................................................................................................... 33 6 Reporting and Record Keeping ........................................................................................... 34 6.1 Record Keeping ............................................................................................................ 34 6.1.1 Site Log Book ........................................................................................................ 34 6.1.2 Records Retention ................................................................................................. 34 6.1.3 Updating the SWPPP ............................................................................................ 34 6.2 Reporting ...................................................................................................................... 35 6.2.1 Discharge Monitoring Reports ............................................................................... 35 6.2.2 Notification of Noncompliance ............................................................................... 35 List of Tables Table 1 – Summary of Site Pollutant Constituents ....................................................................... 5 Table 2 – Pollutants .................................................................................................................... 18 Table 3 – pH-Modifying Sources ................................................................................................. 23 Table 5 – Management ............................................................................................................... 27 Table 6 – BMP Implementation Schedule ................................................................................... 27 Table 7 – Team Information ........................................................................................................ 29 Table 8 – Turbidity Sampling Method ......................................................................................... 30 Table 9 – pH Sampling Method .................................................................................................. 32 List of Appendices A. Site Map B. BMP Detail C. Correspondence D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information G. Contaminated Site Information H. Engineering Calculations List of Acronyms and Abbreviations Acronym / Abbreviation Explanation 303(d) Section of the Clean Water Act pertaining to Impaired Waterbodies BFO Bellingham Field Office of the Department of Ecology BMP(s) Best Management Practice(s) CESCL Certified Erosion and Sediment Control Lead CO2 Carbon Dioxide CRO Central Regional Office of the Department of Ecology CSWGP Construction Stormwater General Permit CWA Clean Water Act DMR Discharge Monitoring Report DO Dissolved Oxygen Ecology Washington State Department of Ecology EPA United States Environmental Protection Agency ERO Eastern Regional Office of the Department of Ecology ERTS Environmental Report Tracking System ESC Erosion and Sediment Control GULD General Use Level Designation NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Units NWRO Northwest Regional Office of the Department of Ecology pH Power of Hydrogen RCW Revised Code of Washington SPCC Spill Prevention, Control, and Countermeasure su Standard Units SWMMEW Stormwater Management Manual for Eastern Washington SWMMWW Stormwater Management Manual for Western Washington SWPPP Stormwater Pollution Prevention Plan TESC Temporary Erosion and Sediment Control SWRO Southwest Regional Office of the Department of Ecology TMDL Total Maximum Daily Load VFO Vancouver Field Office of the Department of Ecology WAC Washington Administrative Code WSDOT Washington Department of Transportation WWHM Western Washington Hydrology Model Project Information (1.0) This Stormwater Pollution Prevention Plan (SWPPP) has been prepared per the requirements of the Washington State NPDES Construction Stormwater General Permit Conditions of Approval for the Penwell Property. The site is located within a portion of Section 6, Township 21 North, Range 4 East, Willamette Meridian, in Federal Way, Washington. The parcel for the property is 199600-3800 and contains an existing shared access road connecting to 2nd Ave SW at the northeast corner of the site and extending to the neighboring property on the southwest corner of the site. Onsite vegetation is mostly forested with an unnamed stream flowing northwest bisecting the site on the east side. Elevations range from 136 to 202 feet across the site sloping down to the unnamed stream. The low point of the site is located at the centerline of the stream as it leaves the site to the north. A portion of the slopes on-site exceed 40% in grade and may be considered a potential landslide hazard area. This project will re-consturct and widen the existing shared access road and construct a single- family residence on the southwest portion of the site. In addition, the project will install stormwater pipes and catch basins, a stormwater detention system and water quality unit, sewer facilities and water facilities to serve the property. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, inspection/monitoring activities, and recordkeeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to: 1. Implement Best Management Practices (BMPs) to prevent erosion and sediment, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. During the construction phase prevent adverse water quality impacts including, impacts of beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template. The Template has been revised to incorporate all items in the General NPDES Permit as well as provide more project specific BMPs that will be utilized onsite. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit, Stormwater Management Manual for Western Washington (SWMMWW 2012). The site project information for the site is summarized below. Project/Site Name: Penwell Property Street/Location: South End of 2nd Ave SW City: Federal Way State: WA Zip code: 98023 Subdivision: Receiving waterbody: Unnamed Stream and the Puget Sound Existing Conditions (1.1) Total acreage (including support activities such as off-site equipment staging yards, material storage areas, borrow areas). Total acreage: 0.94 Disturbed acreage: 0.31 Existing structures: None Landscape topography: Most site topography slopes northeast towards the unnamed stream on the east portion of the stie. Drainage patterns: Stormwater runoff flows towards the unnamed stream and flows northwest along the stream flowpath as it leaves the site near the north boundary. Existing Vegetation: Forested Critical Areas (wetlands, streams, high erosion risk, steep or difficult to stabilize slopes): Steep Slopes, Wetland, Unnamed Stream List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: Table 1 includes a list of suspected and/or known contaminants associated with the construction activity. Table 1 – Summary of Site Pollutant Constituents Constituent (Pollutant) Location Depth Concentration None identified N/A N/A N/A Proposed Construction Activities (1.2) This project phase will consist of the construction of the re-construction of a shared access road, single-family residence, stormwater utilities sewer facilities and water facilities. Stormwater runoff in the fully developed stage will be routed to a water quality unit near the northeast corner of the site before entering an underground stormwater detention system. After detention, runoff will be discharged into the unnamed stream near the north boundary line using a rock lining discharge pad. Contaminated Site Information: Ther are no known activities that will result in the contamination of soil and or groundwater planned for the site during clearing, grading, an/or the construction of the development. Construction Stormwater Best Management Practices (BMPs) (2.0) The following sections describe BMPs that will be utilized during the construction of the project. Alternate BMPs for the 13 BMP Elements may be implemented on a need by need basis, should the 13 Elements below be deemed ineffective or inappropriate during the construction to satisfy the requirements set forth in the General NPDES Permit. To avoid potential erosion and sediment control issues that may cause violation(s) of the NPDES Construction Stormwater permit, the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more alternate BMPs after the first sign that existing BMPs are ineffective or failing. A suggested BMP implementation schedule follows. Note that some of these BMPs will have already been installed during the Early Clear and Grade permit. All BMPs should be verified for compliance. 1. Mark clearing limits 2. Hold pre-construction conference 3. Install construction entrance 4. Install perimeter protection 5. Grade and stabilize construction roads and staging areas 6. Install surface water controls (interceptor swales and check dams) as clearing and grading progresses 7. Install cover measures on all areas that will be unworked for more than 7 days during the dry season or 2 days during the wet season 8. Install stabilization measures within 7 days of reaching final grade 9. Maintain erosion control measures and update BMPs as required by construction or changes in site conditions Upon project completion, stabilize all disturbed areas and remove BMPs when appropriate The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e. hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. Element 1: Preserve Vegetation / Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native top soil shall be retained in an undisturbed state wherever practical. Native top soil which is cleared, and appropriate for reuse on the site, shall be stockpiled separately and protected from contamination using silt fencing and appropriate cover measures. The BMPs relevant to marking the clearing limits that will be applied for this project include the following: List and describe BMPs: · High Visibility Fence (BMP C103) and Tree Protection Fence Install colored orange fence to protect areas that are not to be disturbed, and mark trees to be preserved. · Silt Fence (BMP C233) Silt fencing shall be used to reduce sediment flow offsite throughout the construction process. Installation Schedules: All BMPs to preserve vegetation and mark clearing limits are to be installed prior to clearing and grading. Inspection and Maintenance plan: All fencing is to be inspected at the end of each day's work and following significant rain events. Repairs should be performed if found to be noncompliant with BMP specifications. Responsible Staff: Certified Erosion and Sediment Control Lead Element 2: Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads. Street sweeping and street cleaning shall be employed where necessary to prevent sediment from entering state waters. All wash wastewater shall be controlled onsite. The specific BMPs related to establishing construction access that will be used on this project are as follows: List and describe BMPs: · Stabilized Construction Entrance (BMP C105) One quarry spall construction entrance will be placed at the end of 2nd Ave SW on the northwest corner of the site. This stabilized construction entrance will be used to minimize the amount of sediment transported off site onto the existing roadway by construction traffic. · Construction Road/Parking Area Stabilization (BMP C107) Disturbed areas shall be stabilized immediately after desired grading to reduce erosion by construction traffic or surface water runoff. A designated parking and maintenance area shall be stabilized and maintained to help contain spills. · Concrete Washout Area (BMP C154) Conduct washout off-site, or perform on-site concrete washout in a designated area. This is done to prevent pollutants from entering surface or ground water. If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day or more frequently, as necessary. Remove sediment from roads by shoveling, sweeping, or pickup and transport of the sediment to a controlled sediment disposal area. Conduct street washing only after sediment removal in accordance with special condition S9.D.2.d. Control street wash wastewater by pumping back on site or otherwise preventing it from discharging off site into stormwater conveyance systems, creek, or rivers that connect to waters of the State. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work and following significant rain events. Responsible Staff: Certified Erosion and Sediment Control Lead Element 3: Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The Specific BMPs for the flow control that shall be used on this project include the following: Will you construct stormwater retention and/or detention facilities? Yes No Will you use permanent infiltration ponds or other low impact development (example: rain gardens, bio-retention, porous pavement) to control flow during construction? Yes No List and describe BMPs: · Check Dams (BMP C207) Check dams located within temporary roadside ditches will be be used to reduce the velocity and energy of the concentrated low flows expected from the project before discharging to the rock lining discharge pad. The project site is located west of the Cascade Mountain Crest. As a result, the project must comply with the Minimum Requirement 7 (Ecology 2012). Minimum Requirement 7 states that projects must provide flow control to reduce the impacts of stormwater runoff from impervious surfaces and land cover conversions. Essentially, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). Installation Schedules: To be installed in the early stages of grading and utility construction. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work and following significant rain events. Responsible Staff: Certified Erosion and Sediment Control Lead Element 4: Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site. The specific BMPs to be used for controlling sediment on this project are as follows: List and describe BMPs: · Silt Fence (BMP C233) During site development phase, silt fence will be used along the downhill perimeter of the project to prevent sediment from leaving the site. · Construction Stormwater Filtration (BMP C251) if needed · Construction Stormwater Chemical Treatment (BMP C250) (Implemented only with prior written approval from Ecology.) Implement BMP C250/251 above end-of-pipe measures only if sediment sources and erosion control and soil stabilization BMP efforts are not sufficient to reduce sedimentation. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Element 5: Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used in this project are as follows: West of the Cascade Mountains Crest Season Dates Number of Days Soils Can be Left Exposed During the Dry Season May 1 – September 30 7 days During the Wet Season October 1 – April 30 2 days Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Anticipated project dates: Start date: April 2023 End date: December 2028 Will you construct during the wet season? Yes No List and describe BMPs: · Temporary and Permanent Seeding (BMP C120) Following final or fine grading activity in new pervious areas, permanent seeding shall be placed on exposed soil to provide permanent erosion protection. · Mulching (BMP C121) During the site development phase, mulching will be used for areas that will be unworked for more than 2 days. Temporary seeding will be applied to areas that will be unworked for more than 7 days. During the building phase, the construction area will be significantly stabilized through well established grass cover. Proposed driveways will receive base course materials as described under Element #2 above. Areas cleared for building foundations or utility and irrigation placement will be temporarily stabilized by one of the following methods which are based on the period exposed soils are left unworked: o If exposed soils are left unworked for more than 7 days during the dry season and 2 days during the wet season but less than 30 days, mulching shall be applied. o If exposed soils are left unworked for more than 30 days, temporary or permanent seeding shall be applied. · Nets and Blankets (BMP C122) Once final or fine grading activity has been completed, install Jute Matting on slopes prior to planting. · Sodding (BMP C124) Following final or fine grading activity in the front yard, sod shall be placed on exposed soil to provide permanent and immediate erosion protection. · Plastic Covering (BMP C123) · Topsoiling (BMP C125) Utilize stockpile management during all phases of construction per BMP. Cover stockpiles with plastic covering to prevent erosion during rain events. · Wattles (BMP C235) Install wattles downslope of newly landscaped areas to control sediment runoff until stabilization. Cement or Calcium Chloride may be used for soil stabilization and dewatering with prior approval. See section 4.2.2 for pH Sampling Requirements. The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain exposed and unworked for more than 7 days during the dry season (May 1 to September 30) and 2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. Cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Element 6: Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner that minimizes erosion. Will steep slopes be present at the site during construction? Yes No List and describe BMPs: · Temporary and Permanent Seeding (BMP C120) The site has steep slopes (more than 15%). Short sections of sloped grading will be treated as described under Element 5 above. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work and following significant rain events. Responsible Staff: Certified Erosion and Sediment Control Lead Element 7: Protect Drain Inlets The following BMPs will be used to protect catch basin inlets during construction: List and describe BMPs: · Storm Drain Inlet Protection (BMP C220). Prior to construction, storm drain inlet protection will be utilized on all catch basins which may receive stormwater from the construction area. Also install inlet protection once permanent storm drain inlets on site are constructed. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work and following significant rain events. Responsible Staff: Certified Erosion and Sediment Control Lead Element 8: Stabilize Channels and Outlets Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural drainage point, efforts will be made to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all conveyance systems. List and describe BMPs: · Interceptor Dike and Swale (BMP C200) During the site development phase, interceptor dikes and swales shall be constructed to convey stormwater to the rock lining discharge pad. · Check Dams (BMP C207) Check dams shall be used to reduce the velocity and energy of concentrated flow in ditches. Installation Schedules: Installation schedule to be determined by the General Contractor Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work and following significant rain events. Responsible Staff: Certified Erosion and Sediment Control Lead Element 9: Control Pollutants All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. The following pollutants are anticipated to be present on-site: Table 2 – Pollutants Pollutant (List pollutants and source, if applicable) Grease, fuel, oils from construction equipment operation and maintenance Trash from construction activity Temporary Sanitary Facilities Fertilizers (if used to establish lawn/landscaping areas) Concrete products List and describe BMPs: Housekeeping BMPs The following sections describe the controls, including storage practices to minimize exposure of the materials to stormwater as well as spill prevention and response practices. All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Vehicles, construction equipment, and/or petroleum product storage/dispensing: · All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. Secondary containment such as drip pans will be placed under any leaking vehicles or equipment. All petroleum product storage containers will be placed in secondary containment (see spill prevention and control below). · On-site fueling tanks and petroleum product storage containers shall include secondary containment. · Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment or when vehicle/equipment leaks are observed. · In order to perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. · Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Chemical storage: · Any chemicals stored in the construction areas will conform to the appropriate source control BMPs listed in Volume IV of the Ecology stormwater manual. In Western WA, all chemicals shall have cover, containment, and protection provided on site, per BMP C153 for Material Delivery, Storage and Containment in SWMMWW 2012. · Application of agricultural chemicals, including fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers’ recommendations for application procedures and rates shall be followed. Concrete and grout: · Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C151) and Sawcutting and Surfacing Pollution Prevention (BMP C152). Sanitary wastewater: · Proper sanitary and septic waste management are waste management and material pollution controls that prevent the discharge of pollutants to stormwater from sanitary and septic waste by providing convenient, well-maintained facilities, and arranging for regular service and disposal. Implement as follows: o Facilities should be located away from drainage facilities, watercourses, and from traffic circulation. o Provide a sufficient quantity of facilities to accommodate the workforce. o Temporary sanitary facilities must be equipped with containment to prevent discharge of pollutants to the stormwater drainage system of the receiving water. o When subjected to high winds or risk of high winds, temporary sanitary facilities should be secured to prevent overturning. o Sanitary facilities should be located in a convenient location. o Sanitary or septic wastes should be treated or disposed of in accordance with state and local requirements. o Sanitary facilities should be maintained in good working order by a licensed service. Solid and Liquid Waste: · Solid and liquid waste generated during construction such as construction materials, contaminated materials, and waste materials from maintenance activities will be prevented from entering the waters of the State. Solid and liquid waste shall be handled in accordance with BMPs for Storage of Liquid, Food Waste, or Dangerous Waste Containers and BMPs for Loading and Unloading Areas for Liquid or Solid Materials. o Solid waste will be stored in secure, clearly marked containers. o Promptly contain and clean up solid and liquid pollutant leaks and spills including oils, solvents, fuels, and dust from manufacturing operations on any exposed soil, vegetation, or paved area. o Sweep paved material handling and storage areas regularly as needed, for the collection and disposal of dust and debris that could contaminate stormwater. Do not hose down pollutants from any area to the ground, storm drain, conveyance ditch, or receiving water unless necessary for dust control purposes to meet air quality regulations. Installation Schedules: The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? Yes No If yes, describe spill prevention and control measures in place while conducting maintenance, fueling, and repair of heavy equipment and vehicles. If yes, also provide the total volume of fuel on-site and capacity of the secondary containment for each fuel tank. Secondary containment structures shall be impervious. List and describe BMPs: Spill Prevention and Control BMPs Prevent or reduce the discharge of pollutants to drainage systems or watercourses from leaks and spills by reducing the chance for spills, stopping the source of spills, containing and cleaning up spills, properly disposing of spill materials, and training employees. This best management practice covers only spill prevention and control. However, Materials Delivery and Storage (BMP C153), also contains useful information, particularly on spill prevention. · To the extent that the work can be accomplished safely, spills of oil, petroleum products, and substances listed under 40 CFR parts 110,117, and 302, and sanitary and septic wastes should be contained and cleaned up immediately. · Store hazardous materials and wastes in covered containers and protect from vandalism. · Place a stockpile of spill cleanup materials where it will be readily accessible. · Train employees in spill prevention and cleanup. · Designate responsible individuals to oversee and enforce control measures. · Spills should be covered and protected from stormwater runon during rainfall to the extent that it doesn’t compromise cleanup activities. · Do not bury or wash spills with water. · Store and dispose of used clean up materials, contaminated materials, and recovered spill material that is no longer suitable for the intended purpose in conformance with the provisions in applicable BMPs. · Do not allow water used for cleaning and decontamination to enter storm drains or watercourses. Collect and dispose of contaminated water in accordance WSDOE regulations. · Contain water overflow or minor water spillage and do not allow it to discharge into drainage facilities or watercourses. · Place proper storage, cleanup, and spill reporting instructions for hazardous materials stored or used on the project site in an open, conspicuous, and accessible location. · Keep waste storage areas clean, well organized, and equipped with ample clean supplies as appropriate for the materials being stored. Perimeter controls, containment structures, covers, and liners should be repaired or replaced as needed to maintain proper function. Cleanup: · Clean up leaks and spills immediately. · Use a rag for small spills on paved surfaces, a damp mop for general cleanup, and absorbent material for larger spills. If the spilled material is hazardous, then the used cleanup materials are also hazardous and must be sent to either a certified laundry (rags) or disposed of as hazardous waste. · Never hose down or bury dry material spills. Clean up as much of the material as possible and dispose of properly. · The spill kit should include, at a minimum: o 1-Water Resistant Nylon Bag o 3-Oil Absorbent Socks 3”x 4’ o 2-Oil Absorbent Socks 3”x 10’ o 12-Oil Absorbent Pads 17”x19” o 1-Pair Splash Resistant Goggles o 3-Pair Nitrile Gloves o 10-Disposable Bags with Ties o Instructions · Spill kits will be located in areas with a high potential for spills and deployed in a manner that allows rapid access and use by contractors. Some heavy equipment may have on- board spill kits for small spills. Spill control kits will be inspected and inventoried each construction season to confirm all required items are present. Spill control kits will be inventoried after each emergency event and restocked as needed. Minor Spills: · Minor spills typically involve small quantities of oil, gasoline, paint, etc. which can be controlled at the discovery of the spill. · Contain the spread of the spill. · Use absorbent materials on small spills rather than hosing down or burying the spill. · Notify the project foreman immediately · Recover spilled materials. · Clean the contaminated area and properly dispose of contaminated materials. · If the spill occurs on paved or impermeable surfaces, clean up using "dry" methods (absorbent materials, cat litter and/or rags). Contain the spill by encircling with absorbent materials and do not let the spill spread widely. · If the spill occurs in dirt areas, immediately contain the spill by constructing an earthen dike. Dig up and properly dispose of contaminated soil. · If the spill occurs during rain, cover spill with tarps or other material to prevent contaminating runoff. Semi-Significant Spills: · Semi-significant spills still can be controlled by the first responder along with the aid of other personnel such as laborers and the foreman, etc. This response may require the cessation of all other activities. Spills should be cleaned up immediately. Significant/Hazardous Spills · For significant or hazardous spills that cannot be controlled by personnel in the immediate vicinity, the following steps should be taken: o Notify the local emergency response by dialing 911. In addition to 911, the contractor will notify the proper City or County officials. All emergency phone numbers will be posted at the construction site. o Contact your Supervisor and the Divisional Environmental Manager. For spills of federal reportable quantities, (examples are listed below) in conformance with the requirements in 40 CFR parts 110,119, and 302, the Division Environmental Manager (DEM) will notify the National Response Center at (800) 424-8802. The DEM will notify the Department of Ecology and any other applicable agencies. · The services of a spills contractor or a Haz-Mat team should be obtained immediately. Construction personnel should not attempt to clean up until the appropriate and qualified staffs have arrived at the job site. · Notification should first be made by telephone and followed up with a written report. Other agencies which may need to be consulted include, but are not limited to, the Public Works Department, the Coast Guard, the Highway Patrol, the City/County Police Department and Department of Ecology. · Federal regulations require that any significant oil spill into a water body or onto an adjoining shoreline be reported to the National Response Center (NRC) at 800-424-8802 (24 hours) Installation Schedules: The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work. Responsible Staff: Certified Erosion and Sediment Control Lead Will wheel wash or tire bath system BMPs be used during construction? Yes No Will pH-modifying sources be present on-site? Yes No Table 3 – pH-Modifying Sources None Bulk cement Cement kiln dust Fly ash Other cementitious materials New concrete washing or curing waters Waste streams generated from concrete grinding and sawing Exposed aggregate processes Dewatering concrete vaults Concrete pumping and mixer washout waters Recycled concrete Other (i.e., calcium lignosulfate) [please describe: ] List and describe BMPs: · pH Control for High pH Water (BMP C253) · High pH Neutralization using CO2 (BMP C252) (Implemented only after notifying the local Jurisdiction.) · Sawcutting and Surfacing Pollution Prevention (BMP C152) Sawcutting shall be performed in accordance with this BMP, including proper containment and disposal of sawcutting slurry. Installation Schedules: The described BMPs will be implemented while all pollution generating materials are onsite. Inspection and Maintenance plan: Inspection and maintenance is to take place at the end of each day's work and following significant rain events. Responsible Staff: Certified Erosion and Sediment Control Lead Adjust pH of stormwater if outside the range of 6.5 to 8.5 su. Obtain written approval from Ecology before using chemical treatment with the exception of CO2 or dry ice to modify pH. Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches, streets, or streams. Excess concrete must not be dumped on-site, except in designated concrete washout areas with appropriate BMPs installed. Element 10: Control Dewatering Dewatering may be required during utility construction, especially during the wet season. Contaminated water is not anticipated for this site. Table 4 – Dewatering BMPs Infiltration  Transport off-site in a vehicle (vacuum truck for legal disposal)  Ecology-approved on-site chemical treatment or other suitable treatment technologies  Sanitary or combined sewer discharge with local sewer district approval (last resort)  Use of sedimentation bag with discharge to ditch or swale (small volumes of localized dewatering) List and describe BMPs: · Vac truck offsite disposal can be used at contractor's option to remove highly turbid water from the site. · DOE-approved on-site chemical treatment may be used if other techniques are not successful. · Sanitary sewer disposal may be allowed subject to approval by the local sewer district. · Sedimentation bag with discharge to ditch or swale if volumes of dewatering are small and high turbidity is not present. Installation Schedules: One or more of the described BMPs will be implemented at all times while dewatering activities are being performed. Inspection and Maintenance plan: Inspection and maintenance is to take place contiuously during dewatering activity. Responsible Staff: Certified Erosion and Sediment Control Lead Element 11: Maintain BMPs All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained and repaired as needed to ensure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMP specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW). Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to once every calendar month. All temporary ESC BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal of either BMPs or vegetation shall be permanently stabilized. Additionally, protection must be provided for all BMPs installed for the permanent control of stormwater from sediment and compaction. BMPs that are to remain in place following completion of construction shall be examined and restored to full operating condition. If sediment enters these BMPs during construction, the sediment shall be removed and the facility shall be returned to conditions specified in the construction documents. Element 12: Manage the Project The project will be managed based on the following principles: · Projects will be phased to the maximum extent practicable and seasonal work limitations will be taken into account. · Inspection and monitoring: o Inspection, maintenance and repair of all BMPs will occur as needed to ensure performance of their intended function. o Site inspections and monitoring will be conducted in accordance with Special Condition S4 of the CSWGP. Sampling locations are indicated on the Site Map. Sampling station(s) are located in accordance with applicable requirements of the CSWGP. · Maintain an updated SWPPP. o The SWPPP will be updated, maintained, and implemented in accordance with Special Conditions S3, S4, and S9 of the CSWGP. As site work progresses the SWPPP will be modified routinely to reflect changing site conditions. The SWPPP will be reviewed monthly to ensure the content is current. Table 5 – Management Design the project to fit the existing topography, soils, and drainage patterns Emphasize erosion control rather than sediment control Minimize the extent and duration of the area exposed Keep runoff velocities low Retain sediment on-site Thoroughly monitor site and maintain all ESC measures Schedule major earthwork during the dry season Other (please describe) Element 13: Protect Low Impact Development (LID) BMPs LID facilities are not proposed for this project. This element is not applicable. Pollution Prevention Team (3.0) Table 7 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD TBD Resident Engineer Barry Talkington (425) 251-6222 Emergency Ecology Contact Staff on Duty (360) 407-6242 Emergency Permittee/ Owner Contact TBD TBD Non-Emergency Owner Contact Chris Penwell (206) 651-9323 Monitoring Personnel TBD TBD Ecology Regional Office 3190 160th Ave SE, Bellevue, WA (425) 649-7000 Monitoring and Sampling Requirements (4.0) Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: · A record of the implementation of the SWPPP and other permit requirements · Site inspections · Stormwater sampling data The site log book must be maintained on-site within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See CSWGP Special Condition S8 and Section 5 of this template. Site Inspection (4.1) Site inspections will be conducted at least once every calendar week and within 24 hours following any discharge from the site. For sites that are temporarily stabilized and inactive, the required frequency is reduced to once per calendar month. The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with the applicable requirements of the CSWGP. Stormwater Quality Sampling (4.2) Turbidity Sampling (4.2.1) Requirements include calibrated turbidity meter or transparency tube to sample site discharges for compliance with the CSWGP. Sampling will be conducted at all discharge points at least once per calendar week. Method for sampling turbidity: Table 8 – Turbidity Sampling Method Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size) Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size) The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency less than 33 centimeters. If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to or greater than 6 cm, the following steps will be conducted: 1. Review the SWPPP for compliance with Special Condition S9. Make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. 3. Document BMP implementation and maintenance in the site log book. If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following steps will be conducted: 1. Telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) within 24 hours. https://www.ecology.wa.gov/About-us/Get-involved/Report-an-environmental-issue · Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period 3. Document BMP implementation and maintenance in the site log book. 4. Continue to sample discharges daily until one of the following is true: · Turbidity is 25 NTU (or lower). · Transparency is 33 cm (or greater). · Compliance with the water quality limit for turbidity is achieved. o 1 - 5 NTU over background turbidity, if background is less than 50 NTU o 1% - 10% over background turbidity, if background is 50 NTU or greater · The discharge stops or is eliminated. pH Sampling (4.2.2) pH monitoring is required for “Significant concrete work” (i.e. greater than 1000 cubic yards poured concrete or recycled concrete over the life of the project).The use of engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD] or fly ash) also requires pH monitoring. For significant concrete work, pH sampling will start the first day concrete is poured and continue until it is cured, typically three (3) weeks after the last pour. For engineered soils and recycled concrete, pH sampling begins when engineered soils or recycled concrete are first exposed to precipitation and continues until the area is fully stabilized. If the measured pH is 8.5 or greater, the following measures will be taken: 1. Prevent high pH water from entering storm sewer systems or surface water. 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate technology such as carbon dioxide (CO2) sparging (liquid or dry ice). 3. Written approval will be obtained from Ecology prior to the use of chemical treatment other than CO2 sparging or dry ice. Method for sampling pH: Table 8 – pH Sampling Method pH meter pH test kit Wide range pH indicator paper Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies (5.0) 303(d) Listed Waterbodies (5.1) Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? Yes No List the impairment(s): This section does not apply. TMDL Waterbodies (5.2) Waste Load Allocation for CWSGP discharges: List and describe BMPs: This section does not apply. Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. Reporting and Record Keeping (6.0) Record Keeping (6.1) Site Log Book (6.1.1) A site log book will be maintained for all on-site construction activities and will include: · A record of the implementation of the SWPPP and other permit requirements · Site inspections · Sample logs Records Retention (6.1.2) Records will be retained during the life of the project and for a minimum of three (3) years following the termination of permit coverage in accordance with Special Condition S5.C of the CSWGP. Permit documentation to be retained on-site: · CSWGP · Permit Coverage Letter · SWPPP · Site Log Book Permit documentation will be provided within 14 days of receipt of a written request from Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP. Updating the SWPPP (6.1.3) The SWPPP will be modified if: · Found ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. · There is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine additional or modified BMPs are necessary for compliance. An updated timeline for BMP implementation will be prepared. Reporting (6.2) Discharge Monitoring Reports (6.2.1) Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given monitoring period the DMR will be submitted as required, reporting “No Discharge”. The DMR due date is fifteen (15) days following the end of each calendar month. DMRs will be reported online through Ecology’s WQWebDMR System. To sign up for WQWebDMR go to: https://www.ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Water-quality- permits-guidance/WQWebPortal-guidance Notification of Noncompliance (6.2.2) If any of the terms and conditions of the permit is not met, and the resulting noncompliance may cause a threat to human health or the environment, the following actions will be taken: 1. Ecology will be notified within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number (Regional office numbers listed below). 2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or correct the noncompliance. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Specific information to be included in the noncompliance report is found in Special Condition S5.F.3 of the CSWGP. Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6 cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as required by Special Condition S5.A of the CSWGP. · Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County Include the following information: 1. Your name and / Phone number 2. Permit number 3. City / County of project 4. Sample results 5. Date / Time of call 6. Date / Time of sample 7. Project name In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water. Appendix/Glossary A. Site Map B. BMP Detail C. Correspondence D. Site Inspection Form Create your own or download Ecology’s template: https://www.ecology.wa.gov/Regulations-Permits/Permits-certifications/Stormwater- general-permits/Construction-stormwater-permit E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information Not applicable to this project G. Contaminated Site Information Not applicable to this project H. Engineering Calculations Not applicable to this project Appendix A: Site Map Title:For: 12 7708 CHRIS PENWELL 696 MOSS FARM ROAD CHESHIRE, CT 06410 PENWELL PROPERTYFORCITY OF FEDERAL WAY, KING COUNTY, WASHINGTONPTN. OF THE SE 1/4, OF THE NE 1/4, SEC. 06, TWP 21 N., RGE 04 E., W.M.FOR PENWELL PROPERTYCALL BEFORE YOU DIG: 8118/3 /2 3 TESC PLAN11 TESC PLANSCALE: 1"=20'2ND AV E S W TEMPORARY "V" DITCHROCK CHECK DAM DETAILCHECK DAM SPACINGRECOMMENDED CONSTRUCTION SEQUENCEFILTER FABRIC SILT FENCE DETAILTABLE D.3.2.B TEMPORARY EROSION CONTROL SEED MIXTEMPORARY SEEDING STANDARDS AND SPECIFICATIONSSEEDING NOTESLEGEND:EROSION/SEDIMENT CONTROL NOTES Appendix B: BMP Details SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-10 D.2.1 ESC MEASURES This section details the ESC measures that are required to minimize erosion and sediment transport off a construction site and protect areas of existing and proposed flow control BMPs. These ESC measures represent Best Management Practices (BMPs)6 for the control of erosion and entrained sediment as well as other impacts related to construction such as increased runoff due to land disturbing activities. The measures and practices are grouped into nine sections corresponding to each of the nine categories of ESC measures in Core Requirement #5, Section 1.2.5 of the King County Surface Water Design Manual. The introductory paragraphs at the beginning each section present the basic requirement for that category of measures, the purpose of those measures, installation requirements relative to construction activity, guidelines for the conditions of use, and other information relevant to all measures in the section/category. Compliance with each of the nine categories of the ESC measures, to the extent applicable and necessary to meet the performance criteria in Section D.2.1, and compliance with the ESC implementation requirements in Section D.2.4, constitutes overall compliance with King County's ESC Standards. Note: Additional measures shall be required by the County if the existing standards are insufficient to protect adjacent properties, drainage facilities, or water resources. The standards for each individual ESC measure are divided into four sections: 1. Purpose 2. Conditions of Use 3. Design and Installation Specifications 4. Maintenance Requirements. A code and symbol for each measure have also been included for ease of use on ESC plans. Note that the "Conditions of Use" always refers to site conditions. As site conditions change, ESC measures must be changed to remain in compliance with the requirements of this appendix. Whenever compliance with King County ESC Standards is required, all of the following categories of ESC measures must be considered for application to the project site as detailed in the following sections: 1. Clearing Limits: Prior to any site clearing or grading, areas to remain undisturbed during project construction shall be delineated on the project's ESC plan and physically marked on the project site. 2. Cover Measures: Temporary and permanent cover measures shall be provided when necessary to protect disturbed areas. The intent of these measures is to prevent erosion by having as much area as possible covered during any period of precipitation. 3. Perimeter Protection: Perimeter protection to filter sediment from sheet flow shall be provided downstream of all disturbed areas prior to upslope grading. 4. Traffic Area Stabilization: Unsurfaced entrances, roads, and parking areas used by construction traffic shall be stabilized to minimize erosion and tracking of sediment offsite. 5. Sediment Retention: Surface water collected from all disturbed areas of the site shall be routed through a sediment pond or trap prior to release from the site, except those areas at the perimeter of the site small enough to be treated solely with perimeter protection. Sediment retention facilities shall be installed prior to grading any contributing area. 6. Surface Water Collection: Surface water collection measures (e.g., ditches, berms, etc.) shall be installed to intercept all surface water from disturbed areas, convey it to a sediment pond or trap, and discharge it downstream of any disturbed areas. Areas at the perimeter of the site, which are small enough to be treated solely with perimeter protection, do not require surface water collection. 6 Best Management Practices (BMPs) means the best available and reasonable physical, structural, managerial, or behavioral activities, that when singly or in combination, eliminate or reduce the contamination of surface and/or ground waters. D.2.1.1 CLEARING LIMITS 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-11 Significant sources of upstream surface water that drain onto disturbed areas shall be intercepted and conveyed to a stabilized discharge point downstream of the disturbed areas. Surface water collection measures shall be installed concurrently with or immediately following rough grading and shall be designed, constructed, and stabilized as needed to minimize erosion. 7. Dewatering Control: The water resulting from construction site de-watering activities must be treated prior to discharge or disposed of as specified. 8. Dust Control: Preventative measures to minimize wind transport of soil shall be implemented when a traffic hazard may be created or when sediment transported by wind is likely to be deposited in water resources. 9. Flow Control: Surface water from disturbed areas must be routed through the project's onsite flow control facility or other provisions must be made to prevent increases in the existing site conditions 2- year and 10-year runoff peaks discharging from the project site during construction (flow control BMP areas (existing or proposed) shall not be used for this purpose). 10. Control Pollutants: Stormwater pollution prevention (SWPPS) measures are required to prevent, reduce, or eliminate the discharge of pollutants to onsite or adjacent stormwater systems or watercourses from construction-related activities such as materials delivery and storage, onsite equipment fueling and maintenance, demolition of existing buildings and disposition of demolition materials and other waste, and concrete handling, washout and disposal. Section D.2.2 describes BMPs specific to this purpose; additionally, several of the ESC BMPs described herein are applicable. 11. Protect Existing and Proposed Flow Control BMPs: Sedimentation and soil compaction reduce the infiltration capacity of native and engineered soils. Protection measures shall be applied/installed and maintained so as to prevent adverse impacts to existing flow control BMPs and areas of proposed flow control BMPs for the project. Adverse impacts can prompt the requirement to restore or replace affected BMPs. 12. Maintain BMPs: Protection measures shall be maintained to assure continued performance of their intended function, to prevent adverse impacts to existing flow control BMPs and areas of proposed flow control BMPs, and protect other disturbed areas of the project. 13. Manage the Project: Coordination and timing of site development activities relative to ESC concerns, and timely inspection, maintenance and update of protective measures are necessary to effectively manage the project and assure the success of protective ESC and SWPPS design and implementation. D.2.1.1 CLEARING LIMITS Prior to any site clearing or grading, those areas that are to remain undisturbed during project construction shall be delineated. At a minimum, clearing limits shall be installed at the edges of all critical area buffers and any other areas required to be left uncleared such as portions of the site subject to clearing limits under KCC 16.82.150, areas around significant trees identified to be retained, flow control BMP areas to be protected, and other areas identified to be left undisturbed to protect sensitive features. Purpose: The purpose of clearing limits is to prevent disturbance of those areas of the project site that are not designated for clearing or grading. This is important because limiting site disturbance is the single most effective method for reducing erosion. Clearing limits may also be used to control construction traffic, thus reducing the disturbance of soil and limiting the amount of sediment tracked off site. When to Install: Clearing limits shall be installed prior to the clearing and/or grading of the site. Measures to Use: Marking clearing limits by delineating the site with a continuous length of brightly colored survey tape is sometimes sufficient. The tape may be supported by vegetation or stakes, and it shall be 3 to 6 feet high and highly visible. Critical areas and their buffers require more substantial protection and shall be delineated with plastic or metal safety fences or stake and wire fences. Fencing may be required at the County's discretion to control construction traffic or at any location where greater SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-12 protection is warranted. Permanent fencing may also be used if desired by the applicant. Silt fence, in combination with survey flagging, is also an acceptable method of marking critical areas and their buffers. D.2.1.1.1 PLASTIC OR METAL FENCE Code: FE Symbol: Purpose Fencing is intended to (1) restrict clearing to approved limits; (2) prevent disturbance of critical areas, their buffers, and other areas required to be left undisturbed; (3) limit construction traffic to designated construction entrances or roads; and (4) protect areas where marking with survey tape may not provide adequate protection. Conditions of Use To establish clearing limits, plastic or metal fence may be used: 1. At the boundary of critical areas, their buffers, and other areas required to be left uncleared. 2. As necessary to control vehicle access to and on the site (see Sections D.2.1.4.1 and D.2.1.4.2). Design and Installation Specifications 1. The fence shall be designed and installed according to the manufacturer's specifications. 2. The fence shall be at least 3 feet high and must be highly visible. 3. The fence shall not be wired or stapled to trees. Maintenance Requirements 1. If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. 2. Disturbance of a critical area, critical area buffer, native growth retention area, or any other area required to be left undisturbed shall be reported to the County for resolution. D.2.1.2 COVER MEASURES Temporary and permanent cover measures shall be provided to protect all disturbed areas, including the faces of cut and fill slopes. Temporary cover shall be installed if an area is to remain unworked for more than seven days during the dry season (May 1 to September 30) or for more than two consecutive working days during the wet season (October 1 to April 30). These time limits may be relaxed if an area poses a low risk of erosion due to soil type, slope gradient, anticipated weather conditions, or other factors. Conversely, the County may reduce these time limits if site conditions warrant greater protection (e.g., adjacent to significant aquatic resources or highly erosive soils) or if significant precipitation (see Section D.2.4.2) is expected. Any area to remain unworked for more than 30 days shall be seeded or sodded, unless the County determines that winter weather makes vegetation establishment infeasible. During the wet season, slopes and stockpiles at 3H:1V or steeper and with more than ten feet of vertical relief shall be covered if they are to remain unworked for more than 12 hours. Also during the wet season, the material necessary to cover all disturbed areas must be stockpiled on site. The intent of these cover requirements is to have as much area as possible covered during any period of precipitation. Purpose: The purpose of covering exposed soils is to prevent erosion, thus reducing reliance on less effective methods that remove sediment after it is entrained in runoff. Cover is the only practical method of reducing turbidity in runoff. Structural measures, such as silt fences and sediment ponds, are only capable of removing coarse particles and in most circumstances have little to no effect on turbidity. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-16 D.2.1.2.2 MULCHING Code: MU Symbol: Purpose The purpose of mulching soils is to provide immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and moderating soil temperatures. There is an enormous variety of mulches that may be used. Only the most common types are discussed in this section. Conditions of Use As a temporary cover measure, mulch should be used: 1. On disturbed areas that require cover measures for less than 30 days 2. As a cover for seed during the wet season and during the hot summer months 3. During the wet season on slopes steeper than 3H:1V with more than 10 feet of vertical relief. Design and Installation Specifications For mulch materials, application rates, and specifications, see Table D.2.1.2.A. Note: Thicknesses may be increased for disturbed areas in or near critical areas or other areas highly susceptible to erosion. Maintenance Standards 1. The thickness of the cover must be maintained. 2. Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the erosion problem is drainage related, then the drainage problem shall be assessed and alternate drainage such as interceptor swales may be needed to fix the problem and the eroded area remulched. D.2.1.2 COVER MEASURES 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-17 TABLE D.2.1.2.A MULCH STANDARDS AND GUIDELINES Mulch Material Quality Standards Application Rates Remarks Straw Air-dried; free from undesirable seed and coarse material 2"-3" thick; 5 bales per 1000 sf or 2-3 tons per acre Cost-effective protection when applied with adequate thickness. Hand-application generally requires greater thickness than blown straw. Straw should be crimped to avoid wind blow. The thickness of straw may be reduced by half when used in conjunction with seeding. Wood Fiber Cellulose No growth inhibiting factors Approx. 25-30 lbs per 1000 sf or 1500-2000 lbs per acre Shall be applied with hydromulcher. Shall not be used without seed and tackifier unless the application rate is at least doubled. Some wood fiber with very long fibers can be effective at lower application rates and without seed or tackifier. Compost No visible water or dust during handling. Must be purchased from supplier with Solid Waste Handling Permit. 2" thick min.; approx. 100 tons per acre (approx. 1.5 cubic feet per square yard) More effective control can be obtained by increasing thickness to 3" (2.25 cubic feet per square yard). Excellent mulch for protecting final grades until landscaping because it can be directly seeded or tilled into soil as an amendment. Compost may not be used in Sensitive Lake7 basins unless analysis of the compost shows no phosphorous release. Hydraulic Matrices (Bonded Fiber Matrix) This mulch category includes hydraulic slurries composed of wood fiber, paper fiber or a combination of the two held together by a binding system. The BFM shall be a mixture of long wood fibers and various bonding agents. Apply at rates from 3,000 lbs per acre to 4,000 lbs per acre and based on manufacturers recommendations The BFM shall not be applied immediately before, during or immediately after rainfall so that the matrix will have an opportunity to dry for 24 hours after installation. Application rates beyond 2,500 pounds may interfere with germination and are not usually recommended for turf establishment. BFM is generally a matrix where all fiber and binders are in one bag, rather than having to mix components from various manufacturers to create a matrix. BFMs can be installed via helicopter in remote areas. They are approximately $1,000 per acre cheaper to install. Chipped Site Vegetation Average size shall be several inches. 2" minimum thickness This is a cost-effective way to dispose of debris from clearing and grubbing, and it eliminates the problems associated with burning. Generally, it should not be used on slopes above approx. 10% because of its tendency to be transported by runoff. It is not recommended within 200 feet of surface waters. If seeding is expected shortly after mulch, the decomposition of the chipped vegetation may tie up nutrients important to grass establishment. 7 Sensitive lake means a lake that has proved to be particularly prone to eutrophication; the County gives this designation when an active input plan has been adopted to limit the amount of phosphorous entering the lake. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-18 D.2.1.2.3 NETS AND BLANKETS Code: NE Symbol: Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets are strands of material woven into an open, but high-tensile strength net (for example, jute matting). Blankets are strands of material that are not tightly woven, but instead form a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets, but cover the ground more completely. Coir (coconut fiber) fabric comes as both nets and blankets. Conditions of Use Erosion control nets and blankets should be used: 1. For permanent stabilization of slopes 2H:1V or greater and with more than 10 feet of vertical relief. 2. In conjunction with seed for final stabilization of a slope, not for temporary cover. However, they may be used for temporary applications as long as the product is not damaged by repeated handling. In fact, this method of slope protection is superior to plastic sheeting, which generates high-velocity runoff (see Section D.2.1.2.4). 3. For drainage ditches and swales (highly recommended). The application of appropriate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due to their open, porous structure. Synthetic nets and blankets may be used to permanently stabilize channels and may provide a cost-effective, environmentally preferable alternative to riprap. Design and Installation Specifications 1. See Figure D.2.1.2.B and Figure D.2.1.2.C for typical orientation and installation of nettings and blankets. Note: Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. 2. With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the design engineer thoroughly consults the manufacturer's information and that a site visit takes place in order to insure that the product specified is appropriate. 3. Jute matting must be used in conjunction with mulch (Section D.2.1.2.2). Excelsior, woven straw blankets, and coir (coconut fiber) blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. Other types of products will have to be evaluated individually. In general, most nets (e.g., jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. 4. Purely synthetic blankets are allowed but shall only be used for long-term stabilization of waterways. The organic blankets authorized above are better for slope protection and short-term waterway protection because they retain moisture and provide organic matter to the soil, substantially improving the speed and success of re-vegetation. Maintenance Standards 1. Good contact with the ground must be maintained, and there must not be erosion beneath the net or D.2.1.2 COVER MEASURES 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-19 blanket. 2. Any areas of the net or blanket that are damaged or not in close contact with the ground shall be repaired and stapled. 3. If erosion occurs due to poorly controlled drainage, the problem shall be fixed and the eroded area protected. FIGURE D.2.1.2.B WATERWAY INSTALLATION •DO NOT STRETCH BLANKETS/MATTINGS TIGHT - ALLOW THE ROLLS TO MOLD TO ANY IRREGULARITIES. •SLOPE SURFACE SHALL BE SMOOTH BEFORE PLACEMENT FOR PROPER SOIL CONTACT. •ANCHOR, STAPLE, AND INSTALL CHECK SLOTS AS PER MANUFACTURER'S RECOMMENDATIONS. •AVOID JOINING MATERIAL IN THE CENTER OF THE DITCH. •LIME, FERTILIZE AND SEED BEFORE INSTALLATION. MIN.4" OVERLAP' MIN.6" OVERLAP FIGURE D.2.1.2.C SLOPE INSTALLATION SLOPE SURFACE SHALL BE SMOOTH BEFORE PLACEMENT FOR PROPER SOIL CONTACT STAPLING PATTERN AS PER MANUFACTURER'S RECOMMENDATION MIN. 2" OVERLAP LIME, FERTILIZE AND SEED BEFORE INSTALLATION. PLANTING OF SHRUBS, TREES, ETC. SHOULD OCCUR AFTER INSTALLATION DO NOT STRETCH BLANKETS/MATTINGS TIGHT - ALLOW THE ROLLS TO MOLD TO ANY IRREGULARITIES FOR SLOPES LESS THAN 3H:1V, ROLLS MAY BE PLACED IN HORIZONTAL STRIPS BRING MATERIAL DOWN TO A LEVEL AREA, TURN THE END UNDER 4" AND STAPLE AT 12" INTERVALS ANCHOR IN 6"x6" MIN. TRENCH AND STAPLE AT 12" INTERVALS STAPLE OVERLAPS MAX. 5' SPACING IF THERE IS A BERM AT THE TOP OF SLOPE, ANCHOR UPSLOPE OF THE BERM MIN. 6" OVERLAP SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-20 D.2.1.2.4 PLASTIC COVERING Code: PC Symbol: Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Use 1. Plastic covering may be used on disturbed areas that require cover measures for less than 30 days. 2. Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term applications. 3. Clear plastic sheeting may be used over newly-seeded areas to create a greenhouse effect and encourage grass growth. Clear plastic should not be used for this purpose during the summer months because the resulting high temperatures can kill the grass. 4. Due to rapid runoff caused by plastic sheeting, this method shall not be used upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. Note: There have been many problems with plastic, usually attributable to poor installation and maintenance. However, the material itself can cause problems, even when correctly installed and maintained, because it generates high-velocity runoff and breaks down quickly due to ultraviolet radiation. In addition, if the plastic is not completely removed, it can clog drainage system inlets and outlets. It is highly recommended that alternatives to plastic sheeting be used whenever possible and that its use be limited. Design and Installation Specifications 1. See Figure D.2.1.2.D for details. 2. Plastic sheeting shall have a minimum thickness of 0.06 millimeters. 3. If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. FIGURE D.2.1.2.D PLASTIC COVERING TIRES, SANDBAGS, OR EQUIVALENT MAY BE USED TO WEIGHT PLASTIC SEAMS BETWEEN SHEETS MUST OVERLAP A MINIMUM OF 12" AND BE WEIGHTED OR TAPED TOE IN SHEETING IN MINIMUM 4"X4" TRENCH PROVIDE ENERGY DISSIPATION AT TOE WHEN NEEDED 10' MAX. 10' MAX. D.2.1.2 COVER MEASURES 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-21 Maintenance Standards for Plastic Covering 1. Torn sheets must be replaced and open seams repaired. 2. If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and replaced. 3. When the plastic is no longer needed, it shall be completely removed. D.2.1.2.5 STRAW WATTLES Code: SW Symbol: Purpose Wattles are erosion and sediment control barriers consisting of straw wrapped in biodegradable tubular plastic or similar encasing material. Wattles may reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sediment. Straw wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length. The wattles are placed in shallow trenches and staked along the contour of disturbed or newly constructed slopes. Conditions of Use 1. Install on disturbed areas that require immediate erosion protection. 2. Use on slopes requiring stabilization until permanent vegetation can be established. 3. Can be used along the perimeter of a project, as a check dam in unlined ditches and around temporary stockpiles 4. Wattles can be staked to the ground using willow cuttings for added revegetation. 5. Rilling can occur beneath and between wattles if not properly entrenched, allowing water to pass below and between wattles Design and Installation Specifications 1. It is critical that wattles are installed perpendicular to the flow direction and parallel to the slope contour. 2. Narrow trenches should be dug across the slope, on contour, to a depth of 3 to 5 inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and during high rainfall events, the trenches should be dug to a depth of 5 to 7 inches, or ½ to 2/3 of the thickness of the wattle. 3. Start construction of trenches and installing wattles from the base of the slope and work uphill. Excavated material should be spread evenly along the uphill slope and compacted using hand tamping or other method. Construct trenches at contour intervals of 3 to 30 feet apart depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches should be constructed. 4. Install the wattles snugly into the trenches and abut tightly end to end. Do not overlap the ends. 5. Install stakes at each end of the wattle, and at 4 foot centers along the entire length of the wattle. 6. If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. 7. At a minimum, wooden stakes should be approximately ¾ x ¾ x 24 inches. Willow cuttings or 3/8 inch rebar can also be used for stakes. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-22 8. Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake protruding above the wattle. Maintenance Standards 1. Inspect wattles prior to forecasted rain, daily during extended rain events, after rain events, weekly during the wet season, and at two week intervals at all other times of the year. 2. Repair or replace split, torn, raveling, or slumping wattles 3. Remove sediment accumulations when exceeding ½ the height between the top of the wattle and the ground surface. D.2.1.2 COVER MEASURES 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-23 FIGURE D.2.1.2.E STRAW WATTLES 1.STRAW ROLL INSTALLATION REQUIRES THE PLACEMENT AND SECURE STAKING OF THE ROLL IN A TRENCH, 3" x 5" (75-125mm) DEEP, DUG ON CONTOUR. 2.RUNOFF MUST NOT BE ALLOWED TO RUN UNDER OR AROUND ROLL. ROLL SPACING DEPENDS ON SOIL TYPE AND SLOPE STEEPNESS STRAW ROLLS MUST BE PLACED ALONG SLOPE CONTOURS 3'-4' (1.2m) 10'-25' (3-8m) 3"-5" (75-125mm) ADJACENT ROLLS SHALL TIGHTLY ABUT SEDIMENT, ORGANIC MATTER, AND NATIVE SEEDS ARE CAPTURED BEHIND THE ROLLS LIVE STAKE 1" x 1" STAKE 8"-10" DIA. (200-250mm) NOTES: STRAW WATTLES NTS SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-24 D.2.1.2.6 TEMPORARY AND PERMANENT SEEDING Code: SE Symbol: Purpose Seeding is intended to reduce erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducing erosion. Conditions of Use 1. Seeding shall be used throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. 2. Vegetation-lined channels shall be seeded. Channels that will be vegetated should be installed before major earthwork and hydroseeded or covered with a Bonded Fiber Matrix (BFM). 3. Retention/detention ponds shall be seeded as required. 4. At the County's discretion, seeding without mulch during the dry season is allowed even though it will take more than seven days to develop an effective cover. Mulch is, however, recommended at all times because it protects seeds from heat, moisture loss, and transport due to runoff. 5. At the beginning of the wet season, all disturbed areas shall be reviewed to identify which ones can be seeded in preparation for the winter rains (see Section D.2.4.2). Disturbed areas shall be seeded within one week of the beginning of the wet season. A sketch map of those areas to be seeded and those areas to remain uncovered shall be submitted to the DLS-Permitting inspector. The DLS- Permitting inspector may require seeding of additional areas in order to protect surface waters, adjacent properties, or drainage facilities. 6. At final site stabilization, all disturbed areas not otherwise vegetated or stabilized shall be seeded and mulched (see Section D.2.4.5). Design and Installation Specifications 1. The best time to seed is April 1 through June 30, and September 1 through October 15. Areas may be seeded between July 1 and August 31, but irrigation may be required in order to grow adequate cover. Areas may also be seeded during the winter months, but it may take several months to develop a dense groundcover due to cold temperatures. The application and maintenance of mulch is critical for winter seeding. 2. To prevent seed from being washed away, confirm that all required surface water control measures have been installed. 3. The seedbed should be firm but not compacted because soils that are well compacted will not vegetate as quickly or thoroughly. Slopes steeper than 3H:1V shall be surface roughened. Roughening can be accomplished in a variety of ways, but the typical method is track walking, or driving a crawling tractor up and down the slope, leaving cleat imprints parallel to the slope contours. 4. In general, 10-20-20 N-P-K (nitrogen-phosphorus-potassium) fertilizer may be used at a rate of 90 pounds per acre. Slow-release fertilizers are preferred because they are more efficient and have fewer environmental impacts. It is recommended that areas being seeded for final landscaping conduct soil tests to determine the exact type and quantity of fertilizer needed. This will prevent the over- application of fertilizer. Disturbed areas within 200 feet of water bodies and wetlands must use slow- release low-phosphorus fertilizer (typical proportions 3-1-2 N-P-K). 5. The following requirements apply to mulching: a) Mulch is always required for seeding slopes greater than 3H:1V (see Section D.2.1.2.2). D.2.1.2 COVER MEASURES 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-25 b) If seeding during the wet season, mulch is required. c) The use of mulch may be required during the dry season at the County's discretion if grass growth is expected to be slow, the soils are highly erodible due to soil type or gradient, there is a water body close to the disturbed area, or significant precipitation (see Section D.2.4.2) is anticipated before the grass will provide effective cover. d) Mulch may be applied on top of the seed or simultaneously by hydroseeding. 6. Hydroseeding is allowed as long as tackifier is included. Hydroseeding with wood fiber mulch is adequate during the dry season. During the wet season, the application rate shall be doubled because the mulch and tackifier used in hydroseeding break down fairly rapidly. It may be necessary in some applications to include straw with the wood fiber, but this can be detrimental to germination. 7. Areas to be permanently landscaped shall use soil amendments. Good quality topsoil shall be tilled into the top six inches to reduce the need for fertilizer and improve the overall soil quality. Most native soils will require the addition of four inches of well-rotted compost to be tilled into the soil to provide a good quality topsoil. Compost used should meet specifications provided in Reference 11-C of the SWDM. 8. The seed mixes listed below include recommended mixes for both temporary and permanent seeding. These mixes, with the exception of the wetland mix, shall be applied at a rate of 120 pounds per acre. This rate may be reduced if soil amendments or slow-release fertilizers are used. Local suppliers should be consulted for their recommendations because the appropriate mix depends on a variety of factors, including exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the County may be used. Table D.2.1.2.B presents the standard mix for those areas where just a temporary vegetative cover is required. TABLE D.2.1.2.B TEMPORARY EROSION CONTROL SEED MIX % Weight % Purity % Germination Chewings or red fescue Festuca rubra var. commutata or Festuca rubra 40 98 90 Annual or perennial rye Lolium multiflorum or Lolium perenne 40 98 90 Redtop or colonial bentgrass Agrostis alba or Agrostis tenuis 10 92 85 White dutch clover Trifolium repens 10 98 90 SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-26 Table D.2.1.2.C provides just one recommended possibility for landscaping seed. TABLE D.2.1.2.C LANDSCAPING SEED MIX % Weight % Purity % Germination Perennial rye blend Lolium perenne 70 98 90 Chewings and red fescue blend Festuca rubra var. commutata or Festuca rubra 30 98 90 This turf seed mix in Table D.2.1.2.D is for dry situations where there is no need for much water. The advantage is that this mix requires very little maintenance. TABLE D.2.1.2.D LOW-GROWING TURF SEED MIX % Weight % Purity % Germination Dwarf tall fescue (several varieties) Festuca arundinacea var. 45 98 90 Dwarf perennial rye (Barclay) Lolium perenne var. barclay 30 98 90 Red fescue Festuca rubra 20 98 90 Colonial bentgrass Agrostis tenuis 5 98 90 Table D.2.1.2.E presents a mix recommended for bioswales and other intermittently wet areas. Sod shall generally not be used for bioswales because the seed mix is inappropriate for this application. Sod may be used for lining ditches to prevent erosion, but it will provide little water quality benefit during the wet season. TABLE D.2.1.2.E BIOSWALE SEED MIX* % Weight % Purity % Germination Tall or meadow fescue Festuca arundinacea or Festuca elatior 75-80 98 90 Seaside/Creeping bentgrass Agrostis palustris 10-15 92 85 Redtop bentgrass Agrostis alba or Agrostis gigantea 5-10 90 80 * Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix D.2.1.2 COVER MEASURES 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-27 The seed mix shown in Table D.2.1.2.F is a recommended low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wetlands (if planting in wetland areas, see Section 6.3.1 of the King County Surface Water Design Manual). Other mixes may be appropriate, depending on the soil type and hydrology of the area. Apply this mixture at a rate of 60 pounds per acre. TABLE D.2.1.2.F WET AREA SEED MIX* % Weight % Purity % Germination Tall or meadow fescue Festuca arundinacea or Festuca elatior 60-70 98 90 Seaside/Creeping bentgrass Agrostis palustris 10-15 98 85 Meadow foxtail Alepocurus pratensis 10-15 90 80 Alsike clover Trifolium hybridum 1-6 98 90 Redtop bentgrass Agrostis alba 1-6 92 85 * Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix The meadow seed mix in Table D.2.1.2.G is recommended for areas that will be maintained infrequently or not at all and where colonization by native plants is desirable. Likely applications include rural road and utility right-of -way. Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter months. The appropriateness of clover in the mix may need to be considered as this can be a fairly invasive species. If the soil is amended, the addition of clover may not be necessary. TABLE D.2.1.2.G MEADOW SEED MIX % Weight % Purity % Germination Redtop or Oregon bentgrass Agrostis alba or Agrostis oregonensis 40 92 85 Red fescue Festuca rubra 40 98 90 White dutch clover Trifolium repens 20 98 90 Maintenance Standards for Temporary and Permanent Seeding 1. Any seeded areas that fail to establish at least 80 percent cover within one month shall be reseeded. If reseeding is ineffective, an alternate method, such as sodding or nets/blankets, shall be used. If winter weather prevents adequate grass growth, this time limit may be relaxed at the discretion of the County when critical areas would otherwise be protected. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-28 2. After adequate cover is achieved, any areas that experience erosion shall be re-seeded and protected by mulch. If the erosion problem is drainage related, the problem shall be fixed and the eroded area re-seeded and protected by mulch. 3. Seeded areas shall be supplied with adequate moisture, but not watered to the extent that it causes runoff. D.2.1.2.7 SODDING Code: SO Symbol: Purpose The purpose of sodding is to establish permanent turf for immediate erosion protection and to stabilize drainage ways where concentrated overland flow will occur. Conditions of Use Sodding may be used in the following areas: 1. Disturbed areas that require short-term or long-term cover 2. Disturbed areas that require immediate vegetative cover 3. All waterways that require vegetative lining (except biofiltration swales—the seed mix used in most sod is not appropriate for biofiltration swales). Waterways may also be seeded rather than sodded, and protected with a net or blanket (see Section D.2.1.2.3). Design and Installation Specifications Sod shall be free of weeds, of uniform thickness (approximately 1-inch thick), and shall have a dense root mat for mechanical strength. The following steps are recommended for sod installation: 1. Shape and smooth the surface to final grade in accordance with the approved grading plan. 2. Amend four inches (minimum) of well-rotted compost into the top eight inches of the soil if the organic content of the soil is less than ten percent. Compost used shall meet compost specifications per SWDM Reference 11-C. 3. Fertilize according to the supplier's recommendations. Disturbed areas within 200 feet of water bodies and wetlands must use non-phosphorus fertilizer. 4. Work lime and fertilizer 1 to 2 inches into the soil, and smooth the surface. 5. Lay strips of sod beginning at the lowest area to be sodded and perpendicular to the direction of water flow. Wedge strips securely into place. Square the ends of each strip to provide for a close, tight fit. Stagger joints at least 12 inches. Staple on slopes steeper than 3H:1V. 6. Roll the sodded area and irrigate. 7. When sodding is carried out in alternating strips or other patterns, seed the areas between the sod immediately after sodding. Maintenance Standards If the grass is unhealthy, the cause shall be determined and appropriate action taken to reestablish a healthy groundcover. If it is impossible to establish a healthy groundcover due to frequent saturation, instability, or some other cause, the sod shall be removed, the area seeded with an appropriate mix, and protected with a net or blanket. D.2.1.2 COVER MEASURES 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-29 D.2.1.2.8 POLYACRYLAMIDE FOR SOIL EROSION PROTECTION Purpose Polyacrylamide (PAM) is used on construction sites to prevent soil erosion. Applying PAM to bare soil in advance of a rain event significantly reduces erosion and controls sediment in two ways. First, PAM increases the soil's available pore volume, thus increasing infiltration through flocculation and reducing the quantity of stormwater runoff. Second, it increases flocculation of suspended particles and aids in their deposition, thus reducing stormwater runoff turbidity and improving water quality. Conditions of Use 1. PAM shall not be directly applied to water or allowed to enter a water body. 2. PAM may be applied to wet soil, but dry soil is preferred due to less sediment loss. 3. PAM will work when applied to saturated soil but is not as effective as applications to dry or damp soil. 4. PAM may be applied only to the following types of bare soil areas that drain to a sediment trap or a sediment pond: • Staging areas • Stockpiles • Pit sites • Balanced cut and fill earthwork • Haul roads prior to placement of crushed rock surfacing • Compacted soil road base 5. PAM may be applied only during the following phases of construction: • During rough grading operations • After final grade and before paving or final seeding and planting • During a winter shut down of site work. In the case of winter shut down, or where soil will remain unworked for several months, PAM should be used together with mulch. 6. Do not use PAM on a slope that flows directly to a stream or wetland. The stormwater runoff shall pass through a sediment control measure prior to discharging to surface waters. Design and Installation Specifications 1. PAM must be applied using one of two methods of application, "preferred" or "alternative." The specifications for these methods are described under separate headings below. 2. PAM may be applied in dissolved form with water, or it may be applied in dry, granular or powdered form. The preferred application method is the dissolved form. 3. PAM is to be applied at a maximum rate of ½ pound PAM per 1000 gallons of water per 1 acre of bare soil. Table D.2.1.2.H may be used to determine the PAM and water application rate for disturbed soil areas. Higher concentrations of PAM do not provide any additional effectiveness. 4. Do not add PAM to water discharging from the site. 5. PAM shall be used in conjunction with other ESC measures and not in place of them. When the total drainage area is greater than or equal to 3 acres, PAM treated areas shall drain to a sediment pond per Section D.2.1.5.2. For drainage areas less than 3 acres, PAM treated areas must drain to a sediment trap per Section D.2.1.5.1. Other normally required sediment control measures such as perimeter SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-30 protection measures (Section D.2.1.3) and surface water collection measures (Section D.2.1.6) shall be applied to PAM treated areas. 6. All areas not being actively worked shall be covered and protected from rainfall. PAM shall not be the only cover BMP used. 7. Keep the granular PAM supply out of the sun. Granular PAM loses its effectiveness in three months after exposure to sunlight and air. 8. Care must be taken to prevent spills of PAM powder onto paved surfaces. PAM, combined with water, is very slippery and can be a safety hazard. During an application of PAM, prevent over-spray from reaching pavement as the pavement will become slippery. If PAM powder gets on skin or clothing, wipe it off with a rough towel rather than washing with water. Washing with water only makes cleanup more difficult, messier, and time consuming. 9. The specific PAM copolymer formulation must be anionic. Cationic PAM shall not be used in any application because of known aquatic toxicity concerns. Only the highest drinking water grade PAM, certified for compliance with ANSI/NSF Standard 60 for drinking water treatment, may be used for soil applications. The Washington State Department of Transportation (WSDOT) lists approved PAM products on their web page. All PAM use shall be reviewed and approved by DLS-Permitting. 10. The PAM anionic charge density may vary from 2 – 30 percent; a value of 18 percent is typical. Studies conducted by the United States Department of Agriculture (USDA)/ARS demonstrated that soil stabilization was optimized by using very high molecular weight (12 – 15 mg/mole), highly anionic (>20% hydrolysis) PAM. 11. PAM must be "water soluble" or "linear" or "non-cross-linked." Cross-linked or water absorbent PAM, polymerized in highly acidic (pH<2) conditions, are used to maintain soil moisture content. TABLE D.2.1.2.H PAM AND WATER APPLICATION RATES Disturbed Area (ac) PAM (lbs) Water (gal) 0.50 0.25 500 1.00 0.50 1,000 1.50 0.75 1,500 2.00 1.00 2,000 2.50 1.25 2,500 3.00 1.50 3,000 3.50 1.75 3,500 4.00 2.00 4,000 4.50 2.25 4,500 5.00 2.50 5,000 Preferred Application Method 1. Pre-measure the area where PAM is to be applied and calculate the amount of product and water necessary to provide coverage at the specified application rate (1/2 pound PAM/1,000 gallons/acre). 2. Dissolve pre-measured dry granular PAM with a known quantity of clean water in a bucket several hours or overnight. PAM has infinite solubility in water, but dissolves very slowly. Mechanical mixing will help dissolve PAM. Always add PAM to water – not water to PAM. D.2.1.2 COVER MEASURES 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-31 3. Pre-fill the water truck about 1/8 full with water. The water does not have to be potable, but it must have relatively low turbidity – in the range of 20 NTU or less. 4. Add PAM/Water mixture to the truck. 5. Completely fill the water truck to specified volume. 6. Spray PAM/Water mixture onto dry soil until the soil surface is uniformly and completely wetted. Alternate Application Method PAM may also be applied as a powder at the rate of 5 pounds per acre. This must be applied on a day that is dry. For areas less than 5-10 acres, a hand-held "organ grinder" fertilized spreader set to the smallest setting will work. Tractor mounted spreaders will work for larger areas. Maintenance Standards 1. PAM may be reapplied on actively worked areas after a 48-hour period 2. Reapplication is not required unless PAM treated soil is disturbed or unless turbidity levels show the need for an additional application. If PAM treated soil is left undisturbed, a reapplication may be necessary after two months. More PAM applications may be required for steep slopes, silty and clay soils, (USDA classification Type "C" and "D" soils), long grades, and high precipitation areas. When PAM is applied first to bare soil and then covered with straw, a reapplication may not be necessary for several months. D.2.1.2.9 COMPOST BLANKETS Code: COBL Symbol: Purpose Compost blankets are intended to: • Provide immediate temporary protection from erosion by protecting soil from rainfall and slowing flow velocity over the soil surface. • Enhance temporary or permanent plant establishment by conserving moisture, holding seed and topsoil in place, providing nutrients and soil microorganisms, and moderating soil temperatures. • Compost blankets, applied at the proper thickness and tilled into the soil, are also an option for amending soils for permanent landscaping. • Compost generally releases and adds phosphorous to stormwater. Therefore, compost blankets are not recommended for use in watersheds where phosphorous sensitive water resources are located. Unless prior approval is given by the County, they should not be used in Sensitive Lake Watersheds. Conditions of Use 1. Compost blankets may be used unseeded on disturbed areas that require temporary cover measures up to 1 year. Compost applied as temporary cover may be reclaimed and re-used for permanent cover. 2. Compost provides cover for protecting final grades until landscaping can be completed as it can be directly seeded or tilled into soil as an amendment. 3. Compost blankets meet mulch requirements for seed. 4. Seed may be applied to a compost blanket at any time for permanent or temporary stabilization of disturbed areas. Seed may be applied prior to blanket application, on top of blankets, or injected and mixed into the compost as it is applied. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-32 5. Compost blankets may be applied on slopes up to 2H:1V. Design and Installation Specifications 1. Compost shall be applied at a minimum of 2 inches thick, unless otherwise directed by an ESC supervisor or King County. At an application of 2 inches, this will equal approximately 100 tons per acre (compost generally weighs approximately 800 lbs per cubic yard). Thickness shall be increased at the direction of the design engineer for disturbed areas in or near critical areas or other areas highly susceptible to erosion. 2. Compost shall meet criteria in Reference 11-C of the SWDM. 3. Compost shall be obtained from a supplier meeting the requirements in Reference 11-C. 4. Compost blankets shall be applied over the top of the slope to which it is applied, to prevent water from running under the blanket 5. Compost blankets shall not be used in areas exposed to concentrated flow (e.g. channels, ditches, dikes) Maintenance Standards 1. The specified thickness of the blanket/cover must be maintained. 2. Any areas that show signs of erosion must be re-mulched. If the erosion problem is drainage related, then the drainage problem must first be remedied and then the eroded area re-mulched. D.2.1.3 PERIMETER PROTECTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-33 D.2.1.3 PERIMETER PROTECTION Perimeter protection to filter sediment from sheetwash shall be located downslope of all disturbed areas and shall be installed prior to upslope grading. Perimeter protection includes the use of vegetated strips as well as, constructed measures, such as silt fences, fiber rolls, sand/gravel barriers, brush or rock filters, triangular silt dikes and other methods. During the wet season, 50 linear feet of silt fence (and the necessary stakes) per acre of disturbed area must be stockpiled on site. Purpose: The purpose of perimeter protection is to reduce the amount of sediment transported beyond the disturbed areas of the construction site. Perimeter protection is primarily a backup means of sediment control. Most, if not all, sediment-laden water is to be treated in a sediment trap or pond. The only circumstances in which perimeter control is to be used as a primary means of sediment removal is when the catchment is very small (see below). When to Install: Perimeter protection is to be installed prior to any upslope clearing and grading. Measures to Use: The above measures may be used interchangeably and are not the only perimeter protection measures available. If surface water is collected by an interceptor dike or swale and routed to a sediment pond or trap, there may be no need for the perimeter protection measures specified in this section. Criteria for Use as Primary Treatment: At the boundary of a site, perimeter protection may be used as the sole form of treatment when the flowpath meets the criteria listed below. If these criteria are not met, perimeter protection shall only be used as a backup to a sediment trap or pond. Average Slope Slope Percent Flowpath Length 1.5H:1V or less 67% or less 100 feet 2H:1V or less 50% or less 115 feet 4H:1V or less 25% or less 150 feet 6H:1V or less 16.7% or less 200 feet 10H:1V or less 10% or less 250 feet D.2.1.3.1 SILT FENCE Code: SF Symbol: Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use 1. Silt fence may be used downslope of all disturbed areas. 2. Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment trap or pond. The only circumstance in which overland flow may be treated solely by a silt fence, rather than by a sediment trap or pond, is when the area draining to the fence is small (see "Criteria for Use as Primary Treatment" in Section D.2.1.3 above). Design and Installation Specifications 1. See Figure D.2.1.3.A and Figure D.2.1.3.B for details. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-34 2. The geotextile used must meet the standards listed below. A copy of the manufacturer's fabric specifications must be available on site. AOS (ASTM D4751) 30-100 sieve size (0.60-0.15 mm) for slit film 50-100 sieve size (0.30-0.15 mm) for other fabrics Water Permittivity (ASTM D4491) 0.02 sec-1 minimum Grab Tensile Strength (ASTM D4632) (see Specification Note 3) 180 lbs. min. for extra strength fabric 100 lbs. min. for standard strength fabric Grab Tensile Elongation (ASTM D4632) 30% max. (woven) Ultraviolet Resistance (ASTM D4355) 70% min. 3. Standard strength fabric requires wire backing to increase the strength of the fence. Wire backing or closer post spacing may be required for extra strength fabric if field performance warrants a stronger fence. 4. Where the fence is installed, the slope shall be no steeper than 2H:1V. 5. If a typical silt fence (per Figure D.2.1.3.A) is used, the standard 4 x 4 trench may be reduced as long as the bottom 8 inches of the silt fence is well buried and secured in a trench that stabilizes the fence and does not allow water to bypass or undermine the silt fence. Maintenance Standards 1. Any damage shall be repaired immediately. 2. If concentrated flows are evident uphill of the fence, they must be intercepted and conveyed to a sediment trap or pond. 3. It is important to check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. 4. Sediment must be removed when the sediment is 6 inches high. 5. If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, it shall be replaced. FIGURE D.2.1.3.A SILT FENCE 2"X2" BY 14 Ga. WIRE OR EQUIVALENT, IF STANDARD STRENGTH FABRIC USED NOTE: FILTER FABRIC FENCES SHALL BE INSTALLED ALONG CONTOURS WHENEVER POSSIBLE JOINTS IN FILTER FABRIC SHALL BE SPLICED AT POSTS. USE STAPLES, WIRE RINGS OR EQUIVALENT TO ATTACH FABRIC TO POSTS. FILTER FABRIC BACKFILL TRENCH WITH NATIVE SOIL OR 3/4" TO 1-1/2" WASHED GRAVEL MINIMUM 4"x4" TRENCH 2"x4" WOOD POSTS, STEEL FENCE POSTS, REBAR, OR EQUIVALENT POST SPACING MAY BE INCREASED TO 8' IF WIRE BACKING IS USED 6' MAX.2' MIN.12" MIN. D.2.1.3 PERIMETER PROTECTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-35 FIGURE D.2.1.3.B SILT FENCE INSTALLATION BY SLICING 1.GATHER FABRIC AT POSTS, IF NEEDED. 2.UTILIZE THREE TIES PER POST, ALL WITHIN TOP 8" OF FABRIC. 3.POSITION EACH TIE DIAGONALLY, PUNCTURING HOLES VERTICALLY A MINIMUM OF 1" APART. 4.HANG EACH TIE ON A POST NIPPLE AND TIGHTEN SECURELY. USE CABLE TIES (50 LBS) OF SOFT WIRE. TOP OF FABRIC BELT DIAGONAL ATTACHMENT DOUBLES STRENGTH FLOW STEEL SUPPORT POST1.POST SPACING: 7' MAX. ON OPEN RUNS 4' MAX. ON POOLING AREAS. 2.POST DEPTH: AS MUCH BELOW GROUND AS FABRIC ABOVE GROUND. 3.PONDING HEIGHT MAX. 24" ATTACH FABRIC TO UPSTREAM SIDE OF POST. 4.DRIVE OVER EACH SIDE OF SILT FENCE 2 TO 4 TIMES WITH DEVICE EXERTING 60 P.S.I. OR GREATER. 5.NO MORE THAN 24" OF A 36" FABRIC IS ALLOWED ABOVE GROUND. 6.VIBRATORY PLOW IS NOT ACCEPTABLE BECAUSE OF HORIZONTAL COMPACTION. 100% COMPACTION EACH SIDE OPERATION ROLL OF SILT FENCE PLOW FABRIC ABOVE GROUND HORIZONTAL CHISEL POINT (76 mm WIDTH)200-300mm SILT FENCE TOP 8" NOTES: ATTACHMENT DETAILS: SILT FENCE INSTALLATION BY SLICING METHOD NTS SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-36 D.2.1.3.2 BRUSH BARRIER Code: BB Symbol: Purpose The purpose of brush barriers is to reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use 1. Brush barriers may be used downslope of all disturbed areas. 2. Brush barriers are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment trap or pond. The only circumstance in which overland flow may be treated solely by a barrier, rather than by a sediment trap or pond, is when the area draining to the barrier is small (see "Criteria for Use as Primary Treatment" on page D-33). Design and Installation Specifications 1. See Figure D.2.1.3.C for details. 2. King County may require filter fabric (geotextile) anchored over the brush berm to enhance the filtration ability of the barrier. Maintenance Standards 1. There shall be no signs of erosion or concentrated runoff under or around the barrier. If concentrated flows are bypassing the barrier, it must be expanded or augmented by toed-in filter fabric. 2. The dimensions of the barrier must be maintained. FIGURE D.2.1.3.C BRUSH BARRIER IF REQUIRED, DRAPE FILTER FABRIC OVER BRUSH AND SECURE IN 4"x4" MIN. TRENCH WITH COMPACTED BACKFILL MAX. 6" DIAMETER WOODY DEBRIS FOR BARRIER CORE. ALTERNATIVELY TOPSOIL STRIPPINGS MAY BE USED TO FORM THE BARRIER. ANCHOR DOWNHILL EDGE OF FILTER FABRIC WITH STAKES, SANDBAGS, OR EQUIVALENT 2' MIN. HEIGHT 5' MIN. D.2.1.3 PERIMETER PROTECTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-37 D.2.1.3.3 VEGETATED STRIP Code: VS Symbol: Purpose Vegetated strips reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use 1. Vegetated strips may be used downslope of all disturbed areas. 2. Vegetated strips are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the draina ge system to a sediment trap or pond. The only circumstance in which overland flow may be treated solely by a strip, rather than by a sediment trap or pond, is when the area draining to the strip is small (see "Criteria for Use as Primary Treatment" on page D-33). Design and Installation Specifications 1. The vegetated strip shall consist of a 25-foot minimum width continuous strip of dense vegetation with a permeable topsoil. Grass-covered, landscaped areas are generally not adequate because the volume of sediment overwhelms the grass. Ideally, vegetated strips shall consist of undisturbed native growth with a well-developed soil that allows for infiltration of runoff. 2. The slope within the strip shall not exceed 4H:1V. 3. The uphill boundary of the vegetated strip shall be delineated with clearing limits as specified in Section D.2.1.1 (p. D-11). Maintenance Standards 1. Any areas damaged by erosion or construction activity shall be seeded immediately and protected by mulch. 2. If more than 5 feet of the original vegetated strip width has had vegetation removed or is being eroded, sod must be installed using the standards for installation found in Section D.2.1.2.7. If there are indications that concentrated flows are traveling across the buffer, surface water controls must be installed to reduce the flows entering the buffer, or additional perimeter protection must be installed. D.2.1.3.4 TRIANGULAR SILT DIKE (GEOTEXTILE ENCASED CHECK DAM) Code: TSD Symbol: Purpose Triangular silt dikes (TSDs) may be used as check dams, for perimeter protection, for temporary soil stockpile protection, for drop inlet protection, or as a temporary interceptor dike. Silt dikes, if attached to impervious surfaces with tack or other adhesive agent may also be used as temporary wheel wash areas, or concrete washout collection areas. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-38 Conditions of Use 1. May be used for temporary check dams in ditches. 2. May be used on soil or pavement with adhesive or staples. 3. TSDs have been used to build temporary sediment ponds, diversion ditches, concrete washout facilities, curbing, water bars, level spreaders, and berms. Design and Installation Specifications 1. TSDs must be made of urethane foam sewn into a woven geosynthetic fabric. 2. TSDs are triangular, 10 inches to 14 inches high in the center, with a 20-inch to 28-inch base. A 2- foot apron extends beyond both sides of the triangle along its standard section of 7 feet. A sleeve at one end allows attachment of additional sections as needed 3. Install TSDs with ends curved up to prevent water from flowing around the ends 4. Attach the TSDs and their fabric flaps to the ground with wire staples. Wire staples must be No. 11 gauge wire or stronger and shall be 200 mm to 300 mm in length. 5. When multiple units are installed, the sleeve of fabric at the end of the unit shall overlap the abutting unit and be stapled. 6. TSDs must be located and installed as soon as construction will allow. 7. TSDs must be placed perpendicular to the flow of water. 8. When used as check dams, the leading edge must be secured with rocks, sandbags, or a small key slot and staples. 9. When used in grass-lined ditches and swales, the TSD check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the TSD check dams shall be seeded and mulched immediately after dam removal. Maintenance Standards 1. Triangular silt dikes shall be monitored for performance and sediment accumulation during and after each runoff producing rainfall event. Sediment shall be removed when it reaches one half the height of the silt dike. 2. Anticipate submergence and deposition above the triangular silt dike and erosion from high flows around the edges of the dike/dam. Immediately repair any damage or any undercutting of the dike/dam. D.2.1.3.5 COMPOST BERMS Code: COBE Symbol: Purpose Compost berms are an option to meet the requirements of perimeter protection. Compost berms may reduce the transport of sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Compost berms trap sediment by filtering water passing through the berm and allowing water to pond, creating a settling area for solids behind the berm. Organic materials in the compost can also reduce concentrations of metals and petroleum hydrocarbons from construction runoff. Due to the increase in phosphorous seen in the effluent data from compost berms, they should be used with some cautions in areas that drain to phosphorus sensitive water D.2.1.3 PERIMETER PROTECTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-39 bodies, and should only be used in Sensitive Lake watersheds, such as Lake Sammamish, with the approval from the County or the local jurisdiction. Conditions of Use 1. Compost berms may be used in most areas requiring sediment or erosion control where runoff is in the form of sheet flow or in areas where silt fence is normally considered acceptable. Compost berms may be used in areas where migration of aquatic life such as turtles and salamanders are impeded by the use of silt fence. 2. Compost berms are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed via a drainage system to a sediment pond or trap. 3. For purposes of long-term sediment control objectives, berms may be seeded at the time of installation to create an additional vegetated filtering component. Design and Installation Specifications 1. Compost berms shall be applied using a pneumatic blower device or equivalent, to produce a uniform cross-section and berm density. 2. Compost berms shall be triangular in cross-section. The ratio of base to height dimensions shall be 2:1. 3. The minimum size of a compost berm is a 2-foot base with a 1-foot height. 4. Compost berms shall be sized and spaced as indicated in the table below. SLOPE SLOPE Maximum Slope Length or Berm Spacing (linear feet) Berm Size Required (height x base width) 0% - 2% Flatter than 50:1 250 1 ft x 2 ft 2% - 10% 50:1 – 10:1 125 1 ft x 2 ft 10% - 20% 10:1 – 5:1 100 1 ft x 2 ft 20% - 33% 5:1 – 3:1 75 1 ft x 2 ft 33% - 50% 3:1 – 2:1 50 1.5 ft x 3 ft 5. Compost berms shall not be used on slopes greater than 2H:1V. 6. Compost shall meet criteria in Reference 11-C of the SWDM except for the particle size distribution (see Bullet 8). 7. Compost shall be obtained from a supplier meeting the requirements in Reference 11-C. 8. Compost particle size distribution shall be as follows: 99% passing a 1 inch sieve, 90% passing a ¾ inch sieve and a minimum of 70% greater than the 3/8 inch sieve. A total of 98% shall not exceed 3 inches in length. 9. Berms shall be placed on level contours to assist in dissipating flow into sheet flow rather than concentrated flows. Berms shall not be constructed to concentrate runoff or channel water. Sheet flow of water shall be perpendicular to the berm at impact. No concentrated flow shall be directed towards compost berms. 10. Where possible, berms shall be placed 5 feet or more from the toe of slopes to allow space for sediment deposition and collection. 11. In order to prevent water from flowing around the ends of the berms, the ends of the berm shall be constructed pointing upslope so the ends are at a higher elevation than the rest of the berm. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-40 12. A compost blanket extending 10 – 15 feet above the berm is recommended where the surface above the berm is rutted or uneven, to reduce concentrated flow and promote sheet flow into the berm. Maintenance Standards 1. Compost berms shall be regularly inspected to make sure they retain their shape and allow adequate flow-through of stormwater. 2. When construction is completed on site, the berms shall be dispersed for incorporation into the soil or left on top of the site for final seeding to occur. 3. Any damage to berms must be repaired immediately. Damage includes flattening, compacting, rills, eroded areas due to overtopping. 4. If concentrated flows are evident uphill of the berm, the flows must be intercepted and conveyed to a sediment trap or pond. 5. The uphill side of the berm shall be inspected for signs of the berm clogging and acting as a barrier to flows and causing channelization of flows parallel to the berm. If this occurs, replace the berm or remove the trapped sediment. 6. Sediment that collects behind the berm must be removed when the sediment is more than 6 inches deep. D.2.1.3.6 COMPOST SOCKS Code: COSO Symbol: Purpose Compost socks reduce the transport of sediment from a construction site by providing a temporary physical barrier to sediment-laden water and reducing the runoff velocities of overland flow. Compost socks trap sediment by filtering water that passes through the sock and allows water to pond behind the sock, creating a settling area for solids. Organic materials in the compost also may reduce metal and petroleum hydrocarbon concentrations in construction runoff. Compost socks function similarly to compost berms; however, because the compost is contained in a mesh tube, they are appropriate for both concentrated flow and sheet flow. Compost socks may be used to channel concentrated flow on hard surfaces. Conditions of Use 1. Compost socks may be used in areas requiring sediment or erosion control where runoff is in the form of sheet flow or in areas that silt fence is normally considered acceptable. Compost socks may also be used in sensitive environmental areas where migration of aquatic life, including turtles, salamanders and other aquatic life may be impeded by the used of silt fence. 2. Compost socks are not intended to treat substantial amounts of overland flow. However, compost socks may be subjected to some ponding and concentrated flows. If intended primarily as a filtration device, the socks should be sized and placed so that flows do not overtop the socks. 3. For purposes of long term sediment control objectives, compost socks may be seeded at the time of installation to create an additional vegetated filtering component. Design and Installation Specifications 1. Compost socks shall be produced using a pneumatic blower hose or equivalent to fill a mesh tube with compost to create a uniform cross-section and berm density. D.2.1.4 TRAFFIC AREA STABILIZATION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-41 2. Socks shall be filled so they are firmly – packed yet flexible. Upon initial filling, the socks shall be filled to have a round cross-section. Once placed on the ground, it is recommended to apply weight to the sock to improve contact with the underlying surface. This may cause the sock to assume an oval shape. 3. Compost socks shall be a minimum of 8 inches in diameter. Larger diameter socks are recommended for areas where ponding is expected behind the sock. 4. Compost socks shall not be used on slopes greater than 2H:1V. 5. Compost shall meet criteria in Reference 11-C of the SWDM, except for the particle size distribution (see Bullet 7). 6. Compost shall be obtained from a supplier meeting the requirements in Reference 11-C. 7. Compost particle size distribution shall be as follows: 99% passing a 1 inch sieve, 90% passing a ¾ inch sieve and a minimum of 70% greater than the 3/8 inch sieve. A total of 98% shall not exceed 3 inches in length. 8. In order to prevent water from flowing around the ends of compost socks, the ends must be pointed upslope so the ends of the socks are at a higher elevation than the remainder of the sock. Maintenance Standards 1. Compost socks shall be regularly inspected to make sure the mesh tube remains undamaged, the socks retain their shape, and allow adequate flow through of surface water. If the mesh tube is torn, it shall be repaired using twine, zip-ties, or wire. Large sections of damaged socks must be replaced. Any damage must be repaired immediately upon discovery of damage. 2. When the sock is no longer needed, the socks shall be cut open and the compost dispersed to be incorporated into the soil or left on top of the soil for final seeding to occur. The mesh material must be disposed of properly as solid waste. If spills of oil, antifreeze, hydraulic fluid, or other equipment fluids have occurred that have saturated the sock, the compost must be disposed of properly as a waste. 3. Sediment must be removed when sediment accumulations are within 3 inches of the top of the sock. D.2.1.4 TRAFFIC AREA STABILIZATION Unsurfaced entrances, roads, and parking areas used by construction traffic shall be stabilized to minimize erosion and tracking of sediment off site. Stabilized construction entrances shall be installed as the first step in clearing and grading. At the County's discretion, road and parking area stabilization is not required during the dry season (unless dust is a concern) or if the site is underlain by coarse-grained soils. Roads and parking areas shall be stabilized immediately after initial grading. Purpose: The purpose of traffic area stabilization is to reduce the amount of sediment transported off site by construction vehicles and to reduce the erosion of areas disturbed by vehicle traffic. Sediment transported off site onto paved streets is a significant problem because it is difficult to effectively remove, and any sediment not removed ends up in the drainage system. Additionally, sediment on public right-of- way can pose a serious traffic hazard. Construction road and parking area stabilization is important because the combination of wet soil and heavy equipment traffic typically forms a slurry of easily erodible mud. Finally, stabilization also is an excellent form of dust control in the summer months. When to Install: The construction entrance is to be installed as the first step in clearing and grading. Construction road stabilization shall occur immediately after initial grading of the construction roads and parking areas. Measures to Use: There are two types of traffic area stabilization: (1) a stabilized construction entrance and (2) construction road/parking area stabilization. Both measures must be used as specified under "Conditions of Use" for each measure. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-42 D.2.1.4.1 STABILIZED CONSTRUCTION ENTRANCE Code: CE Symbol: Purpose Construction entrances are stabilized to reduce the amount of sediment transported onto paved roads by motor vehicles or runoff by constructing a stabilized pad of quarry spalls at entrances to construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be leaving a construction site and traveling on paved roads or other paved areas within 1,000 feet of the site. Access and exits shall be limited to one route if possible, or two for linear projects such as roadway where more than one access/exit is necessary for maneuvering large equipment. For residential construction provide stabilized construction entrances for each residence in addition to the main subdivision entrance. Stabilized surfaces shall be of sufficient length/width to provide vehicle access/parking, based on lot size/configuration. Design and Installation Specifications 1. See Figure D.2.1.4.A for details. 2. A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the following standards: Grab Tensile Strength (ASTM D4632) 200 lbs min. Grab Tensile Elongation (ASTM D4632) 30% max.(woven) Puncture Strength (ASTM D6241) 495 lbs min. AOS (ASTM D4751) 20-45 (U.S. standard sieve size) 3. Do not use crushed concrete, cement, or calcium chloride for construction entrance stabilization because these products raise pH levels in stormwater and concrete discharge to surface waters of the State is prohibited. 4. Hog fuel (wood based mulch) may be substituted for or combined with quarry spalls in areas that will not be used for permanent roads. The effectiveness of hog fuel is highly variable, but it has been used successfully on many sites. It generally requires more maintenance than quarry spalls. Hog fuel is not recommended for entrance stabilization in urban areas. The inspector may at any time require the use of quarry spalls if the hog fuel is not preventing sediment from being tracked onto pavement or if the hog fuel is being carried onto pavement. Hog fuel is prohibited in permanent roadbeds because organics in the subgrade soils cause difficulties with compaction. 5. Fencing (see Section D.2.1.1) shall be installed as necessary to restrict traffic to the construction entrance. 6. Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. Maintenance Standards 1. Quarry spalls (or hog fuel) shall be added if the pad is no longer in accordance with the specifications. D.2.1.4 TRAFFIC AREA STABILIZATION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-43 2. If the entrance is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash. If washing is used, it shall be done on an area covered with crushed rock, and wash water shall drain to a sediment trap or pond. 3. Any sediment that is tracked onto pavement shall be removed immediately by sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when sweeping is ineffective and there is a threat to public safety. If it is necessary to wash the streets, a small sump must be constructed. The sediment would then be washed into the sump where it can be controlled. Wash water must be pumped back onto the site and cannot discharge to systems tributary to surface waters. 4. Any quarry spalls that are loosened from the pad and end up on the roadway shall be removed immediately. 5. If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing (see Section D.2.1.1) shall be installed to control traffic. FIGURE D.2.1.4.A STABILIZED CONSTRUCTION ENTRANCE •PER KING COUNTY ROAD DESIGN AND CONSTRUCTION STANDARDS (KCRDCS), DRIVEWAYS SHALL BE PAVED TO EDGE OF R-O-W PRIOR TO INSTALLATION OF THE CONSTRUCTION ENTRANCE TO AVOID DAMAGING OF THE ROADWAY. •IT IS RECOMMENDED THAT THE ENTRANCE BE CROWNED SO THAT RUNOFF DRAINS OFF THE PAD. 12" MIN. THICKNESS PROVIDE FULL WIDTH OF INGRESS/EGRESS AREA IF A ROADSIDE DITCH IS PRESENT, INSTALL DRIVEWAY CULVERT PER KCRDCS GEOTEXTILE 4"- 8" QUARRY SPALLS R=25' MIN. 100 ' M I N . EXISTI N G R O A D 15' MI N. NOTES: SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-44 D.2.1.4.2 CONSTRUCTION ROAD/PARKING AREA STABILIZATION Code: CRS Symbol: Purpose Stabilizing subdivision roads, parking areas and other onsite vehicle transportation routes immediately after grading reduces erosion caused by construction traffic or runoff. Conditions of Use 1. Roads or parking areas shall be stabilized wherever they are constructed, whether permanent or temporary, for use by construction traffic. 2. Fencing (see Section D.2.1.1) shall be installed, if necessary, to limit the access of vehicles to only those roads and parking areas that are stabilized. Design and Installation Specifications 1. A 6-inch depth of 2- to 4-inch crushed rock, gravel base, or crushed surfacing base course shall be applied immediately after grading or utility installation. A 4-inch course of asphalt treated base (ATB) may also be used, or the road/parking area may be paved. It may also be possible to use cement or calcium chloride for soil stabilization. If the area will not be used for permanent roads, parking areas, or structures, a 6-inch depth of hog fuel may also be used, but this is likely to require more maintenance. Whenever possible, construction roads and parking areas shall be placed on a firm, compacted subgrade. Note: If the area will be used for permanent road or parking installation later in the project, the subgrade will be subject to inspection. 2. Temporary road gradients shall not exceed 15 percent. Roadways shall be carefully graded to drain transversely. Drainage ditches shall be provided on each side of the roadway in the case of a crowned section, or on one side in the case of a super-elevated section. Drainage ditches shall be designed in accordance with the standards given in Section D.2.1.6.4 (p. D-64) and directed to a sediment pond or trap. 3. Rather than relying on ditches, it may also be possible to grade the road so that runoff sheet-flows into a heavily vegetated area with a well-developed topsoil. Landscaped areas are not adequate. If this area has at least 50 feet of vegetation, then it is generally preferable to use the vegetation to treat runoff, rather than a sediment pond or trap. The 50 feet shall not include vegetated wetlands. If runoff is allowed to sheet flow through adjacent vegetated areas, it is vital to design the roadways and parking areas so that no concentrated runoff is created. 4. In order to control construction traffic, the County may require that signs be erected on site informing construction personnel that vehicles, other than those performing clearing and grading, are restricted to stabilized areas. 5. If construction roads do not adequately reduce trackout to adjacent property or roadways, a wheel wash system will be required. Maintenance Standards Crushed rock, gravel base, hog fuel, etc. shall be added as required to maintain a stable driving surface and to stabilize any areas that have eroded. D.2.1.4 TRAFFIC AREA STABILIZATION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-45 D.2.1.4.3 WHEEL WASH Code: WW Symbol: Purpose Wheel wash systems reduce the amount of sediment transported onto paved roadways and into surface water systems by construction vehicles. Conditions of Use When a stabilized construction entrance is not preventing sediment from being tracked onto pavement: • Wheel washing is generally an effective erosion and sediment control method and BMP when installed with careful attention to topography. For example, a wheel wash can be detrimental if installed at the top of a slope abutting a right-of-way where the water from the dripping truck wheels and undercarriage can run unimpeded into the street. • Pressure washing combined with an adequately sized and properly surfaced wash pad with direct drainage discharge to a large 10 foot x 10-foot sump can be very effective. Design and Installation Specifications A suggested detail is shown in Figure D.2.1.4.B. 1. A minimum of 6inches of asphalt treated base (ATB) over crushed base material or 8 inches over a good subgrade is recommended to pave the wheel wash area. 2. Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will work well to test clearance. 3. Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck tongues with water. 4. Midpoint spray nozzles are only needed in very muddy conditions. 5. Wheel wash systems should be designed with a small grade change, 6 to 12 inches for a 10-foot wide pond, to allow sediment to flow to the low side of the pond and to help prevent re-suspension of sediment. 6. A drainpipe with a 2 to 3 foot riser should be installed on the low side of the wheel wash pond to allow for easy cleaning and refilling. Polymers may be used to promote coagulation and flocculation in a closed-loop system. 7. Polyacrylamide (PAM) added to the wheel washwater at a rate of 0.25 – 0.5 pounds per 1,000 gallons of water increases effectiveness and reduces cleanup time. If PAM is already being used for dust or erosion control and is being applied by a water truck, the same truck may be used to change the washwater. Maintenance Standards 1. The wheel wash should start out each day with clean, fresh water. 2. The washwater should be changed a minimum of once per day. On large earthwork jobs where more than 10-20 trucks per hour are expected, the washwater will need to be changed more often. 3. Wheel wash or tire bath wastewater shall be discharged to a separate on-site treatment system that prevents discharge to surface water, or to the sanitary sewer system with proper local sewer district approval or permits. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-46 FIGURE D.2.1.4.B WHEEL WASH AND PAVED CONSTRUCTION ENTRANCE 2% SLOPE 15'15'20'15'50' 18' 12' 3' 5' BUILD 8'x8' SUMP TO ACCOMODATE CLEANING BY TRACKHOE. SECTION A-A NTS 8'x8' SUMP, SEE NOTE LOCATE INVERT OF TOP PIPE 1' ABOVE BOTTOM OF WHEEL WASH DRAIN PIPE 1:1 SLOPE WATER LEVEL ELEVATION VIEW NTS PLAN VIEW NTS 6" SLEEVE CURB ASPHALT CURB ON THE LOW ROAD SIDE TO DIRECT WATER BACK TO POND 6" ATB CONSTRUCTION ENTRANCE 1-1/2" SCHEDULE 40 FOR SPRAYERS 2% SLOPE MIDPOINT SPRAY NOZZLES, IF NEEDED 3" TRASH PUMP WITH FLOATS ON SUCTION HOSE 2" SCHEDULE 40 6" SLEEVE UNDER ROAD 8'x8' SUMP WITH 5' OF CATCH 6" SEWER PIPE WITH BUTTERFLY VALVES 1:1 SLOPE A A 5:1 SLOPE 5:1 SLOPE 15' ATB APRON TO PROTECT GROUND FROM SPLASHING WATER BALL VALVES NOTE: D.2.1.5 SEDIMENT RETENTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-53 FIGURE D.2.1.5.D SEDIMENT POND RISER DETAIL 3.5' MIN. 18" MIN. 2X RISER DIA. MIN. CORRUGATED METAL RISER CONCRETE BASE ALTERNATIVELY, METAL STAKES AND WIRE MAY BE USED TO PREVENT FLOTATION DEWATERING ORIFICE, SCHEDULE 40 STEEL STUB MIN. DIAMETER AS PER CALCULATIONS 6" MIN. PROVIDE ADEQUATE STRAPPING POLYETHYLENE CAP PERFORATED DEWATERING DEVICE, SEE NOTE WATERTIGHT COUPLING TACK WELD NOTE: PERFORATED CORRUGATED POLYETHYLENE (CPE) DRAINAGE TUBING, DIAMETER MIN. 2" LARGER THAN DEWATERING ORIFICE. TUBING SHALL COMPLY WITH ASTM F667 AND AASHTO M294. D.2.1.5.3 STORM DRAIN INLET PROTECTION Code: FFP or CBI or CBP Symbol: or or Purpose Storm drain inlets are protected to prevent coarse sediment from entering storm drainage systems. Temporary devices around storm drains assist in improving the quality of water discharged to inlets or catch basins by ponding sediment-laden water. These devices are effective only for relatively small drainage areas. Conditions of Use 1. Protection shall be provided for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless the runoff that enters the catch basin will be conveyed to a sediment pond or trap. 2. Inlet protection may be used anywhere at the applicant's discretion to protect the drainage system. This will, however, require more maintenance, and it is highly likely that the drainage system will still require some cleaning. 3. The contributing drainage area must not be larger than one acre. Design and Installation Specifications 1. There are many options for protecting storm drain inlets. Two commonly used options are filter fabric protection and catch basin inserts. Filter fabric protection (see Figure D.2.1.5.E) is filter fabric (geotextile) placed over the grate. This method is generally very ineffective and requires intense maintenance efforts. Catch basin inserts (see Figure D.2.1.5.F) are manufactured devices that nest inside a catch basin. This method also requires a high frequency of maintenance to be effective. Both SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-54 options provide adequate protection, but filter fabric is likely to result in ponding of water above the catch basin, while the insert will not. Thus, filter fabric is only allowed where ponding will not be a traffic concern and where slope erosion will not result if the curb is overtopped by ponded water. Trapping sediment in the catch basins is unlikely to improve the water quality of runoff if it is treated in a pond or trap because the coarse particles that are trapped at the catch basin settle out very quickly in the pond or trap. Catch basin protection normally only improves water quality where there is no treatment facility downstream. In these circumstances, catch basin protection is an important last line of defense. It is not, however, a substitute for preventing erosion. The placement of filter fabric under grates is generally prohibited and the use of filter fabric over grates is strictly limited and discouraged. 2. It is sometimes possible to construct a small sump around the catch basin before final surfacing of the road. This is allowed because it can be a very effective method of sediment control. 3. Block and gravel filters, gravel and wire mesh filter barriers, and bag barriers filled with various filtering media placed around catch basins can be effective when the drainage area is 1 acre or less and flows do not exceed 0.5 cfs. It is necessary to allow for overtopping to prevent flooding. Many manufacturers have various inlet protection filters that are very effective in keeping sediment-laden water from entering the storm drainage system. The following are examples of a few common methods. a) Block and gravel filters (Figure D.2.1.5.G) are a barrier formed around an inlet with standard concrete block and gravel, installed as follows: • Height is 1 to 2 feet above the inlet. • Recess the first row of blocks 2 inches into the ground for stability. • Support subsequent rows by placing a 2x4 through the concrete block opening. • Do not use mortar. • Lay some blocks in the bottom row on their side for dewatering the pooled water. • Place cloth or mesh with ½ inch openings over all block openings. • Place gravel below the top of blocks on slopes of 2:1 or flatter. • An alternate design is a gravel donut. b) Gravel and wire mesh filters consist of a gravel barrier placed over the top of an inlet. This structure generally does not provide overflow. Install as follows: • Cloth or comparable wire mesh with ½ inch openings is placed over inlet. • Coarse aggregate covers the cloth or mesh. • Height/depth of gravel should be 1 foot or more, 18 inches wider than inlet on all sides. c) Curb inlet protection with a wooden weir is a barrier formed around an inlet with a wooden frame and gravel, installed as follows: • Construct a frame and attach wire mesh (½ inch openings) and filter fabric to the frame. • Pile coarse washed aggregate against the wire/fabric. • Place weight on frame anchors. d) Curb and gutter sediment barriers (Figure D.2.1.5.H) consist of sandbags or rock berms (riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape, installed as follows: • Bags of either burlap or woven geotextile fabric, filled with a variety of media such as gravel, wood chips, compost or sand stacked tightly allows water to pond and allows sediment to separate from runoff. D.2.1.5 SEDIMENT RETENTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-55 • Leave a "one bag gap" in the top row of the barrier to provide a spillway for overflow. • Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 x 3 and at least 2 feet from the inlet. • Construct a horseshoe shaped sedimentation trap on the outside of the berm to sediment trap standards for protecting a culvert inlet. 4. Excavated drop inlet sediment traps are appropriate where relatively heavy flows are expected and overflow capability is needed. If emergency overflow is provided, additional end-of-pipe treatment may be required. Excavated drop inlets consist of an excavated impoundment area around a storm drain. Sediment settles out of the stormwater prior to enter the drain. Install according to the following specifications: a) The impoundment area should have a depth of 1 - 2 feet measured from the crest of the inlet structure. b) Side slopes of the excavated area must be no steeper than 2:1. c) Minimum volume of the excavated area should be 35 cubic yards. d) Install provisions for draining the area to prevent standing water problems. e) Keep the area clear of debris. f) Weep holes may be drilled into the side of the inlet. g) Protect weep holes with wire mesh and washed aggregate. h) Weep holes must be sealed when removing and stabilizing excavated area. i) A temporary dike may be necessary on the down slope side of the structure to prevent bypass flow. Maintenance Standards 1. Any accumulated sediment on or around inlet protection shall be removed immediately. Sediment shall not be removed with water, and all sediment must be disposed of as fill on site or hauled off site. 2. Any sediment in the catch basin insert shall be removed when the sediment has filled one-third of the available storage. The filter media for the insert shall be cleaned or replaced at least monthly. 3. Regular maintenance is critical for all forms of catch basin/inlet protection. Unlike many forms of protection that fail gradually, catch basin protection will fail suddenly and completely if not maintained properly. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-56 FIGURE D.2.1.5.E FILTER FABRIC PROTECTION FIGURE D.2.1.5.F CATCH BASIN INSERT CATCH BASIN NOTE: ONLY TO BE USED WHERE PONDING OF WATER ABOVE THE CATCH BASIN WILL NOT CAUSE TRAFFIC PROBLEMS AND WHERE OVERFLOW WILL NOT RESULT IN EROSION OF SLOPES. GRATE STANDARD STRENGTH FILTER FABRIC NOTE: THIS DETAIL IS ONLY SCHEMATIC. ANY INSERT IS ALLOWED THAT HAS: •A MIN. 0.5 C.F. OF STORAGE, •THE MEANS TO DEWATER THE STORED SEDIMENT, •AN OVERFLOW, AND •CAN BE EASILY MAINTAINED. OVERFLOW GRATECATCH BASIN POROUS BOTTOM SOLID WALLS FILTER MEDIA FOR DEWATERING D.2.1.5 SEDIMENT RETENTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-57 FIGURE D.2.1.5.G BLOCK AND GRAVEL CURB INLET PROTECTION 1.USE BLOCK AND GRAVEL TYPE SEDIMENT BARRIER WHEN CURB INLET IS LOCATED IN GENTLY SLOPING SEGMENT, WHERE WATER CAN POND AND ALLOW SEDIMENT TO SEPARATE FROM RUNOFF. 2.BARRIER SHALL ALLOW FOR OVERFLOW FROM SEVERE STORM EVENT. 3.INSPECT BARRIERS AND REMOVE SEDIMENT AFTER EACH STORM EVENT. SEDIMENT AND GRAVEL MUST BE REMOVED FROM THE TRAVELED WAY IMMEDIATELY. 2x4 WOOD STUD OVERFLOW WATER A A PLAN VIEW NTS SECTION A-A NTS BLOCK AND GRAVEL CURB INLET PROTECTION NTS CATCH BASIN COVER CURB INLET CONCRETE BLOCKS CATCH BASIN COVER CURB INLET CATCH BASIN BACK OF SIDEWALK CURB FACE 3/4" DRAIN GRAVEL (20 mm) WIRE SCREEN OR FILTER FABRIC POND HEIGHT WIRE SCREEN OR FILTER FABRIC 2x4 WOOD STUD (100x50 TIMBER STUD) 3/4" DRAIN GRAVEL (20 mm) NOTES: SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-58 FIGURE D.2.1.5.H CURB AND GUTTER BARRIER PROTECTION RUNOFF RUNOFF SPILLWAY 1.PLACE CURB-TYPE SEDIMENT BARRIERS ON GENTLY SLOPING STREET SEGMENTS, WHERE WATER CAN POND AND ALLOW SEDIMENT TO SEPARATE FROM RUNOFF. 2.SANDBAGS OF EITHER BURLAP OR WOVEN GEOTEXTILE FABRIC ARE FILLED WITH GRAVEL, LAYERED AND PACKED TIGHTLY. 3.LEAVE A ONE-SANDBAG GAP IN THE TOP ROW TO PROVIDE A SPILLWAY FOR OVERFLOW. 4.INSPECT BARRIERS AND REMOVE SEDIMENT AFTER EACH STORM EVENT. SEDIMENT AND GRAVEL MUST BE REMOVED FROM THE TRAVELED WAY IMMEDIATELY. GRAVEL FILLED SANDBAGS STACKED TIGHTLY DRAIN GRATE GUTTER CURB FACE CURB INLET SANDBAGS TO OVERLAP ONTO CURB BACK OF SIDEWALK PLAN VIEW NTS CURB AND GUTTER BARRIER NTS NOTES: SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-64 Design and Installation Specifications 1. Two types of drains may be used as follows: a) Relief drains are used either to lower the water table in large, relatively flat areas, improve the growth of vegetation, or to remove surface water. They are installed along a slope and drain in the direction of the slope. They may be installed in a grid pattern, a herringbone pattern, or a random pattern. b) Interceptor drains are used to remove excess groundwater from a slope, stabilize steep slopes, and lower the water table below a slope to prevent the soil from becoming saturated. They are installed perpendicular to a slope and drain to the side of the slope. They usually consist of a single pipe or single pipes instead of a patterned layout. 2. Size of Drains – Size subsurface drains to carry the required capacity without pressurized flow. Minimum diameter for a subsurface drain is 4 inches. 3. Outlet – Ensure that the outlet of a drain empties into a channel or other watercourse above the normal water level. Maintenance Standards 1. Subsurface drains shall be checked periodically to ensure that they are free flowing and not clogged with sediment or roots. 2. The outlet shall be kept clear and free of debris. 3. Surface inlets shall be kept open and free of sediment and other debris. 4. Trees located too close to a subsurface drain often clog the system with roots. If a drain becomes clogged, relocate the drain or remove the trees as a last resort. Drain placement should be planned to minimize this problem. 5. Where drains are crossed by heavy equipment, the line shall be checked to ensure that it is not crushed and have adequate cover protection. D.2.1.6.4 DITCHES Code: DI Symbol: Purpose Ditches convey intercepted runoff from disturbed areas to and from sediment ponds or traps. They also convey runoff intercepted from undisturbed areas around the site to a non-erosive discharge point. Conditions of Use Ditches may be used anywhere that concentrated runoff is to be conveyed on or around the construction site. Temporary pipe systems may also be used to convey runoff. Design and Installation Specifications 1. Channels and ditches shall be sized to accommodate the developed condition 10-year approved model 15-minute peak flow with 0.5 feet of freeboard. If no hydrologic analysis is required for the site, the Rational Method may be used [see Section 3.2.1 of the King County Surface Water Design Manual (SWDM)]. 2. See SWDM Section 4.4.1 for open-channel design requirements. D.2.1.6 SURFACE WATER COLLECTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-65 3. The only exception to the requirements of SWDM Section 4.4.1 is the use of check dams, rather than grass lining, for channels in which the design flow velocity does not exceed 5 fps. See Figure D.2.1.6.E for details on check dam installation. Maintenance Standards 1. Any sediment deposition of more than 0.5 feet shall be removed so that the channel is restored to its design capacity. 2. If the channel capacity is insufficient for the design flow, it must be determined whether the problem is local (e.g., a constriction or bend) or the channel is under-designed. If the problem is local, the channel capacity must be increased through construction of a berm(s) or by excavation. If the problem is under-design, the design engineer shall be notified and the channel redesigned to a more conservative standard to be approved by King County. 3. The channel shall be examined for signs of scouring and erosion of the bed and banks. If scouring or erosion has occurred, affected areas shall be protected by riprap or an erosion control blanket or net. FIGURE D.2.1.6.E CHECK DAMS 6" MIN. ROCK MUST COMPLETELY COVER THE BOTTOM AND SIDES OF THE DITCH 24" MIN. 2H:1V SLOPES L 2"- 4" ROCKBA L=THE DISTANCE SUCH THAT POINTS A AND B ARE OF EQUAL ELEVATION CROSS SECTION CHECK DAM SPACING D.2.1.6 SURFACE WATER COLLECTION 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-69 D.2.1.7 DEWATERING CONTROL Any runoff generated by dewatering shall be treated through construction of a sediment trap (Section D.2.1.5.1) when there is sufficient space or by releasing the water to a well vegetated, gently sloping area. Since pumps are used for dewatering, it may be possible to pump the sediment-laden water well away from the surface water so that vegetation can be more effectively utilized for treatment. Discharge of sediment-laden water from dewatering activities to surface and storm waters is prohibited. If dewatering occurs from areas where the water has come in contact with new concrete, such as tanks, vaults, or foundations, the pH of the water must be monitored and must be neutralized prior to discharge. Clean non-turbid dewatering water, such as well point ground water can be discharged to systems tributary to, or directly to surface waters provided the flows are controlled so no erosion or flooding occurs. Clean water must not be routed through a stormwater sediment pond. Highly turbid or contaminated dewatering water must be handled separately from stormwater. Purpose: To prevent the untreated discharge of sediment-laden water from dewatering of utilities, excavated areas, foundations, etc. When to Install: Dewatering control measures shall be used whenever there is a potential for runoff from dewatering of utilities, excavations, foundations, etc. Measures to install: 1. Foundation, vault, excavation, and trench dewatering water that has similar characteristics to stormwater runoff at the site shall be discharged into a controlled conveyance system prior to discharge to a sediment trap or sediment pond. Foundation and trench dewatering water that has similar characteristics to stormwater runoff at the site must be disposed of through one of the following options depending on site constraints: a) Infiltration, b) Transport offsite in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute surface waters, c) Discharge to the sanitary sewer discharge with local sewer district approval if there is no other option, or d) Use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized dewatering. 2. Clean, non-turbid dewatering water, such as well-point ground water, may be discharged via stable conveyance to systems tributary to surface waters, provided the dewatering flow does not cause erosion or flooding of receiving waters. 3. Highly turbid or contaminated dewatering water (high pH or other) shall be handled separately from stormwater. See Section D.2.2 (p. D-76), SWPPS Measures. SECTION D.2.1 ESC MEASURES 7/23/2021 2021 Surface Water Design Manual – Appendix D D-70 D.2.1.8 DUST CONTROL Preventative measures to minimize the wind transport of soil shall be taken when a traffic hazard may be created or when sediment transported by wind is likely to be deposited in water resources or adjacent properties. Purpose: To prevent wind transport of dust from exposed soil surfaces onto roadways, drainage ways, and surface waters. When to Install: Dust control shall be implemented when exposed soils are dry to the point that wind transport is possible and roadways, drainage ways, or surface waters are likely to be impacted. Dust control measures may consist of chemical, structural, or mechanical methods. Measures to Install: Water is the most common dust control (or palliative) used in the area. When using water for dust control, the exposed soils shall be sprayed until wet, but runoff shall not be generated by spraying. Calcium chloride, Magnesium chloride, Lignin derivatives, Tree Resin Emulsions, and Synthetic Polymer Emulsions may also be used for dust control. Exposed areas shall be re-sprayed as needed. Oil shall not be used for dust control. The following table lists many common dust control measures. Some of the measures are not recommended for use in King County and must have prior approval prior to use from the DLS-Permitting inspector assigned to specific projects. D.2.1.8 DUST CONTROL 2021 Surface Water Design Manual – Appendix D 7/23/2021 D-71 TABLE D.2.1.8.A DUST CONTROL MEASURES METHOD CONSIDERATIONS SITE PREPARATION RECOMMENDED APPLICATION RATE Water -Most commonly used practice -Evaporates quickly -Lasts less than 1 day For all liquid agents: -Blade a small surface -Crown or slope surface to avoid ponding -Compact soils if needed -Uniformly pre-wet at 0.03 – 0.3 gal/sq yd -Apply solution under pressure. Overlap solution 6 – 12 inches -Allow treated area to cure 0 – 4 hours -Compact area after curing -Apply second treatment before first treatment becomes ineffective 0.125 gal/sq yd every 20 to 30 minutes Salts Calcium Chloride (CaCl) -Restricts evaporation -Lasts 6-12 months -Can be corrosive -Less effective in low humidity -Can build up in soils and leach by rain Apply 38% solution at 1.21L/m2 (0.27 gal/yd2) or as loose dry granules per manufacturer Magnesium Chloride (MgCl) -Restricts evaporation -Works at higher temperatures and lower humidity than CaCl -May be more costly than CaCl Apply 26 – 32% solution at 2.3 L/m2 (0.5 gal/yd2) Sodium Chloride (NaCl) -Effective over smaller range of conditions -Less expensive -Can be corrosive -Less effective in low humidity Per Manufacturer Silicates -Generally expensive -Available in small quantities -Require Second application Surfactants -High evaporation rates -Effective for short time periods -Must apply frequently Copolymers -Forms semi-permeable transparent crust -Resists ultraviolet radiation and moisture induced breakdown -Last 1 to 2 years 750 – 940 L/ha (80 – 100 gal/ac) Petroleum Products -Used oil is prohibited as a dust control method -Bind soil particles -May hinder foliage growth -Environmental and aesthetic concerns -Higher cost Use 57 – 63% resins as base. Apply at 750 – 940 L/ha (80-100 gal/ac) Lignin Sulfonate -Paper industry waste product -Acts as dispersing agent -Best in dry climates -Can be slippery -Will decrease Dissolved Oxygen in waterways therefore cannot be used adjacent to surface water systems Loosen surface 25-50 mm (1 – 2 inches) Need 4-8% fines Vegetable Oils -Coat grains of soils, so limited binding ability -May become brittle -Limited availability Per Manufacturer Spray on Adhesives -Available as organic or synthetic -Effective on dry, hard soils -Forms a crust -Can last 3 to 4 years Per Manufacturer Appendix D: Site Inspection Form Construction Stormwater Site Inspection Form Page 1 Project Name Permit # Inspection Date Time Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre Print Name: Approximate rainfall amount since the last inspection (in inches): Approximate rainfall amount in the last 24 hours (in inches): Current Weather Clear Cloudy Mist Rain Wind Fog A. Type of inspection: Weekly Post Storm Event Other B. Phase of Active Construction (check all that apply): Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads Concrete pours Vertical Construction/buildings Utilities Offsite improvements Site temporary stabilized Final stabilization C. Questions: 1. Were all areas of construction and discharge points inspected? Yes No 2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No 3. Was a water quality sample taken during inspection? (refer to permit conditions S4 & S5) Yes No 4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No 5. If yes to #4 was it reported to Ecology? Yes No 6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken, and when. *If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33 cm or greater. Sampling Results: Date: Parameter Method (circle one) Result Other/Note NTU cm pH Turbidity tube, meter, laboratory pH Paper, kit, meter Construction Stormwater Site Inspection Form Page 2 D. Check the observed status of all items. Provide “Action Required “details and dates. Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 1 Clearing Limits Before beginning land disturbing activities are all clearing limits, natural resource areas (streams, wetlands, buffers, trees) protected with barriers or similar BMPs? (high visibility recommended) 2 Construction Access Construction access is stabilized with quarry spalls or equivalent BMP to prevent sediment from being tracked onto roads? Sediment tracked onto the road way was cleaned thoroughly at the end of the day or more frequent as necessary. 3 Control Flow Rates Are flow control measures installed to control stormwater volumes and velocity during construction and do they protect downstream properties and waterways from erosion? If permanent infiltration ponds are used for flow control during construction, are they protected from siltation? 4 Sediment Controls All perimeter sediment controls (e.g. silt fence, wattles, compost socks, berms, etc.) installed, and maintained in accordance with the Stormwater Pollution Prevention Plan (SWPPP). Sediment control BMPs (sediment ponds, traps, filters etc.) have been constructed and functional as the first step of grading. Stormwater runoff from disturbed areas is directed to sediment removal BMP. 5 Stabilize Soils Have exposed un-worked soils been stabilized with effective BMP to prevent erosion and sediment deposition? Construction Stormwater Site Inspection Form Page 3 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 5 Stabilize Soils Cont. Are stockpiles stabilized from erosion, protected with sediment trapping measures and located away from drain inlet, waterways, and drainage channels? Have soils been stabilized at the end of the shift, before a holiday or weekend if needed based on the weather forecast? 6 Protect Slopes Has stormwater and ground water been diverted away from slopes and disturbed areas with interceptor dikes, pipes and or swales? Is off-site storm water managed separately from stormwater generated on the site? Is excavated material placed on uphill side of trenches consistent with safety and space considerations? Have check dams been placed at regular intervals within constructed channels that are cut down a slope? 7 Drain Inlets Storm drain inlets made operable during construction are protected. Are existing storm drains within the influence of the project protected? 8 Stabilize Channel and Outlets Have all on-site conveyance channels been designed, constructed and stabilized to prevent erosion from expected peak flows? Is stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream conveyance systems? 9 Control Pollutants Are waste materials and demolition debris handled and disposed of to prevent contamination of stormwater? Has cover been provided for all chemicals, liquid products, petroleum products, and other material? Has secondary containment been provided capable of containing 110% of the volume? Were contaminated surfaces cleaned immediately after a spill incident? Were BMPs used to prevent contamination of stormwater by a pH modifying sources? Construction Stormwater Site Inspection Form Page 4 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 9 Cont. Wheel wash wastewater is handled and disposed of properly. 10 Control Dewatering Concrete washout in designated areas. No washout or excess concrete on the ground. Dewatering has been done to an approved source and in compliance with the SWPPP. Were there any clean non turbid dewatering discharges? 11 Maintain BMP Are all temporary and permanent erosion and sediment control BMPs maintained to perform as intended? 12 Manage the Project Has the project been phased to the maximum degree practicable? Has regular inspection, monitoring and maintenance been performed as required by the permit? Has the SWPPP been updated, implemented and records maintained? E. Check all areas that have been inspected. All in place BMPs All disturbed soils All concrete wash out area All material storage areas All discharge locations All equipment storage areas All construction entrances/exits F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number; be specific on location and work needed. Document, initial, and date when the corrective action has been completed and inspected. Element # Description and Location Action Required Completion Date Initials Attach additional page if needed Sign the following certification: “I certify that this report is true, accurate, and complete, to the best of my knowledge and belief” Inspected by: (print) (Signature) Date: Title/Qualification of Inspector: Tab 7.0 7708.016-TIR FINL 7.0 OTHER PERMITS All permits required by the City of Federal Way will be acquired prior to construction. Tab 8.0 7708.016-TIR FINL 8.0 ESC ANALYSIS AND DESIGN A. Erosion and Sediment Control (ESC) Plan Analysis and Design The Erosion Control plan included with the final engineering plans, was prepared in accordance with the 2021 KCSWDM, and standard industry practices throughout the construction process to limit the amount of sediment traveling into the downstream systems. BMPs that are proposed include a rocked construction entrance, silt fence where needed, V- ditch with rock check dams, and hydroseeding. B. Stormwater Pollution Prevention and Spill (SWPPS) Plan Design A Stormwater Pollution Prevention and Spill Site Plan has been prepared for Fay Ridge residential subdivision as a part of the final engineering plans. This is a site-specific plan that outlines the project scope of work and presents a comprehensive plan to prevent, respond to and report spills or release to the environment. It also provides suggested locations for: ● Equipment parking/ maintenance areas ● Chemical storage areas with secondary containment ● Construction materials and construction waste storage areas ● Truck wheel washout areas This plan also provides a general location of erosion control measures such as silt fencing, construction entrance, and clearing limits. Potential Spill Sources or Releases Potential spill sources during construction will include materials and equipment brought on-site. Potential spill sources include; fueling, lubricating oil, hydraulic oil, backhoes, bulldozers, water trucks, support trucks, lighting units, pumps, and generators. Equipment staging and maintenance areas for fueling, hazardous materials, and hazardous waste materials have been designated on the SWPPS. Construction debris will be present during demolition of the existing on-site buildings. No fuel tanks, gasoline, oils and hydraulic fuels will be stored on-site. Control Pollutants Pollutants other than sediment will be controlled as part of the implemented SWPPS plan. Maintenance and repair of heavy equipment and vehicles that may result in discharge or spillage of pollutants to the ground or surface water runoff will be conducted using spill prevention measures. Contaminated surfaces will be cleaned immediately following any discharge or spill incident. Spills will be reported within 24 hours. Emergency repairs may be performed on-site using temporary plastic placed beneath and, if raining, over the vehicle. Concrete truck chutes and pumps shall be washed out only into formed areas awaiting installation of concrete or asphalt. Unused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling. Hand tools including, but not limited to, screeds, shovels, rakes, and trowels shall be washed off only into formed areas awaiting installation of concrete or asphalt. When no formed areas are available, washwater and leftover product shall be contained in a lined container or in a sump designed to receive the materials. Contained concrete shall be disposed of in a manner that does not violate groundwater or surface water quality standards. Recommended BMP’s include Concrete Handling (BMP C151). 7708.016-TIR FINL Spill Prevention and Containment The following is a list of BMP’s that will be used for the project. ● Store and maintain equipment in a designated area. ● Reduce the amount of hazardous materials and waste by substituting non- hazardous or less hazardous materials. ● Use secondary containment (drain pan) to catch spills when removing or changing fluids. ● Use proper equipment (pumps, funnels) to transfer fluids. ● Keep spill kits readily accessible. ● Check incoming vehicles for leaking oil and fluids. ● Transfer used fluids and oil filters to waste or recycling drums. ● Inspect equipment immediately, if necessary. ● Implement a preventative maintenance schedule for equipment and vehicles. ● Perform fueling in designated fueling area. ● Do not “top-off” tanks ● Use secondary containment (drain pan) to catch spills. ● Keep spill kits readily accessible. ● Inspect fueling areas routinely for leaks and spills. ● Monitor pollution prevention BMP’s and maintain records/reports of all inspections using the worksheets at the end of this section. Spill Response Response in the first 15 minutes is critical to minimize the impacts to human health and the environment and to minimize property damage and cleanup costs. The contractor will respond immediately to spills and regulated materials. Spill response equipment shall be stored in spill response kits located in a clearly marked and accessible area. The standard approach toward spill response will be as follows: ● Stop operations. ● Stop the source of the spill. ● Use appropriate materials to absorb, berm, or cover the area to prevent further contamination. ● Notify the construction manager. ● Determine the method of clean up required. All methods shall comply with the state or local requirements to spill response. ● Contact a cleanup response firm if necessary. 7708.016-TIR FINL Contact Personnel The designated personnel responsible for managing, implementing and maintaining this SWPPS plan include: CESCL – TBD Contractor –TBD A SWPPP report has also been prepared following the Department of Ecology (Ecology) format and will be kept on-site during all construction activities. The SWPPP report includes a narrative discussion of construction BMP’s that will be implemented during construction, based on the 13 required elements as defined by Ecology. The SWPPP report also outlines inspection, monitoring, and reporting requirements to meet the requirements of the NPDES permit. Title:For: 12 7708 CHRIS PENWELL 696 MOSS FARM ROAD CHESHIRE, CT 06410 PENWELL PROPERTYFORCITY OF FEDERAL WAY, KING COUNTY, WASHINGTONPTN. OF THE SE 1/4, OF THE NE 1/4, SEC. 06, TWP 21 N., RGE 04 E., W.M.FOR PENWELL PROPERTYCALL BEFORE YOU DIG: 8118/3 /2 3 TESC PLAN11 TESC PLANSCALE: 1"=20'2ND AV E S W TEMPORARY "V" DITCHROCK CHECK DAM DETAILCHECK DAM SPACINGRECOMMENDED CONSTRUCTION SEQUENCEFILTER FABRIC SILT FENCE DETAILTABLE D.3.2.B TEMPORARY EROSION CONTROL SEED MIXTEMPORARY SEEDING STANDARDS AND SPECIFICATIONSSEEDING NOTESLEGEND:EROSION/SEDIMENT CONTROL NOTESFigure 8.0.1 Tab 9.0 7708.016-TIR FINL 9.0 BOND QUANTITIES AND FACILITY SUMMARIES 9.1 Erosion Control Bond Quantity Worksheet 9.2 Stormwater Facility Summary Sheet EROSION/SEDIMENT CONTROL BOND QUANTITY WORKSHEET Project Name: Penwell Property Project No.: Parcel Number: 119600-3800 Reference #Unit Price Unit Quantity Cost EROSION/SEDIMENT CONTROL Backfill & compaction-embankment 6.50$ CY 1200 7,800$ Check dams, 4" minus rock SWDM 5.4.6.3 78.00$ Each 7 546$ Crushed surfacing 1 1/4" minus WSDOT 9-03.9(3)98.00$ CY -$ Ditching 8.00$ CY 25 200$ Excavation-bulk 3.00$ CY 200 600$ Fence, silt SWDM 5.4.3.1 2.00$ LF 1100 2,200$ Fence, Temporary (NGPE)2.00$ LF -$ Hydroseeding SWDM 5.4.2.4 1.00$ SY 650 650$ Jute Mesh SWDM 5.4.2.2 2.00$ SY -$ Mulch, by hand, straw, 3" deep SWDM 5.4.2.1 3.00$ SY 650 1,950$ Mulch, by machine, straw, 2" deep SWDM 5.4.2.1 1.00$ SY -$ Piping, temporary, CPP, 6"12.50$ LF -$ Piping, temporary, CPP, 8"19.00$ LF -$ Piping, temporary, CPP, 12"24.00$ LF -$ Plastic covering, 6mm thick, sandbagged SWDM 5.4.2.3 3.00$ SY -$ Rip Rap, machine placed; slopes WSDOT 9-13.1(2)50.00$ CY -$ Rock Construction Entrance, 50'x15'x1'SWDM 5.4.4.1 1,800.00$ Each 1 1,800$ Rock Construction Entrance, 100'x15'x1'SWDM 5.4.4.1 3,600.00$ Each -$ Sediment pond riser assembly SWDM 5.4.5.2 3,050.00$ Each -$ Sediment trap, 5' high berm SWDM 5.4.5.1 21.00$ LF -$ Sed. trap, 5' high, riprapped spillway berm section SWDM 5.4.5.1 79.00$ LF -$ Seeding, by hand SWDM 5.4.2.4 1.00$ SY -$ Sodding, 1" deep, level ground SWDM 5.4.2.5 8.00$ SY -$ Sodding, 1" deep, sloped ground SWDM 5.4.2.5 9.50$ SY -$ Figure 9.0.1 TESC Supervisor 84.00$ HR 25 2,100$ Water truck, dust control SWDM 5.4.7 130.00$ HR 25 3,250$ WRITE-IN-ITEMS -$ Each -$ -$ -$ ESC SUBTOTAL:3,883$ 20% CONTINGENCY 777$ 4,660$ ESC TOTAL: 4 STORMWATER FACILITY SUMMARY SHEET ( provide one Stormwater Facility Summary Sheet per Natural Discharge Location) Major Basin Name __ Immediate Basin Name GENERAL FACILITY INFORMATION: Detention Infiltration Water Quality Flow Control Type # of Type # of Type #of Performance Std Pond s Ponds Ponds □ Basic Vaults Tanks Vaults □ Conservation Tanks renches Tanks □ Flood Problem DPER Permit No. Date NPDES Permit No. Parcel No. Retired Parcel No. Project includes Landscape Management Plan? yes □ (include copy with TIR as Appendix) no □ Declarations of Covenant Recording No. Leachable Metals Impervious Surface Limit Flow Control BMPs Clearing Limit Drainage Facility Landscape Management Plan If no flow control facility, check one: □ Project qualifies for KCSWDM Exemption (KCSWDM 1.2.3): □ Basic Exemption □ Impervious Surface Exemption for Transportation Redevelopment projects □ Cost Exemption for Parcel Redevelopment projects □ Direct Discharge Exemption □ Other___________________ □ Project qualifies for 0.1 cfs Exception per KCSWDM 1.2.3 □ No flow control required per approved KCSWDM Adjustment No.________________ □ Flow control provided in regional/shared facility per approved approved KCSWDM Adjustment No.________________ Shared Facility Name/Locati nn____________________ □ No flow control required (other, provide justification): TREATMENT SUMMARY FOR TOTAL IMPERVIOUS SURFACES (Applies to Commercial parcels only)Area % of Total Total Acreage (ac) Total Impervious Acreage (ac) Total impervious surface served by flow control facility(ies) (sq ft) Impervious surface served by flow control facility(ies) designed 1990 or later (sq ft) Impervious surface served by pervious surface absorption (sq ft) Impervious surface served by approved water quality facility(ies) (sq ft) PROVIDE FACILITY DETAILS AND FACILITY SKETCH FOR EACH FACILITY ON REVERSE. USE ADDITIONAL SHEETS AS NEEDED FOR ADDITIONAL FACILITIES 2021 KING COUNTY SURFACE WATER DESIGN MANUAL, REFERENCE D 7/23/2021 Page 1 Penwell Property South End of 2nd Ave SW, Federal Way, WA 119600-3800 Lower Puget Sound x 1 1 x Figure 9.0.2 STORMWATER FACILITY SUMMARY SHEET DPER Permit No. ( provide one Stormwater Facility Summary Sheet per Natural Discharge Location) Project Name Project Location Downstream Drainage Basins: Major Basin Nam__________ Immediate Basin Nam______ FLOW CONTROL FACILITY: Basin: Facility Name/Number___________________________________□ New Facility □ Existing FacilityFacility Location UIC? □ yes □ no UIC Site ID: Live Storage □ cu.ft. Volume □ ac.ft. Live Storage Depth (ft) Volume Factor of Safety ______ Project Impervious Acres Served % of Total Project Impervious Acres Served No. of Lots Served Control Structure location:_ Type of Control Structure: □ Riser in vault □ Riser in Type II CB □ Weir in Type II CB No. of Orifices/Restrictions Size of Orifice/Restriction (in.) (numbered starting with lowest orifice): (inches in decimal format) N o . 1 No.2 No.3 No.4 Dam Safety Regulations (WA State Dept of Ecology): Re servoir Volume above natural grade □ cu.ft. □ ac.ft. Depth of Reservoir above natural grade (ft) WATER QUALITY FACILITIES Indicate no. of water quality facilities/BMPs for each type: _____Flow dispersion _____Filter strip _____Biofiltration swale □ regular, □ wet or □ continuous inflow _____Wetvault □ combined w/detention _____Wetpond □ basic □ large □ combined w/detention _____Pre-settling pond Design Information Water Quality design flow (cfs) Water Quality treated volume (sandfilter) (cu.ft.) Water Quality storage volume (wetpool) (cu.ft.) □ Landscape management plan □ Farm management plan High flow bypass structure (e.g., flow-splitter catch basin) Oil/water separator □ baffle □ coalescing plate _torm filter Stormwater wetland Sand filter □ basic □ large Sand bed depth Catch basin inserts (Manufacturer: ) □ regular □ linear □ vault (inches)__urce controls • Is facility lined? □ yes □ no If so, what marker is used above liner?What type of liner is used? Facility Summary Sheet Sketch: All detention, infiltration and water quality facilities must include a detailed sketch (11"x17" reduced size plan sheets preferred). 2021 KING COUNTY SURFACE WATER DESIGN MANUAL, REFERENCE D 7/23/2021 Page 2 Penwell Property South End of 2nd Ave SW, Federal Way, WA Lower Puget Sound Stormbrixx Detention System Northwest area of property x 0.21 100 1 CB#1 x 3 0.36 0.40 0.43 3,704 x x 8.5 1 1 Contech Modular Wetland Contech Tab 10.0 7708.016-TIR FINL 10.0 OPERATIONS AND MAINTENANCE MANUAL The drainage facilities constructed with this project will be private facilities owned and maintained by the homeowner. Storm drainage will be collected by a tightlined conveyance system and conveyed to a pre-settling CDS unit before entering the Modular Wetland System for Enhanced Basic Water Quality Treatment. Once runoff leaves the water quality unit, it will enter the Stormbrixx detention system to comply with the Conservation Flow Control standards before discharging to the existing stream near the north boundary line. The maintenance standards for each applicable drainage item have been provided in this section. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2021 Surface Water Design Manual – Appendix A 7/23/2021 A-9 NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Structure Sediment Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 7/23/2021 2021 Surface Water Design Manual – Appendix A A-10 NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Metal Grates (Catch Basins) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. Damaged or missing Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2021 Surface Water Design Manual – Appendix A 7/23/2021 A-11 NO. 6 – CONVEYANCE PIPES AND DITCHES Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/roots Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vegetation Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If Applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2021 Surface Water Design Manual – Appendix A 7/23/2021 A-37 NO. 28 – NATIVE VEGETATED SURFACE / NATIVE VEGETATED LANDSCAPE BMP Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance Is Performed Site Trash and debris Trash and debris accumulated on the native vegetated surface/native vegetated landscape site. Native vegetated surface site free of any trash or debris. Vegetation Native vegetation type Less than two species each of native trees, shrubs, and groundcover occur in the design area. A minimum of two species each of native trees, shrubs, and groundcover is established and healthy. Native vegetated area Less than 90% if the required vegetated ar ea has healthy growth. A minimum of 90% of the required vegetated area has healthy growth. Undesirable vegetation Weeds, blackberry, and other undesirable plants are invading more than 10% of vegetated area. Less than 10% undesirable vegetation occurs in the required native vegetated surface area. Vegetated Area Soil compaction Soil in the native vegetation area compacted. Less than 8% of native vegetation area is compacted. Insufficient area Less than 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. A minimum of 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. Excess slope Slope of native vegetation area greater than 15%. Slope of native growth area does not exceed 15%. Inspection Frequency Annually Inspect native vegetation area for any defects of deficiencies NO. 29 – PERFORATED PIPE CONNECTIONS BMP Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Preventative Blocking, obstructions Debris or trash limiting flow into perforated pipe system or outfall of BMP is plugged or otherwise nonfunctioning. Outfall of BMP is receiving designed flows from perforated pipe connection. Inflow Inflow impeded Inflow into the perforated pipe is partially or fully blocked or altered to prevent flow from getting into the pipe. Inflow to the perforated pipe is unimpeded. Pipe Trench Area Surface compacted Ground surface over the perforated pipe trench is compacted or covered with impermeable material. Ground surface over the perforated pipe is not compacted and free of any impervious cover. Outflow Outflow impeded Outflow from the perforated pipe into the public drainage system is blocked. Outflow to the public drainage system is unimpeded. Outfall Area Erosion or landslides Existence of the perforated pipe is causing or exasperating erosion or landslides. Perforated pipe system is sealed off and an alternative BMP is implemented. Inspection Frequency Annually and prior to and following significant storms. Perforated pipe system is operating as designed. CDS Guide Operation, Design, Performance and Maintenance ENGINEERED SOLUTIONS 2 CDS® Using patented continuous deflective separation technology, the CDS system screens, separates and traps debris, sediment, and oil and grease from stormwater runoff. The indirect screening capability of the system allows for 100% removal of floatables and neutrally buoyant material without blinding. Flow and screening controls physically separate captured solids, and minimize the re-suspension and release of previously trapped pollutants. Inline units can treat up to 6 cfs, and internally bypass flows in excess of 50 cfs (1416 L/s). Available precast or cast-in- place, offline units can treat flows from 1 to 300 cfs (28.3 to 8495 L/s). The pollutant removal capacity of the CDS system has been proven in lab and field testing. Operation Overview Stormwater enters the diversion chamber where the diversion weir guides the flow into the unit’s separation chamber and pollutants are removed from the flow. All flows up to the system’s treatment design capacity enter the separation chamber and are treated. Swirl concentration and screen deflection force floatables and solids to the center of the separation chamber where 100% of floatables and neutrally buoyant debris larger than the screen apertures are trapped. Stormwater then moves through the separation screen, under the oil baffle and exits the system. The separation screen remains clog free due to continuous deflection. During the flow events exceeding the treatment design capacity, the diversion weir bypasses excessive flows around the separation chamber, so captured pollutants are retained in the separation cylinder. Design Basics There are three primary methods of sizing a CDS system. The Water Quality Flow Rate Method determines which model size provides the desired removal efficiency at a given flow rate for a defined particle size. The Rational Rainfall Method™ or the and Probabilistic Method is used when a specific removal efficiency of the net annual sediment load is required. Typically in the Unites States, CDS systems are designed to achieve an 80% annual solids load reduction based on lab generated performance curves for a gradation with an average particle size (d50) of 125 microns (μm). For some regulatory environments, CDS systems can also be designed to achieve an 80% annual solids load reduction based on an average particle size (d50) of 75 microns (μm) or 50 microns (μm). Water Quality Flow Rate Method In some cases, regulations require that a specific treatment rate, often referred to as the water quality design flow (WQQ), be treated. This WQQ represents the peak flow rate from either an event with a specific recurrence interval, e.g. the six-month storm, or a water quality depth, e.g. 1/2-inch (13 mm) of rainfall. The CDS is designed to treat all flows up to the WQQ. At influent rates higher than the WQQ, the diversion weir will direct most flow exceeding the WQQ around the separation chamber. This allows removal efficiency to remain relatively constant in the separation chamber and eliminates the risk of washout during bypass flows regardless of influent flow rates. Treatment flow rates are defined as the rate at which the CDS will remove a specific gradation of sediment at a specific removal efficiency. Therefore the treatment flow rate is variable, based on the gradation and removal efficiency specified by the design engineer. Rational Rainfall Method™ Differences in local climate, topography and scale make every site hydraulically unique. It is important to take these factors into consideration when estimating the long-term performance of any stormwater treatment system. The Rational Rainfall Method combines site-specific information with laboratory generated performance data, and local historical precipitation records to estimate removal efficiencies as accurately as possible. Short duration rain gauge records from across the United States and Canada were analyzed to determine the percent of the total annual rainfall that fell at a range of intensities. US stations’ depths were totaled every 15 minutes, or hourly, and recorded in 0.01-inch increments. Depths were recorded hourly with 1-mm resolution at Canadian stations. One trend was consistent at all sites; the vast majority of precipitation fell at low intensities and high intensity storms contributed relatively little to the total annual depth. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Rainfall Method. Since most sites are relatively small and highly impervious, the Rational Rainfall Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS system are GRATE INLET (CAST IRON HOOD FOR CURB INLET OPENING) CREST OF BYPASS WEIR (ONE EACH SIDE) INLET (MULTIPLE PIPES POSSIBLE) OIL BAFFLE SUMP STORAGESEPARATION SLAB TREATMENT SCREEN OUTLET INLET FLUME SEPARATION CYLINDER CLEAN OUT (REQUIRED) DEFLECTION PAN, 3 SIDED (GRATE INLET DESIGN) 3 determined. Performance efficiency curve determined from full scale laboratory tests on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Probabilistic Rational Method The Probabilistic Rational Method is a sizing program Contech developed to estimate a net annual sediment load reduction for a particular CDS model based on site size, site runoff coefficient, regional rainfall intensity distribution, and anticipated pollutant characteristics. The Probabilistic Method is an extension of the Rational Method used to estimate peak discharge rates generated by storm events of varying statistical return frequencies (e.g. 2-year storm event). Under the Rational Method, an adjustment factor is used to adjust the runoff coefficient estimated for the 10-year event, correlating a known hydrologic parameter with the target storm event. The rainfall intensities vary depending on the return frequency of the storm event under consideration. In general, these two frequency dependent parameters (rainfall intensity and runoff coefficient) increase as the return frequency increases while the drainage area remains constant. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Method. Since most sites are relatively small and highly impervious, the Rational Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS are determined. Performance efficiency curve on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Treatment Flow Rate The inlet throat area is sized to ensure that the WQQ passes through the separation chamber at a water surface elevation equal to the crest of the diversion weir. The diversion weir bypasses excessive flows around the separation chamber, thus preventing re-suspension or re-entrainment of previously captured particles. Hydraulic Capacity The hydraulic capacity of a CDS system is determined by the length and height of the diversion weir and by the maximum allowable head in the system. Typical configurations allow hydraulic capacities of up to ten times the treatment flow rate. The crest of the diversion weir may be lowered and the inlet throat may be widened to increase the capacity of the system at a given water surface elevation. The unit is designed to meet project specific hydraulic requirements. Performance Full-Scale Laboratory Test Results A full-scale CDS system (Model CDS2020-5B) was tested at the facility of University of Florida, Gainesville, FL. This CDS unit was evaluated under controlled laboratory conditions of influent flow rate and addition of sediment. Two different gradations of silica sand material (UF Sediment & OK-110) were used in the CDS performance evaluation. The particle size distributions (PSDs) of the test materials were analyzed using standard method “Gradation ASTM D-422 “Standard Test Method for Particle-Size Analysis of Soils” by a certified laboratory. UF Sediment is a mixture of three different products produced by the U.S. Silica Company: “Sil-Co-Sil 106”, “#1 DRY” and “20/40 Oil Frac”. Particle size distribution analysis shows that the UF Sediment has a very fine gradation (d50 = 20 to 30 μm) covering a wide size range (Coefficient of Uniformity, C averaged at 10.6). In comparison with the hypothetical TSS gradation specified in the NJDEP (New Jersey Department of Environmental Protection) and NJCAT (New Jersey Corporation for Advanced Technology) protocol for lab testing, the UF Sediment covers a similar range of particle size but with a finer d50 (d50 for NJDEP is approximately 50 μm) (NJDEP, 2003). The OK-110 silica sand is a commercial product of U.S. Silica Sand. The particle size distribution analysis of this material, also included in Figure 1, shows that 99.9% of the OK-110 sand is finer than 250 microns, with a mean particle size (d50) of 106 microns. The PSDs for the test material are shown in Figure 1. Figure 1. Particle size distributions Tests were conducted to quantify the performance of a specific CDS unit (1.1 cfs (31.3-L/s) design capacity) at various flow rates, ranging from 1% up to 125% of the treatment design capacity of the unit, using the 2400 micron screen. All tests were conducted with controlled influent concentrations of approximately 200 mg/L. Effluent samples were taken at equal time intervals across the entire duration of each test run. These samples were then processed with a Dekaport Cone sample splitter to obtain representative sub-samples for Suspended Sediment Concentration (SSC) testing using ASTM D3977-97 “Standard Test Methods for Determining Sediment Concentration in Water Samples”, and particle size distribution analysis. Results and Modeling Based on the data from the University of Florida, a performance model was developed for the CDS system. A regression analysis was used to develop a fitting curve representative of the scattered data points at various design flow rates. This model, which demonstrated good agreement with the laboratory data, can then be used to predict CDS system performance with respect 4 to SSC removal for any particle size gradation, assuming the particles are inorganic sandy-silt. Figure 2 shows CDS predictive performance for two typical particle size gradations (NJCAT gradation and OK-110 sand) as a function of operating rate. Figure 2. CDS stormwater treatment predictive performance for various particle gradations as a function of operating rate. Many regulatory jurisdictions set a performance standard for hydrodynamic devices by stating that the devices shall be capable of achieving an 80% removal efficiency for particles having a mean particle size (d50) of 125 microns (e.g. Washington State Department of Ecology — WASDOE - 2008). The model can be used to calculate the expected performance of such a PSD (shown in Figure 3). The model indicates (Figure 4) that the CDS system with 2400 micron screen achieves approximately 80% removal at the design (100%) flow rate, for this particle size distribution (d50 = 125 μm). Figure 3. WASDOE PSD Figure 4. Modeled performance for WASDOE PSD. Maintenance The CDS system should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit. For example, unstable soils or heavy winter sanding will cause the grit chamber to fill more quickly but regular sweeping of paved surfaces will slow accumulation. Inspection Inspection is the key to effective maintenance and is easily performed. Pollutant transport and deposition may vary from year to year and regular inspections will help ensure that the system is cleaned out at the appropriate time. At a minimum, inspections should be performed twice per year (e.g. spring and fall) however more frequent inspections may be necessary in climates where winter sanding operations may lead to rapid accumulations, or in equipment washdown areas. Installations should also be inspected more frequently where excessive amounts of trash are expected. The visual inspection should ascertain that the system components are in working order and that there are no blockages or obstructions in the inlet and separation screen. The inspection should also quantify the accumulation of hydrocarbons, trash, and sediment in the system. Measuring pollutant accumulation can be done with a calibrated dipstick, tape measure or other measuring instrument. If absorbent material is used for enhanced removal of hydrocarbons, the level of discoloration of the sorbent material should also be identified 5 during inspection. It is useful and often required as part of an operating permit to keep a record of each inspection. A simple form for doing so is provided. Access to the CDS unit is typically achieved through two manhole access covers. One opening allows for inspection and cleanout of the separation chamber (cylinder and screen) and isolated sump. The other allows for inspection and cleanout of sediment captured and retained outside the screen. For deep units, a single manhole access point would allows both sump cleanout and access outside the screen. The CDS system should be cleaned when the level of sediment has reached 75% of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accumulated. If absorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100% of the sump capacity is exceeded however it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimating the level of sediment in the chamber, the measuring device must be lowered to the top of the sediment pile carefully. Particles at the top of the pile typically offer less resistance to the end of the rod than consolidated particles toward the bottom of the pile. Once this measurement is recorded, it should be compared to the as-built drawing for the unit to determine weather the height of the sediment pile off the bottom of the sump floor exceeds 75% of the total height of isolated sump. Cleaning Cleaning of a CDS systems should be done during dry weather conditions when no flow is entering the system. The use of a vacuum truck is generally the most effective and convenient method of removing pollutants from the system. Simply remove the manhole covers and insert the vacuum hose into the sump. The system should be completely drained down and the sump fully evacuated of sediment. The area outside the screen should also be cleaned out if pollutant build-up exists in this area. In installations where the risk of petroleum spills is small, liquid contaminants may not accumulate as quickly as sediment. However, the system should be cleaned out immediately in the event of an oil or gasoline spill. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use absorbent pads since they are usually less expensive to dispose than the oil/water emulsion that may be created by vacuuming the oily layer. Trash and debris can be netted out to separate it from the other pollutants. The screen should be cleaned to ensure it is free of trash and debris. Manhole covers should be securely seated following cleaning activities to prevent leakage of runoff into the system from above and also to ensure that proper safety precautions have been followed. Confined space entry procedures need to be followed if physical access is required. Disposal of all material removed from the CDS system should be done in accordance with local regulations. In many jurisdictions, disposal of the sediments may be handled in the same manner as the disposal of sediments removed from catch basins or deep sump manholes. Check your local regulations for specific requirements on disposal. 6 Note: To avoid underestimating the volume of sediment in the chamber, carefully lower the measuring device to the top of the sediment pile. Finer silty particles at the top of the pile may be more difficult to feel with a measuring stick. These finer particles typically offer less resistance to the end of the rod than larger particles toward the bottom of the pile. CDS Model Diameter Distance from Water Surface to Top of Sediment Pile Sediment Storage Capacity ft m ft m y3 m3 CDS1515 3 0.9 3.0 0.9 0.5 0.4 CDS2015 4 1.2 3.0 0.9 0.9 0.7 CDS2015 5 1.5 3.0 0.9 1.3 1.0 CDS2020 5 1.5 3.5 1.1 1.3 1.0 CDS2025 5 1.5 4.0 1.2 1.3 1.0 CDS3020 6 1.8 4.0 1.2 2.1 1.6 CDS3025 6 1.8 4.0 1.2 2.1 1.6 CDS3030 6 1.8 4.6 1.4 2.1 1.6 CDS3035 6 1.8 5.0 1.5 2.1 1.6 CDS4030 8 2.4 4.6 1.4 5.6 4.3 CDS4040 8 2.4 5.7 1.7 5.6 4.3 CDS4045 8 2.4 6.2 1.9 5.6 4.3 CDS5640 10 3.0 6.3 1.9 8.7 6.7 CDS5653 10 3.0 7.7 2.3 8.7 6.7 CDS5668 10 3.0 9.3 2.8 8.7 6.7 CDS5678 10 3.0 10.3 3.1 8.7 6.7 Table 1: CDS Maintenance Indicators and Sediment Storage Capacities 7 CDS Inspection & Maintenance Log CDS Model: Location: Water Floatable Describe Maintenance Date depth to Layer Maintenance Personnel Comments sediment1 Thickness2 Performed —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— 1. The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than the values listed in table 1 the system should be cleaned out. Note: to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. 2. For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. SUPPORT • Drawings and specifications are available at www.ContechES.com. • Site-specific design support is available from our engineers. ©2017 Contech Engineered Solutions LLC, a QUIKRETE Company Contech Engineered Solutions provides site solutions for the civil engineering industry. Contech’s portfolio includes bridges, drainage, sanitary sewer, earth stabilization and stormwater treatment products. For information on other Contech division offerings, visit www.ContechES.com or call 800.338.1122 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. The product(s) described may be protected by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6,027,639; 6,350,374; 6,406,218; 6,641,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296,692; 7,297,266; related foreign patents or other patents pending. 800-338-1122 www.ContechES.com cds_manual 3/17 PDF ENGINEERED SOLUTIONS ENGINEERED SOLUTIONS Modular Wetlands® Linear Operation & Maintenance Manual 2 MODULAR WETLANDS® LINEAR OPERATION & MAINTENANCE MANUAL TABLE OF CONTENTS Overview ........................................................................................................3 Inspection Summary .......................................................................................4 Inspection Process ..........................................................................................5 Maintenance Indicators ..................................................................................6 Inspection Process ..........................................................................................7 Maintenance Summary ..................................................................................8 Pretreatment Chamber ................................................................9 Prefilter Cartridge ......................................................................10 Biofiltration Chamber ................................................................11 Discharge Chamber ...................................................................12 Inspection Report .........................................................................................13 Cleaning and Maintenance Report ................................................................14 3 OVERVIEW The Modular Wetlands® Linear Biofilter is designed to remove high levels of trash, debris, sediments, nutrients, metals, and hydrocarbons. Its simple design allows for quick and easy installation. The system is housed in a standard precast structure and can be installed at various depths to meet site-specific conditions. INTRODUCTION This is the Modular Wetlands Linear Biofilter operation and maintenance manual. Before starting, read the instructions and equipment lists closely. It is important to follow all necessary safety procedures associated with state and local regulations. Some steps required confined space entry. Please contact Contech for more information on pre-authorized third party contractors who can provide installation services in your area. For a list of service providers in your area please visit: www.conteches.com/maintenance. Pretreatment Chamber Biofiltration Chamber Discharger Chamber Prefilter Box Biofiltration Media Flow Control Riser Vertical Underdrain Outfl o w Inflow 4 INSTRUCTIONS INSPECTION SUMMARY Stormwater regulations require BMPs be inspected and maintained to ensure they are operating as designed to allow for effective pollutant removal and provide protection to receiving water bodies. It is recommended that inspections be performed multiple times during the first year to assess the site specific loading conditions. The first year of inspections can be used to set inspection and maintenance intervals for subsequent years to ensure appropriate maintenance is provided. •Inspect pre-treatment, biofiltration, and discharge chambers an average of once every six to twelve months. Varies based on site specific and local conditions. •Average inspection time is approximately 15 minutes. Always ensure appropriate safety protocol and procedures are followed. The following is a list of equipment required to allow for simple and effective inspection of the Modular Wetlands Linear: •Modular Wetlands Linear Inspection Form •Flashlight •Manhole hook or appropriate tools to remove access hatches and covers •Appropriate traffic control signage and procedures •Measuring pole and/or tape measure •Protective clothing and eye protection •7/16” open or closed ended wrench •Large permanent black marker (initial inspections only - first year) Note: entering a confined space requires appropriate safety and certification. It is generally not required for routine inspections of the system INSPECTION AND MAINTENANCE NOTES 1. Following maintenance and/or inspection, it is recommended that the maintenance operator prepare a maintenance/inspection record. The record should include any maintenance activities performed, amount and description of debris collected, and condition of the system and its various filter mechanisms. 2. The owner should keep maintenance/inspection record(s) for a minimum of five years from the date of maintenance. These records should be made available to the governing municipality for inspection upon request at any time. 3. Transport all debris, trash, organics, and sediments to approved facility for disposal in accordance with local and state requirements. 4. Entry into chambers may require confined space training based on state and local regulations. 5. No fertilizer shall be used in the biofiltration chamber. 6. Irrigation should be provided as recommended by manufacturer and/or landscape architect. Amount of irrigation required is dependent on plant species. Some plants may not require irrigation after initial establishment. 5 INSPECTION PROCESS 1. Prepare the inspection form by writing in the necessary information including project name, location, date & time, unit number and other information (see inspection form). 2. Observe the inside of the system through the access covers. If minimal light is available and vision into the unit is impaired, utilize a flashlight to see inside the system and all of its chambers. 3. Look for any out of the ordinary obstructions in the inflow pipe, pre-treatment chamber, biofiltration chamber, discharge chamber or outflow pipe. Write down any observations on the inspection form. 4. Through observation and/or digital photographs, estimate the amount of trash, debris accumulated in the pre-treatment chamber. Utilizing a tape measure or measuring stick, estimate the amount of sediment in this chamber. Record this depth on the inspection form. 5. Through visual observation, inspect the condition of the pre-filter cartridges. Look for excessive build-up of sediment on the cartridges, any build-up on the tops of the cartridges, or clogging of the holes. Record this information on the inspection form. The prefilter cartridges can be further inspected by removing the cartridge tops and assessing the color of the BioMediaGREEN filter cubes (requires entry into pre-treatment chamber - see notes previous notes regarding confined space entry). Record the color of the material. New material is a light green color. As the media becomes clogged, it will turn darker in color, eventually becoming dark brown or black. The closer to black the media is the higher percentage that the media is exhausted and is in need of replacement. 6. The biofiltration chamber is generally maintenance-free due to the system’s advanced pre-treatment chamber. For units which have open planters with vegetation, it is recommended that the vegetation be inspected. Look for any plants that are dead or showing signs of disease or other negative stressors. Record the general health of the plants on the inspection form and indicate through visual observation or digital photographs if trimming of the vegetation is required. 7. The discharge chamber houses the orifice control structure, drain down filter (only in California - older models), and is connected to the outflow pipe. It is important to check to ensure the orifice is in proper operating conditions and free of any obstructions. It is also important to assess the condition of the drain down filter media which utilizes a block form of the BioMediaGREEN. Assess in the same manner as the cubes in the pre- filter cartridge as mentioned above. Generally, the discharge chamber will be clean and free of debris. Inspect the water marks on the side walls. If possible, inspect the discharge chamber during a rain event to assess the amount of flow leaving the system while it is at 100% capacity (pre-treatment chamber water level at peak HGL - top of bypass weir). The water level of the flowing water should be compared to the watermark level on the side walls, which is an indicator of the highest discharge rate the system achieved when initially installed. Record on the form if there is any difference in level from the watermark in inches. INSPECTION •Excessive accumulation of sediment in the pre-treatment chamber of more than 6" in depth. •Excessive accumulation of sediment on the BioMediaGREEN media housed within the pre- treatment cartridges. The following chart shows photos of the condition of the BioMediaGREEN contained within the pre-filter cartridges. When media is more than 85% clogged, replacement is required. 7 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS INSPECTION •Excessive accumulation of sediment in the pre-treatment chamber of more than 6" in depth. •Excessive accumulation of sediment on the BioMediaGREEN media housed within the pre- treatment cartridges. The following chart shows photos of the condition of the BioMediaGREEN contained within the pre-filter cartridges. When media is more than 85% clogged, replacement is required. 7 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS New BioMediaGREEN 0% Exhausted BioMediaGREEN 100%85% 6 MAINTENANCE INDICATORS Based upon the observations made during inspection, maintenance of the system may be required based on the following indicators: •Missing or damaged internal components or cartridges •Obstructions in the system or its inlet and/or outlet pipes •Excessive accumulation of floatables in the pretreatment chamber in which the length and width of the chamber is fully impacted more than 18”. See photo below. •Excessive accumulation of sediment in the pretreatment chamber of more than 6” in depth. •Excessive accumulation of sediment on the BioMediaGREEN media housed within the pretreatment cartridges. The following chart shows photos of the condition of the BioMediaGREEN contained within the pre-filter cartridges. When media is more than 85% clogged, replacement is required. •Excessive accumulation of sediment on the BioMediaGREEN media housed within the pretreatment cartridges. When media is more than 85% clogged, replacement is required. The darker the BioMediaGREEN, the more clogged it is and in need of replacement. INSPECTION MAINTENANCE INDICATORS Based upon the observations made during inspection, maintenance of the system may be required based on the following indicators: •Missing or damaged internal components or cartridges •Obstructions in the system or its inlet and/or outlet pipes •Excessive accumulation of floatables in the pre-treatment chamber in which the length and width of the chamber is fully impacted more than 18". See photo below. 8.Finalize the inspection report for analysis by the maintenance manager to determine if maintenance is required. 6 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS INSPECTION •Excessive accumulation of sediment in the pre-treatment chamber of more than 6" in depth. •Excessive accumulation of sediment on the BioMediaGREEN media housed within the pre- treatment cartridges. The following chart shows photos of the condition of the BioMediaGREEN contained within the pre-filter cartridges. When media is more than 85% clogged, replacement is required. 7 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS INSPECTION MAINTENANCE INDICATORS Based upon the observations made during inspection, maintenance of the system may be required based on the following indicators: •Missing or damaged internal components or cartridges •Obstructions in the system or its inlet and/or outlet pipes •Excessive accumulation of floatables in the pre-treatment chamber in which the length and width of the chamber is fully impacted more than 18". See photo below. 8.Finalize the inspection report for analysis by the maintenance manager to determine if maintenance is required. 6 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS INSPECTION MAINTENANCE INDICATORS Based upon the observations made during inspection, maintenance of the system may be required based on the following indicators: •Missing or damaged internal components or cartridges •Obstructions in the system or its inlet and/or outlet pipes •Excessive accumulation of floatables in the pre-treatment chamber in which the length and width of the chamber is fully impacted more than 18". See photo below. 8.Finalize the inspection report for analysis by the maintenance manager to determine if maintenance is required. 6 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS NOTE: During the first few storms, the water level in the outflow chamber should be observed and a 6” long horizontal watermark line drawn (using a large permanent marker) at the water level in the discharge chamber while the system is operating at 100% capacity. The diagram below illustrates where the line should be drawn. This line is a reference point for future inspections of the system. Water level in the discharge chamber is a function of flow rate and pipe size. Observation of the water level during the first few months of operation can be used as a benchmark level for future inspections. The initial mark and all future observations shall be made when the system is at 100% capacity (water level at maximum level in the pre-treatment chamber). If future water levels are below this mark when the system is at 100% capacity, this is an indicator that maintenance to the pre-filter cartridges may be needed. 8. Finalize the inspection report for analysis by the maintenance manager to determine if maintenance is required. 7 INSPECTION PROCESS •Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required. •Overgrown vegetation. •Water level in the discharge chamber during 100% operating capacity (pretreatment chamber water level at max height) is lower than the water mark by 20%. INSPECTION •Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required. •Overgrown vegetation. •Water level in the discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%. 8 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS INSPECTION •Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required. •Overgrown vegetation. •Water level in the discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%. 8 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 8 MAINTENANCE SUMMARY The time has come to maintain your Modular Wetlands® Linear. All necessary pre-maintenance steps must be carried out before maintenance occurs. Once traffic control has been set up per local and state regulations and access covers have been safely opened, the maintenance process can begin. It should be noted that some maintenance activities require confined space entry. All confined space requirements must be strictly followed before entry into the system. In addition, the following is recommended: •Prepare the maintenance form by writing in the necessary information including project name, location, date & time, unit number and other info (see maintenance form). •Set up all appropriate safety and cleaning equipment. •Ensure traffic control is set up and properly positioned. •Prepared pre-checks (OSHA, safety, confined space entry) are performed. The following is a list of equipment to required for maintenance of the Modular Wetlands® Linear: •Modular Wetlands Linear Maintenance Form •Manhole hook or appropriate tools to access hatches and covers •Protective clothing, flashlight, and eye protection •7/16” open or closed ended wrench •Vacuum assisted truck with pressure washer •Replacement BioMediaGREEN for pre-filter cartridges if required (order from one of Contech’s Maintenance Team members at https://www.conteches.com/maintenance). 9 MAINTENANCE | PRETREATMENT CHAMBER 1. Remove access cover over pre-treatment chamber and position vacuum truck accordingly. 2. With a pressure washer, spray down pollutants accumulated on walls and pre-filter cartridges. 3. Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean. 4. If pre-filter cartridges require media replacement, continue to step 5. If not, replace access cover and move to step 11. 1.MAINTENANCE (PRE-TREATMENT CHAMBER)Remove access cover over pre-treatment chamber and position vacuum truck accordingly.2.With a pressure washer, spray down pollutants accumulated on walls and pre-filter cartridges. 3.Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean. 4.If pre-filter cartridges require media replacement, move on to next page. If not, replace access cover. 11 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 1.MAINTENANCE (PRE-TREATMENT CHAMBER)Remove access cover over pre-treatment chamber and position vacuum truck accordingly.2.With a pressure washer, spray down pollutants accumulated on walls and pre-filter cartridges. 3.Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean. 4.If pre-filter cartridges require media replacement, move on to next page. If not, replace access cover. 11 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 1.MAINTENANCE (PRE-TREATMENT CHAMBER)Remove access cover over pre-treatment chamber and position vacuum truck accordingly.2.With a pressure washer, spray down pollutants accumulated on walls and pre-filter cartridges. 3.Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean. 4.If pre-filter cartridges require media replacement, move on to next page. If not, replace access cover. 11 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 1.MAINTENANCE (PRE-TREATMENT CHAMBER)Remove access cover over pre-treatment chamber and position vacuum truck accordingly.2.With a pressure washer, spray down pollutants accumulated on walls and pre-filter cartridges. 3.Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean. 4.If pre-filter cartridges require media replacement, move on to next page. If not, replace access cover. 11 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 10 MAINTENANCE | PREFILTER CARTRIDGES 5. After successfully cleaning out the pre-treatment chamber (previous page) enter the pre-treatment chamber. 6. Unscrew the two bolts (circles shown below) holding the lid on each cartridge filter and remove lid. 7. Place the vacuum hose over each individual media filter to suck out filter media. 8. Once filter media has been sucked out, use a pressure washer to spray down the inside of the cartridge and it’s media cages. Remove cleaned media cages and place to the side. Once removed, the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge. 9. Reinstall media cages and fill with new media from the manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. Utilize the manufacture-provided refilling tray and place on top of the cartridge. Fill the tray with new bulk media and shake down into place. Using your hands, lightly compact the media into each filter cage. Once the cages are full, remove the refilling tray and replace the cartridge top, ensuring bolts are properly tightened. 10. Exit the pre-treatment chamber. Replace access hatch or manhole cover. 1. MAINTENANCE (PRE-FILTER CARTRIDGES) After successfully cleaning out the pre-treatment chamber (previous page) enter the pre-treatment chamber. 2. Unscrew the two bolts (red circles) holding the lid on each cartridge filter and remove lid. 3.Place the vacuum hose over each individual media filter to suck out filter media. 4.Once filter media has been sucked out, use a pressure washer to spray down the inside of the cartridge and it's media cages. Remove cleaned media cages and place to the side. Once removed, the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge. 12 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 0 0 1. MAINTENANCE (PRE-FILTER CARTRIDGES) After successfully cleaning out the pre-treatment chamber (previous page) enter the pre-treatment chamber. 2. Unscrew the two bolts (red circles) holding the lid on each cartridge filter and remove lid. 3.Place the vacuum hose over each individual media filter to suck out filter media. 4.Once filter media has been sucked out, use a pressure washer to spray down the inside of the cartridge and it's media cages. Remove cleaned media cages and place to the side. Once removed, the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge. 12 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 0 0 1.MAINTENANCE (PRE-FILTER CARTRIDGES)After successfully cleaning out the pre-treatment chamber (previous page) enter the pre-treatment chamber. 2. Unscrew the two bolts (red circles) holding the lid on each cartridge filter and remove lid. 3.Place the vacuum hose over each individual media filter to suck out filter media. 4.Once filter media has been sucked out, use a pressure washer to spray down the inside of the cartridge and it's media cages. Remove cleaned media cages and place to the side. Once removed, the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge. 12 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 0 0 5. MAINTENANCE (PRE-FILTER CARTRIDGES) Reinstall media cages and fill with new media from the manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. utilize the manufacture-provided refilling tray and place on top of the cartridge. Fill the tray with new bulk media and shake down into place. using your hands, lightly compact the media into each filter cage. Once the cages are full, remove the refilling tray and replace the cartridge top, ensuring bolts are properly tightened. 6.Exit the pre-treatment chamber. Replace access hatch or manhole cover. 13 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 5. MAINTENANCE (PRE-FILTER CARTRIDGES) Reinstall media cages and fill with new media from the manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. utilize the manufacture-provided refilling tray and place on top of the cartridge. Fill the tray with new bulk media and shake down into place. using your hands, lightly compact the media into each filter cage. Once the cages are full, remove the refilling tray and replace the cartridge top, ensuring bolts are properly tightened. 6.Exit the pre-treatment chamber. Replace access hatch or manhole cover. 13 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 5. MAINTENANCE (PRE-FILTER CARTRIDGES) Reinstall media cages and fill with new media from the manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. utilize the manufacture-provided refilling tray and place on top of the cartridge. Fill the tray with new bulk media and shake down into place. using your hands, lightly compact the media into each filter cage. Once the cages are full, remove the refilling tray and replace the cartridge top, ensuring bolts are properly tightened. 6.Exit the pre-treatment chamber. Replace access hatch or manhole cover. 13 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 11 MAINTENANCE | BIOFILTRATION CHAMBER 11. In general, the biofiltration chamber is maintenance-free with the exception of maintaining the vegetation. The Modular Wetlands Linear utilizes vegetation similar to surrounding landscape areas, therefore trim vegetation to match surrounding vegetation. If any plants have died, replace them with new ones. 12. Each vertical under drain on the biofiltration chamber has a removable (threaded cap) that can be taken off to check any blockages or root growth. Once removed, a jetting attachment can be used to clean out the under drain and orifice riser. 13. As with all biofilter systems, at some point the biofiltration media (WetlandMedia) will need to be replaced. Either because of physical clogging of sorptive exhaustion of the media ion exchange capacity (to remove dissolved metals and phosphorous). The general life of this media is 10 to 20 years based on site specific conditions and pollutant loading. Utilize the vacuum truck to vacuum out the media by placing the hose into the chamber. Once all the media is removed use the power washer to spray down all the netting on the outer metal cage. Inspect the netting for any damage or holes. If the netting is damaged it can be repaired or replaced with guidance by the manufacturer. 14. Contact one of Contech’s Maintenance Team members at https://www.conteches.com/maintenance to order new WetlandMedia. The quantity of media needed can be determined by providing the model number and unit depth. Media will be provided in super sacks for easy installation. Each sack will weigh between 1000 and 2000 lbs. A lifting apparatus (backhoe, boom truck, or other) is recommended to position the super sack over the biofiltration chamber. Fill the media cages up to the same level as the old media. Replant with vegetation. 1.MAINTENANCE (BIOFILTRATION CHAMBER)In general, the biofiltration chamber is maintenance-free with the exception of maintaining the vegetation. Using standard gardening tools, properly trim back the vegetation to healthy levels. The MW Linear™ utilizes vegetation similar to surrounding landscape areas, therefore trim vegetation to match surrounding vegetation. If any plants have died, replace them with new ones. 14 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 3.As with all biofilter systems, at some point the biofiltration media (WetlandMedia) will need to be replaced. Either because of physical clogging of sorptive exhaustion of the media ion exchange capacity (to remove dissolved metals and phosphorous). The general life of this media is 10 to 20 years based on site specific conditions and pollutant loading. Utilize the vacuum truck to vacuum out the media by placing the hose into the chamber. Once all the media is removed use the power washer to spray down all the netting on the outer metal cage. Inspect the netting for any damage or holes. If the netting is damaged it can be repaired or re- placed with guidance by the manufacturer. 4.The first step is to contact the manufacturer and order new WetlandMedia. The quantity of media needed can be determined by providing the model number and unit depth. Media will be provided in super sacks for easy installation. Each sack will weigh between 1000 and 2000 lbs. A lifting apparatus (backhoe, boom truck, or other) is rec-ommended to position the super sack over the biofiltration chamber. Fill the media cages up to the same level as the old media. Replant with vegetation. 2.Each vertical under drain on the biofiltration chamber has a removable (threaded) that can be taken off to check any blockages or root growth. Once removed a a jetting attachment can be used to clean out the under drain and orifice riser. 1.MAINTENANCE (BIOFILTRATION CHAMBER)In general, the biofiltration chamber is maintenance-free with the exception of maintaining the vegetation. Using standard gardening tools, properly trim back the vegetation to healthy levels. The MW Linear™ utilizes vegetation similar to surrounding landscape areas, therefore trim vegetation to match surrounding vegetation. If any plants have died, replace them with new ones. 14 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 3.As with all biofilter systems, at some point the biofiltration media (WetlandMedia) will need to be replaced. Either because of physical clogging of sorptive exhaustion of the media ion exchange capacity (to remove dissolved metals and phosphorous). The general life of this media is 10 to 20 years based on site specific conditions and pollutant loading. Utilize the vacuum truck to vacuum out the media by placing the hose into the chamber. Once all the media is removed use the power washer to spray down all the netting on the outer metal cage. Inspect the netting for any damage or holes. If the netting is damaged it can be repaired or re- placed with guidance by the manufacturer. 4.The first step is to contact the manufacturer and order new WetlandMedia. The quantity of media needed can be determined by providing the model number and unit depth. Media will be provided in super sacks for easy installation. Each sack will weigh between 1000 and 2000 lbs. A lifting apparatus (backhoe, boom truck, or other) is rec-ommended to position the super sack over the biofiltration chamber. Fill the media cages up to the same level as the old media. Replant with vegetation. 2.Each vertical under drain on the biofiltration chamber has a removable (threaded) that can be taken off to check any blockages or root growth. Once removed a a jetting attachment can be used to clean out the under drain and orifice riser.1. MAINTENANCE (BIOFILTRATION CHAMBER) In general, the biofiltration chamber is maintenance-free with the exception of maintaining the vegetation. Using standard gardening tools, properly trim back the vegetation to healthy levels. The MW Linear™ utilizes vegetation similar to surrounding landscape areas, therefore trim vegetation to match surrounding vegetation. If any plants have died, replace them with new ones. 14 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 3.As with all biofilter systems, at some point the biofiltration media (WetlandMedia) will need to be replaced. Either because of physical clogging of sorptive exhaustion of the media ion exchange capacity (to remove dissolved metals and phosphorous). The general life of this media is 10 to 20 years based on site specific conditions and pollutant loading. Utilize the vacuum truck to vacuum out the media by placing the hose into the chamber. Once all the media is removed use the power washer to spray down all the netting on the outer metal cage. Inspect the netting for any damage or holes. If the netting is damaged it can be repaired or re- placed with guidance by the manufacturer. 4.The first step is to contact the manufacturer and order new WetlandMedia. The quantity of media needed can be determined by providing the model number and unit depth. Media will be provided in super sacks for easy installation. Each sack will weigh between 1000 and 2000 lbs. A lifting apparatus (backhoe, boom truck, or other) is rec-ommended to position the super sack over the biofiltration chamber. Fill the media cages up to the same level as the old media. Replant with vegetation. 2.Each vertical under drain on the biofiltration chamber has a removable (threaded) that can be taken off to check any blockages or root growth. Once removed a a jetting attachment can be used to clean out the under drain and orifice riser. 12 MAINTENANCE | DISCHARGE CHAMBER 15. Remove access hatch or manhole cover over discharge chamber. 16. Enter chamber to gain access to the drain down filter. Unlock the locking mechanism and lift up drain down filter housing to remove used BioMediaGREEN filter block as shown below. NOTE: Drain down filter is only found on units installed in California prior to 2023. If no drain down filter is present, skip steps 16 and 17. 17. Insert a new BioMediaGREEN filter block and lock drain down filter housing back in place. 18. Replace access hatch or manhole cover over discharge chamber. INSPECTION •Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required. •Overgrown vegetation. •Water level in the discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%. 8 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS INSPECTION •Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required. •Overgrown vegetation. •Water level in the discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%. 8 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS 13 NOTES _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ 14 For Office Use Only (city)(Zip Code)(Reviewed By) Owner / Management Company (Date) Contact Phone ( )_ Inspector Name Date //Time AM / PM Weather Condition Additional Notes Yes Depth: Yes No Modular Wetland System Type (Curb, Grate or UG Vault):Size (22', 14' or etc.): Other Inspection Items: Storm Event in Last 72-hours? No YesType of Inspection Routine Follow Up Complaint Storm Office personnel to complete section to the left. Inspection Report Modular Wetlands Linear Is the filter insert (if applicable) at capacity and/or is there an accumulation of debris/trash on the shelf system? Does the cartridge filter media need replacement in pre-treatment chamber and/or discharge chamber? Any signs of improper functioning in the discharge chamber? Note issues in comments section. Chamber: Is the inlet/outlet pipe or drain down pipe damaged or otherwise not functioning properly? Structural Integrity: Working Condition: Is there evidence of illicit discharge or excessive oil, grease, or other automobile fluids entering and clogging the unit? Is there standing water in inappropriate areas after a dry period? Damage to pre-treatment access cover (manhole cover/grate) or cannot be opened using normal lifting pressure? Damage to discharge chamber access cover (manhole cover/grate) or cannot be opened using normal lifting pressure? Does the MWS unit show signs of structural deterioration (cracks in the wall, damage to frame)? Project Name Project Address Inspection Checklist CommentsNo Does the depth of sediment/trash/debris suggest a blockage of the inflow pipe, bypass or cartridge filter? If yes, specify which one in the comments section. Note depth of accumulation in in pre-treatment chamber. Is there a septic or foul odor coming from inside the system? Is there an accumulation of sediment/trash/debris in the wetland media (if applicable)? Is it evident that the plants are alive and healthy (if applicable)? Please note Plant Information below. Sediment / Silt / Clay Trash / Bags / Bottles Green Waste / Leaves / Foliage Waste:Plant Information No Cleaning Needed Recommended Maintenance Additional Notes: Damage to Plants Plant Replacement Plant Trimming Schedule Maintenance as Planned Needs Immediate Maintenance ENGINEERED SOLUTIONS 15 For Office Use Only (city)(Zip Code)(Reviewed By) Owner / Management Company (Date) Contact Phone ( )_ Inspector Name Date //Time AM / PM W eather Condition Additional Notes Site Map # Comments: Inlet and Outlet Pipe Condition Drain Down Pipe Condition Discharge Chamber Condition Drain Down Media Condition Plant Condition Media Filter Condition Long: MW S Sedimentation Basin Total Debris Accumulation Condition of Media 25/50/75/100 (will be changed @ 75%) Operational Per Manufactures' Specifications (If not, why?) Lat:MW S Catch Basins GPS Coordinates of Insert Manufacturer / Description / Sizing Trash Accumulation Foliage Accumulation Sediment Accumulation Type of Inspection Routine Follow Up Complaint Storm Storm Event in Last 72-hours? No Yes Office personnel to complete section to the left. Project Address Project Name Cleaning and Maintenance Report Modular Wetlands LinearENGINEERED SOLUTIONS SUPPORT DRAWINGS AND SPECIFICATIONS ARE AVAILABLE AT WWW.CONTECHES.COM © 2023 CONTECH ENGINEERED SOLUTIONS LLC, A QUIKRETE COMPANY 800-338-1122 WWW.CONTECHES.COM ALL RIGHTS RESERVED. PRINTED IN THE USA. CONTECH ENGINEERED SOLUTIONS LLC PROVIDES SITE SOLUTIONS FOR THE CIVIL ENGINEERING INDUSTRY. CONTECH’S PORTFOLIO INCLUDES BRIDGES, DRAINAGE, SANITARY SEWER, STORMWATER AND EARTH STABILIZATION PRODUCTS. FOR INFORMATION ON OTHER CONTECH DIVISION OFFERINGS, VISIT CONTECHES.COM OR CALL 800-338-1122. Modular Wetlands Maintenance Guide 1/2023 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. ENGINEERED SOLUTIONS ACO StormBrixx® Prevention Inspection Maintenance Cleaning Geocellular Stormwater Storage Product Maintenance 888-490-9552 www.acousa.comSTORMBRIXX® MAINTENANCE MANUAL1 Contents ACO StormBrixx® 1 System Components 2 1. Prevention Measures 3 1.1 Prior to & During Construction 3 1.2 Post Construction 3 2. Inspections 4 2.1 Visual Inspection 4 2.2 Annual Inspection 4 2.3 Items To Inspect 4 2.4 Identify and Report 4 3. Maintenance Procedure 5 3.1 Surface Access 5 3.2 Safety 5 3.3 System Inspection 5 3.4 Standing Water 5 3.5 High Pressure 5 3.6 Water Level 6 3.7 Vacuum Hose 6 3.8 Repeat 6 3.9 Final Inspection 6 3.10 Remove Equipment 6 4. Cleaning Procedures 7 4.1 Frequency 7 4.2 Evaluation 7 4.3 Maintenance 7 7. askACO 8 ACO StormBrixx® SD and HD ACO StormBrixx® is a unique and patented geocellular stormwater management system for detention and infiltration usage. Its versatile design allows the system to be used in configurations and applications across all construction environments as a standalone solution or as part of an integrated LID (Low Impact Development) or BMP (Best Management Practices). Systems may or may not include pre-treatment to remove sediment and/or contaminants prior to entering the storage area. Those without pre-treatment require greater attention to system functionality and may require additional maintenance. In order to sustain proper system functionality, ACO offers the following general maintenance guidelines for the StormBrixx® product. 888-490-9552 www.acousa.com STORMBRIXX® MAINTENANCE MANUALACO STORMBRIXX 2 System Components 1. StormBrixx Tank Bodies* 2. Side Panel* 3. Top Cover* 4. Remote Access Unit* 5. Remote Access Cover - Ductile Iron 6. Extension Shaft* 2 1 4 6 5 * Image shown represents a StormBrixx® SD system. The Remote Access Unit may be swapped out with the Remote Access Plate. ACO offers vented and non-vented Remote Access Covers. 3 888-490-9552 www.acousa.comSTORMBRIXX® MAINTENANCE MANUAL3 The prevention measures we recommend will increase the efficiency of the installed tank and the life of the entire system. StormBrixx® is built to be used in areas in which protecting the environment is important. The prevention measures allow for the system as well as the locale it is installed to be sustainable. StormBrixx® provides top of the line stormwater management solutions for detention, retention, reuse, and infiltration systems. The long term environmental focuses of StormBrixx® through LID, SuDS, MS4, and BMP will benefit the installer, the land owner, and the nearby environment. 1.1 PRIOR TO & DURING CONSTRUCTION Siltation Prevention of the Stormwater System Conform to all local, state, and federal regulations for sediment and erosion control during construction. Install site erosion and sediment BMP’s (Best Management Practices) required to prevent siltation of the stormwater system. Inspect and maintain erosion and sediment BMP’s during construction. 1.2 POST CONSTRUCTION Prior to Commissioning the ACO StormBrixx® System Remove and properly dispose of construction erosion and sediment BMP’s per all local, state, and federal regulations. Care should be taken during removal of the BMP devices to prevent collected sediment or debris falling into the stormwater system. Flush the ACO StormBrixx® system to remove any sediment or construction debris immediately after the BMP’s removal. Follow the maintenance procedure outlined. 1 Prevention Measures Prevention measure 888-490-9552 www.acousa.com STORMBRIXX® MAINTENANCE MANUALACO STORMBRIXX 4 2 Follow all local, state, and federal regulations regarding stormwater BMP inspection requirements. The results of the visual inspection, notes and repairs can be recorded in an operating logbook as a recommended best practice. These records will allow decisions to be made about the necessary frequency of future inspection and maintenance measures. ACO makes the following recommendations: Inspections 2.1 VISUAL INSPECTION Year One During the first service year a visual inspection should be completed during and after each major rainfall event, in addition to every 6 month period to monitor and establish what sediment and debris buildup occurs. Each ACO StormBrixx® system is unique to the application and multiple criteria can affect maintenance frequency as such:  System Design: pre-treatment/no- treatment, inlet protection, stand-alone device.  Surface area collecting from: hardscape, gravel, soil, or any other surface.  Adjacent Area: soil runoff, gravel, trash. 2.2 ANNUAL INSPECTION Year Two Establish an annual inspection frequency based on the information collected during the first year. At a minimum an inspection should be performed at 6 month intervals. 2.3 ITEMS TO INSPECT Components  ACO StormBrixx® Remote Access Units/ Plates and inspection ports.  Inlet and Outlet points.  Discharge area. 2.4 IDENTIFY AND REPORT Maintenance required if:  Sediment and debris accumulation 6” or more.  System backing up.  Make operating logbook notes if needed. Inspection camera 888-490-9552 www.acousa.comSTORMBRIXX® MAINTENANCE MANUAL5 3 Maintenance Procedure 3.1 SURFACE ACCESS Regulations Conform to all local, state, and federal regulations. Access Cover Locate access cover(s) at the surface connected to the tank. 3.2 SAFETY Access Cover Once located, safely open lid and remove. 3.3 SYSTEM INSPECTION System Debris Perform an inspection of the tank to locate any debris. This can be done visually, with or without an inspection camera. 3.4 STANDING WATER Remove Water If the tank has standing water in it, you will need to vacuum the water first before visually inspecting the tank. 3.5 HIGH PRESSURE System Clearing Use the high pressure jet nozzle/wand to loosen and suspend any solid debris that has built up. Access to high pressure water and vacuum will be needed to clear the tank of any built up debris. A minimum water pressure of 2,500 PSI is recommended. The maximum pressure depends on the geotextile fabric chosen. Please check with fabric manufacturer for max PSI. To ensure correct insertion angle of the high pressure jet nozzle, we recommend using a pipe elbow. Alternatively, a nearby fire hydrant can be used to suspend debris within the StormBrixx® system before vacuuming up the water. Maintenance Procedure Vacuum removal of debris Wand used to loosen debris 888-490-9552 www.acousa.com STORMBRIXX® MAINTENANCE MANUALACO STORMBRIXX 6 3 3.6 WATER LEVEL Optimal Water Depth Once the water level has reached 12” or more, shut off and remove high pressure jet nozzle/wand. 3.7 VACUUM HOSE Remote Access Unit/Plate Insert vacuum hose via the remote access unit/plate and begin removing all debris that is now suspended in water. Do this until all water has been removed. 3.8 REPEAT Water and Debris Not all water and debris may be removed in the first round, you may need to add and remove more water. 3.9 FINAL INSPECTION Cleared Tank Once all debris has been removed, inspect tank again to make sure everything has been cleared. 3.10 REMOVE EQUIPMENT Replace Cover Once the tank is clear of debris and water, remove all equipment and place the cover back on the tank. Secure cover accordingly. Maintenance Procedure For further information on ACO products, please visit the ACO USA website. This allows access to technical data, videos, images, specifications, and installation instructions. www.acoswm.com/stormbrixx Camera view of clean tank Final inspection © March 2021 ACO, Inc. All reasonable care has been taken in compiling the information in this document. All recommendations and suggestions on the use of ACO products are made without guarantee since the conditions of use are beyond the control of the company. It is the customer's responsibility to ensure that each product is fit for its intended purpose and that the actual conditions of use are suitable. ACO, Inc. reserves the right to change products and specifications without notice. Print #SB701 info@acousa.com www.acousa.com ACO, Inc. ACO. creating the future of drainage West Sales Office 825 W. Beechcraft St. Casa Grande, AZ 85122 Tel: (520) 421-9988 Toll Free: (888) 490-9552 Fax: (520) 421-9899 Northeast Sales Office 9470 Pinecone Drive Mentor, OH 44060 Tel: (440) 639-7230 Toll free: (800) 543-4764 Fax: (440) 639-7235 Southeast Sales Office 4211 Pleasant Road Fort Mill, SC 29708 Toll free: (800) 543-4764 Fax: (803) 802-1063