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22-102751-SU-Technical Information Report-06-15-2022-V1 TECHNICAL INFORMATION REPORT FOR PLANT 2 RELOCATION JUNE 9, 2022 TABLE OF CONTENTS Page SECTION 1 – PROJECT OVERVIEW ..................................................................................................................................................... 1 FIGURE 1.1 – TIR WORKSHEET ................................................................................................................................................ 3 FIGURE 1.2 – SITE LOCATION .................................................................................................................................................. 9 FIGURE 1.3 - DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS ......................................................................... 11 FIGURE 1.4 - SOILS ................................................................................................................................................................. 14 SECTION 2 – CONDITIONS AND REQUIREMENTS SUMMARY ......................................................................................................... 18 SECTION 3 – OFFSITE ANALYSIS ...................................................................................................................................................... 21 FIGURE 3.1 – DOWNSTREAM ANALYSIS ................................................................................................................................ 24 FIGURE 3.2 – FEMA FIRM ...................................................................................................................................................... 27 FIGURE 3.3 – CRITICAL AREAS MAP ....................................................................................................................................... 29 FIGURE 3.4 – DRAINAGE COMPLAINTS ................................................................................................................................. 31 FIGURE 3.5 – ASSESSED WATER QUALITY AREAS .................................................................................................................. 34 SECTION 4 – FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID) AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ........ 41 Part A – EXISTING SITE HYDROLOGY .......................................................................................................................................... 41 FIGURE 4.A.1 – PRE-DEVELOPED BASIN MAP ........................................................................................................................ 42 Part B – DEVELOPED SITE HYDROLOGY ...................................................................................................................................... 44 FIGURE 4.B.1 – DEVELOPED BASIN MAP ............................................................................................................................... 45 Part C – PERFORMANCE STANDARDS ........................................................................................................................................ 47 FIGURE 4.C.1 - FEDERAL WAY FLOW CONTROL APPLICATION MAP ...................................................................................... 48 FIGURE 4.C.2 - FEDERAL WAY WATER QUALITY APPLICATION MAP ..................................................................................... 50 Part D – FLOW CONTROL SYSTEM .............................................................................................................................................. 52 FIGURE 4.D.1 – WATER QUANTITY BASIN ANALYSIS ............................................................................................................. 53 FIGURE 4.D.2 – FLOW CONTROL WWHM CALCULATIONS .................................................................................................... 55 Part E – WATER QUALITY SYSTEM .............................................................................................................................................. 68 FIGURE 4.E.1 - COALESCING PLATE OIL/WATER SEPARATOR SIZING .................................................................................... 69 FIGURE 4.E.2 - WESTERN KING COUNTY 2-YEAR 24-HOUR ISOPLUVIAL ............................................................................... 73 FIGURE 4.E.3 – KCSWDM TABLE 6.2.1.A ................................................................................................................................ 75 FIGURE 4.E.4 – ONSITE BIOPOD BIOFILTER DETAIL ............................................................................................................... 77 FIGURE 4.E.5 – 351ST STREET BIOPOD BIOFILTER DETAIL ...................................................................................................... 79 FIGURE 4.E.6 – WATER QUALITY WWHM CALCULATIONS .................................................................................................... 81 SECTION 5 – CONVEYANCE SYSTEM ANALYSIS AND DESIGN .......................................................................................................... 91 FIGURE 5.1 – CONVEYANCE BASIN MAP ............................................................................................................................... 92 FIGURE 5.2 – CONVEYANCE BASIN ANALYSIS ........................................................................................................................ 94 FIGURE 5.3 – STORMSHED 3G CALCULATIONS ..................................................................................................................... 96 SECTION 6 – SPECIAL REPORTS AND STUDIES ............................................................................................................................... 125 FIGURE 6.1 – GEOTECHNICAL ENGINEERING REPORT ......................................................................................................... 126 SECTION 7 – OTHER PERMITS ....................................................................................................................................................... 139 SECTION 8 – CSWPP ANALYSIS AND DESIGN ................................................................................................................................ 140 Part A – ESC PLAN ANALYSIS AND DESIGN ............................................................................................................................... 140 FIGURE 8.A.1 – TESC BASIN MAP ........................................................................................................................................ 142 FIGURE 8.A.2 – SEDIMENT POND ANALYSIS ........................................................................................................................ 144 FIGURE 8.A.3 – TEMPORARY SWALE ANALYSIS ................................................................................................................... 146 FIGURE 8.A.4 – TESC WWHM CALCULATIONS ..................................................................................................................... 148 Part B – STORMWATER POLLUTION PREVENTION AND SPILL CONTROL PLAN (SWPPS) DESIGN ............................................ 153 FIGURE 8.B.1 – CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN............................................................... 154 SECTION 9 – BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ..................................................... 180 SECTION 10 – OPERATIONS AND MAINTENANCE MANUAL ......................................................................................................... 181 FIGURE 10.1 – OPERATIONS AND MAINTENANCE MANUAL ............................................................................................... 182 35072_Fed Way Plant 2 Relocation_TIR_060922.doc 1 SECTION 1 – PROJECT OVERVIEW This report contains the preliminary technical and background information in support of the site development associated with parcels 202104-9043, 202104-9155, 202104-9162, and 202104-9163. A concrete batch plant is proposed on the project site. The analysis included in this report summarizes the preliminary design of the stormwater facilities, pollution prevention, and erosion and sediment control. Refer to the attached preliminary TIR worksheet, Figure 1.1, and the Site Plan, Figure 1.5 for additional information. The proposed project site is within a portion of the southeast quarter of the southeast quarter of Section 20, Township 21 North, Range 4 East, W.M., City of Federal Way, Washington. Refer to the attached Vicinity Map, Figure 1.2. The parcels, 202104-9043, 202104-9155, 202104-9162, and 202104-9163, containing approximately 4.19 acres, are located at 35000 Pacific Highway South and are currently being used as a truck storage facility. The project site is abutted by a commercial shopping center to the north and east, Pacific Highway South (State Route 99) to the west, and a King County fire protection facility to the south. Refer to Figure 1.3 for a map of the drainage basins. The existing parcels have three buildings and are covered predominantly with gravel and asphalt paving with limited vegetation. The project site consists of a single Threshold Discharge Area. Generally, runoff from the western half of the site flows to the west to the existing storm conveyance system located within Pacific Hwy. S., and runoff from the eastern half of the site flows to the south to the existing storm conveyance system located within S. 351st Street which is then conveyed to the west to Pacific Hwy. S. Runoff from adjacent properties does not appear to drain onto the project site. Refer to Section 4, Part A of this report for further details regarding the existing site hydrology and topography. A concrete batch plant is proposed on the project site. The majority of the site is proposing to be paved for plant operation and parking areas and will also include a shop/storage building, covered storage bins, concrete plant silos and equipment, and perimeter landscape buffer. Full roadway improvements to S. 351st Street are proposed. The roadway is currently private but is proposing to be built to public standards (Cross Section Type R) including 40 feet of pavement with curb and gutter, 4 foot planter strip, and 6 foot sidewalk both sides. The coverages for the developed project site are summarized in the following table. Basin Total Area (acres) Impervious Area (acres) Pervious Area - Till, Forest Area (acres) Pervious Area - Till, Lawn Area (acres) TOTAL 4.19 3.74 0 0.45 The majority of the project site is providing oil control and enhanced basic water quality treatment through the use of a coalescing plate oil/water separator, presettling vault, and Oldcastle BioPod Biofilter, which has a Washington State Department of Ecology (WSDOE) General Use Level Designation (GULD) for enhanced treatment. Water quantity control is 2 proposed with an underground infiltration vault. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities. This basin is proposing an Oldcastle Biopod Biofilter for water quality treatment and will discharge to the existing conveyance system within Pacific Highway South. This discharge is proposing to meet the Conservation Flow Control criteria. Refer to Section 4 of this report for additional details regarding the proposed storm systems. NRCS’ web soil survey information was referenced for the soil mapping of the site. The site consists of Everett-Alderwood gravelly sandy loams for the northern portion of the site and Urban land for the southern portion of the site per the mapping. South Sound Geotechnical Consulting (SSGC) completed a geotechnical engineering report and infiltration assessment, dated June 18, 2021. The soils were described as consisting of an upper layer of fill with underlying native soils of silty sand with gravel and occasional cobbles. Groundwater was not observed at the time of excavation. One small-scale Pilot Infiltration Test (PIT) was completed in the area of the proposed stormwater facilities. Based on the field results, SSGC recommended a design infiltration rate of 2 inches per hour. The report should be referenced for additional information regarding the site soils. The Hylebos Wetland is south of site but located greater than one-quarter mile downstream. No critical conditions or difficult site parameters are known to exist at this time. The project is not located within a known floodplain and/or floodway per FEMA mapping. Refer to the FEMA FIRM included as Figure 3.2. 3 FIGURE 1.1 – TIR WORKSHEET KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner ___________________________ Phone _________________________________ Address _______________________________ _______________________________________ Project Engineer _________________________ Company ______________________________ Phone _________________________________ Project Name _________________________ DPER Permit # ________________________ Location Township ______________ Range ________________ Section ________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Landuse (e.g.,Subdivision / Short Subd. / UPD) Building (e.g.,M/F / Commercial / SFR) Clearing and Grading Right-of-Way Use Other _______________________ DFW HPA COE 404 DOE Dam Safety FEMA Floodplain COE Wetlands Other ________ Shoreline Management Structural Rockery/Vault/_____ ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review (check one): Date (include revision dates): Date of Final: Full Targeted Simplified Large Project Directed __________________ __________________ __________________ 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: ______________________ 2016 Surface Water Design Manual 4/24/20161 35000 Pacific Hwy S LLC (253)-826-5003 P.O. Box 94176 Seattle, WA 98124 Gabe L. Jellison, PE Apex Engineering, PLLC (253) 473-4494 Plant 2 Relocation 21N 4E 20 35050 Pacific Hwy S Federal Way, WA Site Development N/A KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ 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 ________________________ Lake ______________________________ Wetlands ____________________________ Closed Depression ____________________ Floodplain ___________________________ Other _______________________________ _______________________________ Steep Slope __________________________ Erosion Hazard _______________________ Landslide Hazard ______________________ Coal Mine Hazard ______________________ Seismic Hazard _______________________ Habitat Protection ______________________ _____________________________________ Part 10 SOILS Soil Type _________________ _________________ _________________ _________________ Slopes _________________ _________________ _________________ _________________ Erosion Potential _________________ _________________ _________________ _________________ High Groundwater Table (within 5 feet) Other ________________________________ Sole Source Aquifer Seeps/Springs Additional Sheets Attached 2016 Surface Water Design Manual 4/24/20162 Aquifer Recharge Federal Way N/A Hylebos Creek Enhanced Basic Water Quality and Oil Control Everett-Alderwood gravelly sandy loams Urban land 6 to 15 N/A N/A N/A KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core 2 – Offsite Analysis_________________ Sensitive/Critical Areas__________________ SEPA________________________________ LID Infeasibility________________________ Other________________________________ _____________________________________ LIMITATION / SITE CONSTRAINT _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ 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 summary sheet) Level: 1 / 2 / 3 or Exemption Number ____________ Flow Control BMPs _______________________________ Conveyance System Spill containment located at: _________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: _____________________ 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 summary sheet) Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. ______________________ Landscape Management Plan: Yes / No 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: 2016 Surface Water Design Manual 4/24/20163 N/A Aquifer Recharge N/A N/A N/A 1 2/11/2022 To be determined To be provided as required N/A Plant 2 Relocation TDA Infiltration Vault CPS/Presettling Vault To be determined To be determined 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) 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 ______________________ Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Type/Description Water Quality Type/Description Detention Infiltration Regional Facility Shared Facility Flow Control BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ Vegetated Flowpath Wetpool Filtration Oil Control Spill Control Flow Control BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ ________________ 2016 Surface Water Design Manual 4/24/20164 Infiltration Vault Presettling vault BioPod Biofilter Vault CPS Oil Water Sep. Downturned Elbow Concrete Batch Plant CPS/Presettling Vault CPS Oil Water Separator Presettling Vault, Biopod Biofilter Vault, Infiltration Vault KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Covenant Tract Other ___________________________ Cast in Place Vault Retaining Wall Rockery > 4’ High Structural on Steep Slope 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 2016 Surface Water Design Manual 4/24/20165 Presettling and Infiltration vault 9 FIGURE 1.2 – SITE LOCATION 11 FIGURE 1.3 - DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS 14 FIGURE 1.4 - SOILS Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/15/2022 Page 1 of 3523725052372705237290523731052373305237350523737052373905237410523725052372705237290523731052373305237350523737052373905237410551420551440551460551480551500551520551540551560551580551600551620551640551660 551420 551440 551460 551480 551500 551520 551540 551560 551580 551600 551620 551640 551660 47° 17' 17'' N 122° 19' 12'' W47° 17' 17'' N122° 18' 59'' W47° 17' 11'' N 122° 19' 12'' W47° 17' 11'' N 122° 18' 59'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 50 100 200 300 Feet 0 15 30 60 90 Meters Map Scale: 1:1,200 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 17, Aug 23, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 6, 2020—Jul 20, 2020 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/15/2022 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI EwC Everett-Alderwood gravelly sandy loams, 6 to 15 percent slopes 1.8 40.6% Ur Urban land 2.7 59.4% Totals for Area of Interest 4.5 100.0% Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/15/2022 Page 3 of 3 18 SECTION 2 – CONDITIONS AND REQUIREMENTS SUMMARY Enclosed is a brief review/discussion of Core Requirements #1 through #9 in Section 1.2 of the 2016 King County Surface Water Design Manual (KCSWDM), and Special Requirements #1 through #5 in Section 1.3 of the KCSWDM. Core Requirements 1. Core Requirement #1 – Discharge at a Natural Location The majority of the developed project site is proposing water quantity control through an underground infiltration vault. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities. Runoff from this basin is proposing to discharge to the existing conveyance system within Pacific Highway South, which is the current/natural discharge location. 2. Core Requirement #2 – Off-Site Analysis Refer to Section 3 of this report for the upstream and downstream analyses. 3. Minimum Requirement #3 – Flow Control The project is required to meet the Level 2 (Conservation) Flow Control Standard per the KCSWDM. The majority of the developed project site is proposing water quantity control through an underground infiltration vault. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities. Runoff from this basin is proposing to discharge to the existing conveyance system within Pacific Highway South, and is proposing to meet the Conservation Flow Control criteria. Refer to Section 4 of this report for additional information. See Figure 4.C.1 for the City of Federal Way Flow Control Application Map. 4. Core Requirement #4 – Conveyance System The proposed conveyance system is designed to adequately convey the 25-year and 100- year peak flows per Section 1.2.4.1 of the KCSWDM. In addition, a backwater analysis was completed and headwater elevations calculated for the proposed system to confirm if the 100-year runoff event is contained within the system without exceeding catch basin rims. Per the results of the backwater calculations, the proposed conveyance system should be adequate. Refer to Section 5 of this report for additional information. 5. Core Requirement #5 – Erosion and Sediment Control 19 Refer to Section 8 of this report for an Erosion and Sedimentation Control Plan (ESC) and proposed ESC measures. 6. Core Requirement #6 – Maintenance and Operations Refer to Section 10 of this report for an Operations and Maintenance Manual for the proposed stormwater facilities. 7. Core Requirement #7 – Financial Guarantee and Liability Financial guarantees will be provided as necessary prior to permit issuance. Refer to Section 9 of this report for additional information. 8. Core Requirement #8 – Water Quality The project is required to meet Enhanced Basic Water Quality Treatment Standards per Section 6 of the KCSWDM. The majority of the project site is providing oil control and enhanced basic water quality treatment through the use of a coalescing plate oil/water separator, presettling vault, and Oldcastle BioPod Biofilter, which has a Washington State Department of Ecology (WSDOE) General Use Level Designation (GULD) for enhanced treatment. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities. This basin is proposing an Oldcastle Biopod Biofitler for water quality treatment. Refer to Section 4 of this report for additional information. See Figure 4.C.2 for the City of Federal Way Water Quality Application Map. 9. Core Requirement #9 – Flow Control BMPs Per Section 1.2.9 of the KCSWDM and the City of Federal Way Addendum to the KCSWDM (CFWA), the project shall demonstrate compliance with the Low Impact Development (LID) Performance Standard. The majority of the developed project site is proposing water quantity control through an underground infiltration vault. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities. Runoff from this basin is proposing to discharge to the existing conveyance system within Pacific Highway South, and is proposing to meet the LID Performance Standard. Additionally, the soil moisture holding capacity of new pervious surfaces shall be protected per King County Code 16.82.100 (G), and the disturbed project soils are proposed to be amended to meet these criteria. Refer to Section 4 of this report for additional information. Special Requirements 1. Special Requirement #1 – Other Adopted Area-Specific Requirements 20 The project site is located within the Hylebos Creek and Lower Puget Sound Basin Plan area. The requirements of the Basin Plan should not be more restrictive than the requirements of the KCSMDM and COFA. 2. Special Requirement #2 – Floodplain/Floodway Delineation The project is not located within a known floodplain and/or floodway per FEMA mapping. Refer to the FEMA FIRM included as Figure 3.2. 3. Special Requirement #3 – Flood Protection Facilities The project is not proposing any flood protection facilities. 4. Special Requirement #4 – Source Control The project is classified as a commercial development and is proposing structural and nonstructural source control measures. Refer to Section 10 of this report for additional information. 5. Special Requirement #5 – Oil Control The project is classified as a high-use site and is providing oil control using a coalescing plate oil/water separator. Refer to Section 4 of this report for additional information. 21 SECTION 3 – OFFSITE ANALYSIS Task 1. Study Area Definition and Maps Federal Way as-built/record drawings and GIS maps were obtained for the off-site areas and are referenced for the downstream drainage path. The site discharges to a catch basin within Pacific Highway South to the west, which conveys the drainage to the south where it discharges to a City regional storm facility located approximately one-quarter mile downstream. These facilities discharge to Hylebos Creek where drainage would flow generally to the south to a point one mile downstream. Refer to the Downstream Drainage Path map and associated documentation in this section for additional information. The Federal Way Crossings commercial development is located upstream of the project site and has separate stormwater facilities. Run-on from adjacent properties is assumed to be negligible. Task 2. Resource Review The project site is located within the Hylebos Creek and Lower Puget Sound Basin Plan area. The requirements of the Basin Plan should not be more restrictive than the requirements of the KCSMDM and COFA. The project is not located within a known floodplain and/or floodway per FEMA mapping. Refer to the FEMA FIRM included as Figure 3.2. There are no other known offsite analysis reports within the same subbasin. There are no known erosion hazard or landslide hazard areas located on the project site or within one mile downstream of the site per City of Federal Way critical area mapping. There are no known wetlands on the project site, but the Hylebos wetland and creek is located approximately one-half mile downstream of the site. Refer to Figure 3.3 for the City of Federal Way Critical Areas Map. Per King County GIS, there are no listed drainage complaints within one mile downstream of the project site. One drainage complaint is listed for a parcel south of the project site that is not within the downstream drainage path. The complaint was for a water quality audit inspection and was closed in June 2013. Refer to Figure 3.4 for further information. There are no known road drainage problems within one mile downstream of the project site. 22 NRCS’ web soil survey information was referenced for the soil mapping of the site. The site consists of Everett-Alderwood gravelly sandy loams for the northern portion of the site and Urban land for the southern portion of the site per the mapping. Per King County GIS, there are no channel migration hazard areas within one mile downstream of the project site. The Washington State Department of Ecology’s (ECY) published Clean Water Act Section 303d list of polluted waters has identified an unnamed water body in the area of the project site as a Category 5 water due to temperature and dissolved oxygen. The water body is listed as unmappable and it is unclear from the available information if the project site drains to this water body. Additionally, Hylebos Creek greater than a mile downstream of the project is identified as a Category 5 water due to temperature, dissolved oxygen, and bacteria. No additional requirements from these assessments have been identified at this time. Refer to Figure 3.5 for reports of the assessed water quality areas. There are no known designated water quality problems, and no additional requirements from adopted stormwater compliance plans downstream of the project site have been identified at this time. Task 3. Field Inspection A Level 1 field inspection was performed on February 11, 2022. The weather was overcast and approximately 45 degrees. The drainage path to a point more than one- quarter mile downstream was observed. Refer to the Downstream Drainage Path Map and associated Drainage System Table in this section for additional information. From the field inspection, it was determined that run-on from adjacent properties can be considered negligible. The Federal Way Crossings commercial development is located upstream of the project site on the north and east sides and has separate stormwater facilities that will collect runoff. Pacific Highway South to the west and South 351st Street to the south is located downgrade of the project site. Task 4. Drainage System Description and Problem Descriptions The majority of the project site is proposing infiltration for water quantity control. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities and will discharge to the existing conveyance system within Pacific Highway South, which is the current discharge location for the existing site. The field inspection was aided by King County GIS information and City of Federal Way record drawings. Runoff from the site discharges to a catch basin within the 23 easternmost Pacific Highway South/State Route 99 (SR99) northbound travel lane. Runoff would then continue generally south within 36-inch pipes for approximately 253 feet. Runoff would then continue generally south within 48-inch pipes for approximately 354 feet to a catch basin within the eastern sidewalk of SR99. Runoff would then continue generally east within a 48-inch pipe for approximately 173 feet to a flow splitter for a City regional stormwater facility. Runoff would then continue generally south within 48-inch and 60-inch pipes for approximately 39 feet where it enters the City regional stormwater facility. Runoff would continue generally south within the City facility for approximately 650 feet to a point more than one-quarter mile downstream. Refer to the Downstream Drainage Path Map and associated Drainage System Table in this section for additional information. Task 5. Mitigation of Existing or Potential Problems No existing or potential problems within a mile downstream have been identified at this time. 24 FIGURE 3.1 – DOWNSTREAM ANALYSIS Hylebos Creek -- 45 degrees, overcast 9:30 AM 2/11/2022BasinSubbasin Name Subbasin Number Weather ConditionsDateDrainage Component Type, Name, and SizeDrainage Component Description Slope Existing Problems Potential Problems Observations of field inspector, resource reviewer, or residentType: sheet flow, swale, stream, channel, pipe, pond; Size: diameter, surface areaDrainage basin, vegetation, cover, depth, type of sensitive area, volume+/-, %Tributary area, likelihood of problem, overflow pathways, potential impactsCatchbasinExisting 10' +/- deep cb(1)(2)None observed Sedimentation Impacts not expected1 - 2 36-inch pipe0.70(1)0 - 29 None observed Under capacity Impacts not expectedCatchbasinExisting 10' +/- deep cb(1)(2)None observed Sedimentation Impacts not expected2 - 3 36-inch pipe0.64(1)29 - 203 None observed Under capacity Impacts not expectedStorm ManholeExisting 7' +/- deep sdmh(1)(2)None observed Sedimentation Impacts not expected3 - 4 36-inch pipe0.60(1)203 - 253 None observed Under capacity Impacts not expectedCatchbasinExisting 11' +/- deep cb(1)(2)None observed Sedimentation Impacts not expected4 - 5 48-inch pipe1.66(1)253 - 494 None observed Under capacity Impacts not expectedCatchbasin Existing 11' +/- deep cbNone observed Sedimentation Impacts not expected5 - 6 48-inch pipe1.15(1)494 - 607 None observed Under capacity Impacts not expectedCatchbasin Existing 12' +/- deep cbNone observed Sedimentation Impacts not expected6 - 7 48-inch pipe0.81(1)607 - 780 None observed Under capacity Impacts not expected7 Diversion ManholeExisting 10' +/- deep cb - Flow splitter prior to regional storm facility(1)(3)None observed Sedimentation Impacts not expected7 - 8 60-inch pipe4.62(1)780 - 793 None observed Under capacity Impacts not expected8 CatchbasinExisting 17' +/- deep cb(1)(3)None observed Sedimentation Impacts not expected8 - 9 48-inch pipe0.92(1)793 - 819 None observed Under capacity Impacts not expectedPond InletInlet to existing City of Federal Way regional storm facility(1)(3)None observed Erosion/scouring Impacts not expected9 - 10 Regional pondExisting City of Federal Way regional storm facilityN/A 819 - 1469 None observed Under capacity Impacts not expectedPond outlet structureControl structure for existing City of Federal Way regional storm facility(1)(3)None observed Sedimentation Impacts not expected10 - 11 48-inch pipe0.20(1)1469 - 1520 None observed Under capacity Impacts not expectedCatchbasinExisting 5' +/- deep cb with debris cage top(1)(3)None observed Sedimentation Impacts not expected11 - 12 48-inch pipe0.37(1)1520 - 1574 None observed Under capacity Impacts not expectedCatchbasinExisting 7.5' +/- deep cb(1)(3)None observed Sedimentation Impacts not expected12 - 13 48-inch pipe0.37(1)1574 - 1672 None observed Under capacity Impacts not expectedCatchbasin Existing 7.5' +/- deep cbNone observed Sedimentation Impacts not expected13 - 14 48-inch pipe0.46(1)1672 - 1803 None observed Under capacity Impacts not expectedCatchbasin Existing 7.5' +/- deep cbNone observed Sedimentation Impacts not expected14 - 15 48-inch pipe0.37(1)1803 - 1825 None observed Under capacity Impacts not expectedPipe end Outlet to unnamed stream w/ rip rapNone observed Erosion/scouring Impacts not expectedNotes:(1) Slope/inverts per City of Federal Way Record Drawings(2) Unable to access/open structure, located within SR99 travel lane(3) Unable to access/open structure, located within fenced/locked City facility111520121574OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLEKING COUNTY SURFACE WATER DESIGN MANUAL, CORE REQUIREMENT #2Constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosionPlant 2 Relocation (Job #35072) - Downstream Analysis229SymbolDistance from Site Discharge (+/-, ft)See Map1/4 mi = 1,320 ft1010146932034253549466079819780793131672141803151825 27 FIGURE 3.2 – FEMA FIRM PROJECT SITE 29 FIGURE 3.3 – CRITICAL AREAS MAP Critical Areas!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! SW 312th St SW 320th St Interstate 5Port of Tacoma RdMa ri n e Vi e w Dr MarineViewDr Northshore Pkw y Military R d S 28th Av SE n c h a n t e d P k wy Military Rd SPe a s l eyCanyonRdRedondoWySRedondoBeachDrSPacific Hwy SMarineViewDrInterstate 5StarLake R d 1stWySS 324th St E 11th StInterstate5SW Dash Point RdS W D ashP ointR dNE 49th St10thAvSWSW Campus Dr SWCampus Dr S 336th St Pacific Hwy SSW 330th St SW 356th St NorpointWyNES 356th St Pacific Hwy SS356thSt Hwy 18WeyerhaeuserWySSDashPointRd1st Av SS 304th St Mi l i t ar yRdS S 288th St Military Rd SS 288th St S 272nd St Pacific Hwy SS 312th St I nt er st at e5Military Rd SS 272nd St Pacific Hwy S16th Av SMarineView Dr E n c h a n t e d P k wy MilitaryRd1st Av S9thAvS21st Av SW23rd Av S51st Av S16thAvSHwy 18S 348th St S 308th St PacificHwySMilitaryRdSSW 340th StHoy t R dS W SW 336th St 21st Av SWH oytR d S WSW 320th St SW 308th St SW Dash Point RdSWD ash P oi nt R d 35th Av SW47th Av SW12th Av SW21st Av SW11th Av SW8th Av SWS 3 2 8 thSt5th Av SS 336th St 7th Av6thAv8thAv6th Av SWSW 344th St 28th Av S20th Av SS 373rd St 34th Av SS 298th St 37th Av SS 304th St 31stAvSS 320th St20th Av SS 312th St Pacific Hwy SS 320th St 11th Pl S1st Av S8th Av SPavillionsCenter CelebrationCenter SeaTacVillage Pal-doWorldPlaza The Commons atFederal Way GatewayCenter Twin LakesVillage CampusSquare Federal WayMarketplace Federal WayCrossings LakehavenTreatmentCenter(Redondo) LakehavenTreatmentCenter (Lakota)LakeGroveElem. LakeDolloffElem. LakelandElem ValhallaElem. SilverLakeElem. WildwoodElem. BrigadoonElem. Twin LakesElem. AdelaideElem. SherwoodForestElem. PantherLakeElem. CamelotElem. NautilusElem. Mark TwainElem. Rainier ViewElem. OlympicViewElem.GreenGablesElem. EnterpriseElem. MirrorLakeElem. Star LakeElem. WoodmontElem. IllaheeMiddle School LakotaMiddleSchool SacajaweaMiddle School KiloMiddleSchool SaghalieMiddleSchool SequoyahMiddleSchool PublicAcademy DecaturHigh School Federal WayHigh School ThomasJeffersonHigh School Todd BeamerHigh School TrumanH.S. TotemMiddle School Golf Golf Twin Course Course Lakes NorthshoreGolf Course Star LakePark &Ride Federal Way/S 320th StreetPark & Ride Twin LakesPark &Ride South FederalWay Park &Ride RedondoHeightsPark & Ride TransitCenter Federal WayCommunityCenter SteelLakeAnnex CityHall Dumas BayCentre KnutzenTheatre ParkLakota SacajaweaPark FrenchParkLakePark AdelaidePark CamelotPark Dash PointState Park SaghaliePark LakeGenevaPark GlenNelsonPark WestHylebosWetlandsPark FiveMileLakePark BingamanPond Park B.P.A. TrailB.P.A. TrailWestCampusTrailB.P.A.TrailSteel LakePark CelebrationPark Dumas Bay Sanctuary Park LaurelwoodPark TownSquarePark Brooklake CommunityCenter South CountyBallfields Alderbrook Park Dash PointHighlands Park Spring ValleyOpen Space Fisher'sPond Panther LakeOpen SpacePark PovertyBayOpenSpace Pacific RimBonsai Collection Rhododendron SpeciesBotanical Garden EnchantedPark Pierce County King County Pierce County King County Pierce County King CountyPierce County King County FireStation 73(Kent) FireStation65 FireStation 61 FireStation 64 FireStation 63 TrainingCenter FireStation62 FireStation66 Federal WayRegional Library 320thStreetLibrary Fife Milton Tacoma DesMoines Edgewood Pacific Kent FederalWay FederalWay Hylebos Creek WaterwayBlair Waterway P uyallu p R i v erPuget Sound BayDumas PovertyBay Sitcu m W aterw ay CommencementBay LakeSteel Star Lake MirrorLake GenevaLake North Lake EasterLake Dolloff LakeLakeFenwi ckTroutLake FiveMileLakeLakeKillarneyLake Lorene JeaneLake !"#$5 !"#$5 509 18 509 509 161 509 509 161 99 99 !"#$5 99 !"#$5 WhiteRiver Mill Creek HylebosCreek LowerPugetSound Lower GreenRiver HylebosCreek LowerPugetSound 5 City of Federal Way Critical Areas Map Map Date: May 2016City of Federal Way,GIS Division33325 8th Ave SFederal Way, WA 98003(253) 835-7000www.cityoffederalway.com ´ This map is accompanied by NO warranties, and is simply a graphic representation.J:\standard\reference\sensitive.mxd KingCounty Vicinity MapHylebos Creek Lower Green River Lower Puget Sound Mill Creek White River Erosion Hazard Area Landslide Hazard Areas Wetlands (1998 City Survey) Lakes Streams Drainage Basins:Critical Areas:Water Features: Legend: Boundaries are approximate. Remember, ADDITIONAL SENSITIVE AREAS MAY EXIST. See Map Notes below for more information.Please Note:Map Notes: Wetlands and streams were identified in a1998 City of Federal Way survey. Data for the Landslide hazard and erosion hazard areas is provided by King County. Drainage basin boundaries within city limits havebeen verified by the City of Federal Way. Basin boundaries outside of city limits are provided by King County and have not been verified by the City of Federal Way. Critical area information is provided forillustrative purposes ONLY. Actual boundaries are subject of field verification. ADDITIONAL CRITICAL AREAS MAY EXIST. Critical areas in Pierce County are not shown. The City of Federal Wayshall not be liable for any damages due to the use or misuse of the information represented on this map. Wetlands are onlyshown in Federal Way and its Potential Annexation Area.Contact the City for an explanation of these areas and theregulations that govern them.Source: City of Federal Way, King County 0 0.5 10.25 Miles Scale: 50 Acres 5 20 47°15'5.46831"N122°25'3.78156"W47°21'46.42899"N 122°25'3.78156"W47°21'46.42899"N 122°16'19.25508"W47°15'5.46831"N 122°16'19.25508"WA B C D E F A B C D E F 1 2 3 4 5 6 7 1 2 3 4 5 6 7 PROJECT SITE 31 FIGURE 3.4 – DRAINAGE COMPLAINTS K in g Date : 3/18/20 22 Notes: ±The informati on included on this map has been c ompil ed by King County s taff from a variety of sources and issubject to change without notice. King County makes no repr esentations or warr anties, ex press or implied,as to accurac y, completeness, timel iness, or rights to the us e of such information. T hi s doc ument i s not intendedfor use as a s urvey product. Ki ng County shall not be l iable for any general , special, indirect, incidental, orconsequential damages i ncl uding, but not li mited to, lost revenues or los t profits resulting from the us e or mi sus eof the information contained on this map. Any sale of thi s map or informati on on this map is prohi bited exc ept bywritten permi ss i on of Ki ng County. King C ou nty iMap PROJECT SITE Figure 3.4: Downstream Drainage Complaints PLANT 2 RELOCATION Apex Job #35072 #Parcel Address Type Problem Date Closed Comments 2013-0132 2021049059 1393 S 351st St WQAL WQAI 6/11/2013 N/A 34 FIGURE 3.5 – ASSESSED WATER QUALITY AREAS Fed Way Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS,FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, EsriJapan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and March 17, 2022 0 0.5 10.25Miles K Assessed Water/SedimentWater Category 5 - 303d Category 4C Category 4B Category 4A Category 2 Category 1 Sediment Category 5 - 303d Category 4C Category 4B Category 4A Category 2 Category 1 PROJECT SITE 41 SECTION 4 – FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID) AND WATER QUALITY FACILITY ANALYSIS AND DESIGN Part A – EXISTING SITE HYDROLOGY The existing project site has three buildings and is covered predominantly with gravel and asphalt paving with limited vegetation. Slopes onsite are generally one to two percent. The existing site entrances near the southwest corner and southeast corner slope up to the site at approximately 7 percent. The project site consists of a single Threshold Discharge Area. Generally, runoff from the western half of the site flows to the west to the existing storm conveyance system located within Pacific Hwy. S., and runoff from the eastern half of the site flows to the south to the existing storm conveyance system located within S. 351st Street which is then conveyed to the west to Pacific Hwy. S. Runoff from adjacent properties does not appear to drain onto the project site and run-on drainage is considered insignificant. Refer to Figure 4.A.1 in this section for a Pre-Developed Basin Map. The Western Washington Hydrology Model (WWHM) program was used to model pre- developed conditions. Historic site conditions (forested) were assumed for the pre-developed scenarios. Table 4.A.1– Summary of Pre-developed Site Land Cover Basin Total Area (acres) Impervious Area (acres) Pervious Area - Till, Forest Area (acres) Pervious Area - Till, Lawn Area (acres) ONSITE 4.19 0 4.19 0 42 FIGURE 4.A.1 – PRE-DEVELOPED BASIN MAP 44 Part B – DEVELOPED SITE HYDROLOGY A concrete batch plant is proposed on the project site. The majority of the site is proposing to be paved for plant operation and parking areas and will also include a shop/storage building, covered storage bins, concrete plant silos and equipment, and perimeter landscape buffer. Full roadway improvements to S. 351st Street are proposed. The roadway is currently private but is proposing to be built to public standards (Cross Section Type R) including 40 feet of pavement with curb and gutter, 4 foot planter strip, and 6 foot sidewalk both sides. The majority of the project site is providing oil control and enhanced basic water quality treatment through the use of a coalescing plate oil/water separator, presettling vault, and Oldcastle BioPod Biofilter, which has a Washington State Department of Ecology (WSDOE) General Use Level Designation (GULD) for enhanced treatment. Water quantity control is proposed with an underground infiltration vault. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities. This basin is proposing an Oldcastle Biopod Biofilter for water quality treatment and will discharge to the existing conveyance system within Pacific Highway South. This discharge is proposing to meet the Conservation Flow Control criteria. Refer to Section 4, Part D and Part E of this report for additional details regarding the proposed storm systems. The Western Washington Hydrology Model (WWHM) program was used to model developed conditions. Refer to Figure 4.B.1 in this section for a Developed Basin Map. Table 4.B.1– Summary of Developed Site Land Cover Basin Total Area (acres) Impervious Area (acres) Pervious Area - Till, Forest Area (acres) Pervious Area - Till, Lawn Area (acres) ONSITE 3.80 3.42 0 0.38 BYPASS 0.39 0.32 0 0.07 OFFSITE* 0.25 0.22 0 0.03 *Offsite area from Pacific Highway South that will contribute to the Biopod water quality system located within South 351st Street. 45 FIGURE 4.B.1 – DEVELOPED BASIN MAP 47 Part C – PERFORMANCE STANDARDS Drainage facilities were designed to conform to the KCSWDM and CFWA. The majority of the project site is directing runoff to an underground infiltration vault for water quantity control. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities and will discharge to the existing conveyance system within Pacific Highway South. The discharge is proposing to meet the Level 2 Conservation Flow Control Standard, matching developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow, and match pre-developed 2- and 10-year peak flows. Historic (forested) site conditions were assumed for the pre-developed condition. Refer to Section 4, Part D for further details. Additionally, the discharge is proposing to meet the Low Impact Development (LID) Performance Standard, matching developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 8% of the 2-year peak flow to 50% of the 2- year peak flow. Refer to Section 4, Part D of this report for further details. The proposed water quality facilities are designed to meet the Enhanced Basic Water Quality Treatment Standard. The project is proposing Oldcastle BioPod Biofilters, which have a Washington State Department of Ecology (WSDOE) General Use Level Designation (GULD) for enhanced treatment. Refer to Section 4, Part E of this report for further details. The project site is considered high use and is providing oil control through the use of a coalescing plate oil/water separator. Refer to Section 4, Part E of this report for further details. The capacity standard for the proposed conveyance system is the 25-year event per Section 1.2.4.1 of the KCSWDM. Refer to Section 5 of this report for further information. 48 FIGURE 4.C.1 - FEDERAL WAY FLOW CONTROL APPLICATION MAP Fife Milton Tacoma DesMoines Edgewood Pacific AuburnFederalWay Kent Hyl e b o s C r e e k W a t e r w a y Bla i r W a t e r w a y P uyallu p R i v erPuget Sound BayDumas PovertyBay Sit c u m W a t e r w a y CommencementBay LakeSteel Star Lake MirrorLake GenevaLake North Lake Lorene Lake JeaneLake EasterLake Dolloff LakeTroutLake FiveMileLakeLake KillarneyHOYT RD SW MILITARY RD SWEST VALLEY HWYS 288th ST DASH POINT R D DASH PT RDMILITARY RD S21st AVE SWPACIFIC HWYMARINE VIEW DRSW 336th ST NORTHSHORE PK W Y INTERSTATE 5E 11th STHWY 18H W Y 18PACIFIC HWY S28TH AVE SENC HAN T ED P KW Y 51st AVE SINTERSTATE 51st AVE SPACIFIC HWY SS 320th ST 21st AVE SWS 336th ST1st AVE SS 312th ST SW 320th ST SW 356th ST S 348th ST SR 99S 272nd ST 33rd ST NE Lower PugetSound Basin HylebosCreekBasin MillCreekBasin LowerGreenRiverBasin 0 0.5 10.25 Mile This map is intended for use as a graphical representation only. The City of Federal Way makes no warranty as to its accuracy. Legend Drainage Basin Boundary Streams City Limits Lakes and Wetlands Scale: City of Federal Way Flow ControlApplications Map Map Date: February, 2010SWM DivisionCity of Federal Way33325 8th Ave SPO Box 9718Federal Way, WA 98063(253) 835-2700www.cityoffederalway.com R:\erike\swm\FlowControl\flowcontrol.mxd Flow Control Basic Flow Control Areas Conservation Flow Control Areas Flood Problem Flow Control Areas Major Receiving Waters1. Puget Sound PROJECT SITE 50 FIGURE 4.C.2 - FEDERAL WAY WATER QUALITY APPLICATION MAP !!7Ái Hyl e b o s C r e e k W a t e r w a y Bla i r W a t e r w a y P uyallu p R i v erPuget Sound BayDumas PovertyBay Sit c u m W a t e r w a y CommencementBay HOYT RD SW MILITARY RD SWEST VALLEY HWYMILTON WAY S 288th ST DASH POINT R D DASH PT RDMILITARY RD S21st AVE SWPACIFIC HWYMARINE VIEW DRSW 336th ST NORTHSHORE PK W Y INTERSTATE 5E 11th STHWY 18H W Y 18PACIFIC HWY S28TH AVE SENC HAN T ED P KW Y 51st AVE SINTERSTATE 51st AVE SPACIFIC HWY SS 320th ST 21st AVE SWS 336th ST1st AVE SS 312th ST SW 320th ST SW 356th ST S 348th ST SR 99S 272nd ST 33rd ST NE Fife Milton Tacoma DesMoines Edgewood Pacific Auburn Algona FederalWay Kent Lower PugetSound Basin HylebosCreekBasin LowerGreenRiverBasin 126286.04851 ft MillCreekBasin City ofFederal Way Water QualityApplicationsMap This map is intended for use as a graphical representation only. The City of Federal Way makes no warranty as to its accuracy. Map Date: November 2013SWM DivisionCity of Federal Way33325 8th Ave S.Federal Way, WA. 98003(253) 835 - 2700www.cityoffederalway.com \\users\erike\swm\watqual.mxd * High density single family, multi-family, commercial, and industrial uses, as well as most roads, are subject to Enhanced Basic Water Quality Treatment Requirements. Legend Drainage Basin Boundary Streams City Limits 0 0.5 10.25 Mile´ Enhanced Basic Water QualityTreatment Menu Required* Sensitive Lake !!7Ái Identified Sphagnum Bog Wetlands Water Quality Treatment Area Types Scale: PROJECT SITE 52 Part D – FLOW CONTROL SYSTEM The majority of the project site is directing runoff to an underground infiltration vault for water quantity control. South Sound Geotechnical Consulting (SSGC) completed a geotechnical engineering report and infiltration assessment, dated June 18, 2021. The soils were described as consisting of an upper layer of fill with underlying native soils of silty sand with gravel and occasional cobbles. Groundwater was not observed at the time of excavation. One small-scale Pilot Infiltration Test (PIT) was completed in the area of the proposed infiltration vault. Based on the field results, SSGC recommended a design infiltration rate of 2 inches per hour for infiltration facilities. The report should be referenced for additional information regarding the site soils. The infiltration system was analyzed using the WWHM program. Per this analysis, a vault with 5 feet of head and a footprint of 54 feet by 148 feet should be adequate to infiltrate 100 percent of the contributory runoff. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities and will discharge to the existing conveyance system within Pacific Highway South. The discharge is proposing to meet the Level 2 Conservation Flow Control Standard, matching developed discharge durations to pre-developed durations for the range of pre- developed discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow, and match pre-developed 2- and 10-year peak flows. Additionally, the discharge is proposing to meet the Low Impact Development (LID) Performance Standard, matching developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 8% of the 2-year peak flow to 50% of the 2-year peak flow. Historic (forested) site conditions were assumed for the pre-developed condition. The WWHM program was used for the Conservation Flow Control and LID Performance Standard analyses. Refer to the calculations included in this section for additional information. 53 FIGURE 4.D.1 – WATER QUANTITY BASIN ANALYSIS Plant 2 Relocation Basin Analysis Basin Total Area (sf) Total Project Area (ac) Total Impervious Area (sf) Total Impervious Area (ac) Pervious Area - Grass (sf) Pervious Area - Grass (ac) ONSITE 166,271 3.82 149,653 3.44 16,618 0.38 BYPASS 16,451 0.38 13,372 0.31 3,079 0.07 OFFSITE 10,903 0.25 9,492 0.22 1,411 0.03 55 FIGURE 4.D.2 – FLOW CONTROL WWHM CALCULATIONS WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: 35072 Site Name: Plant 2 Site Address: City : Federal Way Report Date: 3/18/2022 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/10/10 Version : 4.2.16 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : ONSITE Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Flat 4.19 Pervious Total 4.19 Impervious Land Use acre Impervious Total 0 Basin Total 4.19 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : ONSITE Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .38 Pervious Total 0.38 Impervious Land Use acre DRIVEWAYS FLAT 3.44 Impervious Total 3.44 Basin Total 3.82 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater Infiltration Vault Infiltration Vault ___________________________________________________________________ Name : Infiltration Vault Width : 54 ft. Length : 148 ft. Depth: 6 ft. Infiltration On Infiltration rate: 4.5 Infiltration safety factor: 0.45 Total Volume Infiltrated (ac-ft.): 570.657 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 570.657 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 5 ft. Riser Diameter: 8 in. Element Flows To: Outlet 1 Outlet 2 ___________________________________________________________________ Vault Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.183 0.000 0.000 0.000 0.0667 0.183 0.012 0.000 0.374 0.1333 0.183 0.024 0.000 0.374 0.2000 0.183 0.036 0.000 0.374 0.2667 0.183 0.048 0.000 0.374 0.3333 0.183 0.061 0.000 0.374 0.4000 0.183 0.073 0.000 0.374 0.4667 0.183 0.085 0.000 0.374 0.5333 0.183 0.097 0.000 0.374 0.6000 0.183 0.110 0.000 0.374 0.6667 0.183 0.122 0.000 0.374 0.7333 0.183 0.134 0.000 0.374 0.8000 0.183 0.146 0.000 0.374 0.8667 0.183 0.159 0.000 0.374 0.9333 0.183 0.171 0.000 0.374 1.0000 0.183 0.183 0.000 0.374 1.0667 0.183 0.195 0.000 0.374 1.1333 0.183 0.207 0.000 0.374 1.2000 0.183 0.220 0.000 0.374 1.2667 0.183 0.232 0.000 0.374 1.3333 0.183 0.244 0.000 0.374 1.4000 0.183 0.256 0.000 0.374 1.4667 0.183 0.269 0.000 0.374 1.5333 0.183 0.281 0.000 0.374 1.6000 0.183 0.293 0.000 0.374 1.6667 0.183 0.305 0.000 0.374 1.7333 0.183 0.318 0.000 0.374 1.8000 0.183 0.330 0.000 0.374 1.8667 0.183 0.342 0.000 0.374 1.9333 0.183 0.354 0.000 0.374 2.0000 0.183 0.366 0.000 0.374 2.0667 0.183 0.379 0.000 0.374 2.1333 0.183 0.391 0.000 0.374 2.2000 0.183 0.403 0.000 0.374 2.2667 0.183 0.415 0.000 0.374 2.3333 0.183 0.428 0.000 0.374 2.4000 0.183 0.440 0.000 0.374 2.4667 0.183 0.452 0.000 0.374 2.5333 0.183 0.464 0.000 0.374 2.6000 0.183 0.477 0.000 0.374 2.6667 0.183 0.489 0.000 0.374 2.7333 0.183 0.501 0.000 0.374 2.8000 0.183 0.513 0.000 0.374 2.8667 0.183 0.526 0.000 0.374 2.9333 0.183 0.538 0.000 0.374 3.0000 0.183 0.550 0.000 0.374 3.0667 0.183 0.562 0.000 0.374 3.1333 0.183 0.574 0.000 0.374 3.2000 0.183 0.587 0.000 0.374 3.2667 0.183 0.599 0.000 0.374 3.3333 0.183 0.611 0.000 0.374 3.4000 0.183 0.623 0.000 0.374 3.4667 0.183 0.636 0.000 0.374 3.5333 0.183 0.648 0.000 0.374 3.6000 0.183 0.660 0.000 0.374 3.6667 0.183 0.672 0.000 0.374 3.7333 0.183 0.685 0.000 0.374 3.8000 0.183 0.697 0.000 0.374 3.8667 0.183 0.709 0.000 0.374 3.9333 0.183 0.721 0.000 0.374 4.0000 0.183 0.733 0.000 0.374 4.0667 0.183 0.746 0.000 0.374 4.1333 0.183 0.758 0.000 0.374 4.2000 0.183 0.770 0.000 0.374 4.2667 0.183 0.782 0.000 0.374 4.3333 0.183 0.795 0.000 0.374 4.4000 0.183 0.807 0.000 0.374 4.4667 0.183 0.819 0.000 0.374 4.5333 0.183 0.831 0.000 0.374 4.6000 0.183 0.844 0.000 0.374 4.6667 0.183 0.856 0.000 0.374 4.7333 0.183 0.868 0.000 0.374 4.8000 0.183 0.880 0.000 0.374 4.8667 0.183 0.892 0.000 0.374 4.9333 0.183 0.905 0.000 0.374 5.0000 0.183 0.917 0.000 0.374 5.0667 0.183 0.929 0.121 0.374 5.1333 0.183 0.941 0.329 0.374 5.2000 0.183 0.954 0.547 0.374 5.2667 0.183 0.966 0.711 0.374 5.3333 0.183 0.978 0.808 0.374 5.4000 0.183 0.990 0.885 0.374 5.4667 0.183 1.003 0.956 0.374 5.5333 0.183 1.015 1.022 0.374 5.6000 0.183 1.027 1.084 0.374 5.6667 0.183 1.039 1.143 0.374 5.7333 0.183 1.051 1.198 0.374 5.8000 0.183 1.064 1.252 0.374 5.8667 0.183 1.076 1.303 0.374 5.9333 0.183 1.088 1.352 0.374 6.0000 0.183 1.100 1.399 0.374 6.0667 0.183 1.113 1.445 0.374 6.1333 0.000 0.000 1.490 0.000 ___________________________________________________________________ Name : BYPASS Bypass: Yes GroundWater: No Pervious Land Use acre C, Lawn, Flat .07 Pervious Total 0.07 Impervious Land Use acre ROADS FLAT 0.31 Impervious Total 0.31 Basin Total 0.38 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:4.19 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.45 Total Impervious Area:3.75 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.12319 5 year 0.193474 10 year 0.233305 25 year 0.275503 50 year 0.301615 100 year 0.323825 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.122662 5 year 0.156531 10 year 0.179725 25 year 0.209997 50 year 0.233293 100 year 0.257257 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.121 0.163 1950 0.151 0.167 1951 0.271 0.102 1952 0.085 0.086 1953 0.069 0.093 1954 0.106 0.100 1955 0.169 0.112 1956 0.135 0.111 1957 0.109 0.128 1958 0.122 0.101 1959 0.105 0.100 1960 0.183 0.105 1961 0.103 0.109 1962 0.064 0.092 1963 0.088 0.105 1964 0.116 0.099 1965 0.083 0.133 1966 0.080 0.086 1967 0.168 0.150 1968 0.104 0.170 1969 0.102 0.121 1970 0.084 0.114 1971 0.090 0.137 1972 0.202 0.147 1973 0.092 0.082 1974 0.100 0.126 1975 0.135 0.138 1976 0.098 0.098 1977 0.012 0.101 1978 0.086 0.124 1979 0.052 0.170 1980 0.191 0.165 1981 0.077 0.128 1982 0.147 0.183 1983 0.132 0.144 1984 0.081 0.093 1985 0.048 0.128 1986 0.214 0.109 1987 0.189 0.167 1988 0.075 0.100 1989 0.049 0.125 1990 0.395 0.237 1991 0.238 0.185 1992 0.092 0.092 1993 0.096 0.078 1994 0.032 0.083 1995 0.137 0.113 1996 0.289 0.125 1997 0.241 0.120 1998 0.055 0.117 1999 0.226 0.249 2000 0.095 0.122 2001 0.017 0.130 2002 0.104 0.160 2003 0.133 0.125 2004 0.172 0.232 2005 0.124 0.106 2006 0.146 0.095 2007 0.293 0.218 2008 0.378 0.181 2009 0.186 0.153 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.3949 0.2486 2 0.3781 0.2369 3 0.2931 0.2316 4 0.2886 0.2175 5 0.2713 0.1847 6 0.2413 0.1829 7 0.2378 0.1814 8 0.2263 0.1702 9 0.2135 0.1696 10 0.2020 0.1670 11 0.1915 0.1670 12 0.1889 0.1650 13 0.1857 0.1632 14 0.1834 0.1603 15 0.1724 0.1530 16 0.1693 0.1495 17 0.1675 0.1468 18 0.1509 0.1443 19 0.1472 0.1381 20 0.1459 0.1366 21 0.1370 0.1329 22 0.1350 0.1297 23 0.1347 0.1283 24 0.1332 0.1276 25 0.1319 0.1275 26 0.1237 0.1260 27 0.1225 0.1250 28 0.1210 0.1250 29 0.1164 0.1246 30 0.1087 0.1236 31 0.1062 0.1219 32 0.1051 0.1209 33 0.1045 0.1200 34 0.1044 0.1170 35 0.1035 0.1145 36 0.1022 0.1127 37 0.0996 0.1122 38 0.0976 0.1107 39 0.0955 0.1088 40 0.0952 0.1087 41 0.0918 0.1061 42 0.0917 0.1053 43 0.0902 0.1050 44 0.0884 0.1018 45 0.0856 0.1006 46 0.0855 0.1006 47 0.0843 0.1002 48 0.0833 0.1000 49 0.0814 0.0999 50 0.0801 0.0994 51 0.0765 0.0975 52 0.0745 0.0947 53 0.0691 0.0927 54 0.0644 0.0927 55 0.0546 0.0920 56 0.0517 0.0918 57 0.0486 0.0863 58 0.0483 0.0858 59 0.0321 0.0834 60 0.0171 0.0821 61 0.0116 0.0782 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0616 17552 1694 9 Pass 0.0640 16164 1498 9 Pass 0.0664 14964 1283 8 Pass 0.0689 13851 1112 8 Pass 0.0713 12810 982 7 Pass 0.0737 11811 872 7 Pass 0.0761 10898 770 7 Pass 0.0786 10119 682 6 Pass 0.0810 9381 616 6 Pass 0.0834 8729 558 6 Pass 0.0858 8145 500 6 Pass 0.0883 7593 439 5 Pass 0.0907 7060 398 5 Pass 0.0931 6588 361 5 Pass 0.0955 6147 330 5 Pass 0.0980 5775 301 5 Pass 0.1004 5443 266 4 Pass 0.1028 5097 244 4 Pass 0.1052 4808 222 4 Pass 0.1077 4530 203 4 Pass 0.1101 4261 184 4 Pass 0.1125 4017 165 4 Pass 0.1149 3784 151 3 Pass 0.1174 3551 141 3 Pass 0.1198 3341 128 3 Pass 0.1222 3138 116 3 Pass 0.1246 2954 110 3 Pass 0.1271 2789 100 3 Pass 0.1295 2603 89 3 Pass 0.1319 2447 82 3 Pass 0.1343 2306 79 3 Pass 0.1368 2162 75 3 Pass 0.1392 2029 69 3 Pass 0.1416 1898 62 3 Pass 0.1440 1790 61 3 Pass 0.1465 1689 56 3 Pass 0.1489 1590 51 3 Pass 0.1513 1484 48 3 Pass 0.1537 1381 44 3 Pass 0.1561 1293 40 3 Pass 0.1586 1222 38 3 Pass 0.1610 1156 34 2 Pass 0.1634 1098 30 2 Pass 0.1658 1048 27 2 Pass 0.1683 997 23 2 Pass 0.1707 930 20 2 Pass 0.1731 883 16 1 Pass 0.1755 838 16 1 Pass 0.1780 789 15 1 Pass 0.1804 743 12 1 Pass 0.1828 713 11 1 Pass 0.1852 669 8 1 Pass 0.1877 633 8 1 Pass 0.1901 596 8 1 Pass 0.1925 565 8 1 Pass 0.1949 539 8 1 Pass 0.1974 497 8 1 Pass 0.1998 473 8 1 Pass 0.2022 434 8 1 Pass 0.2046 399 8 2 Pass 0.2071 368 7 1 Pass 0.2095 348 7 2 Pass 0.2119 323 6 1 Pass 0.2143 296 6 2 Pass 0.2168 272 6 2 Pass 0.2192 256 5 1 Pass 0.2216 235 4 1 Pass 0.2240 217 4 1 Pass 0.2265 197 4 2 Pass 0.2289 180 3 1 Pass 0.2313 158 3 1 Pass 0.2337 145 2 1 Pass 0.2362 129 2 1 Pass 0.2386 119 1 0 Pass 0.2410 109 1 0 Pass 0.2434 97 1 1 Pass 0.2459 91 1 1 Pass 0.2483 82 1 1 Pass 0.2507 76 0 0 Pass 0.2531 69 0 0 Pass 0.2556 61 0 0 Pass 0.2580 54 0 0 Pass 0.2604 48 0 0 Pass 0.2628 41 0 0 Pass 0.2652 38 0 0 Pass 0.2677 33 0 0 Pass 0.2701 27 0 0 Pass 0.2725 22 0 0 Pass 0.2749 21 0 0 Pass 0.2774 20 0 0 Pass 0.2798 19 0 0 Pass 0.2822 17 0 0 Pass 0.2846 14 0 0 Pass 0.2871 12 0 0 Pass 0.2895 9 0 0 Pass 0.2919 4 0 0 Pass 0.2943 3 0 0 Pass 0.2968 3 0 0 Pass 0.2992 3 0 0 Pass 0.3016 3 0 0 Pass _____________________________________________________ ___________________________________________________________________ LID Duration LID Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.121 0.163 1950 0.151 0.167 1951 0.271 0.102 1952 0.085 0.086 1953 0.069 0.093 1954 0.106 0.100 1955 0.169 0.112 1956 0.135 0.111 1957 0.109 0.128 1958 0.122 0.101 1959 0.105 0.100 1960 0.183 0.105 1961 0.103 0.109 1962 0.064 0.092 1963 0.088 0.105 1964 0.116 0.099 1965 0.083 0.133 1966 0.080 0.086 1967 0.168 0.150 1968 0.104 0.170 1969 0.102 0.121 1970 0.084 0.114 1971 0.090 0.137 1972 0.202 0.147 1973 0.092 0.082 1974 0.100 0.126 1975 0.135 0.138 1976 0.098 0.098 1977 0.012 0.101 1978 0.086 0.124 1979 0.052 0.170 1980 0.191 0.165 1981 0.077 0.128 1982 0.147 0.183 1983 0.132 0.144 1984 0.081 0.093 1985 0.048 0.128 1986 0.214 0.109 1987 0.189 0.167 1988 0.075 0.100 1989 0.049 0.125 1990 0.395 0.237 1991 0.238 0.185 1992 0.092 0.092 1993 0.096 0.078 1994 0.032 0.083 1995 0.137 0.113 1996 0.289 0.125 1997 0.241 0.120 1998 0.055 0.117 1999 0.226 0.249 2000 0.095 0.122 2001 0.017 0.130 2002 0.104 0.160 2003 0.133 0.125 2004 0.172 0.232 2005 0.124 0.106 2006 0.146 0.095 2007 0.293 0.218 2008 0.378 0.181 2009 0.186 0.153 ___________________________________________________________________ LID Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.3949 0.2486 2 0.3781 0.2369 3 0.2931 0.2316 4 0.2886 0.2175 5 0.2713 0.1847 6 0.2413 0.1829 7 0.2378 0.1814 8 0.2263 0.1702 9 0.2135 0.1696 10 0.2020 0.1670 11 0.1915 0.1670 12 0.1889 0.1650 13 0.1857 0.1632 14 0.1834 0.1603 15 0.1724 0.1530 16 0.1693 0.1495 17 0.1675 0.1468 18 0.1509 0.1443 19 0.1472 0.1381 20 0.1459 0.1366 21 0.1370 0.1329 22 0.1350 0.1297 23 0.1347 0.1283 24 0.1332 0.1276 25 0.1319 0.1275 26 0.1237 0.1260 27 0.1225 0.1250 28 0.1210 0.1250 29 0.1164 0.1246 30 0.1087 0.1236 31 0.1062 0.1219 32 0.1051 0.1209 33 0.1045 0.1200 34 0.1044 0.1170 35 0.1035 0.1145 36 0.1022 0.1127 37 0.0996 0.1122 38 0.0976 0.1107 39 0.0955 0.1088 40 0.0952 0.1087 41 0.0918 0.1061 42 0.0917 0.1053 43 0.0902 0.1050 44 0.0884 0.1018 45 0.0856 0.1006 46 0.0855 0.1006 47 0.0843 0.1002 48 0.0833 0.1000 49 0.0814 0.0999 50 0.0801 0.0994 51 0.0765 0.0975 52 0.0745 0.0947 53 0.0691 0.0927 54 0.0644 0.0927 55 0.0546 0.0920 56 0.0517 0.0918 57 0.0486 0.0863 58 0.0483 0.0858 59 0.0321 0.0834 60 0.0171 0.0821 61 0.0116 0.0782 ___________________________________________________________________ LID Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0099 229502 77085 33 Pass 0.0104 221160 73214 33 Pass 0.0109 212947 69471 32 Pass 0.0114 205311 66091 32 Pass 0.0119 198060 62862 31 Pass 0.0125 191088 59846 31 Pass 0.0130 184478 56916 30 Pass 0.0135 178318 54114 30 Pass 0.0140 172458 51633 29 Pass 0.0146 166918 49237 29 Pass 0.0151 161571 46927 29 Pass 0.0156 156502 44767 28 Pass 0.0161 151754 42735 28 Pass 0.0166 147198 40810 27 Pass 0.0172 142706 38863 27 Pass 0.0177 138471 37088 26 Pass 0.0182 134300 35420 26 Pass 0.0187 130365 33837 25 Pass 0.0193 126365 32340 25 Pass 0.0198 122643 30950 25 Pass 0.0203 119029 29602 24 Pass 0.0208 115435 28297 24 Pass 0.0214 112035 27100 24 Pass 0.0219 108741 25923 23 Pass 0.0224 105490 24832 23 Pass 0.0229 102324 23720 23 Pass 0.0234 99372 22715 22 Pass 0.0240 96506 21774 22 Pass 0.0245 93704 20837 22 Pass 0.0250 90988 19956 21 Pass 0.0255 88421 19143 21 Pass 0.0261 85983 18424 21 Pass 0.0266 83630 17682 21 Pass 0.0271 81256 16966 20 Pass 0.0276 79010 16260 20 Pass 0.0281 76850 15599 20 Pass 0.0287 74775 14974 20 Pass 0.0292 72701 14388 19 Pass 0.0297 70818 13832 19 Pass 0.0302 69000 13312 19 Pass 0.0308 67075 12833 19 Pass 0.0313 65321 12384 18 Pass 0.0318 63653 11907 18 Pass 0.0323 62028 11452 18 Pass 0.0329 60466 10981 18 Pass 0.0334 59012 10545 17 Pass 0.0339 57579 10145 17 Pass 0.0344 56124 9792 17 Pass 0.0349 54713 9430 17 Pass 0.0355 53365 9105 17 Pass 0.0360 52082 8787 16 Pass 0.0365 50820 8453 16 Pass 0.0370 49579 8147 16 Pass 0.0376 48360 7882 16 Pass 0.0381 47226 7578 16 Pass 0.0386 46093 7266 15 Pass 0.0391 44938 7024 15 Pass 0.0396 43911 6748 15 Pass 0.0402 42906 6502 15 Pass 0.0407 41901 6288 15 Pass 0.0412 40938 6074 14 Pass 0.0417 40018 5854 14 Pass 0.0423 39035 5668 14 Pass 0.0428 38158 5452 14 Pass 0.0433 37238 5274 14 Pass 0.0438 36404 5091 13 Pass 0.0443 35548 4909 13 Pass 0.0449 34735 4733 13 Pass 0.0454 33923 4575 13 Pass 0.0459 33153 4419 13 Pass 0.0464 32404 4269 13 Pass 0.0470 31677 4128 13 Pass 0.0475 30950 3959 12 Pass 0.0480 30244 3837 12 Pass 0.0485 29538 3717 12 Pass 0.0491 28875 3600 12 Pass 0.0496 28233 3499 12 Pass 0.0501 27592 3384 12 Pass 0.0506 26971 3277 12 Pass 0.0511 26372 3176 12 Pass 0.0517 25816 3091 11 Pass 0.0522 25260 3001 11 Pass 0.0527 24704 2902 11 Pass 0.0532 24191 2804 11 Pass 0.0538 23699 2714 11 Pass 0.0543 23228 2629 11 Pass 0.0548 22758 2550 11 Pass 0.0553 22309 2473 11 Pass 0.0558 21902 2411 11 Pass 0.0564 21453 2342 10 Pass 0.0569 21021 2267 10 Pass 0.0574 20621 2201 10 Pass 0.0579 20225 2139 10 Pass 0.0585 19795 2084 10 Pass 0.0590 19374 2009 10 Pass 0.0595 18991 1939 10 Pass 0.0600 18610 1875 10 Pass 0.0605 18240 1818 9 Pass 0.0611 17879 1760 9 Pass 0.0616 17552 1694 9 Pass ___________________________________________________________________ ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ 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. 2005-2022; All Rights Reserved. 68 Part E – WATER QUALITY SYSTEM The proposed water quality facilities are designed to meet the Enhanced Basic Water Quality Treatment Standard. The project is proposing Oldcastle BioPod Biofilters, which have a Washington State Department of Ecology (WSDOE) General Use Level Designation (GULD) for enhanced treatment. The Biopod systems have an internal bypass for higher flows and have been sized based on the offline peak 15-minute water quality design flow rate as calculated by the WWHM software. The onsite area and eastern portion of the South 351st Street improvements basin has a water quality flow rate of 0.3135 cubic feet per second (cfs) per WWHM. A Biopod Biofilter Model BPU-816IB has a treatment flow capacity of 0.384 cfs, therefore it should be adequate. The western portion of the South 351st Street improvements basin has a water quality flow rate of 0.0480 cfs per WWHM. A Biopod Biofilter Model BPU-46IB has a treatment flow capacity of 0.057 cfs, therefore it should be adequate. Refer to the calculations included in this section for additional information. The project site is considered high use and is providing oil control through the use of a coalescing plate oil/water separator (CPS). Per the KCSWDM, oil/water separators should be offline facilities therefore a flow splitter is proposed upstream of the CPS. The KCSWDM requires sizing based on a modified offline water quality design flow that is established through an adjustment factor, k. The modified flow rate is 1.154 cfs, which requires an effective plate media surface area of 1,874 square feet. An Oldcastle oil/water separator Model 816-2-CPS has a projected coalescing plate area of 2,368 square feet and should be adequate. Refer to the calculations included in this section for additional information. Although not required by Code, the project is proposing a pre-settling vault for additional water quality treatment. The vault is proposing a dead storage volume equal to 0.25 times the water quality volume of 0.4354 acre-feet per WWHM. A 15 foot by 63 foot by 5.1 foot deep vault provides 4,820 cubic feet of volume which should be adequate. Refer to the calculations included in this section for additional information. 69 FIGURE 4.E.1 - COALESCING PLATE OIL/WATER SEPARATOR SIZING Plant 2 Relocation Water Quality Analysis Coalescing Plate Oil/Water Separator Sizing Ah = Q/Vt = 60*Q/[0.00386*((Sw - So)/(µw))] Where: Sw = specific gravity of water = 1.0 So = specific gravity of oil =0.85 µw = absolute viscosity of water (poises) =0.015674 Q = modified off-line water quality design flow rate per Section 6.2.1 (cfs) = 1.154 Where: 2-year 24-hour precipitation (in) = 2.07 6-month 24-hour precipitation (72% of the 2-yr) (in) = 1.5 k (ratio per Table 6.2.1.A KCSWDM) = 3.68 Off-line facility target flow per WWHM (cfs) = 0.3135 Vt = rise rate of the oil droplet Ah = required effective (horizontal) surface area of plate media (sf) The equation is based on an oil droplet diameter of 60 microns. Ah = 1,874 Oil/Water Separator Flow Splitter Sizing dorifice = (36.88Q/h1/2)1/2 Where:Q = water quality flow rate (ft3/sec) =1.154 d = orifice diameter (inches) h = hydraulic head (ft)0.44 dorifice = 8.0 oldcastleprecast.com/wilsonville File Name: PO Box 323, Wilsonville, Oregon 97070-0323 Tel: (503) 682-2844 Fax: (503) 682-2657 Issue Date: 816-2-CPS 2018 020-816CPS2 816-2-CPS OIL / WATER SEPARATOR COALESCING - 560 GPM 816-2-CPS 11.0 TOP No. 816-T-CPS BASE ASSEMBLY No. 816-B-CPS OPTIONAL TOP - HEAVY TRAFFIC No. 816-T-CPS-HD A PLAN VIEW SECTION AA A Issue Date: File Name: PO Box 323, Wilsonville, Oregon 97070-0323 Tel: (503) 682-2844 Fax: (503) 682-2657 oldcastleprecast.com/wilsonville 816-2-CPS 2018 020-816CPS2 816-2-CPS OIL / WATER SEPARATOR COALESCING - 560 GPM 816-2-CPS 11.1 73 FIGURE 4.E.2 - WESTERN KING COUNTY 2-YEAR 24-HOUR ISOPLUVIAL SECTION 3.2 RUNOFF COMPUTATION AND ANALYSIS METHODS FIGURE 3.2.1.A 2-YEAR 24-HOUR ISOPLUVIALS 6/15/2016 2016 Surface Water Design Manual 3-16 PROJECT SITE 75 FIGURE 4.E.3 – KCSWDM TABLE 6.2.1.A 77 FIGURE 4.E.4 – ONSITE BIOPOD BIOFILTER DETAIL 16'-0" 17'-0" ELEVATION VIEWLEFT END VIEW PLAN VIEW 8'-0"9'-0" 2X Ø36" BOLTED & GASKETED ACCESS COVERS, FIELD POURED CONCRETE COLLAR REQUIRED, BY OTHERS. DIVIDER WALL RIM 4'-0" 6" VARIES 2'-0" 2X Ø24" BOLTED & GASKETED ACCESS COVERS, FIELD POURED CONCRETE COLLAR REQUIRED, BY OTHERS. ALTERNATE OUTLET LOCATION OUTLET 4" MIN TO 5' MAX COVER (SEE NOTE 1.B) OPTIONAL DRAIN DOWN DEVICE INLET Ø18" RCP MAX. OUTLET Ø18" RCP MAX. INLET 2'-8" BYPASS WEIR 3'-10" DIVIDER WALL 2'-2" [26"] DROP RECOMMENDED, 6" MIN. INLET WINDOW ALTERNATE INLET LOCATION SAUDFI1325-0510USAXXXXSAUDFI1325-0510USAXXXX5'-1-1/4" MIN 13'-10" MAX 3'-10" 4" 3'-10" ENERGY DISSIPATION STONEFIDSAUXXXXUSADFI11540010FIDSAUXXXXUSADFI11540010OUTLET INLET UNDERDRAIN PIPE 2" MULCH 6" DRAIN ROCK 1'-6" StormMix™ MEDIA Bioretention/ Biofiltration Ph: 800.579.8819 | www.oldcastleinfrastructure.com/stormwater THI S DOC UMENT IS THE P ROPERTY OF OLD CASTLE INFRASTRU CTUR E, IN C. IT I S CO N FI DEN T I A L, S UBM I T TED F O R R E F ER E N CE P U RPO SES O NLY AN D S H ALL N OT BE U S E D I N AN Y W AY I N J UR I OU S T O T H E I N T E REST S O F , O R WITHOUT THE WRITTEN PERMISSI ON OF OLDCASTLE INFRASTRUCTURE, INC. COPYRIGHT © 2021 OLDCASTLE INFRASTRUCTURE, INC. ALL RIGHTS RESERVED. SHEET NAME REVISION SHEET REV DATE - BioPod™ Biofilter System CUSTOMER PROJECT NAME - - - (STANDARD) 1 OF 1Specifier Drawing BPU-816IB Underground Vault with Internal Bypass NOTES: 1.DESIGN LOADINGS: A.AASHTO HS-20-44 (WITH IMPACT) B.DESIGN SOIL COVER: 5'-0" MAXIMUM C.ASSUMED WATER TABLE: BELOW BASE OF PRECAST (ENGINEER-OF-RECORD TO CONFIRM SITE WATER TABLE ELEVATION) D.LATERAL EARTH PRESSURE: 45 PCF (DRAINED) E.LATERAL LIVE LOAD SURCHARGE: 80 PSF (APPLIED TO 8'-0" BELOW GRADE) F.NO LATERAL SURCHARGE FROM ADJACENT BUILDINGS, WALLS, PIERS, OR FOUNDATIONS. 2.CONCRETE 28-DAY MINIMUM COMPRESSIVE STRENGTH: 5,000 PSI MINIMUM. 3.REINFORCING: REBAR, ASTM A615/A706, GRADE 60 4.CEMENT: ASTM C150 5.REQUIRED ALLOWABLE SOIL BEARING CAPACITY: 2,500 PSF 6.REFERENCE STANDARD: A.ASTM C890 B.ASTM C913 C.ACI 318-14 7.THIS STRUCTURE IS DESIGNED TO THE PARAMETERS NOTED HEREIN. ENGINEER-OF-RECORD SHALL VERIFY FY THAT NOTED PARAMETERS MEET OR EXCEED PROJECT REQUIREMENTS. IF DESIGN PARAMETERS ARE INCORRECT, REVIEWING ENGINEER/AUTHORITY SHALL NOTIFY OLDCASTLE INFRASTRUCTURE UPON REVIEW. 8.INLET AND OUTLET HOLES WILL BE FACTORY CORED/CAST PER PLANS AND CUSTOMER REQUIREMENTS. INLET AND OUTLET LOCATIONS CAN BE MIRRORED. 9.CONTRACTOR RESPONSIBLE TO VERIFY ALL SIZES, LOCATIONS, AND ELEVATIONS OF OPENINGS. 10.CONTRACTOR RESPONSIBLE TO ENSURE ADEQUATE BEARING SURFACE IS PROVIDED (I.E. COMPACTED AND LEVEL PER PROJECT SPECIFICATIONS). 11.SECTION HEIGHTS, SLAB/WALL THICKNESSES, AND KEYWAYS ARE SUBJECT TO CHANGE AS REQUIRED FOR SITE REQUIREMENTS AND/OR DUE TO PRODUCT AVAILABILITY AND PRODUCTION FACILITY CONSTRAINTS. 12.MAXIMUM PICK WEIGHTS": A.TOP: XX,XXX LBS B.BASE: XX,XXX LBS* (* COMBINED WEIGHT OF BASE INCLUDES BYPASS WEIR, DIVIDER WALL, ROCK & MEDIA) 13.INTERNALS SHALL CONSIST OF UNDERDRAIN PIPE, ROCK, STORMMIX™ MEDIA, MULCH, DIVIDER WALL, BYPASS WEIR AND OPTIONAL DRAIN DOWN. PERFORMANCE SPECIFICATIONS Treatment Flow Capacities:* NJDEP 80% Removal, 75 micron 0.432 cfs 0.384 cfs *Contact Oldcastle for alternative treatment flow capacities. WA Ecology GULD - Basic, Enhanced & Phosphorus Bypass Capacity 6.5 cfs SITE SPECIFIC DATA Structure ID Treatment Flow Rate (cfs) Peak Flow Rate (cfs) Rim Elevation Pipe Data Pipe Size Pipe Type Invert Elevation Inlet Outlet Notes: Pipe Location Top of Vault Elevation ID 0.3117 2.7412 252.28 250.50 SIDE SIDE 18" 18" ADS-N12 ADS-N12 243.46 242.96 79 FIGURE 4.E.5 – 351ST STREET BIOPOD BIOFILTER DETAIL 6'-0" 7'-0" ELEVATION VIEWLEFT END VIEW PLAN VIEW 4'-0"5'-0"SAUDFI1325-0510USAXXXXØ36" BOLTED & GASKETED ACCESS COVER, FIELD POURED CONCRETE COLLAR REQUIRED, BY OTHERS. DIVIDER WALL RIM 4'-0" 6" VARIES 1'-6" 2X Ø18" TRAFFIC RATED CAST IRON COVERS, FIELD POURED CONCRETE COLLAR REQUIRED, BY OTHERS. ALTERNATE OUTLET LOCATION OUTLET 4" MIN TO 5' MAX COVER (SEE NOTE 1.B) OPTIONAL DRAIN DOWN DEVICE INLET Ø12" RCP MAX. OUTLET Ø12" RCP MAX. INLET 2'-8" BYPASS WEIR 3'-10" DIVIDER WALL 2'-2" [26"] DROP RECOMMENDED, 6" MIN. INLET WINDOW ALTERNATE INLET LOCATION INLET OUTLET 1'-10"4"1'-10" 5'-1-1/4" MIN 13'-10" MAX ENERGY DISSIPATION STONE UNDERDRAIN PIPE 2" MULCH 1'-6" StormMix™ MEDIA 6" DRAIN ROCK Bioretention/ Biofiltration Ph: 800.579.8819 | www.oldcastleinfrastructure.com/stormwater THI S DOCU MENT IS THE PR OPER TY OF O LDC ASTLE INFRASTRUC TURE, INC . I T IS C O NFID EN TI AL, SU BMI TTED F OR R E FER E NC E P UR POSES O NLY AN D S HALL NO T BE U S E D I N AN Y WAY I NJU R I O U S T O T HE I N T ER EST S O F , O R WITHOUT THE WRITTEN PERMI SSION OF OLDCASTLE INFRASTRUCTURE, IN C. COPYRIGHT © 2021 OLDCASTLE INFRASTRUCTURE, INC. ALL RIGHTS RESERVED. SHEET NAME REVISION SHEET REV DATE - BioPod™ Biofilter System CUSTOMER PROJECT NAME - - - (STANDARD) 1 OF 1Specifier Drawing BPU-46IB Underground Vault with Internal Bypass PERFORMANCE SPECIFICATIONS Treatment Flow Capacities:* NJDEP 80% Removal, 75 micron 0.064 cfs 0.057 cfs *Contact Oldcastle for alternative treatment flow capacities. WA Ecology GULD - Basic, Enhanced & Phosphorus Bypass Capactiy 5.0 cfs NOTES: 1.DESIGN LOADINGS: A.AASHTO HS-20-44 (WITH IMPACT) B.DESIGN SOIL COVER: 5'-0" MAXIMUM C.ASSUMED WATER TABLE: BELOW BASE OF PRECAST (ENGINEER-OF-RECORD TO CONFIRM SITE WATER TABLE ELEVATION) D.LATERAL EARTH PRESSURE: 45 PCF (DRAINED) E.LATERAL LIVE LOAD SURCHARGE: 80 PSF (APPLIED TO 8'-0" BELOW GRADE) F.NO LATERAL SURCHARGE FROM ADJACENT BUILDINGS, WALLS, PIERS, OR FOUNDATIONS. 2.CONCRETE 28-DAY MINIMUM COMPRESSIVE STRENGTH: 5,000 PSI MINIMUM. 3.REINFORCING: REBAR, ASTM A615/A706, GRADE 60 4.CEMENT: ASTM C150 5.REQUIRED ALLOWABLE SOIL BEARING CAPACITY: 2,500 PSF 6.REFERENCE STANDARD: A.ASTM C890 B.ASTM C913 C.ACI 318-14 7.THIS STRUCTURE IS DESIGNED TO THE PARAMETERS NOTED HEREIN. ENGINEER-OF-RECORD SHALL VERIFY FY THAT NOTED PARAMETERS MEET OR EXCEED PROJECT REQUIREMENTS. IF DESIGN PARAMETERS ARE INCORRECT, REVIEWING ENGINEER/AUTHORITY SHALL NOTIFY OLDCASTLE INFRASTRUCTURE UPON REVIEW. 8.INLET AND OUTLET HOLES WILL BE FACTORY CORED/CAST PER PLANS AND CUSTOMER REQUIREMENTS. INLET AND OUTLET LOCATIONS CAN BE MIRRORED. 9.CONTRACTOR RESPONSIBLE TO VERIFY ALL SIZES, LOCATIONS, AND ELEVATIONS OF OPENINGS. 10.CONTRACTOR RESPONSIBLE TO ENSURE ADEQUATE BEARING SURFACE IS PROVIDED (I.E. COMPACTED AND LEVEL PER PROJECT SPECIFICATIONS). 11.SECTION HEIGHTS, SLAB/WALL THICKNESSES, AND KEYWAYS ARE SUBJECT TO CHANGE AS REQUIRED FOR SITE REQUIREMENTS AND/OR DUE TO PRODUCT AVAILABILITY AND PRODUCTION FACILITY CONSTRAINTS. 12.MAXIMUM PICK WEIGHTS": A.TOP: XX,XXX LBS B.BASE: XX,XXX LBS* (* COMBINED WEIGHT OF BASE INCLUDES BYPASS WEIR, DIVIDER WALL, ROCK & MEDIA) 13.INTERNALS SHALL CONSIST OF UNDERDRAIN PIPE, ROCK, STORMMIX™ MEDIA, MULCH, DIVIDER WALL, BYPASS WEIR AND OPTIONAL DRAIN DOWN. SITE SPECIFIC DATA Structure ID Treatment Flow Rate (cfs) Peak Flow Rate (cfs) Rim Elevation Pipe Data Pipe Size Pipe Type Invert Elevation Inlet Outlet Notes: Pipe Location Top of Vault Elevation ID 0.0490 0.4426 242.46 241.46 SIDE SIDE 12" 12" ADS-N12 ADS-N12 237.50 237.00 81 FIGURE 4.E.6 – WATER QUALITY WWHM CALCULATIONS WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: 35072-WQ Site Name: Plant 2 Site Address: City : Federal Way Report Date: 3/18/2022 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/10/10 Version : 4.2.16 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ Low Flow Threshold for POC 2 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 2: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : ONSITE Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Flat 3.82 Pervious Total 3.82 Impervious Land Use acre Impervious Total 0 Basin Total 3.82 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : 351ST Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Flat .38 Pervious Total 0.38 Impervious Land Use acre Impervious Total 0 Basin Total 0.38 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : OFFSITE Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Flat .25 Pervious Total 0.25 Impervious Land Use acre Impervious Total 0 Basin Total 0.25 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : ONSITE Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .38 Pervious Total 0.38 Impervious Land Use acre DRIVEWAYS FLAT 3.44 Impervious Total 3.44 Basin Total 3.82 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : 351ST Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .07 Pervious Total 0.07 Impervious Land Use acre ROADS FLAT 0.31 Impervious Total 0.31 Basin Total 0.38 __________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : OFFSITE Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .03 Pervious Total 0.03 Impervious Land Use acre ROADS FLAT 0.22 Impervious Total 0.22 Basin Total 0.25 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:3.82 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.38 Total Impervious Area:3.44 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.112311 5 year 0.176389 10 year 0.212703 25 year 0.251175 50 year 0.274981 100 year 0.295229 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 1.335964 5 year 1.69574 10 year 1.941103 25 year 2.260316 50 year 2.505267 100 year 2.756676 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.110 1.754 1950 0.138 1.844 1951 0.247 1.094 1952 0.078 0.948 1953 0.063 1.024 1954 0.097 1.087 1955 0.154 1.227 1956 0.123 1.209 1957 0.099 1.386 1958 0.112 1.103 1959 0.096 1.111 1960 0.167 1.127 1961 0.094 1.180 1962 0.059 1.013 1963 0.081 1.142 1964 0.106 1.098 1965 0.076 1.432 1966 0.073 0.943 1967 0.153 1.630 1968 0.095 1.855 1969 0.093 1.303 1970 0.077 1.245 1971 0.082 1.486 1972 0.184 1.565 1973 0.084 0.911 1974 0.091 1.363 1975 0.123 1.532 1976 0.089 1.056 1977 0.011 1.116 1978 0.078 1.368 1979 0.047 1.875 1980 0.175 1.752 1981 0.070 1.392 1982 0.134 1.980 1983 0.120 1.587 1984 0.074 1.010 1985 0.044 1.391 1986 0.195 1.195 1987 0.172 1.841 1988 0.068 1.110 1989 0.044 1.388 1990 0.360 2.480 1991 0.217 1.956 1992 0.084 1.000 1993 0.087 0.859 1994 0.029 0.926 1995 0.125 1.232 1996 0.263 1.339 1997 0.220 1.293 1998 0.050 1.285 1999 0.206 2.680 2000 0.087 1.324 2001 0.016 1.432 2002 0.095 1.719 2003 0.121 1.336 2004 0.157 2.502 2005 0.113 1.145 2006 0.133 1.016 2007 0.267 2.344 2008 0.345 1.922 2009 0.169 1.696 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.3600 2.6800 2 0.3447 2.5018 3 0.2672 2.4801 4 0.2632 2.3442 5 0.2473 1.9801 6 0.2200 1.9563 7 0.2168 1.9217 8 0.2063 1.8746 9 0.1947 1.8547 10 0.1842 1.8444 11 0.1745 1.8409 12 0.1722 1.7538 13 0.1693 1.7515 14 0.1672 1.7188 15 0.1572 1.6963 16 0.1543 1.6302 17 0.1527 1.5867 18 0.1376 1.5652 19 0.1342 1.5318 20 0.1330 1.4858 21 0.1249 1.4318 22 0.1230 1.4317 23 0.1228 1.3925 24 0.1214 1.3911 25 0.1203 1.3875 26 0.1128 1.3862 27 0.1117 1.3676 28 0.1103 1.3632 29 0.1061 1.3391 30 0.0991 1.3356 31 0.0968 1.3241 32 0.0958 1.3031 33 0.0953 1.2928 34 0.0952 1.2854 35 0.0943 1.2454 36 0.0932 1.2324 37 0.0908 1.2267 38 0.0889 1.2086 39 0.0871 1.1954 40 0.0868 1.1797 41 0.0837 1.1448 42 0.0836 1.1420 43 0.0822 1.1271 44 0.0806 1.1160 45 0.0780 1.1113 46 0.0779 1.1095 47 0.0769 1.1027 48 0.0760 1.0984 49 0.0743 1.0944 50 0.0730 1.0870 51 0.0698 1.0556 52 0.0679 1.0241 53 0.0630 1.0164 54 0.0587 1.0129 55 0.0498 1.0101 56 0.0472 1.0005 57 0.0443 0.9481 58 0.0441 0.9432 59 0.0293 0.9259 60 0.0156 0.9112 61 0.0106 0.8593 ___________________________________________________________________ Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0.4355 acre-feet On-line facility target flow: 0.5543 cfs. Adjusted for 15 min: 0.5543 cfs. Off-line facility target flow: 0.3135 cfs. Adjusted for 15 min: 0.3135 cfs. ___________________________________________________________________ ___________________________________________________________________ Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #2 Total Pervious Area:0.63 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #2 Total Pervious Area:0.1 Total Impervious Area:0.53 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #2 Return Period Flow(cfs) 2 year 0.018523 5 year 0.02909 10 year 0.035079 25 year 0.041424 50 year 0.04535 100 year 0.04869 Flow Frequency Return Periods for Mitigated. POC #2 Return Period Flow(cfs) 2 year 0.208468 5 year 0.265565 10 year 0.304613 25 year 0.355525 50 year 0.394667 100 year 0.434902 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #2 Year Predeveloped Mitigated 1949 0.018 0.276 1950 0.023 0.285 1951 0.041 0.172 1952 0.013 0.147 1953 0.010 0.158 1954 0.016 0.170 1955 0.025 0.191 1956 0.020 0.188 1957 0.016 0.218 1958 0.018 0.171 1959 0.016 0.171 1960 0.028 0.178 1961 0.016 0.185 1962 0.010 0.157 1963 0.013 0.179 1964 0.017 0.170 1965 0.013 0.225 1966 0.012 0.147 1967 0.025 0.254 1968 0.016 0.289 1969 0.015 0.205 1970 0.013 0.194 1971 0.014 0.232 1972 0.030 0.248 1973 0.014 0.140 1974 0.015 0.214 1975 0.020 0.236 1976 0.015 0.165 1977 0.002 0.172 1978 0.013 0.211 1979 0.008 0.290 1980 0.029 0.278 1981 0.012 0.217 1982 0.022 0.310 1983 0.020 0.246 1984 0.012 0.158 1985 0.007 0.217 1986 0.032 0.185 1987 0.028 0.285 1988 0.011 0.171 1989 0.007 0.214 1990 0.059 0.398 1991 0.036 0.311 1992 0.014 0.156 1993 0.014 0.133 1994 0.005 0.143 1995 0.021 0.192 1996 0.043 0.211 1997 0.036 0.203 1998 0.008 0.199 1999 0.034 0.421 2000 0.014 0.207 2001 0.003 0.221 2002 0.016 0.271 2003 0.020 0.211 2004 0.026 0.393 2005 0.019 0.180 2006 0.022 0.160 2007 0.044 0.368 2008 0.057 0.306 2009 0.028 0.261 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #2 Rank Predeveloped Mitigated 1 0.0594 0.4212 2 0.0569 0.3977 3 0.0441 0.3925 4 0.0434 0.3684 5 0.0408 0.3111 6 0.0363 0.3102 7 0.0358 0.3056 8 0.0340 0.2896 9 0.0321 0.2893 10 0.0304 0.2851 11 0.0288 0.2850 12 0.0284 0.2782 13 0.0279 0.2762 14 0.0276 0.2711 15 0.0259 0.2615 16 0.0255 0.2542 17 0.0252 0.2478 18 0.0227 0.2460 19 0.0221 0.2360 20 0.0219 0.2320 21 0.0206 0.2251 22 0.0203 0.2214 23 0.0203 0.2175 24 0.0200 0.2169 25 0.0198 0.2169 26 0.0186 0.2138 27 0.0184 0.2137 28 0.0182 0.2113 29 0.0175 0.2111 30 0.0163 0.2106 31 0.0160 0.2070 32 0.0158 0.2048 33 0.0157 0.2032 34 0.0157 0.1994 35 0.0156 0.1945 36 0.0154 0.1917 37 0.0150 0.1909 38 0.0147 0.1882 39 0.0144 0.1853 40 0.0143 0.1847 41 0.0138 0.1798 42 0.0138 0.1788 43 0.0136 0.1777 44 0.0133 0.1722 45 0.0129 0.1720 46 0.0129 0.1714 47 0.0127 0.1712 48 0.0125 0.1709 49 0.0122 0.1697 50 0.0120 0.1696 51 0.0115 0.1654 52 0.0112 0.1602 53 0.0104 0.1583 54 0.0097 0.1576 55 0.0082 0.1569 56 0.0078 0.1561 57 0.0073 0.1468 58 0.0073 0.1465 59 0.0048 0.1427 60 0.0026 0.1404 61 0.0017 0.1333 ___________________________________________________________________ ___________________________________________________________________ Water Quality BMP Flow and Volume for POC #2 On-line facility volume: 0.0683 acre-feet On-line facility target flow: 0.0852 cfs. Adjusted for 15 min: 0.0852 cfs. Off-line facility target flow: 0.048 cfs. Adjusted for 15 min: 0.048 cfs. ___________________________________________________________________ ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ 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. 2005-2022; All Rights Reserved. 91 SECTION 5 – CONVEYANCE SYSTEM ANALYSIS AND DESIGN New pipe systems are required to adequately convey and contain (at minimum) the 25-year peak flows per Section 1.2.4.1 of the KCSWDM. The project’s proposed conveyance systems are designed to adequately convey and contain the 100-year peak flows without overtopping any catch basin rims. The storm conveyance systems and contributory areas were analyzed using the “StormShed 3G” software, Manning’s equation, and the SBUH Method. The analysis assumed a Manning’s roughness coefficient (n) of 0.014. Backwater and hydraulic grade line analyses are calculated for the systems to ensure that the 100-year storms are contained within the systems without exceeding any catch basin grates. For the on-site system, a tailwater equal to the design water surface elevation of the infiltration facility is assumed. For the western portion of the South 351st Street conveyance system, a tailwater equal to the crown of the proposed pipe at the connection point is assumed. The results show that the proposed drainage systems should be adequate, and the 100-year storms should be contained within the systems below the catch basin grates. It should also be noted that the pipe numbering scheme used in the analysis corresponds to the outlet pipe from the appropriate catch basin. For example, the pipe exiting CB05 is labeled P05. The other pipes in the analysis are labeled in the same fashion. Refer to the calculations included in this section for additional information. 92 FIGURE 5.1 – CONVEYANCE BASIN MAP 94 FIGURE 5.2 – CONVEYANCE BASIN ANALYSIS Plant 2 Relocation Conveyance Basin Analysis Basin ID Total Basin Area Total Basin Area Impervious Area Impervious Area Pervious Area - Lawn Pervious Area - Lawn (ft2)(ac)(ft2)(ac)(ft2)(ac) B05 32,162 0.74 32,162 0.74 0 0.00 B07 44,139 1.01 40,567 0.93 3,572 0.08 B08 11,531 0.26 7,939 0.18 3,592 0.08 B09 8,867 0.20 7,368 0.17 1,499 0.03 B11 33,772 0.78 33,772 0.78 0 0.00 B12 2,087 0.05 2,087 0.05 0 0.00 B13 7,205 0.17 6,589 0.15 616 0.01 B15 9,860 0.23 9,001 0.21 859 0.02 B16 9,598 0.22 8,737 0.20 861 0.02 B17 11,702 0.27 10,028 0.23 1,674 0.04 B18 20,051 0.46 14,422 0.33 5,629 0.13 96 FIGURE 5.3 – STORMSHED 3G CALCULATIONS Appended on: Monday, March 21, 2022 11:27:13 AM ROUTEHYD [] THRU [PLANT 2] USING [25 year] AND [TYPE1A.RAC] NOTZERO RELATIVE SCS/SBUH Gravity Analysis using 24 hr duration storm Reach ID Area (ac) Flow (cfs) Full Q (cfs) Full ratio nDepth (ft) Depth ratio Size nVel (ft/s) fVel (ft/s) Infil Vol (cf) CBasin / Hyd P05 0.74 0.5723 2.3538 0.2431 0.3355 0.3355 12 in Diam 2.4756 2.997 0.00 B05 P04 0.74 0.5723 7.0968 0.0806 0.1917 0.1917 12 in Diam 5.4393 9.0359 0.00 P09 0.20 0.146 2.3456 0.0622 0.1691 0.1691 12 in Diam 1.6611 2.9865 0.00 B09 P08 0.46 0.3238 2.3789 0.1361 0.2492 0.2492 12 in Diam 2.1187 3.029 0.00 B08 P07 1.01 0.7578 3.2694 0.2318 0.3271 0.3271 12 in Diam 3.3943 4.1628 0.00 B07 P06 1.47 1.0816 2.098 0.5155 0.5094 0.5094 12 in Diam 2.6899 2.6713 0.00 B06 P12 0.05 0.0387 4.7716 0.0081 0.0636 0.0636 12 in Diam 1.8428 6.0754 0.00 B12 P11 0.78 0.6032 2.3456 0.2572 0.3458 0.3458 12 in Diam 2.5031 2.9865 0.00 B11 P16 0.22 0.1643 2.3456 0.0701 0.1793 0.1793 12 in Diam 1.7187 2.9865 0.00 B16 P15 0.45 0.3364 3.9952 0.0842 0.1959 0.1959 12 in Diam 3.0979 5.0868 0.00 B15 P14 0.45 0.3364 6.5057 0.0517 0.1544 0.1544 12 in Diam 4.3681 8.2832 0.00 P13 0.61 0.4572 4.9273 0.0928 0.2058 0.2058 12 in Diam 3.9252 6.2736 0.00 B13 P10 2.22 1.7023 2.9293 0.5811 0.5474 0.5474 12 in Diam 3.8685 3.7297 0.00 B11 P02 4.43 3.3562 9.7803 0.3432 0.6059 0.4039 18 in Diam 5.0188 5.5345 0.00 P03 4.43 3.3562 30.9924 0.1083 0.3326 0.2217 18 in Diam 11.5133 17.5381 0.00 B03 P-VLT- PRE 4.43 3.3562 7.393 0.454 0.7091 0.4727 18 in Diam 4.0817 4.1836 0.00 P-VLT- BIO 4.43 3.3562 9.7803 0.3432 0.6059 0.4039 18 in Diam 5.0188 5.5345 0.00 P01 4.43 3.3562 7.3189 0.4586 0.7133 0.4755 18 in Diam 4.0506 4.1416 0.00 HGL Analysis From Node To Node HG El (ft) App (ft) Bend (ft) Junct Loss (ft) Adjusted HG El (ft) Max El (ft) 247.00 CB01 VLT-INFILT 247.0774 0.0560 0.0615 ------ 247.0829 252.0400 VLT-BIOPOD CB01 247.1572 --na-- --na-- --na-- 247.1572 252.2800 VLT-PRESETT VLT-BIOPOD 247.2327 --na-- --na-- --na-- 247.2327 252.0000 CB03 VLT-PRESETT 247.3281 0.0560 0.0771 ------ 247.3492 251.8900 CB02 CB03 247.4553 0.0729 0.0357 0.0395 247.4575 252.3900 CB04 CB02 247.4752 0.0082 0.0100 ------ 247.4769 252.2300 CB05 CB04 247.5288 ------ ------ ------ 247.5288 249.9000 CB06 CB02 247.7214 0.0145 0.0018 0.0043 247.7130 250.0400 CB08 CB06 247.7195 0.0005 0.0001 ------ 247.7191 248.2100 CB09 CB08 247.7205 ------ ------ ------ 247.7205 248.2100 CB07 CB06 247.7487 ------ ------ ------ 247.7487 249.4000 CB10 CB02 247.9873 0.0092 0.0169 0.0044 247.9996 252.0000 CB12 CB10 250.0965 ------ ------ ------ 250.0965 253.2100 CB11 CB10 248.0363 ------ ------ ------ 248.0363 249.7600 CB13 CB10 248.0179 0.2963 0.6165 ------ 248.3380 251.1400 CB14 CB13 249.8058 ------ 0.0341 ------ 249.8399 252.9600 CB15 CB14 251.1378 ------ 0.0003 ------ 251.1381 254.4700 CB16 CB15 251.4844 ------ ------ ------ 251.4844 254.4700 Conduit Notes Reach HW Depth (ft) HW/D ratio Q (cfs) TW Depth (ft) Dc (ft) Dn (ft) Comment P01 4.2278 2.8185 3.36 4.1500 0.6982 0.7133 Outlet Control P-VLT-BIO 4.2572 2.8381 3.36 4.1829 0.6982 0.6059 Outlet Control P-VLT-PRE 3.7727 2.5151 3.36 3.6972 0.6982 0.7091 Outlet Control P03 4.8281 3.2188 3.36 4.7327 0.6982 0.3326 Outlet Control P02 2.5453 1.6969 3.36 2.4392 0.6982 0.6059 Outlet Control P04 2.6752 2.6752 0.57 2.6575 0.3144 0.1917 Outlet Control P05 1.5388 1.5388 0.57 1.4869 0.3144 0.3355 Outlet Control P06 2.9214 2.9214 1.08 2.6575 0.4375 0.5094 Outlet Control P08 2.0595 2.0595 0.32 2.0530 0.2345 0.2492 Outlet Control P09 1.8805 1.8805 0.15 1.8791 0.1560 0.1691 Outlet Control P07 2.0887 2.0887 0.76 2.0530 0.3636 0.3271 Outlet Control P10 3.1874 3.1874 1.70 2.6575 0.5550 0.5474 Outlet Control P12 0.0965 0.0965 0.04 1.8896 0.0795 0.0636 SuperCrit flow, Inlet end controls P11 1.9263 1.9263 0.60 1.8896 0.3230 0.3458 Outlet Control P13 1.9078 1.9078 0.46 1.8896 0.2801 0.2058 Outlet Control P14 0.3058 0.3058 0.34 0.8380 0.2391 0.1544 SuperCrit flow, Inlet end controls P15 0.3178 0.3178 0.34 0.3399 0.2391 0.1959 SuperCrit flow, Inlet end controls P16 0.2344 0.2344 0.16 0.3181 0.1658 0.1793 Outlet Control M1 Backwater Reach ID Area (ac) Flow (cfs) Full Q (cfs) Full ratio nDepth (ft) Depth ratio Size nVel (ft/s) fVel (ft/s) Infil Vol (cf) CBasin / Hyd P17 0.27 0.1972 2.3456 0.0841 0.1958 0.1958 12 in Diam 1.8181 2.9865 0.00 B17 P18 0.73 0.5151 11.6481 0.0442 0.1433 0.1433 12 in Diam 7.4544 14.8309 0.00 B18 P-VLT-BIO- 351ST 0.73 0.5151 10.49 0.0491 0.1505 0.1505 12 in Diam 6.9392 13.3563 0.00 HGL Analysis From Node To Node HG El (ft) App (ft) Bend (ft) Junct Loss (ft) Adjusted HG El (ft) Max El (ft) 237.60 VLT-BIO-351ST CB19 237.6090 --na-- --na-- --na-- 237.6090 242.4300 CB18 VLT-BIO-351ST 238.2166 ------ 0.0694 ------ 238.2859 242.3000 CB17 CB18 238.3698 ------ ------ ------ 238.3698 241.2800 Conduit Notes Reach HW Depth (ft) HW/D ratio Q (cfs) TW Depth (ft) Dc (ft) Dn (ft) Comment P-VLT-BIO-351ST 1.0090 1.0090 0.52 1.0000 0.2978 0.1505 Outlet Control P18 0.3466 0.3466 0.52 0.2978 0.2978 0.1433 SuperCrit flow, Inlet end controls P17 0.2698 0.2698 0.20 0.4159 0.1822 0.1958 Outlet Control M1 Backwater Licensed to: Debug License Appended on: Monday, March 21, 2022 11:07:07 AM ROUTEHYD [] THRU [PLANT 2] USING [100 year] AND [TYPE1A.RAC] NOTZERO RELATIVE SCS/SBUH Gravity Analysis using 24 hr duration storm Reach ID Area (ac) Flow (cfs) Full Q (cfs) Full ratio nDepth (ft) Depth ratio Size nVel (ft/s) fVel (ft/s) Infil Vol (cf) CBasin / Hyd P05 0.74 0.6957 2.3538 0.2956 0.3727 0.3727 12 in Diam 2.6081 2.997 0.00 B05 P04 0.74 0.6957 7.0968 0.098 0.2114 0.2114 12 in Diam 5.7469 9.0359 0.00 P09 0.20 0.1793 2.3456 0.0765 0.1868 0.1868 12 in Diam 1.7689 2.9865 0.00 B09 P08 0.46 0.4006 2.3789 0.1684 0.2771 0.2771 12 in Diam 2.2574 3.029 0.00 B08 P07 1.01 0.9263 3.2694 0.2833 0.3642 0.3642 12 in Diam 3.5817 4.1628 0.00 B07 P06 1.47 1.3269 2.098 0.6325 0.5771 0.5771 12 in Diam 2.8263 2.6713 0.00 B06 P12 0.05 0.047 4.7716 0.0099 0.0697 0.0697 12 in Diam 1.9585 6.0754 0.00 B12 P11 0.78 0.7333 2.3456 0.3126 0.383 0.383 12 in Diam 2.6496 2.9865 0.00 B11 P16 0.22 0.201 2.3456 0.0857 0.1977 0.1977 12 in Diam 1.8272 2.9865 0.00 B16 P15 0.45 0.4115 3.9952 0.103 0.2163 0.2163 12 in Diam 3.2912 5.0868 0.00 B15 P14 0.45 0.4115 6.5057 0.0632 0.1705 0.1705 12 in Diam 4.6289 8.2832 0.00 P13 0.61 0.559 4.9273 0.1134 0.2279 0.2279 12 in Diam 4.1493 6.2736 0.00 B13 P10 2.22 2.0726 2.9293 0.7075 0.6212 0.6212 12 in Diam 4.0426 3.7297 0.00 B11 P02 4.43 4.0952 9.7803 0.4187 0.6771 0.4514 18 in Diam 5.288 5.5345 0.00 P03 4.43 4.0952 30.9924 0.1321 0.3681 0.2454 18 in Diam 12.1679 17.5381 0.00 B03 P-VLT- PRE 4.43 4.0952 7.393 0.5539 0.798 0.532 18 in Diam 4.2856 4.1836 0.00 P-VLT- BIO 4.43 4.0952 9.7803 0.4187 0.6771 0.4514 18 in Diam 5.288 5.5345 0.00 P01 4.43 4.0952 7.3189 0.5595 0.8026 0.5351 18 in Diam 4.255 4.1416 0.00 HGL Analysis From Node To Node HG El (ft) App (ft) Bend (ft) Junct Loss (ft) Adjusted HG El (ft) Max El (ft) 247.00 CB01 VLT-INFILT 247.1154 0.0834 0.0916 ------ 247.1237 252.0400 VLT-BIOPOD CB01 247.2343 --na-- --na-- --na-- 247.2343 252.2800 VLT-PRESETT VLT-BIOPOD 247.3466 --na-- --na-- --na-- 247.3466 252.0000 CB03 VLT-PRESETT 247.4887 0.0834 0.1148 ------ 247.5201 251.8900 CB02 CB03 247.6781 0.1081 0.0529 0.0588 247.6816 252.3900 CB04 CB02 247.7076 0.0122 0.0148 ------ 247.7102 252.2300 CB05 CB04 247.7869 ------ ------ ------ 247.7869 249.9000 CB06 CB02 248.0787 0.0216 0.0027 0.0064 248.0663 250.0400 CB08 CB06 248.0762 0.0008 0.0002 ------ 248.0756 248.2100 CB09 CB08 248.0777 ------ ------ ------ 248.0777 248.2100 CB07 CB06 248.1195 ------ ------ ------ 248.1195 249.4000 CB10 CB02 248.4670 0.0135 0.0250 0.0066 248.4850 252.0000 CB12 CB10 250.1076 ------ ------ ------ 250.1076 253.2100 CB11 CB10 248.5394 ------ ------ ------ 248.5394 249.7600 CB13 CB10 248.5124 0.0043 0.0089 ------ 248.5170 251.1400 CB14 CB13 249.8426 ------ 0.0385 ------ 249.8810 252.9600 CB15 CB14 251.1745 ------ 0.0003 ------ 251.1749 254.4700 CB16 CB15 251.5100 ------ ------ ------ 251.5100 254.4700 Conduit Notes Reach HW Depth (ft) HW/D ratio Q (cfs) TW Depth (ft) Dc (ft) Dn (ft) Comment P01 4.2658 2.8439 4.10 4.1500 0.7752 0.8026 Outlet Control P-VLT-BIO 4.3343 2.8895 4.10 4.2237 0.7752 0.6771 Outlet Control P-VLT-PRE 3.8866 2.5911 4.10 3.7743 0.7752 0.7980 Outlet Control P03 4.9888 3.3258 4.10 4.8466 0.7752 0.3681 Outlet Control P02 2.7681 1.8454 4.10 2.6101 0.7752 0.6771 Outlet Control P04 2.9076 2.9076 0.70 2.8816 0.3478 0.2114 Outlet Control P05 1.7968 1.7968 0.70 1.7202 0.3478 0.3727 Outlet Control P06 3.2787 3.2787 1.33 2.8816 0.4870 0.5771 Outlet Control P08 2.4162 2.4162 0.40 2.4063 0.2616 0.2771 Outlet Control P09 2.2377 2.2377 0.18 2.2356 0.1734 0.1868 Outlet Control P07 2.4595 2.4595 0.93 2.4063 0.4037 0.3642 Outlet Control P10 3.6670 3.6670 2.07 2.8816 0.6162 0.6212 Outlet Control P12 0.1076 0.1076 0.05 2.3750 0.0877 0.0697 SuperCrit flow, Inlet end controls P11 2.4294 2.4294 0.73 2.3750 0.3574 0.3830 Outlet Control P13 2.4024 2.4024 0.56 2.3750 0.3106 0.2279 Outlet Control P14 0.3426 0.3426 0.41 1.0170 0.2652 0.1705 SuperCrit flow, Inlet end controls P15 0.3545 0.3545 0.41 0.3810 0.2652 0.2163 SuperCrit flow, Inlet end controls P16 0.2600 0.2600 0.20 0.3549 0.1839 0.1977 Outlet Control M1 Backwater Reach ID Area (ac) Flow (cfs) Full Q (cfs) Full ratio nDepth (ft) Depth ratio Size nVel (ft/s) fVel (ft/s) Infil Vol (cf) CBasin / Hyd P17 0.27 0.2422 2.3456 0.1033 0.2165 0.2165 12 in Diam 1.9341 2.9865 0.00 B17 P18 0.73 0.637 11.6481 0.0547 0.1588 0.1588 12 in Diam 7.9403 14.8309 0.00 B18 P-VLT-BIO- 351ST 0.73 0.637 10.49 0.0607 0.1671 0.1671 12 in Diam 7.3774 13.3563 0.00 HGL Analysis From Node To Node HG El (ft) App (ft) Bend (ft) Junct Loss (ft) Adjusted HG El (ft) Max El (ft) 237.60 VLT-BIO-351ST CB19 237.6137 --na-- --na-- --na-- 237.6137 242.4300 CB18 VLT-BIO-351ST 238.2668 ------ 0.0785 ------ 238.3453 242.3000 CB17 CB18 238.4273 ------ ------ ------ 238.4273 241.2800 Conduit Notes Reach HW Depth (ft) HW/D ratio Q (cfs) TW Depth (ft) Dc (ft) Dn (ft) Comment P-VLT-BIO-351ST 1.0137 1.0137 0.64 1.0000 0.3324 0.1671 Outlet Control P18 0.3968 0.3968 0.64 0.3324 0.3324 0.1588 SuperCrit flow, Inlet end controls P17 0.3273 0.3273 0.24 0.4753 0.2021 0.2165 Outlet Control M1 Backwater Licensed to: Debug License Appended on: Monday, March 21, 2022 11:29:18 AM Layout Report: PLANT 2 Event Precip (in) 2 yr 24 hr 2.06 10 year 2.93 25 year 3.40 100 year 4.11 Reach Records Record Id: P01 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode VLT-INFILT UpNode CB01 Material unspecified Size 18 in Diam Ent Losses Groove End w/Headwall Length 9.00 ft Slope 0.56% Up Invert 242.90 ft Dn Invert 242.85 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P02 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB03 UpNode CB02 Material unspecified Size 18 in Diam Ent Losses Groove End w/Headwall Length 33.00 ft Slope 1.00% Up Invert 245.24 ft Dn Invert 244.91 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P03 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode VLT-PRESETT UpNode CB03 Material unspecified Size 18 in Diam Ent Losses Groove End w/Headwall Length 24.00 ft Slope 10.04% Up Invert 244.91 ft Dn Invert 242.50 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P04 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB02 UpNode CB04 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 26.00 ft Slope 4.58% Up Invert 245.99 ft Dn Invert 244.80 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P05 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB04 UpNode CB05 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 141.00 ft Slope 0.50% Up Invert 246.70 ft Dn Invert 245.99 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P06 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB02 UpNode CB06 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 215.00 ft Slope 0.40% Up Invert 245.66 ft Dn Invert 244.80 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P07 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB06 UpNode CB07 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 35.00 ft Slope 0.97% Up Invert 246.00 ft Dn Invert 245.66 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P08 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB06 UpNode CB08 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 35.00 ft Slope 0.51% Up Invert 245.84 ft Dn Invert 245.66 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P09 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB08 UpNode CB09 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 38.00 ft Slope 0.50% Up Invert 246.03 ft Dn Invert 245.84 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P10 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB02 UpNode CB10 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 168.00 ft Slope 0.78% Up Invert 246.11 ft Dn Invert 244.80 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P11 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB10 UpNode CB11 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 78.00 ft Slope 0.50% Up Invert 246.50 ft Dn Invert 246.11 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P12 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB10 UpNode CB12 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 188.00 ft Slope 2.07% Up Invert 250.00 ft Dn Invert 246.11 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P13 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB10 UpNode CB13 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 63.00 ft Slope 2.21% Up Invert 247.50 ft Dn Invert 246.11 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P14 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB13 UpNode CB14 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 52.00 ft Slope 3.85% Up Invert 249.50 ft Dn Invert 247.50 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P15 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB14 UpNode CB15 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 91.00 ft Slope 1.45% Up Invert 250.82 ft Dn Invert 249.50 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P16 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB15 UpNode CB16 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 86.00 ft Slope 0.50% Up Invert 251.25 ft Dn Invert 250.82 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P17 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB18 UpNode CB17 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 46.00 ft Slope 0.50% Up Invert 238.10 ft Dn Invert 237.87 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P18 Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode VLT-BIO-351ST UpNode CB18 Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 3.00 ft Slope 12.33% Up Invert 237.87 ft Dn Invert 237.50 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P-VLT-BIO Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB01 UpNode VLT-BIOPOD Material unspecified Size 18 in Diam Ent Losses Groove End w/Headwall Length 6.00 ft Slope 1.00% Up Invert 242.96 ft Dn Invert 242.90 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P-VLT-BIO-351ST Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode CB19 UpNode VLT-BIO-351ST Material unspecified Size 12 in Diam Ent Losses Groove End w/Headwall Length 4.00 ft Slope 10.00% Up Invert 237.00 ft Dn Invert 236.60 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Record Id: P-VLT-PRE Section Shape: Circular Uniform Flow Method: Manning's Coefficient: 0.014 Routing Method: Travel Time Shift Contributing Hyd DnNode VLT-BIOPOD UpNode VLT-PRESETT Material unspecified Size 18 in Diam Ent Losses Groove End w/Headwall Length 7.00 ft Slope 0.57% Up Invert 243.50 ft Dn Invert 243.46 ft Conduit Constraints Min Vel Max Vel Min Slope Max Slope Min Cover 2.00 ft/s 15.00 ft/s 0.50% 2.00% 3.00 ft Drop across MH 0.00 ft Ex/Infil Rate 0.00 in/hr Node Records Record Id: CB01 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 242.90 ft Max El. 252.04 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 2-48 Channelization No Special Shape Catch 0.00 ft Bottom Area 12.5664 sf MH/CB Type Node Record Id: CB02 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 244.80 ft Max El. 252.39 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 2-60 Channelization No Special Shape Catch 0.00 ft Bottom Area 19.634 sf MH/CB Type Node Record Id: CB03 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 244.91 ft Max El. 251.89 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 2-48 Channelization No Special Shape Catch 0.00 ft Bottom Area 12.5664 sf MH/CB Type Node Record Id: CB04 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 245.99 ft Max El. 252.23 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 2-48 Channelization No Special Shape Catch 0.00 ft Bottom Area 12.5664 sf MH/CB Type Node Record Id: CB05 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 246.70 ft Max El. 249.90 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB06 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 245.66 ft Max El. 250.04 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 2-48 Channelization No Special Shape Catch 0.00 ft Bottom Area 12.5664 sf MH/CB Type Node Record Id: CB07 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 246.00 ft Max El. 249.40 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB08 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 245.84 ft Max El. 248.21 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB09 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 246.03 ft Max El. 248.21 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB10 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 246.11 ft Max El. 252.00 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 2-48 Channelization No Special Shape Catch 0.00 ft Bottom Area 12.5664 sf MH/CB Type Node Record Id: CB11 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 246.50 ft Max El. 249.76 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB12 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 250.00 ft Max El. 253.21 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB13 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 247.50 ft Max El. 251.14 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB14 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 249.50 ft Max El. 252.96 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB15 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 250.82 ft Max El. 254.47 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB16 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 251.25 ft Max El. 254.47 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB17 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 238.10 ft Max El. 241.28 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB18 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 237.87 ft Max El. 242.30 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 1 Channelization No Special Shape Catch 0.00 ft Bottom Area 3.97 sf MH/CB Type Node Record Id: CB19 Descrip: Proposed Catch Basin Increment 0.10 ft Start El. 236.50 ft Max El. 242.64 ft Void Ratio 100.00 Condition Proposed Structure Type CB-TYPE 2-48 Channelization No Special Shape Catch 0.00 ft Bottom Area 12.5664 sf MH/CB Type Node Record Id: VLT-BIO-351ST Descrip: Proposed Vault Increment 0.10 ft Start El. 237.00 ft Max El. 242.43 ft Void Ratio 100.00 Dummy Type Node Record Id: VLT-BIOPOD Descrip: Proposed Vault Increment 0.10 ft Start El. 242.96 ft Max El. 252.28 ft Void Ratio 100.00 Dummy Type Node Record Id: VLT-INFILT Descrip: Proposed Vault Increment 0.10 ft Start El. 242.85 ft Max El. 250.00 ft Void Ratio 100.00 Dummy Type Node Record Id: VLT-PRESETT Descrip: Proposed Vault Increment 0.10 ft Start El. 242.50 ft Max El. 252.00 ft Void Ratio 100.00 Dummy Type Node Contributing Drainage Areas Record Id: B05 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.00 ac DCIA 0.74 ac Pervious CN 0.00 DC CN 98.00 Pervious TC 0.00 min DC TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.74 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B06 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.00 ac DCIA 0.74 ac Pervious CN 0.00 DC CN 98.00 Pervious TC 0.00 min DC TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.74 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B07 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.08 ac DCIA 0.93 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 5.00 min DC TC 5.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.08 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.93 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B08 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.08 ac DCIA 0.18 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 5.00 min DC TC 5.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.08 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.18 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B09 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.03 ac DCIA 0.17 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 5.00 min DC TC 5.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.03 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.17 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B11 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.00 ac DCIA 0.78 ac Pervious CN 0.00 DC CN 98.00 Pervious TC 0.00 min DC TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.78 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B12 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.00 ac DCIA 0.05 ac Pervious CN 0.00 DC CN 98.00 Pervious TC 0.00 min DC TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.05 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B13 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.01 ac DCIA 0.15 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 5.00 min DC TC 5.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.01 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.15 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B15 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.02 ac DCIA 0.21 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 5.00 min DC TC 5.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.02 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.21 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B16 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.02 ac DCIA 0.20 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 5.00 min DC TC 5.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.02 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.20 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B17 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.04 ac DCIA 0.23 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 5.00 min DC TC 5.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.04 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.23 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Record Id: B18 Design Method SBUH Rainfall type TYPE1A.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs Abstraction Coeff 0.20 Pervious Area 0.13 ac DCIA 0.33 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 5.00 min DC TC 5.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.13 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min DCI - CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.33 ac 98.00 DC Composited CN (AMC 2) 98.00 DCI - TC Calc Type Description Length Slope Coeff Misc TT Sheet Assumed 0.00 ft 0.0% 5.0 0.00 in 5.00 min Pervious TC 5.00 min Licensed to: Debug License 125 SECTION 6 – SPECIAL REPORTS AND STUDIES The Geotechnical Engineering Report by South Sound Geotechnical Consulting (SSGC) has been included in this section. 126 FIGURE 6.1 – GEOTECHNICAL ENGINEERING REPORT South Sound Geotechnical Consulting P.O. Box 39500, Lakewood, WA 98496 (253) 973-0515 June 18, 2021 35000 Pacific Hwy South, LLC 3106 Sumner Tapps Hwy East, Suite A Lake Tapps, WA 98391 Attention: Mr. Eric Corliss Subject: Geotechnical Engineering Report – Infiltration Assessment Plant 2 Relocation 35000 and 35050 Pacific Hwy South Federal Way, WA SSGC Project No. 21041 Mr. Corliss, South Sound Geotechnical Consulting (SSGC) has completed an infiltration assessment for the Plant 2 Relocation at the above addressed property in Federal Way, Washington in support of design of stormwater facilities. Our services have been completed in general conformance with our proposal P21052 (dated May 10, 2021) and authorized per signature of our agreement for services. Our scope of services included completion of one pilot infiltration test and one test pit, laboratory testing, engineering analyses, and preparation of this report. PROJECT INFORMATION The site is on the east side of Pacific Highway South and encompasses four parcels. A new concrete plant is planned on the lots. Preliminary plans have stormwater control facilities in the southwest portion of the site (on the 35050 lot). Infiltration facilities are planned to assist in stormwater control. SITE CONDITIONS The proposed stormwater facility area is currently used as an access drive into the property and parking area for trailers. A short retaining wall (on the order of 2 to 3 feet) is along the sidewalk that borders the western boundary and Pacific Highway South. The access drive rises from street level to the overall generally level property elevation. SUBSURFACE CONDITIONS Subsurface conditions were characterized by completing one infiltration test and one test pit on May 27, 2021. Test holes were advanced to final depths between 7 and 11 feet below existing ground surface. Approximate locations of the explorations are shown on Figure 1, Exploration Plan. A summary description of observed subgrade conditions is provided below. Logs of t he test holes are provided in Appendix A. Infiltration Assessment SSGC Plant 2 Relocation Federal Way, Washington SSGC Project No. 21041 June 18, 2021 2 Soil Conditions Fill was observed below the surface in the test holes and extended to depths between 1.5 to 2.5 feet. Fill consisted of mixed silt, sand, and gravel with variable debris. Native soil below the fill consisted of silty sand with gravel and occasional cobbles. This soil was in a dense condition closer to the surface, grading to medium dense with depth. It extended to the base of the test holes. Groundwater Conditions Groundwater was not observed in the test holes at the time of excavation. No visual evidence of perched seasonal groundwater (such as mottling) was observed. Groundwater levels will vary throughout the year based on seasonal precipitation and on- and off-site drainage patterns. Geologic Setting Native soils on the property are mapped as Vashon recessional outwash per the USGS “Geologic Map of the Poverty Bay 7.5’ Quadrangle, King and Pierce Counties, Washington”. These soils reportedly formed in recessional glacial outwash. However, native soils were not characteristic of recessional outwash and appeared to represent sandy drift or till. INFILTRATION CHARACTERISTICS One small-scale Pilot Infiltration Test (PIT) were completed in general conformance with the 2016 King County Surface Water Design Manual to assess infiltration potential in the native soils. Results of the infiltration test is presented in Table 1. Table 1. Infiltration Test Results Infiltration Test No. Depth of Test from Surface (feet) Soil Type Field Infiltration Rate (in/hr) Corrected Infiltration Rate (in/hr) Correction Factors* (Fg/Ft/Fp) PIT-1 8 Silty SAND with gravel 4.5 2.0 (1.0/0.5/0.9) *Correction Factors from the 2016 KCSWDM. The infiltration test was completed at a depth of 8 feet as we are unaware of planned finish grades of the proposed concrete plant, and to ensure the test was completed below the base of the retaining wall along the Pacific Hwy South sidewalk. Based on field results, we recommend a design rate of 2 inches per hour (in/hr) for the soil at the tested depth. Native soils in the test pit in the north side of the proposed stormwater facility appeared similar. Groundwater was not observed in the test holes to a depth of 11 feet below existing grades. Evidence of seasonal perched groundwater (such as mottling) was not observed in the test holes. Groundwater is not Infiltration Assessment SSGC Plant 2 Relocation Federal Way, Washington SSGC Project No. 21041 June 18, 2021 3 anticipated to affect stormwater facilities in this area of the site. In addition, following completion of the infiltration test, the test hole was advanced to a depth of 11 feet with no evidence of ponded water introduced during the test. Cation Exchange Capacity (CEC) and organic content tests were completed on a soil sample from the base of the infiltration test elevation in the test holes. Test results are summarized in Table 2. Table 2. CEC and Organic Content Results Test Location CEC Results (milliequivalents) CEC Required* (milliequivalents) Organic Content Results (%) Organic Content Required* (%) PIT-1 5.3 ≥ 5 1.02 ≥1.0 * Per the 2016 KCSWDM. CEC and organic content of the tested sample satisfy county requirements. REPORT CONDITIONS This report has been prepared for the exclusive use of 3500 Pacific Hwy South, LLC and their agents for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices in the area. No warranties, either express or i mplied, are intended or made. The analysis and recommendations presented in this report are based on observed soil conditions and test results at the indicated locations, and from other geologic information discussed. This report does not reflect variations that may occur across the project limits, or due to the modifying effects of drainage patterns or weather. This report was prepared for the planned type of development of the site as discussed herein. It is not valid for third party entities or alternate types of development on the site without the express wr itten consent of SSGC. If development plans change, we should be notified to review those changes and modify our recommendations, as necessary. The scope of services for this project does not include any environmental or biological assessment of the site including identification or prevention of pollutants, hazardous materials, or conditions. Other studies should be completed if the owner is concerned about the potential for contamination or pollution. N South Sound Geotechnical Consulting P.O. Box 39500 Lakewood, WA 98496 (253) 973-0515 Figure 1 – Exploration Plan Plant 2 Relocation Federal Way, WA SSGC Project #21041 Approximate Test Pit Location PIT - 1 TP - 1 PIT - 1 Approximate Infiltration Test Location Scale: NTS Base map from drawing titled “Site Plan – Plant 2 Relocation”, by Apex Engineering, dated 2-1-21. Legend PIT-1 TP-1 Infiltration Assessment SSGC Plant 2 Relocation Federal Way, Washington SSGC Project No. 21041 June 18, 2021 5 Appendix A Field Exploration Procedures Infiltration Assessment SSGC Plant 2 Relocation Federal Way, Washington SSGC Project No. 21041 June 18, 2021 6 Field Exploration Procedures Our field exploration for this project included one small-scale Pilot Infiltration Test (PIT) and one test pit completed on May 27, 2021. Approximate locations of the explorations are shown on Figure 1, Exploration Plan. The exploration locations were determined by pacing from site features. Ground surface elevations referenced on the logs were inferred from topography from Google Earth satellite imagery. Exploration locations and elevations should be considered accurate only to the degree implied by the means and methods used. A private excavating contractor subcontracted to SSGC dug the infiltration test holes. Select soil samples were collected and stored in moisture tight for further assessment and laboratory testing. Explorations were backfilled with excavated soils and tamped when completed. Please note that backfill in the explorations will likely settle with time. Backfill located in building or pavement areas should be re- excavated and recompacted, or replaced with structural fill. The following logs indicate the observed lithology of soils and other materials observed in the explorations at the time of excavation. Where a soil contact was observed to be gradational, our log indicates the average contact depth. Our logs also indicate the approximate depth to groundwater (where observed at the time of excavation), along with sample numbers and approximate sample depths. Soil descriptions on the logs are based on the Unified Soil Classification System. Project: Plant 2 Relocation SSGC Job # 21041 EXPLORATION LOGS PAGE 1 OF 1 Location: 35050 Pacific Hwy S., Federal Way, WA EXPLORATION LOGS FIGURE A-1 South Sound Geotechnical Consulting PIT-1, TP-1 Logged by: THR Infiltration Test PIT-1 Depth (feet) Material Description 0 – 2.5 2.5 – 11 Fill: Silt, sand, gravel with some debris (asphalt, brick, plastic sheeting): Loose to medium dense, moist, brown. Silty SAND with gravel and occasional cobble: Dense grading medium dense, moist, gray grading brown at 4 feet. (SM) (Sample S-1 @ 8 feet) Test hole completed at approximately 11 feet on 5/27/21. Infiltration test run at 8 feet. Groundwater not observed at time of excavation. Piezometer set in test hole. Approximate surface elevation: 252 feet Test Pit TP-1 Depth (feet) Material Description 0 – 1.5 1.5 – 7 Fill: Silt, sand, and gravel: Loose to medium dense, moist, brown. Silty SAND with gravel and occasional cobble: Dense grading medium dense, moist, gray grading brown at 3 feet. (SM) Test pit completed at approximately 7 feet on 5/27/21. Groundwater not observed at time of excavation. Approximate surface elevation: 252 feet Infiltration Assessment SSGC Plant 2 Relocation Federal Way, Washington SSGC Project No. 21041 June 18, 2021 7 Appendix B Laboratory Testing and Results Infiltration Assessment SSGC Plant 2 Relocation Federal Way, Washington SSGC Project No. 21041 June 18, 2021 8 Laboratory Testing Organic content and cation exchange capacity (CEC) testing on a sample from the base of the PIT test hole was completed by Northwest Agricultural Consultants of Kennewick, Washington. Results of the laboratory testing are included in this appendix. 2545 W Falls Avenue Kennewick, WA 99336 509.783.7450 www.nwag.com lab@nwag.com Sample ID Organic Matter Cation Exchange Capacity Pit-1, S-1 1.02% 5.3 meq/100g Method ASTM D2974 EPA 9081 South Sound Geotechnical Consulting PO Box 39500 Lakewood, WA 98496 Report: 55334-1-1 Date: June 3, 2021 Project No: 21041 Project Name: Corliss Plant UNIFIED SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification Group Symbol Group NameB Coarse Grained Soils More than 50% retained on No. 200 sieve Gravels More than 50% of coarse fraction retained on No. 4 sieve Clean Gravels Less than 5% finesC Cu  4 and 1  Cc  3E GW Well-graded gravelF Cu  4 and/or 1  Cc  3E GP Poorly graded gravelF Gravels with Fines More than 12% finesC Fines classify as ML or MH GM Silty gravelF,G, H Fines classify as CL or CH GC Clayey gravelF,G,H Sands 50% or more of coarse fraction passes No. 4 sieve Clean Sands Less than 5% finesD Cu  6 and 1  Cc  3E SW Well-graded sandI Cu  6 and/or 1  Cc  3E SP Poorly graded sandI Sands with Fines More than 12% finesD Fines classify as ML or MH SM Silty sandG,H,I Fines Classify as CL or CH SC Clayey sandG,H,I Fine-Grained Soils 50% or more passes the No. 200 sieve Silts and Clays Liquid limit less than 50 inorganic PI  7 and plots on or above “A” lineJ CL Lean clayK,L,M PI  4 or plots below “A” lineJ ML SiltK,L,M organic Liquid limit - oven dried  0.75 OL Organic clayK,L,M,N Liquid limit - not dried Organic siltK,L,M,O Silts and Clays Liquid limit 50 or more inorganic PI plots on or above “A” line CH Fat clayK,L,M PI plots below “A” line MH Elastic SiltK,L,M organic Liquid limit - oven dried  0.75 OH Organic clayK,L,M,P Liquid limit - not dried Organic siltK,L,M,Q Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat A Based on the material passing the 3-in. (75-mm) sieve B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name. C Gravels with 5 to 12% fines require dual symbols: GW -GM well-graded gravel with silt, GW -GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with 5 to 12% fines require dual symbols: SW -SM well-graded sand with silt, SW -SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay E Cu = D60/D10 Cc = 6010 2 30 DxD )(D F If soil contains  15% sand, add “with sand” to group name. G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. HIf fines are organic, add “with organic fines” to group name. I If soil contains  15% gravel, add “with gravel” to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,” whichever is predominant. L If soil contains  30% plus No. 200 predominantly sand, add “sandy” to group name. M If soil contains  30% plus No. 200, predominantly gravel, add “gravelly” to group name. N PI  4 and plots on or above “A” line. O PI  4 or plots below “A” line. P PI plots on or above “A” line. Q PI plots below “A” line. 139 SECTION 7 – OTHER PERMITS There are no other known permits with more restrictive drainage-related requirements. A Construction Stormwater General Permit will be acquired from the Washington State Department of Ecology prior to construction. 140 SECTION 8 – CSWPP ANALYSIS AND DESIGN Part A – ESC PLAN ANALYSIS AND DESIGN A TESC Plan is included in Figure 1.3. The work within the site includes: · Removing/demolishing the existing buildings and pavement. · Clearing and grading. · Installing the sanitary sewer, storm sewer, and water systems. · Paving the onsite areas for the development · Installing road improvements including asphalt, curb, gutter and sidewalk. Therefore, the anticipated TESC BMPs have been selected to minimize sediment leaving the site. The following BMPs are proposed from Appendix D of the KCSWDM: · Clearing Limits (per Section D.2.1.1) · Plastic or Metal Fence (per Section D.2.1.1.1) · Mulching (per Section D.2.1.2.2) · Plastic Covering (per Section D.2.1.2.4) · Temporary and Permanent Seeding (per Section D.2.1.2.6) · Silt Fence (per Section D.2.1.3.1) · Stabilized Construction Entrance (per Section D.2.1.4.1) · Wheel Wash (per Section D.2.1.4.3) · Sediment Pond (per Section D.2.1.5.2) · Storm Drain Inlet Protection (per Section D.2.1.5.3) · Interceptor Dike and Swale (per Section D.2.1.6.1) · Check Dams (per Figure D.2.1.6.E) · Outlet Protection (per Section D.2.1.6.5) · Dust Control (per Section D.2.1.8) · Concrete Handling (per Section D.2.2.1) · Concrete Washout Area (per Section D.2.2.2) · Sawcutting and Surfacing Pollution Prevention (per Section D.2.2.3) · Material Delivery, Storage and Containment (per Section D.2.2.4) · High pH Neutralization Using CO2 (per Section D.2.2.7) · pH Control for High pH Water (per Section D.2.2.8) · Maintain Protective BMPs (per Section D.2.2.10) · Manage the Project (per Section D.2.2.11) There are no known areas onsite with a high susceptibility to erosion. During construction and until the site is completely stabilized, runoff shall not discharge directly into the infiltration system. The bottom of the infiltration system shall not become compacted and construction 141 vehicle access shall be limited at all times. After excavation, delineate the immediate area with protection fencing to prevent vehicles/traffic traversing the infiltration system area. Refer to the calculations in this section for temporary swale and sediment pond analyses. 142 FIGURE 8.A.1 – TESC BASIN MAP 144 FIGURE 8.A.2 – SEDIMENT POND ANALYSIS Plant 2 Relocation TESC Analysis Sediment Pond Analysis Surface Area SA = (2*Q2)/0.00096 Where: SA = surface area at top of riser (sf) Q2 = peak flow for the 2-year runoff event (cfs) = 1.14 (per WWHM analysis) SA (sf) = 2,375 Proposed pond with 26' by 95' at 3.5' riser elev. SA = 2,470 sf which should be adequate Dewatering Orifice Ao = As(2h)0.5/(0.6*3600Tg0.5) Where: Ao = orifice area (sf) As = pond surface area (sf) =2,375 h = head of water above orifice (height of riser in feet) = 3.5 T = dewatering time (hrs) =24 g = acceleration of gravity (ft/sec) = 32.2 Ao (sf) = 0.021 D (in.) = 24*(Ao/pi)0.5 D (in.) = 2.0 Overflow Riser Qriser = 9.739DH3/2 Where: Qriser = Q100 = peak flow for the 100-year runoff event (cfs) = 2.74 H = height of water over riser (ft) =1.00 D (ft) = 0.28 Therefore an 8-inch riser should be adequate Emergency Overflow Spillway L = length of weir (ft) = [Q100/(3.21H3/2)] - 2.4H Where: Q100 = peak flow for the 100-year runoff event (cfs) = 2.74 H = height of water over weir (ft) =0.50 L (ft) = 1.2 Therefore utilize a 6 foot min. spillway 146 FIGURE 8.A.3 – TEMPORARY SWALE ANALYSIS Plant 2 Relocation ESC Temporary Swale Design Job #35072 CAPACITY ANALYSIS: Haestad Method’s Flowmaster 1 (Version 3.16) Results: Solve For......Depth Lt Side Slope......2.00:1 (H:V) Velocity...................1.49 fps Rt Side Slope......2.00:1 (H:V) Flow Area................0.77 sf Manning's n.......0.030 Flow Top Width..…..2.48 ft Channel Slope.....0.0050 ft/ft Wetted Perimeter…2.77 ft Depth.................0.62 ft Critical Depth….…....0.46 ft Discharge...........1.14 cfs Critical Slope...........0.0249 ft/ft Froude Number.......0.47 148 FIGURE 8.A.4 – TESC WWHM CALCULATIONS WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: 35072-TESC Site Name: Plant 2 Site Address: City : Federal Way Report Date: 3/18/2022 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/10/10 Version : 4.2.16 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : TESC Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Flat 3 Pervious Total 3 Impervious Land Use acre Impervious Total 0 Basin Total 3 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : ONSITE Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre DRIVEWAYS FLAT 3 Impervious Total 3 Basin Total 3 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:3 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:3 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.111723 5 year 0.175466 10 year 0.211589 25 year 0.24986 50 year 0.273541 100 year 0.293684 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 1.143794 5 year 1.444744 10 year 1.649219 25 year 1.914453 50 year 2.117455 100 year 2.325388 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.110 1.481 1950 0.137 1.601 1951 0.246 0.925 1952 0.078 0.823 1953 0.063 0.889 1954 0.096 0.930 1955 0.154 1.055 1956 0.122 1.038 1957 0.099 1.177 1958 0.111 0.950 1959 0.095 0.969 1960 0.166 0.951 1961 0.094 1.006 1962 0.058 0.876 1963 0.080 0.973 1964 0.106 0.955 1965 0.076 1.213 1966 0.073 0.811 1967 0.152 1.397 1968 0.095 1.589 1969 0.093 1.104 1970 0.076 1.066 1971 0.082 1.271 1972 0.183 1.312 1973 0.083 0.794 1974 0.090 1.159 1975 0.122 1.336 1976 0.088 0.898 1977 0.011 0.973 1978 0.078 1.190 1979 0.047 1.629 1980 0.174 1.461 1981 0.069 1.195 1982 0.133 1.685 1983 0.120 1.372 1984 0.074 0.865 1985 0.044 1.193 1986 0.194 1.034 1987 0.171 1.595 1988 0.068 0.968 1989 0.044 1.210 1990 0.358 2.038 1991 0.216 1.628 1992 0.083 0.857 1993 0.087 0.742 1994 0.029 0.807 1995 0.124 1.060 1996 0.262 1.128 1997 0.219 1.095 1998 0.050 1.110 1999 0.205 2.271 2000 0.086 1.131 2001 0.015 1.242 2002 0.095 1.449 2003 0.121 1.126 2004 0.156 2.125 2005 0.112 0.971 2006 0.132 0.858 2007 0.266 1.986 2008 0.343 1.600 2009 0.168 1.478 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.3581 2.2713 2 0.3429 2.1251 3 0.2658 2.0383 4 0.2618 1.9862 5 0.2460 1.6855 6 0.2188 1.6287 7 0.2156 1.6283 8 0.2052 1.6008 9 0.1936 1.5999 10 0.1832 1.5948 11 0.1736 1.5887 12 0.1713 1.4814 13 0.1684 1.4784 14 0.1664 1.4612 15 0.1564 1.4491 16 0.1535 1.3973 17 0.1519 1.3718 18 0.1368 1.3356 19 0.1335 1.3120 20 0.1323 1.2709 21 0.1242 1.2422 22 0.1224 1.2126 23 0.1222 1.2100 24 0.1208 1.1953 25 0.1197 1.1925 26 0.1122 1.1898 27 0.1111 1.1772 28 0.1097 1.1593 29 0.1055 1.1305 30 0.0986 1.1278 31 0.0963 1.1259 32 0.0953 1.1102 33 0.0948 1.1044 34 0.0947 1.0953 35 0.0939 1.0655 36 0.0927 1.0599 37 0.0903 1.0546 38 0.0885 1.0377 39 0.0866 1.0336 40 0.0864 1.0057 41 0.0832 0.9735 42 0.0832 0.9726 43 0.0818 0.9711 44 0.0802 0.9689 45 0.0776 0.9675 46 0.0775 0.9546 47 0.0764 0.9508 48 0.0756 0.9499 49 0.0739 0.9301 50 0.0726 0.9254 51 0.0694 0.8981 52 0.0676 0.8889 53 0.0627 0.8763 54 0.0584 0.8653 55 0.0495 0.8578 56 0.0469 0.8570 57 0.0441 0.8232 58 0.0438 0.8108 59 0.0291 0.8074 60 0.0155 0.7945 61 0.0105 0.7422 ___________________________________________________________________ ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ 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. 2005-2022; All Rights Reserved. 153 Part B – STORMWATER POLLUTION PREVENTION AND SPILL CONTROL PLAN (SWPPS) DESIGN This SWPPS consists of an Activities Worksheet together with a series of information sheets listing the best management practices (BMP’s) required for commercial activities. This information was obtained from the KCSWDM. The K.C. SWPPP manual limits the requirements to a number of minimal measures that reasonably balance stormwater pollution reduction with feasibility and cost. The manual also includes recommended BMP’s that should always be considered in the effort to control pollution. The intent and goal is to reduce pollution through education and prevention efforts, emphasizing source control BMP’s before treatment. This property has unique characteristics and drainage systems. These sites have a constructed storm drainage system with catch basin inlets. The pollution generating activities occurring on- site; type of drainage system; as well as the slope and ground cover of a site will affect the selection of BMP’s. The activity sheets offer flexibility in BMP selection and, as much as possible, recognize the wide variety of site conditions that may be encountered. 154 FIGURE 8.B.1 – CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN FOR PLANT 2 RELOCATION JUNE 9, 2022 TABLE OF CONTENTS Stormwater Pollution Prevention Plan SECTION 1 – PROJECT DESCRIPTION: ............................................................................................. 1 SECTION 2 – POLLUTION PREVENTION TEAM: .............................................................................. 1 SECTION 3 – EXISTING CONDITIONS SUMMARY: .......................................................................... 1 SECTION 4 – REQUIRED ACTIVITY-SPECIFIC INFORMATION: ........................................................ 2 Appendices Appendix A BMP Forms Appendix B Miscellaneous Forms 1 SECTION 1 – PROJECT DESCRIPTION: The on-site proposed project includes: · Removing/demolishing the existing buildings and pavement. · Clearing and grading. · Installing the sanitary sewer, storm sewer, and water systems. · Paving the onsite areas for the development. · Installing road improvements including asphalt, curb, gutter, and sidewalk. SECTION 2 – POLLUTION PREVENTION TEAM: Names and contact information for those identified as members of the pollution prevention team are provided in the following table: Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) To Be Assigned ~ Resident Engineer Gabe L. Jellison (253) 473-4494 Emergency Ecology Contact Northwest Regional Office (360) 407-6000 Emergency Owner Contact Sloan Clack (253) 826-5020 Non-Emergency Ecology Contact Northwest Regional Office (360) 407-6000 Monitoring Personnel To Be Assigned ~ SECTION 3 – EXISTING CONDITIONS SUMMARY: The existing project site has three buildings and is covered predominantly with gravel and asphalt paving with limited vegetation. Slopes onsite are generally one to two percent. The existing site entrances near the southwest corner and southeast corner slope up to the site at approximately 7 percent. The project site consists of a single Threshold Discharge Area. Generally, runoff from the western half of the site flows to the west to the existing storm conveyance system located within Pacific Hwy. S., and runoff from the eastern half of the site flows to the south to the existing storm conveyance system located within S. 351st Street which is then conveyed to the west to Pacific Hwy. S. Runoff from adjacent properties does not appear to drain onto the project site and run-on drainage is considered insignificant. 2 SECTION 4 – REQUIRED ACTIVITY-SPECIFIC INFORMATION: Storage and Handling of Liquids 1. The following liquids could be handled or stored on-site, including but not limited to: a. Petroleum products b. Fuel c. Solvents d. Detergents 2. Refer to the Site Development Plans for the location, types and sizes of the liquid containers to be held on-site, if any. 3. On-site fueling tanks and petroleum product storage containers, if any, shall include secondary containment. Storage and Stockpiling of Construction Materials and Wastes 1. No construction materials and wastes are proposed to be stored or stockpiled on-site at this time. 2. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. 3. All pollutants, including waste materials and demolition debris, that occur on-site shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well-organized, and free of debris. Solid waste will be stored in secure, clearly marked containers. Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Fueling 1. No on-site fueling for construction equipment (i.e. stationary tanks, truck mounted tanks, wet hosing, etc.) is proposed at this time. 2. No propane tanks within the project site are proposed at this time. 3. The following containment methods for fuel spills will be performed on-site: a. All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. b. Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. 4. No fueling is proposed to occur during evening hours at this time. 3 Maintenance, Repairs, and Storage of Vehicles and Equipment 1. No maintenance and repair areas and locations are proposed on-site at this time. However, spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment if necessary. 2. The following methods will be used for collection, storage, and disposal of vehicle fluids as required: a. All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. b. On-site fueling tanks and petroleum product storage containers shall include secondary containment. c. Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. d. In order to perform emergency repairs on-site, temporary plastic will be placed beneath and, if raining, over the vehicle. e. Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. 3. No areas are proposed for vehicle maintenance at this time. However, if an area is designated for vehicle maintenance, signs will be posted that state no vehicle washing may occur in the area. Concrete Saw Cutting, Slurry, and Washwater Disposal 1. Hand tools including, but not limited to, screeds, shovels, rakes, floats, and trowels shall be washed off only into formed areas awaiting installation of concrete or asphalt. 2. The following methods will be followed for collecting, treating, and disposal of waste water from exposed aggregate processes, concrete grinding and saw cutting, and new concrete washing and curing water: a. Concrete truck chutes, pumps, and internals shall be washed out only into formed areas awaiting installation of concrete or asphalt. b. Unused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling, as feasible. c. Equipment that cannot be easily moved, such as concrete pavers, shall only be washed in areas that do not directly drain to natural or constructed stormwater conveyances. d. Washdown from areas such as concrete aggregate driveways shall not drain directly to natural or constructed stormwater conveyances. e. When no formed areas are available, washwater and leftover product shall be contained in a lined container or a hole dug on-site. Contained concrete shall be disposed of in a manner that does not violate groundwater or surface water quality standards. 4 Handling of pH Elevated Water New concrete vaults/structures may cause collected water to have an elevated pH. This water cannot be discharged to storm or surface water until neutralized. The key benchmark pH value for stormwater is a maximum of 8.5. If a pH greater than 8.5 is measured in the sedimentation trap/pond(s) that has the potential to discharge to surface water, the following steps will be conducted to treat/neutralize and/or dispose water: a. Sampling and monitoring for pH will occur during the phase of construction when concrete pouring will be conducted until fully cured (3 weeks from last pour) and discharges are documented to be below pH 8.5. Samples will be collected weekly at the sedimentation pond prior to discharge to surface water. Samples will be analyzed for pH using a calibrated pH meter. b. Prevent (detain) all discharges from leaving the site and entering surface waters or storm drains if the pH is greater than 8.5. c. Implement CO2 sparging or dry ice treatment in accordance with Ecology BMP C252. d. Describe inspection results and remedial actions that are taken in the site log book and in monthly discharge monitoring reports. Application of Chemicals including Pesticides and Fertilizers 1. At this time, the chemicals that may be used on the project site and the application rates have not been determined. 2. Refer to the Landscape Plans for locations of on-site landscaping. Application of agricultural chemicals, including fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers’ recommendations for application procedures and rates shall be followed. 3. Any chemicals stored in the construction areas will conform to the appropriate source control BMPs listed in Volume IV of the Ecology Stormwater Manual. In Western WA, all chemicals shall have cover, containment, and protection provided on-site. 35072_Construction SWPPP_031822.doc APPENDIX A CSWPP WORKSHEET/BMP FORMS KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL E S C M A I N T E N A N C E R E P O R T Performed By:___________________________ Date:___________________________ Project Name:___________________________ DPER Permit #:___________________________ Clearing Limits Damage OK Problem Visible OK Problem Intrusions OK Problem Other OK Problem Mulch Rills/Gullies OK Problem Thickness OK Problem Other OK Problem Nets/Blankets Rills/Gullies OK Problem Ground Contact OK Problem Other OK Problem Plastic Tears/Gaps OK Problem Other OK Problem Seeding Percent Cover OK Problem Rills/Gullies OK Problem Mulch OK Problem Other OK Problem Sodding Grass Health OK Problem Rills/Gullies OK Problem Other OK Problem Perimeter Protection including Silt Fence Damage OK Problem Sediment Build-up OK Problem Concentrated Flow OK Problem Other OK Problem Flow Control BMP protection Damage OK Problem Sedimentation OK Problem Concentrated Flow OK Problem Rills/Gullies OK Problem Intrusions OK Problem Other OK Problem Brush Barrier Damage OK Problem Sediment Build-up OK Problem Concentrated Flow OK Problem Other OK Problem Vegetated Strip Damage OK Problem Sediment Build-up OK Problem Concentrated Flow OK Problem Other OK Problem Construction Entrance Dimensions OK Problem Sediment Tracking OK Problem Vehicle Avoidance OK Problem Other OK Problem 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Wheel Wash Dimensions OK Problem Sed build up or tracking OK……. Problem Other OK Problem Construction Road Stable Driving Surf. OK Problem Vehicle Avoidance OK Problem Other OK Problem Sediment Trap/Pond Sed. Accumulation OK Problem Overtopping OK Problem Inlet/Outlet Erosion OK Problem Other OK Problem Catch Basin/Inlet Protection Sed. Accumulation OK Problem Damage OK Problem Clogged Filter OK Problem Other OK Problem Interceptor Dike/Swale Damage OK Problem Sed. Accumulation OK Problem Overtopping OK Problem Other OK Problem Pipe Slope Drain Damage OK Problem Inlet/Outlet OK Problem Secure Fittings OK Problem Other OK Problem Ditches Damage OK Problem Sed. Accumulation OK Problem Overtopping OK Problem Other OK Problem Outlet Protection Scour OK Problem Other OK Problem Level Spreader Damage OK Problem Concentrated Flow OK Problem Rills/Gullies OK Problem Sed. Accumulation OK Problem Other OK Problem Dewatering Controls Sediment OK.. Problem Dust Control Palliative applied OK Problem Miscellaneous Wet Season Stockpile OK Problem Other OK Problem Comments: Actions Taken: Problems Unresolved: 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL BMP Implementation Completed by: Title: Date: Develop a plan for implementing each BMP. Describe the steps necessary to implement the BMP (i.e., any construction or design), the schedule for completing those steps (list dates), and the person(s) responsible for implementation. BMPs Description of Action(s) Required for Implementation Scheduled Milestone and Completion Date(s) Person Responsible for Action Good Housekeeping 1. 2. 3 Preventive Maintenance 1. 2. 3. 4. Spill Prevention and Emergency Cleanup 1. 2. 3. Inspections 1. 2. 3. 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL BMPs Description of Action(s) Required for Implementation Schedule Milestone and Completion Date(s) Person Responsible for Action Source Control BMPs 1. 2. 3 4. 5. 6. 7. 8. Treatment BMPs 1. 2. 3. 4. Emerging technologies 1. 2. Flow Control BMPs 3. 4. 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Pollution Prevention Team Completed by: ______________________ Title: ______________________________ Date: ______________________________ Responsible Official: Title: Team Leader: Office Phone: Cell Phone #: Pager #: Responsibilities: (1) Title: Office Phone: Pager #: Cell Phone: Responsibilities: (2) Title: Office Phone: Pager #: Cell Phone #: Responsibilities: 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Employee Training Completed by: Title: Date: Describe the annual training of employees on the SWPPP, addressing spill response, good housekeeping, and material management practices. Training Topics 1.) LINE WORKERS Brief Description of Training Program/Materials (e.g., film, newsletter course) Schedule for Training (list dates) Attendees Spill Prevention and Response Good Housekeeping Material Management Practices 2.) P2 TEAM: SWPPP Implementation Monitoring Procedures 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL List of Significant Spills and Leaks Completed by: Title: Date: List all spills and leaks of toxic or hazardous pollutants that were significant but are not limited to, release of oil or hazardous substances in excess of reportable quantities. Although not required, we suggest you list spills and leaks of non-hazardous materials. Description Response Procedure Date (month/day/ye ar) Location (as indicated on site map) Type of Material Quantit y Sourc e, If Known Reason for Spill/Leak Amount of Material Recovered Material No longer exposed to Stormwater (Yes/No) Preventive Measure Taken 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Potential Pollutant Source Identification Completed by: Title: Date: List all potential stormwater pollutants from materials handled, treated, or stored on-site. Potential Stormwater Pollutant Stormwater Pollutant Source Likelihood of pollutant being present in your stormwater discharge. If yes, explain 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Material Inventory Completed by: Title: Date: List materials handled, treated, stored, or disposed of at the project site that may potentially be exposed to precipitation or runoff. Quantity (Units) Likelihood of contact with stormwater Past Spill or Used Produced Stored If Yes, describe reason Leak Material Purpose/Location (indicate per/wk. or yr.) Yes No 2016 Surface Water Design Manual – Appendix D CSWPP Forms 4/24/2016 APPENDIX B MISCELLANEOUS FORMS Emergency Phone Numbers Fire, Police, Ambulance 911 Owner: 35000 Pacific Hwy South LLC (253) 826-5020 General Contractor: To be determined Office: N/A Mobile # N/A Subcontractors Sub #1: To be determined Office: N/A Sub #2: To be determined Office: N/A Sub #3: To be determined Office: N/A Sub #4: To be determined Office: N/A City Contact: To be determined N/A State Ecology Dept.: Northwest Region (360) 407-6000 Emergency – Spill Procedures: All discharges to the District or City sewer system (storm or sanitary) require District or City approval. The approval may include a separate Special Approved Discharge (SAD) permit. All pollutants, including waste materials and demolition debris, that occur on-site during construction shall be handled and disposed of in a manner that does not cause contamination of surface water. Cover, containment, and protection from vandalism shall be provided for all chemicals, liquid products, petroleum products, and non-inert wastes present on the site. See Chapter 173-304 WAC for the definition of inert waste. Maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank drain down and removal, and other activities which may result in discharge or spillage of pollutants to the ground or into surface water must be conducted using spill prevention measures, such as drip pans. Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Emergency repairs may be performed on-site using temporary plastic placed beneath and, if raining, over the vehicle. Wheel wash or tire bath wastewater shall be discharged to a separate on-site treatment system or to the sanitary sewer (with the District approval noted above). Application of agricultural chemicals including fertilizers and pesticides shall be conducted in a manner and at application rates that will not result in loss of chemical to surface water runoff. Manufacturers’ recommendations for application rates and procedures shall be followed. A site representative shall notify the City of Federal Way and/or the Lakehaven Water and Sewer District within 24-hours of any spillage or discharge of pollutants. In the event of a spill, make the appropriate notification(s) consistent with the following procedures: · Call 911 for fire department, police, and ambulance if required. · Any spill of oil which 1) violates water quality standards, 2) produces a “sheen” on a surface water, or 3) causes a sludge or emulsion must be reported immediately by telephone to the National Response Center Hotline at (800) 424-8802. · Any oil, hazardous substance, or hazardous waste release which exceeds the reportable quantity must be reported immediately by telephone to the National Response Center Hotline at (800) 424-8802. · Any spill of oil or hazardous substance to waters of the state must be reported immediately by telephone to the Washington State Emergency Management Division at (800) 258-5990. · Any release of a hazardous substance that may be a threat to human health or the environment must be reported to the Ecology Toxics Cleanup Program immediately, but no longer than 90 days from discovery. A site representative will be responsible for completing the spill reporting form and for reporting the spill to the appropriate state or local agency. Facility personnel with primary responsibility for spill response and cleanup will need to be trained as required to respond and clean up spills. This training will include identifying the location of spill kits and other spill response equipment and the use of spill response materials. Spill response equipment will be inspected and maintained as necessary to replace any materials used in spill response activities. Spill Report Form Location: Date:___________________ Time: Regulatory agencies notified (date, time, person, agency, and how): Material spilled: Quantity spilled: Source: Cause: Extent of injuries (if any): Adverse environmental impact (if any): Immediate remedial actions taken at time of spill: Measures taken or planned to prevent recurrence: Additional comments: This report prepared by: (Signature) (Date) (Job title) BMP Maintenance and Inspection Schedule (Source Control BMPs) BMP Designation BMP Name Recommended Maintenance Recommended Schedule of Maintenance D.2.1.4.1 Stabilized Construction Entrance Inspect stabilized areas regularly, especially after large storm events. Add rock (hog fuel), gravel, etc. as needed to maintain a stable surface which won’t erode. Daily D.2.1.2.6 Temporary & Permanent Seeding Re-seed areas failing to establish 80% cover within one month (during growing season). If re-seeding is ineffective, use sodding or nets/blankets. Eroded areas shall be corrected, re-planted, and irrigated as required. Inspect to ensure growth weekly D.2.1.2.2 Mulching Maintain specified thickness of mulch cover. Eroded areas must be corrected and re- mulched. Drainage problems must be corrected. Weekly and following storms D.2.1.6.1 Interceptor Swale Immediately remove sediment from the flow area. Repair damage caused by construction traffic or other activity before the end of each working day. Check outlets and make timely repairs as needed to avoid gully formation. When the area below the temporary diversion dike is permanently stabilized, remove the dike and fill and stabilize the channel to blend with the natural surface. Weekly and following storms D.2.1.8 Dust Control Use dust control practices in areas (including roadways) subject to surface and air movement of dust where on-site and off-site impacts to roadways, drainage ways, or surface waters are likely. Evaluate the potential for dust generation frequently during dry periods. Daily D.2.1.3.1 Silt Fence Repair any damage immediately. Check the uphill side of the fence for signs of the fence clogging, acting as a barrier to flow, and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. Remove sediment deposits when the deposit reaches approximately one-third the height of the silt fence, or install a second silt fence. If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, replace it. Weekly and following storms D.2.1.5.2 Sediment Pond Sediment shall be removed from the pond when it reaches 1 foot in depth. Any damage to the pond embankments or slopes shall be repaired. Inspection daily D.2.1.5.3 Storm Drain Inlet Protection Sediment shall be removed from the catch basin insert when it has filled one-third of the available storage. Inspection daily Erosion and Sediment Control Inspection Form Inspector(s):________________________________Date:________________ Site Name and Location:___________________________________________ Current Weather Conditions:_____________ Last 24 Hours:______________ BMP Designation Not O.K. BMP Condition, Corrective Action, General Notes Construction Access Trackout? Street Clean? Soil Stabilization Signs of Erosion: Gullies? Slope Failures? Rills? Slope Protection Plastic Condition? Grass Growing? Hydroseed Condition? Matting? Perimeter Control Clearing Limits Marked? Silt Fences? Swales? Conveyances Stable Ditches? Check Dams Intact? Sand Bags? Slope Drains? TESC Management Revisions Required? Water Management Infiltration System? Clean and Dirty Water Separated? Off-site Water Bypassing? Outlet Protection Stabilized? Erosion and Sediment Control Inspection Form BMP Designation t O.K. BMP Condition, Corrective Action, General Notes Stormwater Detention And Monitoring BMP Maintenance Inlet Protection Dust Control Spill Prevention Condition of Discharge Water Comments:_______________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ ____ 180 SECTION 9 – BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT A Bond Quantity Worksheet, Stormwater Facility Summary Sheet, and/or Declaration of Covenant shall be provided as required prior to project finalization. 181 SECTION 10 – OPERATIONS AND MAINTENANCE MANUAL The Operation and Maintenance (O&M) Manual will be kept on-site and may be reviewed by the City of Federal Way at its request. The maintenance tasks for the site’s storm system and frequency of each task is included in the the O&M Manual. A sample maintenance activity log indicating emergency and routine actions taken is included as well. 182 FIGURE 10.1 – OPERATIONS AND MAINTENANCE MANUAL OPERATIONS AND MAINTENANCE MANUAL FOR PLANT 2 RELOCATION JUNE 9, 2022 TABLE OF CONTENTS PROJECT DESCRIPTION .................................................................................................................... 1 PREVENTATIVE BMP’s ..................................................................................................................... 1 INSPECTION ............................................................................................................................ 2 MAINTENANCE TASKS AND FREQUENCY ........................................................................................ 2 MAINTENANCE RESPONSIBILITY ..................................................................................................... 2 INSTRUCTIONS FOR MAINTENANCE CHECKLISTS ........................................................................... 2 MAINTENANCE STANDARDS FOR DRAINAGE FACILITIES ............................................................... 3 35072_Fed Way Plant 2 Relocation O&M_060922.doc 1 The maintenance requirements for this storm system and frequencies of each task are included in this Operations and Maintenance (O&M) Manual. PROJECT DESCRIPTION The proposed project site is within a portion of the southeast quarter of the southeast quarter of Section 20, Township 21 North, Range 4 East, W.M., City of Federal Way, Washington. The parcels, 202104-9043, 202104-9155, 202104-9162, and 202104-9163, containing approximately 4.19 acres, are located at 35000 Pacific Highway South and are currently being used as a truck storage facility. The project site is abutted by a commercial shopping center to the north and east, Pacific Highway South (State Route 99) to the west, and a King County fire protection facility to the south. The existing parcels have three buildings and are covered predominantly with gravel and asphalt paving with limited vegetation. The project site consists of a single Threshold Discharge Area. Generally, runoff from the western half of the site flows to the west to the existing storm conveyance system located within Pacific Hwy. S., and runoff from the eastern half of the site flows to the south to the existing storm conveyance system located within S. 351st Street which is then conveyed to the west to Pacific Hwy. S. Runoff from adjacent properties does not appear to drain onto the project site. A concrete batch plant is proposed on the project site. The majority of the site is proposing to be paved for plant operation and parking areas and will also include a shop/storage building, covered storage bins, concrete plant silos and equipment, and perimeter landscape buffer. Full roadway improvements to S. 351st Street are proposed. The roadway is currently private but is proposing to be built to public standards (Cross Section Type R) including 40 feet of pavement with curb and gutter, 4 foot planter strip, and 6 foot sidewalk both sides. The majority of the project site is providing oil control and enhanced basic water quality treatment through the use of a coalescing plate oil/water separator, presettling vault, and Oldcastle BioPod Biofilter. Water quantity control is proposed with an underground infiltration vault. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities. This basin is proposing an Oldcastle Biopod Biofilter for water quality treatment and will discharge to the existing conveyance system within Pacific Highway South. Refer to Section 4 of the Technical Information Report for additional information regarding the proposed storm systems. PREVENTATIVE BMP’s Catch basins are to have sumps to allow large particulate to settle without being introduced to the main conveyance line. Also, the sumps will facilitate in maintaining and cleaning the system. 2 INSPECTION Facility maintenance checklist sheets are contained in this manual. Drainage facilities shall be maintained per King County requirements. Specific maintenance schedule is difficult to anticipate at this time but it is recommend that inspection of the facilities be worked into the regular schedule of the proposed site and other general maintenance, in addition to inspections being made following larger less frequent storm events. Proper correction to observed problems shall be as outlined in the following excerpts from the King County Surface Water Design Manual (KCSWDM). MAINTENANCE TASKS AND FREQUENCY See attached Maintenance checklists. Sediment and objects should be removed from catch basins when a depth of six (6) inches or more has accumulated. Sediment and objects should be removed from pipes when a depth of twenty (20) percent of the diameter of the pipe or more has accumulated. This maintenance activity should be performed by professionals familiar with the proper disposal of hazardous wastes. MAINTENANCE RESPONSIBILITY The property owner will be responsible for the maintenance of the storm system within the site. INSTRUCTIONS FOR MAINTENANCE CHECKLISTS The following pages contain maintenance needs for the components that are part of the drainage system, as well as for some components that may not be included. Ignore the requirements that do not apply. Plan to complete a checklist for all system components on the following schedule: 1. Monthly from November through April 2. Once in late summer (preferably September) 3. After any major storm (Use 1 inch in 24 hours as a guideline) Using photocopies of these pages, check off and date the conditions looked for each time an inspection was completed. Add comments on problems found and actions taken. 3 This O&M Manual/Checklist is to be kept on-site. It is suggested that photocopies of the checklist should be kept in a binder and the checklists updated as required. MAINTENANCE STANDARDS FOR DRAINAGE FACILITIES The following pages contain maintenance standards for typical stormwater facilities that may be required for stormwater mitigation. If the proposed stormwater system contains facilities or components that are not listed, the owner is responsible for developing additional maintenance standards and checklists for the proposed facility or component. Stormwater facilities and components should be inspected as specified in the applicable maintenance standards. The maintenance standards can be used as inspection forms for the system and associated components. Record the date each time an inspection is completed and note any problems and actions taken. Keep completed forms with the Operations and Maintenance Manual. City staff may request to review the maintenance forms as a part of their inspection process. Some components or facilities do not need to be looked at every time an inspection is conducted. Use the suggested frequency at the left of each item as a guideline for activities to be completed with each inspection. The facility-specific maintenance standards contained in this section are intended to be conditions for determining if maintenance actions are required as identified through inspection. They are not intended to be measures of the facility’s required condition at all times between inspections. In other words, exceeding these conditions at any time between inspections and/or maintenance does not automatically constitute a violation of these standards. However, based upon inspection observations, the inspection and maintenance schedules shall be adjusted to minimize the length of time that a facility is in condition that required a maintenance action. MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 2 – INFILTRATION FACILITIES Maintenance Component Defect or Problem Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Infiltration Pond, Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Infiltration Pond, Tank, Vault, Trench, or Small Basin Storage Area Sediment accumulation If two inches or more sediment is present or a percolation test indicates facility is working at or less than 90% of design. Facility infiltrates as designed. Liner damaged (If Applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Infiltration Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Infiltration Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-3 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 2 – INFILTRATION FACILITIES Maintenance Component Defect or Problem Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Infiltration Pond, Tank, Vault, Trench, or Small Basin Filter Bags Plugged Filter bag more than 1/2 full. Replace filter bag or redesign system. Infiltration Pond, Tank, Vault, Trench, or Small Basin Pre- settling Ponds and Vaults Sediment accumulation 6" or more of sediment has accumulated. Pre-settling occurs as designed Infiltration Pond, Rock Filter Plugged High water level on upstream side of filter remains for extended period of time or little or no water flows through filter during heavy rain storms. Rock filter replaced evaluate need for filter and remove if not necessary. Infiltration Pond Emergency Overflow Spillway Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-4 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Structure Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the structure opening or is blocking capacity of the structure by more than 10%. No Trash or debris blocking or potentially blocking entrance to structure. Trash or debris in the structure that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the structure. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Sediment Sediment exceeds 60% of the depth from the bottom of the structure to the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Sump of structure contains no sediment. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering structure through cracks, or maintenance person judges that structure is unsound. Structure is sealed and structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering structure through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Structure has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder rungs missing or unsafe Ladder is unsafe due to missing rungs, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. FROP-T Section Damage T section is not securely attached to structure wall and outlet pipe structure should support at least 1,000 lbs of up or down pressure. T section securely attached to wall and outlet pipe. Structure is not in upright position (allow up to 10% from plumb). Structure in correct position. Connections to outlet pipe are not watertight or show signs of deteriorated grout. Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. Any holes—other than designed holes—in the structure. Structure has no holes other than designed holes. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-7 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate. Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one maintenance person. Gate moves up and down easily and is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing Control device is not working properly due to missing, out of place, or bent orifice plate. Plate is in place and works as designed. Obstructions Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having the potential of blocking) the overflow pipe. Pipe is free of all obstructions and works as designed. Deformed or damaged lip Lip of overflow pipe is bent or deformed. Overflow pipe does not allow overflow at an elevation lower than design Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates (If Applicable) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-8 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Structure Sediment Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-9 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Metal Grates (Catch Basins) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 6 – CONVEYANCE PIPES AND DITCHES Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/roots Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vegetation Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If Applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-11 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 17 – WETVAULT Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from facility site. Treatment Area Trash and debris Any trash and debris accumulated in vault (includes floatables and non-floatables). No trash or debris in vault. Sediment accumulation Sediment accumulation in vault bottom exceeds the depth of the sediment zone plus 6 inches. No sediment in vault. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks, vault does not retain water or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. Baffles damaged Baffles corroding, cracking, warping and/or showing signs of failure or baffle cannot be removed. Repair or replace baffles or walls to specifications. Ventilation Ventilation area blocked or plugged. No reduction of ventilation area exists. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won’t seal Valve does not seal completely. Valve completely seals closed. Access Manhole Access cover/lid damaged or difficult to open Access cover/lid cannot be easily opened by one person. Corrosion/deformation of cover/lid. Access cover/lid can be opened by one person. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Access doors/plate has gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-23 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR Maintenance Component Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed Site Trash and debris Any trash or debris which impairs the function of the facility. Trash and debris removed from facility. Contaminants and pollution Floating oil in excess of 1 inch in first chamber, any oil in other chambers or other contaminants of any type in any chamber. No contaminants present other than a surface oil film. Vault Treatment Area Sediment accumulation in the forebay Sediment accumulation of 6 inches or greater in the forebay. No sediment in the forebay. Discharge water not clear Inspection of discharge water shows obvious signs of poor water quality - effluent discharge from vault shows thick visible sheen. Repair function of plates so effluent is clear. Trash or debris accumulation Trash and debris accumulation in vault (floatables and non-floatables). Trash and debris removed from vault. Oil accumulation Oil accumulation that exceeds 1 inch at the water surface in the in the coalescing plate chamber. No visible oil depth on water and coalescing plates clear of oil. Coalescing Plates Damaged Plate media broken, deformed, cracked and/or showing signs of failure. Replace that portion of media pack or entire plate pack depending on severity of failure. Sediment accumulation Any sediment accumulation which interferes with the operation of the coalescing plates. No sediment accumulation interfering with the coalescing plates. Vault Structure Damage to Wall, Frame, Bottom, and/or Top Slab Cracks wider than ½-inch and any evidence of soil particles entering the structure through the cracks, or maintenance inspection personnel determines that the vault is not structurally sound. Vault replaced or repaired to design specifications. Baffles damaged Baffles corroding, cracking, warping and/or showing signs of failure as determined by maintenance/inspection person. Repair or replace baffles to specifications. Ventilation Pipes Plugged Any obstruction to the ventilation pipes. Ventilation pipes are clear. Shutoff Valve Damaged or inoperable Shutoff valve cannot be opened or closed. Shutoff valve operates normally. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-33 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR Maintenance Component Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat and cover access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. NO. 24 – CATCH BASIN INSERT Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Media Insert Visible Oil Visible oil sheen passing through media Media inset replaced. Insert does not fit catch basin properly Flow gets into catch basin without going through media. All flow goes through media. Filter media plugged Filter media plugged. Flow through filter media is normal. Oil absorbent media saturated Media oil saturated. Oil absorbent media replaced. Water saturated Catch basin insert is saturated with water, which no longer has the capacity to absorb. Insert replaced. Service life exceeded Regular interval replacement due to typical average life of media insert product, typically one month. Media replaced at manufacturer’s recommended interval. Seasonal maintenance When storms occur and during the wet season. Remove, clean and replace or install new insert after major storms, monthly during the wet season or at manufacturer’s recommended interval. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-34 Inspection and Maintenance Guide BIOPODTM SYSTEM WITH STORMMIX™ MEDIA BioPod™ Biofilter with StormMix™ Biofiltration Media Description The BioPod™ Biofilter System (BioPod) is a stormwater biofiltration treatment system used to remove pollutants from stormwater runoff. Impervious surfaces and other urban and suburban landscapes generate a variety of contaminants that can enter stormwater and pollute downstream receiving waters unless treatment is provided. The BioPod system uses proprietary StormMix™ biofiltration media to capture and retain pollutants including total suspended solids (TSS), metals, nutrients, gross solids, trash and debris as well as petroleum hydrocarbons. Function The BioPod system uses engineered, high-flow rate filter media to remove stormwater pollutants, allowing for a smaller footprint than conventional bioretention systems. Contained within a compact precast concrete vault, the BioPod system consists of a biofiltration chamber and an optional integrated high-flow bypass with a contoured inlet rack to minimize scour. The biofiltration chamber is filled with horizontal layers of aggregate (which may or may not include an underdrain), biofiltration media and mulch. Stormwater passes vertically down through the mulch and biofiltration media for treatment. The mulch provides pretreatment by retaining most of the solids or sediment. The biofiltration media provides further treatment by retaining finer sediment and dissolved pollutants. The aggregate allows the media bed to drain evenly for discharge through an underdrain pipe or by infiltration. Configuration The BioPod system can be configured with either an internal or external bypass. The internal bypass allows both water quality and bypass flows to enter the treatment vault. The water quality flows are directed to the biofiltration chamber while the excess flows are diverted over the bypass weir without entering the biofiltration chamber. Both the treatment and bypass flows are combined in the outlet area prior to discharge from the structure. BioPod units without an internal bypass are designed such that only treatment flows enter the treatment structure. When the system has exceeded its treatment capacity, ponding will force bypass flows to continue down the gutter to the nearest standard catch basin or other external bypass structure. The BioPod system can be configured as a tree box filter with tree and grated inlet, as a planter box filter with shrubs, grasses and an open top, or as an underground filter with access risers, doors and a subsurface inlet pipe. The optional internal bypass may be incorporated with any of these configurations. In addition, an open bottom configuration may be used to promote infiltration and groundwater recharge. The configuration and size of the BioPod system is designed to meet the requirements of a specific project. Inspection & Maintenance Overview State and local regulations require all stormwater management systems to be inspected on a regular basis and maintained as necessary to ensure performance and protect downstream receiving waters. Without maintenance, excessive pollutant buildup can limit system performance by reducing the operating capacity of the system and increasing the potential for scouring of pollutants during periods of high flow. Some configurations of the BioPod may require periodic irrigation to establish and maintain vegetation. Vegetation will typically become established about two years after planting. Irrigation requirements are ultimately dependent on climate, rainfall and the type of vegetation selected. 2 INSPECTION AND MAINTENANCE GUIDE 3 Maintenance Frequency Periodic inspection is essential for consistent system performance and is easily completed. Inspection is typically conducted a minimum of twice per year, but since pollutant transport and deposition varies from site to site, a site-specific maintenance frequency should be established during the first two or three years of operation. Inspection Equipment The following equipment is helpful when conducting BioPod inspections: • Recording device (pen and paper form, voice recorder, iPad, etc.) • Suitable clothing (appropriate footwear, gloves, hardhat, safety glasses, etc.) • Traffic control equipment (cones, barricades, signage, flagging, etc.) • Manhole hook or pry bar • Flashlight • Tape measure Inspection Procedures BioPod inspections are visual and are conducted without entering the unit. To complete an inspection, safety measures including traffic control should be deployed before the access covers or tree grates are removed. Once the covers have been removed, the following items should be checked and recorded (see form provided on page 6) to determine whether maintenance is required: • If the BioPod unit is equipped with an internal bypass, inspect the contoured inlet rack and outlet chamber and note whether there are any broken or missing parts. In the unlikely event that internal parts are broken or missing, contact Oldcastle Stormwater at (800) 579-8819 to determine appropriate corrective action. • Note whether the curb inlet, inlet pipe, or – if the unit is equipped with an internal bypass – the inlet rack is blocked or obstructed. • If the unit is equipped with an internal bypass, observe, quantify and record the accumulation of trash and debris in the inlet rack. The significance of accumulated trash and debris is a matter of judgment. Often, much of the trash and debris may be removed manually at the time of inspection if a separate maintenance visit is not yet warranted. • If it has not rained within the past 24 hours, note whether standing water is observed in the biofiltration chamber. • Finally, observe, quantify and record presence of invasive vegetation and the amount of trash and debris and sediment load in the biofiltration chamber. Erosion of the mulch and biofiltration media bed should also be recorded. Sediment load may be rated light, medium or heavy depending on the conditions. Loading characteristics may be determined as follows: o Light sediment load – sediment is difficult to distinguish among the mulch fibers at the top of the mulch layer; the mulch appears almost new. o Medium sediment load – sediment accumulation is apparent and may be concentrated in some areas; probing the mulch layer reveals lighter sediment loads under the top 1” of mulch. o Heavy sediment load – sediment is readily apparent across the entire top of the mulch layer; individual mulch fibers are difficult to distinguish; probing the mulch layer reveals heavy sediment load under the top 1” of mulch. Often, much of the invasive vegetation and trash and debris may be removed manually at the time of inspection if a separate maintenance visit is not yet warranted. 4 Maintenance Indicators Maintenance should be scheduled if any of the following conditions are identified during inspection: •The concrete structure is damaged or the tree grate or access cover is damaged or missing. •The curb inlet or inlet rack is obstructed. •Standing water is observed in the biofiltration chamber more than 24 hours after a rainfall event (use discretion if the BioPod is located downstream of a storage system that attenuates flow). •Trash and debris in the inlet rack cannot be easily removed at the time of inspection. •Trash and debris, invasive vegetation or sediment load in the biofiltration chamber is heavy or excessive erosion has occurred. Maintenance Equipment The following equipment is helpful when conducting BioPod maintenance: •Suitable clothing (appropriate footwear, gloves, hardhat, safety glasses, etc.) •Traffic control equipment (cones, barricades, signage, flagging, etc.) •Manhole hook or pry bar •Flashlight •Tape measure •Rake, hoe, shovel and broom •Bucket •Pruners •Vacuum truck (optional) Maintenance Procedures Maintenance should be conducted during dry weather when no flows are entering the system. All maintenance may be conducted without entering the BioPod structure. Once safety measures such as traffic control are deployed, the access covers may be removed and the following activities may be conducted to complete maintenance: •Remove all trash and debris from the curb inlet and inlet rack manually or by using a vacuum truck as required. •Remove all trash and debris and invasive vegetation from the biofiltration chamber manually or by using a vacuum truck as required. •If the sediment load is medium or light but erosion of the biofiltration media bed is evident, redistribute the mulch with a rake or replace missing mulch as appropriate. If erosion persists, rocks may be placed in the eroded area to help dissipate energy and prevent recurring erosion. •If the sediment load is heavy, remove the mulch layer using a hoe, rake, shovel and bucket, or by using a vacuum truck as required. If the sediment load is particularly heavy, inspect the surface of the biofiltration media once the mulch has been removed. If the media appears clogged with sediment, remove and replace one or two inches of biofiltration media prior to replacing the mulch layer. •Prune vegetation as appropriate and replace damaged or dead plants as required. •Replace the tree grate and/or access covers and sweep the area around the BioPod to leave the site clean. •All material removed from the BioPod during maintenance must be disposed of in accordance with local environmental regulations. In most cases, the material may be handled in the same manner as disposal of material removed from sumped catch basins or manholes. Natural, shredded hardwood mulch should be used in the BioPod. Timely replacement of the mulch layer according to the maintenance indicators described above should protect the biofiltration media below the mulch layer from clogging due to sediment accumulation. However, whenever the mulch is replaced, the BioPod should be visited 24 hours after the next major storm event to ensure that there is no standing water in the biofiltration chamber. Standing water indicates that the biofiltration media below the mulch layer is clogged and must be replaced. Please contact Oldcastle Infrastructure at (800) 579-8819 to purchase the proprietary StormMix™ biofiltration media. 5 BioPod Tree Module BioPod Media Module BioPod Planter Module BioPod Media Vault 6 Curb Inlet or Inlet Rack Blocked Notes: Yes No BioPod Inspection & Maintenance Log BioPod Model__________________________ Inspection Date________________________ Location______________________________________________________________________________ Condition of Internal Components Notes: Good Damaged Missing Standing Water in Biofiltration Chamber Notes: Yes No Trash and Debris in Inlet Rack Notes: Yes No Trash and Debris in Biofiltration Chamber Notes: Yes No Maintenance Requirements Yes - Schedule Maintenance No - Schedule Re-Inspection Invasive Vegetation in Biofiltration Chamber Notes: Yes No Sediment in Biofiltration Chamber Notes: Light Medium Heavy Erosion in Biofiltration Chamber Notes: Yes No BIOPODTM SYSTEM WITH STORMMIX™ MEDIA BUILDING STRUCTURES OUR MARKETS TRANSPORTATION WATER ENERGYCOMMUNICATIONS December 2018 v.1 www.oldcastleinfrastructure.com 800-579-8819