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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. 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File Informa on 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 Se ngs Unit System: U.S. Customary Units Analysis Se ngs Pre-Exis ng - Sta c (2) Kind: SLOPE/W Analysis Type: Morgenstern-Price Se ngs Side Func on Interslice force func on op on: Half-Sine PWP Condi ons from: Piezometric Surfaces Apply Phrea c Correc on: No Use Staged Rapid Drawdown: No Unit Weight of Water: 62.430189 pcf Slip Surface Direc on of movement: Le to Right Use Passive Mode: No Slip Surface Op on: Entry and Exit Cri cal slip surfaces saved: 1 Op mize Cri cal Slip Surface Loca on: No Tension Crack Op on: (none) Distribu on F of S Calcula on Op on: Constant Convergence Geometry Se ngs 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 Se ngs Maximum Number of Itera ons: 100 Tolerable difference in F of S: 0.001 Under-Relaxa on Criteria Ini al Rate: 1 Minimum Rate: 0.1 Rate Reduc on Factor: 0.65 Reduc on Frequency (itera ons): 50 Solu on Se ngs Search Method: Root Finder Tolerable difference between star ng and converged F of S: 3 Maximum itera ons to calculate converged lambda: 20 Max Absolute Lambda: 2 Materials Medium Dense Silty Sand Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effec ve Cohesion: 25 psf Effec ve Fric on Angle: 32 ° Phi-B: 0 ° Medium Dense to Dense Sandy Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 125 pcf Effec ve Cohesion: 100 psf Effec ve Fric on Angle: 32 ° Phi-B: 0 ° Very Dense Silt Slope Stability Material Model: Mohr-Coulomb Unit Weight: 120 pcf Effec ve Cohesion: 250 psf Effec ve Fric on 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 Effec ve Cohesion: 125 psf Effec ve Fric on 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) Se ngs 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 Resis ng Moment: 4,148,166.9 lbf·