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RS_Drainage_Report_180309_v1
TECHNICAL INFORMATION REPORT (FULL DRAINAGE REVIEW) KING COUNTY SOUTH TREATMENT PLANT –BIOGAS AND HEAT SYSTEMS IMPROVEMENTS PARCEL #:2423049006 &2423049097 ADDRESS:1200 MONSTER RD SW,RENTON,WA 98057 PROJECT #TBD February 2018 For Submittal to City of Renton D AVIDO CONSULTING GROUP,INC. 15029 Bothell Way NE, Ste 600 Lake Forest Park, WA 98155 Phone: 206.523.0024 Fax: 206.523.1012 Owner: King County Dept. of Natural Resources & Parks Wastewater Treatment Div. Attn: Susan Hildreth 201 South Jackson Street Seattle, Washington 98104 Phone: (206) 477-5537 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page i TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements CERTIFICATE OF ENGINEER The technical material and data contained within this report has been prepared by or under the direction of the following registered professional engineer(s), licensed in accordance with the laws of the State of Washington to practice in the State of Washington. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page ii TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements QUICK REFERENCE PROJECT INFORMATION General Project Information Project Description Construction of a new Heating and Energy Recovery Building (HERB) and associated driveway, uncovered parking stalls, walkways, concrete equipment pads, stormwater improvements, utility connections, and landscaping. Parcel #2423049006 & 2423049097 Site Address 1200 Monster Rd SW, Renton, WA 98057 Parcel Size 2,186,886 SF (50.2 Acres) Project Size 170,835 SF (3.92 Acres) Owner/Developer King County Dept. of Natural Resources & Parks Wastewater Treatment Div. Attn: Susan Hildreth 201 South Jackson Street Seattle, Washington 98104-3855 Phone:(206)477-5537 Consulting Engineer Erik Davido, P.E. – Davido Consulting Group, Inc. 15029 Bothell Way NE Lake Forest Park, WA 98155 Phone: (206)523-0024 Drainage Study Area The study area is the project site itself including the larger drainage basins for which the project site lies within and the downstream drainage system to its discharge location to the Black River. Drainage Requirements Full Drainage Review Requirements per the 2017 City of Renton Surface Water Design Manual (“the Manual”). Tributary Drainage Area & Land Cover Summary Predeveloped Conditions: Impervious = 615 SF PGIS = 0 SF Pervious Surface = 170,220 SF Total =170,835 SF Redeveloped Conditions: Impervious = 28,376 SF PGIS = 16,107 SF Pervious Surface = 142,459 SF Total =170,835 SF Soils Geotechnical analysis and report completed by Shannon & Wilson, Inc.(S&W)(attached herein) Drainage Improvements ·Stormwater Detention Vault ·Water Quality Facility (MWS-Linear Modular Wetland) ·On-site BMPs (Basic Dispersion) ESC Measures ESC measures per Full Drainage Requirements Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page iii TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements TABLE OF CONTENTS 1.Project Overview ..........................................................................................................5 1.1 General Description of Proposal ...................................................................................8 1.2 Existing Site Conditions ...............................................................................................8 1.3 Developed Site Conditions............................................................................................8 1.4 Site Area and Size of Improvements .............................................................................9 1.5 Disposition of Stormwater before Project......................................................................9 1.6 Disposition of Stormwater after Project ...................................................................... 10 1.7 Soils ........................................................................................................................... 10 2.Conditions and Requirements Summary ..................................................................... 13 2.1 Core Requirement #1: Discharge at Natural Location ................................................. 13 2.2 Core Requirement #2: Offsite Analysis ....................................................................... 13 2.3 Core Requirement #3: Flow Control ........................................................................... 13 2.4 Core Requirement #4: Conveyance System................................................................. 13 2.5 Core Requirement #5: Construction Stormwater Pollution Prevention ........................ 14 2.6 Core Requirement #6: Maintenance and Operations .................................................... 14 2.7 Core Requirement #7: Financial Guarantees and Liability........................................... 14 2.8 Core Requirement #8: Water Quality .......................................................................... 14 2.9 Core Requirement #9: On-Site BMPs ......................................................................... 14 2.10 Special Requirement #1: Other Adopted Area-Specific Requirements ........................ 16 2.11 Special Requirement #2: Flood Hazard Area Delineation ............................................ 16 2.12 Special Requirement #3: Flood Protection Facilities ................................................... 17 2.13 Special Requirement #4: Source Control ..................................................................... 17 2.14 Special Requirement #5: Oil Control .......................................................................... 17 2.15 Special Requirement #6: Aquifer Protection Area ....................................................... 17 3.Offsite Analysis .......................................................................................................... 17 4.Flow Control and Water Quality Facility Analysis and Design.................................... 17 4.1 Existing Site Hydrology .............................................................................................. 17 4.2 Developed Site Hydrology .......................................................................................... 18 4.3 Performance Standards ............................................................................................... 18 4.4 Flow Control .............................................................................................................. 18 4.4.1 Mitigation Trade .................................................................................................... 20 4.5 Water Quality ............................................................................................................. 21 4.5.1 Treatment Trade..................................................................................................... 21 5.Conveyance System Analysis and Design ................................................................... 22 5.1 Existing Conveyance .................................................................................................. 22 5.2 Proposed Conveyance ................................................................................................. 22 6.Special Reports and Studies ........................................................................................ 22 7.Other Permits.............................................................................................................. 23 8.Construction SWPPP Analysis and Design ................................................................. 23 8.1 ESC Plan Analysis and Design ................................................................................... 23 8.2 Stormwater Pollution Prevention and Spill Plan Design .............................................. 24 9.Bond Quantities, Facility Summaries, and Declaration of Covenants .......................... 25 10.Operations and Maintenance Manual .......................................................................... 25 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page iv TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDICES APPENDIX A Figure 1 - Technical Information Report (TIR) Worksheet APPENDIX B Geotechnical Report APPENDIX C Drainage Plans APPENDIX D Temporary Erosion and Sediment Control Plan APPENDIX E Enlargement III Drainage Report APPENDIX F Offsite Analysis Documentation APPENDIX G WWHM Modeling Summaries (Flow Control & Water Quality) APPENDIX H Conveyance Calculations APPENDIX I Stormwater BMP Adjustment APPENDIX J Stormwater Facility Summary Sheet APPENDIX K Declaration of Covenants APPENDIX L Operation and Maintenance Manual APPENDIX M Renton Flood Hazard Map LIST OF TABLES TABLE 1 Project Site Area and Size of Improvements .........................................................9 TABLE 2 WWHM Areas .................................................................................................... 19 TABLE 3 WWHM Input Parameters and Results ................................................................ 19 TABLE 4 Proposed ESC Measures and Construction Sequencing ....................................... 24 LIST OF FIGURES FIGURE 1 TIR Worksheet………………………………………………...….…APPENDIX A FIGURE 2 Vicinity Map ........................................................................................................5 FIGURE 3 Project Limits .......................................................................................................7 FIGURE 4 Drainage Basins, Subbasins, and Site Characteristics .......................................... 11 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 5 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements 1.PROJECT OVERVIEW The project is located at the King County South Treatment Plant which is located at 1200 Monster Road SW (the “Site”) in Renton, WA (the “City”). A vicinity map is provided below in FIGURE 2. The Site is bounded to the north by Oaksdale Ave SW, to the west Monster Road SW, to the east by Springbrook Creek and Oaksdale Ave SW, and to the south by Jackson Pl SW, Longacres Drive SW, and SW Grady Way. The project proposes to replace the Site’s Biogas Upgrading System (BUS) and heating system to improve the beneficial use of digester gas at the Site while also reliably supplying heat to meet process and heating demands. FIGURE 2 Vicinity Map The project involves the construction of a Heating and Energy Recovery Building (HERB), a new thermal oxidizer, heating system improvements within the existing Digester Equipment Building, and utility connections. Site improvements include a new driveway around the west and south sides of the HERB, seven uncovered parking stalls north of the HERB, and concrete walkways and equipment staging areas surrounding the HERB on three sides. The thermal oxidizer will be located outside on a new concrete pad approximately 250’ west of the HERB and just south of an existing waste gas burner facility on the site. Site Location Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 6 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements The proposed location of the HERB is currently occupied by a large mound of soil which is now covered with grass and other vegetation. The large mound of fill was created from spoils from previous construction and expansion projects at the Site. This project proposes to move the spoils pile (approximately 11,000 CY) to a separate spoils pile on the site which is located south of the HERB. FIGURE 3 shows the anticipated project limits including the existing and proposed spoils locations. The project will adhere to the 2017 City of Renton Surface Water Design Manual, which is hereafter referred to as “the Manual”. This report follows the Technical Information Report (TIR) requirements for Full Drainage Review per Section 1.1 of the Manual. The TIR worksheet is attached as FIGURE 1 in APPENDIX A. 0.5' SS IR DRN DRN 126 127 128 1 2 9 1 3 1 129 128 127 126 126 13 0 142 142 141 140140135 1 4 1 1 4 1 14 0 140 140 140 L I M I T S L I M I T S L I M I T S LI M I T S LI M I T S LI M I T S LI M I T S L I M I T S LIMITS LIMITS LIMITS LIMITSLIMITSLIMITSLIMITS L I M I T S LI M I T S LIM I T S LI M I T S LI M I T S LIMITS L I M I T S LIMITS LIMITSFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOODFLOOD200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FTOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWMOHWM WT L B F R LIMITS LIMITSLIMITSAREA 23 AREA 22 AREA 21 AREA 17 AREA 16 AREA 15 AREA 28 AREA 27 AREA 26 AREA 24 AREA 18 AREA 10 AREA 9 AREA 8 AREA 11 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ G - G E N E R A L \ 2 2 4 - 1 1 2 3 6 2 6 G 0 0 0 0 0 1 5 . d w g | L a y o u t : G 0 0 0 0 0 1 5 K E Y P L A N A N D I N D E X PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 4 1 : 3 4 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S u r v . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l E x i s t i n g B a s e m a p . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S i t e P l a n _ C 3 D . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l P i p e _ C 3 D . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S i t e I n d e x . d w g ; W W T P K e y P l a n . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l L i m i t s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l W i p e o u t . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 KEY PLAN AND INDEX AREA 16, 17, 18, 21, 22 G0000015 D. Saarenas E. Davido 1" = 80' 0 R. Bard AREA SHOWN ON THIS PLAN WWTP KEY PLAN NO SCALE 33723 OAKESDALE PROPOSED THERMAL OXIDIZER EXISTING DIGESTERFACILITY PROPOSED HEATING AND ENERGY RECOVERY BUILDING (HERB) EXISTING SPOILS LOCATION PROPOSEDSPOILSLOCATIONAVE SWSPRINGBROOK CREEK SW 7TH ST GENERAL NOTES:1.CIVIL HATCH PATTERNS AREIDENTIFIED ON SHEET C0000001 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 8 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements 1.1 General Description of Proposal The project involves the construction of the HERB which will be located west of the existing Solids MCC Building and will be utilized to house the BUS and boilers. Additional improvements include a new driveway around the west and south sides of the HERB, uncovered parking stalls, walkways, concrete equipment pads, stormwater improvements, utility connections, and landscaping. No changes to vehicular or pedestrian access to the site will occur during this project. However, minor changes to circulation internal of the site include the proposed driveway around the HERB which will connect to existing roads currently providing access around the site and approximately 407 SF of asphalt walkway for pedestrian circulation south of the HERB will require realignment. No frontage improvements or work within the public rights-of-way are proposed for this project. 1.2 Existing Site Conditions The overall South Treatment Plant is comprised mainly of wastewater treatment facilities, roadways, parking areas, and walkways. Most of the site is covered in a combination of impervious surfaces and wastewater treatment facilities. The South Treatment Plant was expanded in the early 1990’s as a part of the Metro Treatment Plant at Renton – Enlargement III project. A drainage report dated April 29, 1992 was created by Brown & Caldwell for the Enlargement III project (hereafter referred to as the “Enlargement III Drainage Report”) and a copy of the Enlargement III Drainage Report is included as APPENDIX J of this report. The Enlargement III Drainage Report provides additional information on the existing site conditions. The project site, for use in this report, is defined as the area of anticipated disturbance associated with the biogas and heat systems improvements, and is shown in FIGURE 3. The proposed location of the HERB is currently occupied by a large mound of fill soil which is now covered with well-established grass. The large mound of fill was created from spoils from previous construction and expansion projects at the Site (hereafter referred to as the “West Spoils Area”). The West Spoils Area is surrounded by roads on three sides which are used for internal access of the Site. To the east of the West Spoils Area is the existing Solids MCC Building. The West Spoils Area will be flattened as a portion of the proposed project and relocated to a separate existing spoils area south of the proposed HERB (hereafter referred to as the “South Spoils Area”. The South Spoils Area is currently a large mound of fill soil that is covered with well- established grass and trees. The entire project site is within Drainage Basin 7, as defined in the Enlargement III Drainage Report, which drains to the stormwater sewer system on the site and ultimately discharges to the Black River. TABLE 1 summarizes the existing land cover of the project site. 1.3 Developed Site Conditions The developed site conditions, shown in the project plans submitted under separate cover, will include the HERB (11,862 SF) and associated new driveway and parking area (10,251), concrete walkways and equipment pad (3,677 SF), and asphalt walkway (407 SF). In addition, the new thermal oxidizer pad (2,437 SF) will be located west of the West Spoils Area. All disturbed pervious areas, including the West and South Spoils Areas, will be improved with new landscaping and is shown on the Landscape Plans submitted separately. Runoff from the entire project area will ultimately drain to the storm sewer system onsite which discharges to the Black Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 9 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements River. TABLE 1 summarizes the developed site conditions and land cover. FIGURE 4 shows the developed project site drainage basin maps. 1.4 Site Area and Size of Improvements The pre-developed and developed site areas and size of improvements are shown in FIGURE 4 and summarized in TABLE 1. TABLE 1 Project Site Area and Size of Improvements Project Site Areas Existing Developed SF Acres SF Acres Impervious Areas: Ex Access Roads 5,382 0.12 5,382 0.12 Ex Asphalt Walkway 1,259 0.03 601 0.01 HERB 11,862 0.27 Driveway & Parking 10,251 0.24 Concrete Walkways & Equipment Pad 3,677 0.08 Asphalt Walkway 407 0.01 Thermal Oxidizer Pad 2,437 0.06 Total Impervious Surface 6,641 0.15 34,617 0.79 Total New/Replaced Impervious Surface:28,634 0.66 Total Pollution Generating Impervious Surface:21,747 0.50 Total New/Replaced Pollution Generating Impervious Surface:16,365 0.38 Pervious Areas: Landscaping/Grass 185,183 4.25 157,207 3.61 Total Pervious Surface 185,183 4.25 157,207 3.61 Total Project Site Area*191,824 4.40 191,824 4.40 *The Project Limits are shown in FIGURE 3. The areas shown in TABLE 1 include land cover areas within the Project Limits only. The land cover areas in TABLE 1 were determined by area measurements in AutoCAD from a topographic survey completed in September, 2017, by True North Land Surveying, Inc. As shown by TABLE 1, the project is adding 28,634 SF of new plus replaced impervious surface comprised of the HERB, new driveway and parking area, concrete walkways and equipment pad, thermal oxidizer pad, and asphalt walkway. The project is adding 16,365 SF of new plus replaced pollution generating impervious surface comprised of the new driveway and parking area, concrete walkways and equipment pads which flow onto the new driveway and parking area, and thermal oxidizer pad which flows onto an existing roadway on the Site. 1.5 Disposition of Stormwater before Project Existing drainage basins and outfalls located within the overall King County South Treatment Plant are shown and described in detail in the Enlargement III Drainage Report attached as APPENDIX J of this report. The Enlargement III Drainage Report explains that the storm drainage systems at the South Treatment Plant are distributed into 7 major drainage basins with Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 10 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements multiple discharge locations. This project is located within Drainage Basin 7, which drains to the stormwater sewer system onsite and eventually discharges to the Black River. 1.6 Disposition of Stormwater after Project Runoff from the developed site will mimic the runoff from the predeveloped site as stormwater from all new and replaced impervious surfaces other than the thermal oxidizer pad and asphalt walkway will be collected and routed to a proposed detention facility which will restrict flow exiting the vault to match the existing site conditions 2, 10, and 100-year peak-rate runoffs. A mitigation trade will be utilized for the thermal oxidizer area which will consist of 2,935 SF of the existing roadway north of the HERB to flow onto the proposed driveway and parking area and be collected and routed to the detention facility in-lieu of collecting stormwater from the thermal oxidizer pad (see Section 4 of this report for additional information on the mitigation trade). The proposed asphalt walkway (approximately 407 SF) will disperse via sheet flow into new and existing landscaped areas. Stormwater discharged from the detention facility will be routed to the existing storm sewer system onsite which is located within the existing road north of the HERB and will ultimately discharge to the Black River. Refer to the project plans and Section 4 of this report for more details about the proposed stormwater mitigation methods. See FIGURE 4 for drainage basin maps of the developed project site. 1.7 Soils Geotechnical investigations were completed by Shannon & Wilson, Inc. (S&W) and the results of these investigations are summarized in a report dated January 6, 2017 and an addendum dated December 8, 2017. S&W performed three Pilot Infiltration Tests (PITs) at the project site between October 9th and 12th, 2017, to evaluate the suitability of soils for onsite infiltration. Test Pit #1, located near the northeast corner of the HERB was excavated to a depth of approximately 7 feet below ground surface. Test Pit #2, located near the northwest corner of the HERB was excavated to a depth of approximately 10 feet below ground surface. Lastly, Test Pit #3, located near the proposed thermal oxidizer pad, was excavated to a depth of approximately 10 feet below ground surface. Test Pit #1 resulted in a measured infiltration rate of 0.02 inches per hour while Test Pit #2 and #3 indicated negligible infiltration rates. A copy of the final S&W report and addendum is included in APPENDIX B. FIGURE 4 - DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS PROPOSED DETENTION VAULT PROPOSED DISCHARGE LOCATION TO EX STORM SYSTEM PROPOSED MODULAR WETLAND WQ FACILITY THERMAL OXIDIZER PAD TO DRAIN TO EX STORM SYSTEM IN ROAD Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 13 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements 2.CONDITIONS AND REQUIREMENTS SUMMARY The project conditions and requirements were stipulated in the Manual. The project is subject to Full Drainage Review requirements specified in Section 1.1.2.4 of the Manual and therefore must comply with all nine Core Requirements and all six Special Requirements. The following sections address the Manual’s Core and Special Requirements. 2.1 Core Requirement #1: Discharge at Natural Location The natural discharge location for the project site prior to the Enlargement III project was the Green River, but the Enlargement III project received a deviation which altered the permanent discharge location from the water quality wetponds (which were constructed as a part of the Enlargement III project) to the Black River. Since the drainage basin for which the project site lies within (Drainage Basin 7) is tributary to the water quality wetponds, the current permanent discharge location is the Black River. Runoff from the proposed improvements will emulate the natural pre-developed conditions of the site as much as possible since runoff will either disperse via sheet flow or be routed to a detention facility meeting the Peak Rate Flow Control Standard prior to discharging to the existing storm sewer system on the site. The existing storm sewer system routs stormwater to a pump station onsite which then pumps stormwater to the water quality wetponds prior to discharging to the Black River. Therefore, the natural, or current, drainage course from the project site will be kept intact, thus satisfying Core Requirement #1 of the Manual (see Sections 1.5 and 1.6). 2.2 Core Requirement #2: Offsite Analysis A detailed qualitative (Level 1) offsite analysis in accordance with Section 1.2.2 of the Manual was completed for Drainage Basin 7. The analysis began at the upstream (i.e. beginning) point of the storm sewer system onsite and ended at the discharge location to the Black River. See Section 3 and APPENDIX F for additional information on the offsite analysis. 2.3 Core Requirement #3: Flow Control The project is subject to Core Requirement #3 since it will add greater than 5,000 SF of new plus replaced impervious surface. Furthermore, the project site lies within the Peak Rate Flow Control Standard (Existing Site Conditions) Area according to the City of Renton Flow Control Application Map and therefore must meet the Peak Rate Flow Control Standard Area Performance Requirement by matching the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10-, and 100-year periods. This project will satisfy the Peak Rate Flow Control Standard Performance Requirement using a detention vault with associated flow restrictor tee. See Section 4.4 for additional information on the proposed flow control facility. 2.4 Core Requirement #4: Conveyance System Section 1.2.4 of the Manual requires that new pipe systems are designed with sufficient capacity to convey and contain (at a minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. The proposed conveyance system has been designed to have sufficient capacity to convey and contain greater Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 14 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements than the 100-year peak flow, as determined using the rational method described in Section 3.2.1 of the Manual. See Section 5 for additional information on the existing and proposed conveyance features and APPENDIX H for conveyance calculations for the proposed conveyance system. 2.5 Core Requirement #5: Construction Stormwater Pollution Prevention Construction Stormwater Pollution Prevention (CSWPP) measures include Erosion and Sediment Control (ESC) measures and Stormwater Pollution Prevention and Spill (SWPPS) measures. Each of the listed categories of ESC measures and SWPPS measures were considered for application to the project site. See Section 8 of this report for additional information on the ESC and SWPPS measures applicable to the project and APPENDIX D for plans showing the proposed ESC measures. 2.6 Core Requirement #6: Maintenance and Operations All proposed drainage facilities will be privately maintained by the King County Wastewater Treatment Division in accordance with Appendix A of the Manual, “Maintenance Requirements for Stormwater Facilities and On-site BMPs”, unless otherwise approved by the City. A copy of the pertinent guidelines is provided as Section 10 and APPENDIX L of this report. 2.7 Core Requirement #7: Financial Guarantees and Liability As a unit of local government, the King County Wastewater Treatment Division is exempted from surety bonds or other financial security devices as permit conditions per RCW 35.21.470. 2.8 Core Requirement #8: Water Quality The project is subject to Core Requirement #8 since it will add greater than 5,000 SF of new plus replaced pollution generating impervious surface (PGIS). Furthermore, since the project site is an industrial site, the Enhanced Basic Water Quality Menu must be used to satisfy Core requirement #8. This project will satisfy Core Requirement #8 using a MWS-Linear Modular Wetland facility, which is listed as an approved proprietary facility on the Enhanced Basic WQ Menu in Table 6.1.2.B of the Manual. See Section 4.5 for additional information on the water quality facility. 2.9 Core Requirement #9: On-Site BMPs Since the project will add greater than 2,000 SF of new plus replaced impervious surface it must provide onsite BMPs to mitigate the impacts of storm and surface water runoff generated by new impervious surfaces, new pervious surfaces, existing impervious surfaces, and replaced impervious surfaces targeted for mitigation. As described within Sections 1.2.9.2 and 1.2.9.3 of the Manual, there are two methods of satisfying the On-site BMP requirement: (1) application of BMPs to the maximum extent feasible using lists specific to the project location, size, and impervious coverage; or (2) using a continuous runoff model to demonstrate compliance with the Low Impact Development (LID) Performance Standard. Since the project is on a lot that is greater than 22,000 SF it is subject to Large Lot BMP Requirements listed in Section 1.2.9.2.2 of the Manual, which states that flow control BMPs must be applied as specified in Section 1.2.9.2.2 of the Manual or it must demonstrate compliance with the LID Performance Standard via an approved continuous modeling program. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 15 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements The project will apply BMPs as specified in Section 1.2.9.2.2 of the Manual and BMPs were evaluated in the order shown below. 1)Full Dispersion – Not feasible because the required native vegetated flowpath is not available onsite. 2)Full Infiltration of Roof Runoff – Not feasible since the onsite soils are not conducive to infiltration (see Section 1.7). 3)Next, the following were evaluated for the remaining target surfaces: ·Full Infiltration – Not feasible since the onsite soils are not conducive to infiltration (see Section 1.7). ·Limited Infiltration – Not feasible since the onsite soils are not conducive to infiltration (see Section 1.7). ·Bioretention – Not feasible since the field testing indicated a measured native soil saturated hydraulic conductivity of less than 0.30 inches per hour (see Section 1.7). ·Permeable Pavement – Not feasible since the field testing indicated a measured native soil saturated hydraulic conductivity of less than 0.30 inches per hour (see Section 1.7). 4)Next, the following was evaluated for the remaining target surfaces: ·Basic Dispersion – Sheet flow dispersion will be utilized for approximately 407 SF of new asphalt walkway located south of the HERB and will meet the requirements listed in Section C.2.4.5 of the Manual. The width of the walkway is 6.5 feet and the associated vegetated flowpath is perpendicular to the walkway with a length greater than 10 feet. A 2-foot strip of crushed rock will not be provided along the edge of the walkway since the walkway width is less than 10 feet. Basic dispersion cannot be applied to additional target impervious surfaces due to the limited pervious areas surrounding the site with the positive slope needed for dispersion. 5)Next, BMPs must be implemented, at a minimum, for impervious area amounts defined by the impervious surface coverage on the buildable portion of the site/lot. Since the project will result in an impervious surface coverage on the buildable portion of the project site/lot of less than 45%, on-site BMPs must be applied to 50% of the target impervious surfaces. The 407 SF of impervious surface for which basic dispersion will be applied results in 1.24% of the target impervious surface. Therefore, one or more of the following BMPs must be implemented to achieve compliance. The BMPs were evaluated as follows: ·Reduced Impervious Surface Credit – This credit does not apply to this project because the following: o The Restricted Footprint credit does not apply to parcels greater than 250,000 SF; and o The Wheel Strip Driveway credit does not apply because the only proposed driveway will be utilized as a fire access; and o The Minimum Disturbance Foundation credit cannot be applied because the necessary positive flow away from the building for dispersion cannot be obtained; and o The Open Grid Decking Over Pervious Surface Credit does not apply since there are no proposed decks. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 16 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements ·Native Growth Retention Credit – This credit cannot be applied to this project because there is very little native vegetated area onsite under the current conditions. Nearly the entire site has been cleared and/or developed for the wastewater treatment plant. Most of the native trees on the site are located around the perimeter of the site and screen the site from surrounding roads. ·Tree Retention Credit – This credit cannot be applied because all existing trees within 20 feet of the proposed impervious surfaces will be required to be removed due to excavation for the HERB and proposed utilities. Since BMPs cannot be applied to a minimum of 50% of the target impervious surfaces, the project is applying for a Standard Adjustment for relief from Core Requirement #9. The Standard Adjustment meets the criteria listed in Section 1.4.2 of the Manual and is attached in APPENDIX I. 6)All new pervious surfaces and disturbed pervious surfaces that will not be replaced with an impervious surface will be protected in accordance with the soil amendment BMP requirements listed in Appendix C, Section C.2.13 of the Manual. See the landscape plans submitted separately for soil amendment details. 7)The project is not proposing a new connection to the local drainage system and therefore is not required to implement a perforated pipe connection. In addition, a perforated pipe connection would likely provide very little, if any, infiltration since the measured infiltration rate in three separate test pits were all less than 0.02 inches per hour (see Section 1.7). 2.10 Special Requirement #1: Other Adopted Area-Specific Requirements In addition to the requirements of the Manual, this project shall comply with the drainage requirements of other adopted area-specific plans. Where conflicts may occur between the area- specific plans and the Manual, the area-specific plans shall have precedence. These area-specific plans include: ·Critical Drainage Areas (CDAs) – There are no CDAs on or around the project site. ·Master Drainage Plans (MDPs) – A MDP is not required for this project since the project is not an urban planned development (UPD) or other large project triggering a MDP. ·Basin Plans (BPs) – The project shall comply with the 2015 City of Renton Comprehensive Plan. ·Salmon Conservation Plans (SCPs) – The project shall comply with the rules and regulations of WRIA 9 Salmon Habitat Plan. ·Stormwater Compliance Plans (SWCPs) – Specific SWCPs do not apply to this project. ·Lake Management Plans (LMPs) – No LMPs apply to this project. ·Flood Hazard Reduction Plan Updates (FHRPs) – FHRPs do not apply to this project. ·Shared Facility Drainage Plans (SFDPs) – There are no existing SFDPs, nor are any proposed for the project. 2.11 Special Requirement #2: Flood Hazard Area Delineation The 100-year floodplain from Springbrook Creek has been determined using the best available GIS data provided by the City of Renton and is shown on the TESC Plans included in Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 17 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX D. Construction activities proposed within the 100-year floodplain will be restricted to temporary grading for installation of a temporary construction entrance which will provide construction machinery access to the South Spoils Area. No permanent grading will occur within the floodplain. See APPENDIX M for the City of Renton Flood Hazard Map. 2.12 Special Requirement #3: Flood Protection Facilities The project is exempt from Special Requirement #3 because it will not rely on an existing flood protection facility (such as a levee or revetment) for protection against hazards posed by erosion or inundation and will not modify or construct a new flood protection facility. 2.13 Special Requirement #4: Source Control The project will comply with the source control requirements stipulated in Section 1.3.4 of the Manual. See the SWPPP for this project, which will be submitted separately by others, as well as Section 8.2 of this report for details on proposed source control measures. 2.14 Special Requirement #5: Oil Control The project site is exempt from Special Requirement #5 because it does not trigger oil control requirements since the project site is under the high-use site thresholds. 2.15 Special Requirement #6: Aquifer Protection Area The project is exempt from Special Requirement #6 because it is not located in Zone 1 or Zone 2 of the Aquifer Protection Areas identified in Reference 15-B of the Manual. 3.OFFSITE ANALYSIS A qualitative (Level 1) offsite analysis was performed from the site to the eventual point of discharge into the Black River. Downstream systems were located based on drawings prepared as a part of Enlargement III and include the route from the project site to the stormwater pump station at the south end of the plant, then picks up at Waterworks Park and follows the wetpond/wetland system to the eventual outlet into the Black River. A map and photos of the downstream analysis is included as APPENDIX F of this report. This combined analysis was performed directly by DCG to assess the condition of the downstream system. There were no apparent problems noted within the analysis, and nothing that would prohibit its continued use by the proposed project. As with any conveyance system, routine maintenance is recommended. 4.FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN The following sections summarize the stormwater flow control and water quality facility analysis and design. 4.1 Existing Site Hydrology The proposed location of the HERB is currently occupied by a large mound of fill soil which is now covered with well-established grass. The large mound of fill was created from spoils from previous construction and expansion projects at the Site. The West Spoils Area is 10-12 feet in Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 18 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements height with side slopes at approximately 15-20%. Stormwater from the West Spoils Area sheet flows off the mound and enters the storm sewer system within the surrounding roads. The storm sewer system ultimately drains to the Black River. The West Spoils Area will be flattened as a portion of this project and relocated to a separate existing spoils area south of the proposed HERB. The South Spoils Area is currently a large mound of fill soil that is covered with well- established grass and trees. The entire project site is within Drainage Basin 7, as defined in the Enlargement III Drainage Report, which drains to the stormwater sewer system on the site and ultimately discharges to the Black River. 4.2 Developed Site Hydrology The developed project site hydrology will mimic the existing project site hydrology as stormwater generated from the new impervious surfaces will be routed to a stormwater detention facility sized to match the developed peak discharge rates to existing site conditions peak discharge rates for the 2-, 10-, and 100-year periods. The detention facility will outlet to the existing storm sewer system within the surrounding roads which ultimately discharges to the Black River. See FIGURE 4 for the developed site drainage basin maps and APPENDIX B for onsite soils information. 4.3 Performance Standards ·The project must meet the Peak Rate Flow Control Standard (Existing Site Conditions). ·The project is subject to Large Lot BMP Requirements listed in Section 1.2.9.2.2 of the Manual. See Section 2.9 for additional information on this requirement. ·The project must meet the Enhanced Basic Water Quality requirements since it will be creating greater than 5,000 SF of new plus replaced pollution generating impervious surface on an industrial site. 4.4 Flow Control The project proposes to meet the Peak Rate Flow Control Standard Area Performance Requirement by matching the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10-, and 100-year periods using a concrete detention vault with associated flow restrictor tee. Stormwater runoff from the HERB, new driveway and parking areas, and new concrete walkways and equipment pads around the HERB, will be collected and routed to a 14’ wide x 70’ long x 10’ deep detention vault located north of the HERB and beneath the proposed parking area. The proposed asphalt walkway and thermal oxidizer pad will bypass the detention vault but will be compensated through a mitigation trade. See Section 4.4.1 for additional information on the mitigation trade. The detention vault has been designed in accordance with Section 5.1.3 of the Manual as a flow- through system and is setback 10 feet from the HERB. The bottom of the vault will slope at 5% minimum from each side towards the center, forming a broad “v” to facilitate sediment removal. In addition, the invert elevation of the outlet is elevated above the bottom of the vault to provide an average of 6 inches of sediment over the entire bottom and is elevated 2 feet minimum above the bottom orifice to retain oil within the vault. The control structure will be located within the detention vault and centered above a 4’x4’x4’ sump in the vault. The flow restrictor tee, or control structure, was designed in accordance with Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 19 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements Section 5.1.4 of the Manual and will consist of three orifices on a tee section. The diameter of all three orifices will be greater than the minimum allowable (0.25 inches). The detention vault and multi-orifice flow restrictor tee were sized in accordance with Section 1.2.3 of the Manual using the WWHM2012 continuous event modeling program to match the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10-, and 100-year periods. In accordance with the Peak Rate Flow Control Standard, the predeveloped land use basin was modeled as the existing conditions (C, Lawn, Mod). The total area included in the model is equal to the total new plus replaced impervious surface. However, in-lieu of including the thermal oxidizer pad and asphalt walkway area (2,844 SF) in the model, an area of the existing roadway (2,935 SF) which will flow onto the proposed driveway and parking areas was included in the model (see Section 4.4.1 for additional information on the mitigation trade). All new and replaced pervious surfaces, as well as existing pervious surfaces, will maintain similar flow characteristics between the predeveloped and post developed conditions. Since the Peak Rate Flow Control Standard requires post developed flowrates to match existing condition flowrates, the pervious areas on the site will have a net-zero peak flowrate change and therefore were excluded from the model. The mitigated land use basin was modeled as impervious surfaces matching the total area as the predeveloped basin. The areas included in the WWHM model are shown in TABLE 2. See TABLE 3 for WWHM input parameters and APPENDIX G for a detailed summary of the WWHM modeling results. TABLE 2 WWHM Areas WWHM Areas Predeveloped Areas C, Lawn, Mod 0.65943 Acres Mitigated Areas Roof Tops,Flat 0.27231 Acres Driveways, Mod 0.30271 Acres C, Lawn, Mod 0.08441 Acres TABLE 3 WWHM Input Parameters and Results Parameter Result Required Vault Depth 10’ (9’ ponding) Required Vault Area 931 SF Design Vault Area 980 SF Design Vault Dimensions 70’Lx14’Wx10’D Orifice #1 Diameter 0.68 inches Orifice #1 Height 0 feet Orifice #2 Diameter 1.47 inches Orifice #2 Height 7.90 feet Orifice #3 Diameter 0.91 inches Orifice #3 Height 8.65 feet Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 20 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements As shown in the WWHM Detention Vault Summary in APPENDIX G, the proposed detention vault passes the peak discharge rates for 2-, 10-, and 100-year periods, thus meeting the Peak Rate Flow Control Standard. 4.4.1 Mitigation Trade A mitigation trade in accordance with Section 1.2.3.2G on Page 1-48 of the Manual will be utilized for runoff from the proposed thermal oxidizer pad and asphalt walkway (2,844 SF) due to the inability to collect and route runoff from these areas via gravity to the detention facility because of location and topography. Instead, a 2,935 SF area of the existing roadway north of the HERB will naturally flow onto the proposed roadway and parking area since the existing roadway is crowned. This area will get collected by the proposed Type I catch basins within the proposed roadway and parking area and will be routed to the detention facility. The portion of the existing roadway which will flow into the proposed drainage system meets the following mitigation trade conditions: 1)The existing developed non-target surface area (i.e., an area of existing impervious surface and/or nonnative pervious surface) must have runoff discharge characteristics (i.e., peak flow and volume) equivalent to those of the target surface area for which mitigation is being traded and must not be currently mitigated to the same flow control performance requirement as the target surface area, AND The existing roadway is asphalt, and the areas being traded are asphalt and concrete and therefore will have equivalent runoff characteristics. In addition, the existing roadway area is not currently subject to a flow control standard of any kind. 2)Runoff from both the target surface area being traded and the flow control facility must converge prior to discharge of the runoff from the target surface area being traded onto private property without an easement or through any area subject to erosion, AND The runoff from the target surface area being traded and the flow control facility will converge onsite within the existing piped storm sewer system downstream of the proposed detention facility. 3)The net effect in terms of flow control at the point of convergence downstream must be the same with or without the mitigation trade, AND The net effect in terms of flow control at the point of convergence downstream will be the same with or without the mitigation trade as all runoff is routed to the same existing onsite piped storm system downstream of the detention facility. The mitigation trade essentially proposes a 1:1 trade for the ease of routing stormwater. 4)The undetained runoff from the target surface area being traded must not create a significant adverse impact to downstream drainage systems, salmonid habitat, or properties prior to convergence with runoff from the flow control facility, AND The undetained runoff from the asphalt walkway will disperse via sheet flow through greater than 10 feet of vegetation prior to entering the existing onsite piped storm sewer system. The undetained runoff from the thermal oxidizer pad will sheet flow across the concrete pad and into the existing roadway onsite where it will get collected within existing catch basins in the roadway which are part of the piped storm sewer system downstream of the detention facility. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 21 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements 5)Consideration of an offsite area to be mitigated for must take into account the likelihood of that area redeveloping in the future. Those areas determined by the City to have a high likelihood of future redevelopment that will provide its own mitigation may not be used as a mitigation trade, AND The existing developed non-target impervious surface area is located onsite. 6)Mitigation trade proposals must be reviewed and approved with input from the City of Renton. We ask for approval of the proposed mitigation trade. 4.5 Water Quality The project proposes to meet the Enhanced Basic Water Quality requirements using a MWS- Linear Modular Wetland facility (hereafter referred to as “Modular Wetland”), which is listed as an approved proprietary facility on the Enhanced Basic WQ Menu in Table 6.1.2.B of the Manual. DCG has been coordinating directly with a representative from BioClean Environmental, a supplier of the Modular Wetland facilities, who is aiding in the design. The Modular Wetland has been sized to treat stormwater for all new and replaced PGIS on the project site, which totals 16,365 SF as shown in TABLE 1. However, the thermal oxidizer pad will bypass the detention vault but will be compensated through a treatment trade (see Section 4.5.1 for additional information on the treatment trade). Therefore, the area tributary to the Modular Wetland totals 16,863 SF (0.38 AC) as it accounts for an area of the existing roadway (2,935 SF) north of the HERB which will flow onto the proposed driveway and parking areas and will be collected and routed to the Modular Wetland. Modular Wetlands are sized using the offline water quality flowrate, which was determined from a WWHM2012 model using a developed basin consisting of 0.38 acres of driveway, moderately sloped. The resulting offline water quality flow rate from the WWHM2012 model is 0.0388 cubic feet per second, which requires a 4’x6’ Modular Wetland as determined by a MWS Linear sizing table and confirmed by the BioClean Environmental representative. A detailed summary of the WWHM2012 water quality flowrate model is included in APPENDIX G. 4.5.1 Treatment Trade A treatment trade in accordance with Section 1.2.8.2C on Page 1-72 of the Manual will be utilized for runoff from the proposed thermal oxidizer pad due to the inability to collect and route runoff from the thermal oxidizer pad (2,437 SF) via gravity to the Modular Wetland because of location and topography. Instead, a 2,935 SF area of the existing roadway north of the HERB will naturally flow onto the proposed roadway and parking area since the existing roadway is crowned. This area will get collected by the proposed Type I catch basins within the proposed roadway and parking area and be routed to the proposed Modular Wetland. The portion of the existing roadway which will flow into the proposed drainage system meets the following mitigation trade conditions: 1)The existing non-targeted pollution-generating surface is not currently being treated, is not required to be treated by any phase of the proposed project, is not subject to NPDES or other permit requirements, and is not under a compliance order or other regulatory action, AND Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 22 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements Runoff from the existing roadway north of the HERB is currently collected and routed to a pump station onsite and then pumped up to water quality wetponds which were constructed as a part of the Enlargement III project. This treatment trade essentially proposes a 1:1 trade where runoff from the thermal oxidizer pad will be routed to the wetponds before being treated, but a slightly greater area of existing roadway which is currently routed to the wetponds will be collected and treated by the Modular Wetland in- lieu of the water quality wetponds. 2)The proposal is reviewed and approved by CED. We ask for approval of the proposed mitigation trade 5.CONVEYANCE SYSTEM ANALYSIS AND DESIGN The existing and proposed conveyance systems are required to have sufficient capacity to convey and contain the 25-year peak flow for the entire contributing drainage area, assuming build-out conditions. The existing and proposed conveyance systems are discussed in the following sections. 5.1 Existing Conveyance According to Section 1.2.4.2 of the Manual, existing onsite conveyance systems that will not experience a change in flow characteristics (e.g., peak flows or volume of flows) as a result of the proposed project need not be analyzed for conveyance capacity. Since the proposed project will provide flow control in accordance with the Peak Rate Flow Control Standard Area Performance Requirement by matching the developed peak discharge rates to existing site conditions peak discharge rates for 2-, 10-, and 100-year periods, the existing flow characteristics of the existing onsite conveyance systems will not change. Since no conveyance issues onsite are known and no issues were found during the offsite analysis, the conveyance capacity of the existing onsite conveyance systems were not analyzed. 5.2 Proposed Conveyance The proposed collection and conveyance system onsite is comprised of a roof gutter downspout system, Type I catch basins, and 8 and 12-inch storm drain pipe. The proposed stormwater conveyance pipes have been sized to have sufficient capacity to convey and contain greater than the 100-year peak flow, as determined using the rational method described in Section 3.2.1 of the Manual. See APPENDIX H for conveyance calculations. 6.SPECIAL REPORTS AND STUDIES Special reports and studies include: ·A geotechnical report completed by Shannon & Wilson, Inc. (S&W) on January 6, 2017 and an addendum dated December 8, 2017. See APPENDIX B for the report and addendum in their entirety. ·A Drainage Report for the Enlargement III Project completed by Brown & Caldwell on April 29, 1992. See APPENDIX E for the full Drainage Report. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 23 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements 7.OTHER PERMITS Other permits required for this project include: ·Building Permit (through City of Renton). ·National Pollution Discharge Elimination System – Construction Stormwater General Permit. ·State Environmental Policy Act (SEPA) Review 8.CONSTRUCTION SWPPP ANALYSIS AND DESIGN A detailed construction stormwater pollution prevention plan (SWPPP) will be prepared for the project for submittal to the Department of Ecology by the King County Wastewater Treatment Division. A copy of the SWPPP document shall be maintained on the site at all times during construction and will be made available to the City of Renton staff upon request. This section summarizes the Construction SWPPP analysis and design. The two components of the Construction SWPPP are the erosion and sediment control (ESC) and the stormwater pollution prevention and spill (SWPPS) plans. Both the ESC and SWPPS Plans serve as guides as the contractor is required to design a working Construction SWPPP for the site. The analysis and design of these plans are discussed in the following sections. 8.1 ESC Plan Analysis and Design The ESC design follows the guidelines provided in Appendix D of The Manual and is intended to satisfy Core Requirement #5 Erosion and Sediment Control. Multiple stabilized construction entrances will be maintained, and the locations will be adjusted throughout construction of the site improvements as required for grading activities. Silt fencing will be installed downslope of the improvements. Chain link fencing will be used to protect all trees that are to be preserved onsite and to mark project limits. The perimeter of the existing wetland located west of the HERB will be flagged with S.A.S.B tape and chain link fencing will be used to mark the associated 50-foot buffer. Street cleaning on the surrounding interior roads as well as the access roads to the site will occur daily or as needed to remove any sediment tracked from the site. Site surface drainage will be maintained to prevent any ponding and inlet protection will be provided at all existing catch basins that may receive runoff during construction. All disturbed areas that will not be paved will be stabilized by planting and mulching immediately after construction. The proposed ESC measures are shown on the Temporary Erosion and Sediment Control Plan in APPENDIX D. An ESC supervisor will be designated for the project and must be a Certified Professional in Erosion and Sediment Control or a Certified Erosion and Sediment Control Lead, as recognized by King County. The ESC supervisor will be responsible for the performance, maintenance, and review of all ESC measures, as well as the compliance with all permit conditions relating to ESC as described in the Manual. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 24 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements TABLE 4 Proposed ESC Measures and Construction Sequencing (ESC Measures Shall Comply with Appendix D of the Manual) ESC Measure Comment 1 Identify Project Limits Mark by fencing or other means to contain the grubbing and grading activities. This includes installing temporary chain link fencing around trees that are to remain. 2 Install temporary silt fence Install fence down-slope of the improvements. 3 Construct stabilized construction entrance Multiple stabilized construction entrances are to be installed and the locations adjusted as necessary throughout construction of the site improvements for grading activities 4 Install inlet protection as required, based on construction sequencing Ensure that sediment cannot enter the existing drainage system. 5 Maintain ESC measures Relocate or install new measures as necessary to meet King County ESC standards (Appendix D of the Manual). 6 Street Cleaning Provide for periodic street cleaning to remove and sediment that may have been tracked out. Sediment should be removed by shoveling or sweeping and carefully removed to a suitable disposal area where it will not be re-eroded. 7 Inspect downstream drainage system, clean if necessary during construction. Verify that all drainage system components are free of sediment. If sediment is present, repair or implement additional ESC measures. 8 Surfacing and Sod/Seed Exposed Areas Construct pavement, sidewalks, etc. as soon as possible. Cleared areas will be sod/seeded as soon as possible after grading is completed. 9 Remove ESC measures after site stabilized and clean system. After hard surfaces are constructed and cleared areas are stabilized, remove ESC measures and clean any sediment/debris in drainage system. 8.2 Stormwater Pollution Prevention and Spill Plan Design The SWPPS plan is intended to prevent pollutants from coming into contact with stormwater runoff, surface waters, or groundwater, during construction. Vehicles, construction equipment, materials, chemical storage, and sediment from clearing and grading all have the potential to pollute stormwater during construction. The following BMPs are required during the construction of this project: ·Maintain good housekeeping. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc.Page 25 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements ·Designate vehicle, equipment, and chemical storage areas. ·Inspect vehicle, equipment, and petroleum product storage and dispensing areas regularly to detect any leaks or spills. ·Store and contain liquid materials in such a manner that if the tank leaks, the contents will not discharge into the storm drainage system, surface waters, or groundwater. ·Provide maintenance and cleaning of the storm drainage system regularly by removing sediment and debris. ·All spills will be cleaned up immediately and disposed of correctly. Do not hose down spill areas into a storm drainage system. ·All toxic materials will be stored under cover when not in use or during a rain event. ·Use storm drain covers or other similarly effective runoff control measures to prevent sediment and other pollutants from entering catch basins. All ESC and SWPPS BMPs will be inspected routinely by the ESC supervisor. All ESC measures will be removed, the site stabilized, and the drainage system cleaned once construction is completed. 9.BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANTS The bond quantities, facility summaries, and declaration of covenants/agreements are addressed in the following sections. ·Bond Quantities – N/A. As a unit of local government, the King County Wastewater Treatment Division is exempted from surety bonds or other financial security devices as permit conditions per RCW 35.21.470. ·Facility Summaries – The stormwater facilities are summarized in the Flow Control and Water Quality Summary Sheet and included in APPENDIX G. ·Declaration of Covenants/Agreements – A draft Declaration of Covenant for Privately Maintained Flow Control and WQ Facilities and Declaration of Covenant for Privately Maintained On-Site BMPs are included in APPENDIX K. 10.OPERATIONS AND MAINTENANCE MANUAL All stormwater components, including the onsite BMPs (basic dispersion), detention vault, flow control tee, catch basins, conveyance pipes, and Modular Wetland, shall be operated and maintained by the King County Wastewater Treatment Division in accordance with Appendix A of the Manual, which is included in APPENDIX L. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX A Figure 1 - Technical Information Report (TIR) Worksheet CITY OF RENTON SURFACE WATER DESIGN MANUAL 2017 City of Renton Surface Water Design Manual 12/12/2016 8-A-1 REFERENCE 8-A 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 __________________________ CED Permit # ________________________ Location Township ________________ Range __________________ Section _________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Land Use (e.g., Subdivision / Short Subd.) Building (e.g., M/F / Commercial / SFR) 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 __________________ __________________ __________________ REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-2 Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Blanket Description: (include conditions in TIR Section 2) ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ Approved Adjustment No. ______________________ Date of Approval: _______________________ Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ Re: SWDM 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 ______________________ _____________________________________ REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2017 City of Renton Surface Water Design Manual 12/12/2016 Ref 8-A-3 Part 10 SOILS Soil Type ______________________ ______________________ ______________________ ______________________ Slopes ________________________ ________________________ ________________________ ________________________ Erosion Potential _________________________ _________________________ _________________________ _________________________ High Groundwater Table (within 5 feet) Other ________________________________ Sole Source Aquifer Seeps/Springs Additional Sheets Attached 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) Standard: _______________________________ or Exemption Number: ____________ On-site 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: _________________________ REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-4 Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) 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. _______________________ Special Requirements (as applicable): Area Specific Drainage Requirements Type: SDO / MDP / BP / Shared Fac. / None Name: ________________________ Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): _______________ Datum: Flood Protection Facilities Describe: Source Control (commercial / industrial land use) Describe land use: Describe any structural controls: Oil Control High-Use Site: Yes / No Treatment BMP: _________________________________ Maintenance Agreement: Yes / No with whom? _____________________________________ Other Drainage Structures Describe: REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2017 City of Renton Surface Water Design Manual 12/12/2016 Ref 8-A-5 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 Control Pollutants Protect Existing and Proposed BMPs/Facilities Maintain Protective 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 BMPs/Facilities, restore operation of BMPs/Facilities as necessary Flag limits of sensitive areas 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 On-site BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ Vegetated Flowpath Wetpool Filtration Oil Control Spill Control On-site BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ ________________ 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 _______________________________ REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-6 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 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX B Geotechnical Report 400 NORTH 34TH STREET, SUITE 100 P.O. BOX 300303 SEATTLE, WASHINGTON 98103 206-632-8020 FAX 206-695-6777 TDD 1-800-833-6388 www.shannonwilson.com 21-1-22210-002 October 31, 2017 Mr. Ian McKelvey Brown and Caldwell 701 Pike Street, Suite 1200 Seattle, WA 98101 RE: GEOTECHNICAL REPORT ADDENDUM, BIOGAS AND HEAT SYSTEMS IMPROVEMENTS PROJECTS, KING COUNTY SOUTH TREATMENT PLANT, RENTON, WASHINGTON Dear Mr. McKelvey: We are pleased to submit this letter to serve as an addendum to our Revised Geotechnical Report for the South Treatment Plant Biogas and Heat Systems Improvements project dated January 6, 2017. This addendum summarizes our recent geotechnical evaluation of three geotechnical issues that were not addressed in our previous report: 1. Infiltration rates to aid in the design of stormwater infiltration facilities 2. Pavement sections for a small area of driveway/parking 3. Evaluation of coal mine hazards Our services were performed in accordance with Amendment No. Three to the Subcontract between Brown and Caldwell and Shannon & Wilson, Inc. for Geotechnical Services, dated June 5, 2017. STORMWATER INFILTRATION RATES Shannon & Wilson staff visited the proposed project site from October 9 to 12, 2017, to perform pilot infiltration tests (PITs) to evaluate suitability of soils for infiltration facilities. Clearcreek Contractors (Clearcreek), under subcontract to Shannon & Wilson, Inc., excavated three test pits designated TP-1, TP-2, and TP-3 at locations determined by the project civil engineer, Davido Consulting Group. The approximate locations of the test pits are shown on the attached Ian McKelvey Brown and Caldwell October 31, 2017 Page 2 of 7 Geotechnical Report Addendum_ South Plant Biogas.docx/wp/s 21-1-22210-002 Figure 1 – Test Pit Locations. Clearcreek used a vacuum truck to pothole and locate subsurface utilities prior to excavating the pits. Previously unknown utilities were encountered at all three test pit locations before and during excavation. Photo 1 shows a presumed electrical conduit running east to west at TP-2 at a depth of approximately 3 feet below ground surface (bgs). Photo 1: Electrical Conduit Running East to West at TP-2. Clearcreek used a mini excavator to excavate the test pits. TP-1 was excavated to a depth of approximately 7 feet bgs, while TP-2 and TP-3 were excavated to a depth of approximately 10 feet bgs. Soils encountered during excavation generally consisted of dense, silty sand and gravel, followed by soft, gray silt. After excavation, we performed PITs at each of the test pits. PITs were performed in accordance with the 2017 City of Renton Surface Water Design Manual. We filled each test pit with water to a depth of approximately 12 inches, then allowed the base of the PITs to soak for six hours. We then performed constant head and falling head tests. Ian McKelvey Brown and Caldwell October 31, 2017 Page 3 of 7 Geotechnical Report Addendum_ South Plant Biogas.docx/wp/s 21-1-22210-002 We observed relatively little infiltration at all three PITs during the constant and falling head tests. At TP-1, we observed an infiltration rate of approximately 0.02 inch/hour (without correction factor), while PIT data at TP-2 and TP-3 indicated negligible infiltration rates. Based on these observations, in our opinion, water infiltration facilities are unfeasible at the depths tested in all three PITs. Following testing, Clearcreek backfilled the test pits with previously excavated soils. We spread grass seed on the disturbed ground surface at TP-1 and TP-2, as shown in Photo 2. We also marked the surfaces of each backfilled test pit location at areas where unknown subsurface utilities were encountered. Photo 2: Grass Seed Spread on TP-1. White Line Indicates an Unknown Utility Observed. PAVEMENT SECTION DESIGN We understand that a relatively small section at the proposed Facility will be paved for vehicle access and parking. This paved area or areas will likely experience vehicle loading comparable Ian McKelvey Brown and Caldwell October 31, 2017 Page 4 of 7 Geotechnical Report Addendum_ South Plant Biogas.docx/wp/s 21-1-22210-002 to current loading conditions at the South Plant. During our recent site visits, we did not observe significant damage to the existing roadways, indicating that current pavement design at the South Plant is adequate for anticipated traffic and loading conditions. We recommend adopting the existing roadway construction methods when designing for new paved areas around the Facility. If as-builts are unavailable, or if construction methods of existing roadways cannot be determined before new paved sections are designed, we recommend referring to Table 4.3 of Chapter 4 of the 2016 King County Road Design and Construction Standards. In our opinion, the native soil subgrades have resilient modulus values of 10,000 pounds per square inch or greater. For commercial access roads, King County recommends 6 inches of hot mix asphalt and 6 inches of crushed surfacing base course. This is based on a design equivalent single axle load of less than 2,500,000 trips. COAL MINE HAZARD EVALUATION The City of Renton has designated the proposed Facility site as located within a critical area consisting of a moderate coal mine hazard. The site has this designation because it is within approximately 200 feet of a mapped historical coal mine consisting of a series of mine adits extending north from the former mine entrance near the northeast corner of the Cogeneration Building, as shown on the City of Renton map below: Ian McKelvey Brown and Caldwell October 31, 2017 Page 5 of 7 Geotechnical Report Addendum_ South Plant Biogas.docx/wp/s 21-1-22210-002 According to the reference documents linked to the City’s sensitive areas website, County Map K29 (King County, 1997 1), this mine operation belonged to the Diamond Coal Company. No other information is available. Based on the relatively specific mapped location of the adits 1 County, King, 19970224, Coal Mine Hazards: King County, King County, WA. http://www5.kingcounty.gov/gisdataportal/Default.aspx Ian McKelvey Brown and Caldwell October 31, 2017 Page 6 of 7 Geotechnical Report Addendum_ South Plant Biogas.docx/wp/s 21-1-22210-002 associated with the Diamond Coal Company mine, it is our opinion that the mine adits do not extend beneath the footprint of the proposed Heat and Energy Recovery building or the proposed thermal oxidizer. During our 2016 subsurface investigation, summarized in our January 6, 2017 report, we advanced two borings to depths of about 91.5 to 121.5 feet bgs at the location of the proposed Heat and Energy Recovery building. Boring results indicated that the project site is underlain by sandstone bedrock consisting of the Renton Formation at depths ranging from 80 to 111 feet bgs. This formation is known for containing coal beds, some used for mining purposes. The soils above the bedrock consist of alluvial sediments that were not associated with coal mines. Previous subsurface explorations, including borings and test pits by others, also did not locate coal mining evidence at the Heating and Energy Recovery building site. Our recent TP-3 and test pits previously performed by others nearby the proposed thermal oxidizer site did not expose evidence of mining activity. In our opinion, there is no subsurface or surface evidence of past mining activity at the proposed Facility site and there is low probability that construction of the proposed Facility is at risk of coal mine hazards such subsidence. Coal mine hazards are not a design issue that require mitigation for the proposed project. CLOSURE AND LIMITATIONS This letter was prepared for the exclusive use of Brown and Caldwell and King County to aid in design of the King County South Treatment Plant Biogas and Heat Systems Improvements. This letter should be relied on for factual data only, and not as a warranty of subsurface conditions, such as those interpreted from our observations. The conclusions and recommendations contained in this letter are based on site conditions observed during our site visit. Within the limitations of the scope, schedule, and budget, the conclusions and recommendations presented in this letter were prepared in accordance with generally accepted professional geotechnical engineering principles and practices in the area at the time this letter was prepared. We make no other warranty, either express or implied. The scope of our services for this project did not include any environmental assessment or evaluation regarding the presence or absence of wetlands or hazardous or toxic materials in the soil, surface water, groundwater, or air on, below, or around the site. Shannon & Wilson, Inc. 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ K i n g C o u n t y \ 1 4 8 6 4 2 K C S P B i o g a s a n d H e a t S y s I m p \ _ C A D \ 2 - S H E E T S \ G - G E N E R A L \ 2 2 4 - 1 1 2 3 6 3 6 G 0 0 0 0 0 0 8 . d w g | L a y o u t : L a y o u t 1 PL O T T E D : M a r 3 0 , 2 0 1 7 - 0 9 : 3 5 : 4 6 a m B y S P l a n c i c XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS MAR 2017 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA PRELIMINARY ISSUE DRAWING 30% DESIGN APRIL 2017 S. Hildreth G0000008 J. Bolton T. Ingraham G. Newman None 0 R. BardKing County South Treatment Plant Biogas and Heat Systems Improvements Shannon & Wilson Project No. 21-1-22210-002 Figure 1 - Test Pit Locations October XX, 2017 Designation and Approximate Location of Test Pits TP-3 TP-1TP-2 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX C Drainage Plans IR SD SD SD SD SD SD SD SD SD REFERENCES:CATCH BASIN - TYPE 1PIPE COMPACTION DESIGN AND BACKFILLRECTANGULAR FRAMERECTANGULAR VANED GRATESTORMWATER FACILITY CLEANOUTMWS-L-4-6.33-G-UG STORMWATERBIOFILTRATION SYSTEMSTORMWATER DETENTION SYSTEM1C2240158 2C22401583C22401585C22401584C22401586C22401581C2240162GENERAL NOTES:1.REFER TO THE PROFILES ON SHEET C2240154FOR STORM ELEVATION INFORMATION. AREA SHOWN ON THIS PLAN WWTP KEY PLAN NO SCALE 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 4 1 . d w g | L a y o u t : C 2 2 4 0 1 4 1 S T O R M W A T E R M A N A G E M E N T P L A N A R E A 2 1 PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 0 : 3 8 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S u r v . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l E x i s t i n g B a s e m a p . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S i t e P l a n _ C 3 D . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l P i p e _ C 3 D . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; W W T P K e y P l a n . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l L i m i t s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l W i p e o u t . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S h e e t N o t e s . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 STORMWATER MANAGEMENT PLAN AREA 21 C2240141 D. Saarenas E. Davido 1" = 20' 0 R. Bard MATCH LINE - SEE DWG C2240142 33723 KEY NOTES:DRAINAGE FROM THERMAL OXIDIZER PAD TO BECOLLECTED IN EX STORM SYSTEM IN ROAD (2,437 SF).SEE AREA 21 PAVING & GRADING PLAN FOR THERMALOXIDIZER PAD GRADINGAREA OF EX ROADWAY TO DRAIN TO PROPOSEDSTORMWATER FACILITIES. 2,935 SF TOTAL (1,490 SFTHIS SHEET). SEE AREA 21 PAVING & GRADING PLANFOR ROADWAY GRADINGCATCH BASIN - TYPE 1 (TYP)W/ VANED GRATEW/ 90° DOWNTURNED ELBOWREFER TO C2240131 FOR MECHANICAL YARD PIPING(TYP)123423 1C2240158 1C2240159 2C2240159BC2240157AC2240157 1 48" SD 8" SD 8" SD LI M I T S LI M I T S LI M I T S LI M I T S LI M I T S LI M I T S LI M I T S LIMITS LIMITS LIMITS LIMITS LIMITS LIMITSLIMITSLIMITSLIMITS LIMITS LIMITS L I M I T S LIMITS LIMITS LIMITS LIMITS LIMITS LIMITS L I M I T S L I M I T S L I M I T S L I M I T S L I M I T S L I M I T S SS SS SS S S SS SS SS SS SS SS S D S D S D SD SD SD SD SD SD SD SD DRN DRN DRN DRN DRN DRN DRN DR N DR N DR N DR N DRN DRN DRN DRN DRN DRN DRN D R N D R N D R N D R N SD SD SD SD SD W 10' BETWEEN HERB & VAULT 11' BETWEEN HERB & VAULT GENERAL NOTES:1.REFER TO THE PROFILES ON SHEET C2240154FOR STORM ELEVATION INFORMATION.2C22401591C2240159 AREA SHOWN ON THIS PLAN WWTP KEY PLAN NO SCALE 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 4 2 . d w g | L a y o u t : C 2 2 4 0 1 4 2 S T O R M W A T E R M A N A G E M E N T P L A N A R E A 2 2 PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 1 : 1 6 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S u r v . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l E x i s t i n g B a s e m a p . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S i t e P l a n _ C 3 D . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l P i p e _ C 3 D . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; W W T P K e y P l a n . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l L i m i t s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l W i p e o u t . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S h e e t N o t e s . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 STORMWATER MANAGEMENT PLAN AREA 22 C2240142 D. Saarenas E. Davido 1" = 20' 0 R. Bard MATCH LINE - SEE DWG C2240141 33723 FLOW F L O W KEY NOTES:STORMWATER DETENTION SYSTEMW/ FLOW RESTRICTOR TEE4'x4'x4' VAULT SUMP LOCATED BENEATH FLOWRESTRICTOR TEEAREA OF EX ROADWAY TO DRAIN TO PROPOSEDSTORMWATER FACILITIES.2,935 SF TOTAL (1,445 SF THIS SHEET).SEE AREA 22 PAVING & GRADING PLAN FORROADWAY GRADINGROOF DOWNSPOUTS PERARCHITECTURAL PLANSPERIMETER FOOTING DRAIN: 4" PVC IN 6"WASHED ROCK WRAPPED IN NON-WOVENGEOTEXTILE FABRIC8" WYE CONNECTION INTO EX 18" STORM MAIN8" IE 112.58EX 18" IE 111.33ROOF OVERHANG PER ARCHITECTURAL PLANSCATCH BASIN - TYPE 1 (TYP)W/ VANED GRATEW/ 90° DOWNTURNED ELBOW 4' x 6' STORMWATER BIOFILTRATION SYSTEM (MWS-L-4-6.33-G-UG) W/ SOLID LID 6" SDCO 2' Ø MANHOLE LID ACCESS TO DETENTION FACILITY W/ INTERNAL LADDER. RIM FLUSH WITH FG (TYP) 10' MINIMUM VEGETATED FLOWPATH FOR BASIC DISPERSION. ARROW INDICATES DIRECTION OF FLOW. REFER TO C2240132 FOR MECHANICAL YARD PIPING (TYP) 12345678 9 10 11 12 132 1 3 45 6 9 10 11 8 A C2240157 B C22 4 0 1 5 7 12 7 1C22401581C2240162 1 C2240161 1 C2240160 13 8" SD 8" SD 8" SD 4" SD 4" DRN 8" SD 8" SD 6" SD 2 C2240160 110115120125130135140 1101151201251301351400+00 0+10 0+20 0+30 0+40 0+50 0+60 0+70 0+80 0+90 1+00 1+10 1+20 1+30 1+40 1+50 1+60 1+70 1+80 1+90 2+000+00 0+10 0+20 0+30 0+40 0+50 0+60 0+70 0+80 0+90 1+00 1+10 1+20 1+30 1+40 1+50 1+60 1+70 1+80 1+90 2+00 105 110 115 120 125 130 135 140 105 110 115 120 125 130 135 1400+00 0+10 0+20 0+30 0+40 0+50 0+60 0+70 0+80 0+90 1+00 1+10 1+20 1+30 1+40 1+50 1+60 1+70 1+80 1+90 2+00 2+10 2+20 2+30 2+40 2+50 2+60 2+70 2+80 0+00 0+10 0+20 0+30 0+40 0+50 0+60 0+70 0+80 0+90 1+00 1+10 1+20 1+30 1+40 1+50 1+60 1+70 1+80 1+90 2+00 2+10 2+20 2+30 2+40 2+50 2+60 2+70 2+80 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 5 7 . d w g | L a y o u t : C 2 2 4 0 1 5 7 S T O R M W A T E R M A N A G E M E N T P R O F I L E S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 3 : 3 1 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S i t e P l a n _ C 3 D . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 STORMWATER MANAGEMENT PROFILES C2240157 D. Saarenas E. Davido AS NOTED 0 R. Bard 33723 SCALE:H.1"=10'; V.1"=5'SD PROFILE AC2240141 NOTES:CONTRACTOR TO POTHOLEEXISTING CROSSING UTILITIESPRIOR TO ONSITE WORK SCALE:H.1"=10'; V.1"=5' SD PROFILE B C2240141 EG FGCATCH BASIN - TYPE 1W/ VANED GRATEW/ 90° DOWNTURNED ELBOWRIM 124.518" IE (S) 120.628" IE (E) 120.622" MIN SUMP 18 LF 8" SD @ 1.00%2C2240158 CATCH BASIN - TYPE 1W/ VANED GRATEW/ 90° DOWNTURNED ELBOWRIM 124.438" IE (SE) 121.818" IE (N) 121.812" MIN SUMP 61 LF 8" SD @ 1.00%2C2240158 CATCH BASIN - TYPE 1W/ VANED GRATEW/ 90° DOWNTURNED ELBOWRIM 125.108" IE (NE) 122.422" MIN SUMP2" NG 2" NG CATCH BASIN - TYPE 1 W/ VANED GRATE W/ 90° DOWNTURNED ELBOW RIM 124.51 8" IE (S) 120.62 8" IE (E) 120.62 2" MIN SUMP 2" NG 8" MSG 24 " L S G 2" H S S G 4' X 6" STORMWATERBIOFILTRATION SYSTEM (SEE STORMWATER MANAGEMENT PLAN AREA 22) STORMWATER DETENTION VAULT W/ FLOW RESTRICTOR TEE (SEE STORMWATER MANAGEMENT PLAN AREA 22) 5 LF 8" SD @ 2.00%2 C2240158 51 LF 8" SD @ 1.00% 2 C2240158 EG EX U T I L I T Y 2" W A T E R S E R V I C E 6" SS 8" W A T E R S E R V I C E FG 177 LF 6" SD @ 2.00%2 C2240158 6" SDCO RIM 125.94 6" IE 123.40 C2240142 C2240142 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 5 8 . d w g | L a y o u t : C 2 2 4 0 1 5 8 S T O R M W A T E R M A N A G E M E N T D E T A I L S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 3 : 4 8 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g IM A G E S : 2 0 0 _ C a t c h B a s i n T y p e 1 . t i f ; 2 2 0 _ P i p e C o m p a c t i o n D e s i g n a n d B a c k f i l l . t i f ; SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 STORMWATER MANAGEMENT DETAILS C2240158 D. Saarenas E. Davido NONE 0 R. Bard 33723 SCALE:SCALE:NTS CATCH BASIN TYPE 1 C2240141 1 NTS PIPE COMPACTION DESIGN AND BACKFILL 2 C2240157 C2240142 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 5 9 . d w g | L a y o u t : C 2 2 4 0 1 5 9 S T O R M W A T E R M A N A G E M E N T D E T A I L S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 4 : 0 4 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g IM A G E S : 2 0 4 . 0 _ R e c t a n g u l a r F r a m e . t i f ; 2 0 4 . 2 _ R e c t a n g u l a r V a n e d G r a t e . t i f ; SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 STORMWATER MANAGEMENT DETAILS C2240159 D. Saarenas E. Davido NONE 0 R. Bard 33723 SCALE:SCALE:NTS RECTANGULAR FRAME 1 NTS RECTANGULAR VANED GRATE 2 C2240141 C2240141 C2240142 C2240142 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 6 0 . d w g | L a y o u t : C 2 2 4 0 1 6 0 S T O R M W A T E R M A N A G E M E N T D E T A I L S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 4 : 2 0 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g IM A G E S : 2 0 4 . 5 _ S t o r m R o u n d F r a m e a n d C o v e r . t i f ; 2 2 6 _ S t o r m w a t e r F a c i l i t y C l e a n o u t . t i f ; SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 STORMWATER MANAGEMENT DETAILS C2240160 D. Saarenas E. Davido NONE 0 R. Bard 33723 SCALE:NTS STORMWATER FACILITY CLEANOUT 1 SCALE:NTS STORM ROUND FRAME AND COVER 2 C2240142C2240142 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 6 1 . d w g | L a y o u t : C 2 2 4 0 1 6 1 S T O R M W A T E R M A N A G E M E N T D E T A I L S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 4 : 3 6 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g IM A G E S : M W S - L - 4 - 6 . 3 3 - V - U G _ 0 1 0 5 2 0 1 7 . t i f ; SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 STORMWATER MANAGEMENT DETAILS C2240161 D. Saarenas E. Davido NONE 0 R. Bard 33723 SCALE:NTS MWS-L-4-6.33-G-UG STORMWATER BIOFILTRATION SYSTEM 1 C2240142 GASKET INSTALLATION DETAIL SECTION VIEW WALL CONNECTION DETAIL PLAN VIEW WELDED ELBOW WITHORIFICE DRILLED IN END PLATE 6" MIN.6"MAX.STANDPIPE ELBOW DETAIL ROUND SOLID COVER MARKED "STORM" WITH LOCKING BOLTS, UNLESS OTHERWISE APPROVED BY ENGINEER 220# CAPACITY ROD SHEAR GATE (SEE DD/C16) 2' - 0 " PIPE SUPPORT(S): 3"x.090 GAGE BOLTED OR IMBEDDED 2" IN WALL AT MAX. 3" SPACING, MIN. ONE SUPPORT MULTI-ORIFICE ELBOW (CC/C16) ORIFICE #2: OUTLET PIPE 8" INVERT ELEV: 113.02 RESTRICTOR PLATE WITH ORIFICE ORIFICE #1: 6" M I N . 20 " M A X . 6" 1'-0"MIN 1' - 0 " MI N 2' - 6 " M I N . NOTES: 1. PIPE SIZES AND SLOPES: PER PLANS 2. FRAME & LADDER OF STEPS OFF SET SO A. CLEANOUT GATE IS VISIBLE FROM TOP B. CLIMB-DOWN SPACE IS CLEAR OF RISER AND CLEANOUT GATE C. FRAME IS CLEAR OF CURB 3. MULTI-ORIFICE ELBOWS MAY BE LOCATED AS SHOWN OR ENTIRELY ON ONE SIDE OF RISER ASSURING ADEQUATE LADDER ACCESS DIA: 1.47" 4. INSTALLATION TO MEET WSDOT STANDARDS FOR TYPE II INSTALLATION. 2' MIN.30°MIN. MI N . 2' - 0 " MI N . DIA: 0.68" ELEV: 109.02 ELEV: 120.92 MULTI-ORIFICE ELBOW (CC/C16) ORIFICE #3: DIA: 0.94" ELEV: 121.67 OVERFLOW ELEV: 122.02 6" DEAD STORAGE 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 6 2 . d w g | L a y o u t : C 2 2 4 0 1 6 2 S T O R M W A T E R M A N A G E M E N T D E T A I L S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 4 : 5 4 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 STORMWATER MANAGEMENT DETAILS C2240162 D. Saarenas E. Davido NTS 0 R. Bard 33723 SCALE:NTS DETENTION VAULT 1 VAULT INLET/OUTLET TABLE#SIZE INLET/OUTLET ELEVATION WALL LOCATION16"INLET 121.06 EAST 2.75' N OF SE CORNER28"INLET 119.61 WEST 3' N OF SW CORNER38"OUTLET 113.02 NORTH 2.75' N OF NW CORNERSCALE:NTSACCESS LADDER 2 SCALE:NTS MULTI-ORIFICE FLOW RESTRICTOR TEE C2240162 3 C2240162 C2240142 3C2240162 2C2240162 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX D Temporary Erosion and Sediment Control Plan LIMITS LIMITSLIMITSLIMITSLIMITS LIMITSLIMITSLIMITS LI M I T S LI M I T S LIMITS LI M I T S LIMITS LIM I T S LIM I T S LIMITS LIMITS LIMITS LIMITSLIMITSLIMITSLIMITSLIMITSLIMITSPPPPPPPPPP PPPPPPPPPP P P P P P P P P P P PPPPPPPPPPPPPPPPPPPPPPPPPP GENERAL NOTES:1.INSTALL PERIMETER PROTECTION SUCH ASSILT FENCE, COMPOST SOCKS, OR STRAWWATTLES IN ACCORDANCE WITH APPENDIX DOF THE 2017 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2.INSTALL PLASTIC COVERING ON DISTURBEDAREAS REQUIRING COVER MEASURES FORLESS THAN 30 DAYS, INCLUDING STOCKPILESAND CUT AND FILL SLOPES.3.CONSTRUCTION ENTRANCES SHALL BE PHASEDAS NECESSARY THROUGHOUT CONSTRUCTIONAS REQUIRED FOR GRADING ACTIVITIES.4.CONTRACTOR TO MAINTAIN EXTRA EROSIONCONTROL AND STORMWATER POLLUTIONPREVENTION MATERIALS ON-SITE FOR REPAIR,MAINTENANCE, AND EMERGENCIESTHROUGHOUT CONSTRUCTION AS REQUIREDBY THE 2016 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2C2240151 AREA SHOWN ON THIS PLAN WWTP KEY PLAN NO SCALE 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 0 1 . d w g | L a y o u t : C 2 2 4 0 1 0 1 D E M O A N D T E S C P L A N A R E A 1 6 PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 2 1 : 5 7 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S u r v . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l E x i s t i n g B a s e m a p . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; W W T P K e y P l a n . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l L i m i t s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l T E S C . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S h e e t N o t e s . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 DEMO AND TESC PLAN AREA 16 . C2240101 D. Saarenas E. Davido 1" = 20' . 0 R. Bard MATCH LINE - SEE DWG C2240102 33723 MA T C H L I N E - S E E D W G C2240105 . KEY NOTES:INSTALL 332 LF PERIMETERPROTECTION (40 THISSHEET) PER GENERALNOTE 1INSTALL 248 LF PERIMETERPROTECTION PERGENERAL NOTE 1INSTALL 258 LF PERIMETERPROTECTION (197 LF THISSHEET) PER GENERALNOTE 1DELINEATE DISTURBANCELIMITS WITHHIGH-VISIBILITY FENCE INPERVIOUS AREASINSTALL CATCH BASINFILTER12345125 5 4 1C2240152 1C22401531C22401511C22401521C22401521C22401531C22401533 LI M I T S LI M I T S L I M I T S L I M I T S LIMITSLIMITSLIMITSLIMITS LIMITSLIMITSLIMITS LIMITS L I M I T S L I M I T S L I M I T S L I M I T S L I M I T S LIM I T S LIM I T S LIM I T S LIMI T S LIMITS LIMITSLIMITS LIMITSLIMITSLIMITSLIMITS PP PP PP PP PP PP PP PP PP PP PP PP PPPP PP PPPPPPPP P P PP P P P P PP PP P P PP PP PP PP PP PP PPPPPPPPPP PP PP PP PP GENERAL NOTES:1.INSTALL PERIMETER PROTECTION SUCH ASSILT FENCE, COMPOST SOCKS, OR STRAWWATTLES IN ACCORDANCE WITH APPENDIX DOF THE 2017 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2.INSTALL PLASTIC COVERING ON DISTURBEDAREAS REQUIRING COVER MEASURES FORLESS THAN 30 DAYS, INCLUDING STOCKPILESAND CUT AND FILL SLOPES.3.CONSTRUCTION ENTRANCES SHALL BE PHASEDAS NECESSARY THROUGHOUT CONSTRUCTIONAS REQUIRED FOR GRADING ACTIVITIES.4.CONTRACTOR TO MAINTAIN EXTRA EROSIONCONTROL AND STORMWATER POLLUTIONPREVENTION MATERIALS ON-SITE FOR REPAIR,MAINTENANCE, AND EMERGENCIESTHROUGHOUT CONSTRUCTION AS REQUIREDBY THE 2016 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2C2240151 AREA SHOWN ON THIS PLAN WWTP KEY PLAN NO SCALE 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 0 2 . d w g | L a y o u t : C 2 2 4 0 1 0 2 D E M O A N D T E S C P L A N A R E A 1 7 PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 2 2 : 3 6 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S u r v . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l E x i s t i n g B a s e m a p . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; W W T P K e y P l a n . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l L i m i t s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l T E S C . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S h e e t N o t e s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S i t e I n d e x . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 DEMO AND TESC PLAN AREA 17 C2240102 D. Saarenas E. Davido 1" = 20' 0 R. Bard MATCH LINE - SEE DWG C2240103 33723 MATCH LINE - SEE DWG C2240101 KEY NOTES:INSTALL 335 LF (114 LF THIS SHEET)PERIMETER PROTECTION PER GENERALNOTE 1INSTALL CATCH BASIN FILTERINSTALL 332 LF (292 THIS SHEET)PERIMETER PROTECTION PER GENERALNOTE 1DELINEATE DISTURBANCE LIMITS WITHHIGH-VISIBILITY FENCE IN PERVIOUSAREASINSTALL 285 LF PERIMETER PROTECTIONPER GENERAL NOTE 11234512 3 2 45 1C2240152 1C22401531C22401511C22401521C22401531C22401521C2240153 PP PP PP PP PP P P P P P P P P P P P P EG 129.33EG 128.87 EG 134.65 EG 134.10 FG 130.06 FG 130.02130131 132 13 3 13 4 LIMITS LIMITS LIMITS LIMITS LI M I T S L I M I T S L I M I T S L I M I T S FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOODFLOODFLOOD200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT 200FT OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM OHWM LI M I T S LI M I T S LIMITS LIMITS LIMITS LI M I T S LI M I T S LI M I T S LIMITS LIMITS LIMITSLIMITS LIMITS LIMITS LIMITSLIMITSLIMITS L I M I T S L I M I T S L I M I T S GENERAL NOTES:1.INSTALL PERIMETER PROTECTION SUCH ASSILT FENCE, COMPOST SOCKS, OR STRAWWATTLES IN ACCORDANCE WITH APPENDIX DOF THE 2017 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2.INSTALL PLASTIC COVERING ON DISTURBEDAREAS REQUIRING COVER MEASURES FORLESS THAN 30 DAYS, INCLUDING STOCKPILESAND CUT AND FILL SLOPES.3.CONSTRUCTION ENTRANCES SHALL BE PHASEDAS NECESSARY THROUGHOUT CONSTRUCTIONAS REQUIRED FOR GRADING ACTIVITIES.4.CONTRACTOR TO MAINTAIN EXTRA EROSIONCONTROL AND STORMWATER POLLUTIONPREVENTION MATERIALS ON-SITE FOR REPAIR,MAINTENANCE, AND EMERGENCIESTHROUGHOUT CONSTRUCTION AS REQUIREDBY THE 2016 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2C2240151 AREA SHOWN ON THIS PLAN WWTP KEY PLAN NO SCALE 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 0 3 . d w g | L a y o u t : C 2 2 4 0 1 0 3 D E M O A N D T E S C P L A N A R E A 1 8 PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 2 3 : 1 2 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S u r v . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l E x i s t i n g B a s e m a p . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; W W T P K e y P l a n . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l L i m i t s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l T E S C . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S h e e t N o t e s . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 DEMO AND TESC PLAN AREA 18 . C2240103 D. Saarenas E. Davido 1" = 20' . 0 R. Bard 33723 MATCH LINE - SEE DWG C2240102 . KEY NOTES:CONSTRUCTION EQUIPMENT ENTRY/EXIT(FROM SW 7TH ST)INSTALL CATCH BASIN FILTERCONTRACTOR TO SWEEP STREETS DAILY ORMORE FREQUENTLY AS REQUIRED TO REMOVETRACKED SEDIMENTEX CURB TO BE REMOVED FORCONSTRUCTION ACCESSINSTALL 335 LF (221 LF THIS SHEET)PERIMETER PROTECTION PER GENERALNOTE 1CONSTRUCTION STAGING & STOCKPILINGAREA DELINEATE DISTURBANCE LIMITS WITH HIGH-VISIBILITY FENCE IN PERVIOUS AREAS INSTALL 175'L x 25'W STABILIZED CONSTRUCTION ENTRANCE LAY BACK SLOPE FOR CONSTRUCTION ENTRANCE TO BE 3H:1V MAX 123456 7 8 9 1 2 4 3 2 5 6 7 83 1C2240151 2 C2240152 1C2240152 1C2240153 APPROX 200-FT SHORELINE JURISDICTION PER COR GIS MAPPING APPROXIMATE OHWM(NOT SURVEYED) 9 PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPLIMITS L I M I T S L I M I T S L I M I T S L I M I T S L I M I T S L I M I T S LI M I T S LI M I T S LIMITSLIMITSLIMITSLIMITSLIMITSLIMITSLIMITSLIMITSLIMITSLIMITS LIMITSWTL BFR WTL BFR WTL BFR WTL BFR WTL BFR WTL BFR WTL BFR50' WETLANDBUFFER LIMITS GENERAL NOTES:1.INSTALL PERIMETER PROTECTION SUCH ASSILT FENCE, COMPOST SOCKS, OR STRAWWATTLES IN ACCORDANCE WITH APPENDIX DOF THE 2017 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2.INSTALL PLASTIC COVERING ON DISTURBEDAREAS REQUIRING COVER MEASURES FORLESS THAN 30 DAYS, INCLUDING STOCKPILESAND CUT AND FILL SLOPES.3.CONSTRUCTION ENTRANCES SHALL BE PHASEDAS NECESSARY THROUGHOUT CONSTRUCTIONAS REQUIRED FOR GRADING ACTIVITIES.4.CONTRACTOR TO MAINTAIN EXTRA EROSIONCONTROL AND STORMWATER POLLUTIONPREVENTION MATERIALS ON-SITE FOR REPAIR,MAINTENANCE, AND EMERGENCIESTHROUGHOUT CONSTRUCTION AS REQUIREDBY THE 2016 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2C2240151 AREA SHOWN ON THIS PLAN WWTP KEY PLAN NO SCALE 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 0 4 . d w g | L a y o u t : C 2 2 4 0 1 0 4 D E M O A N D T E S C P L A N A R E A 2 1 PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 2 3 : 4 7 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S o l i d T u n n e l U p d a t e . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S u r v . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l E x i s t i n g B a s e m a p . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; W W T P K e y P l a n . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l T E S C . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l L i m i t s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S h e e t N o t e s . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 DEMO AND TESC PLAN AREA 21 C2240104 D. Saarenas E. Davido 1" = 20' 0 R. Bard MATCH LINE - SEE DWG C2240105 33723 KEY NOTES:CONSTRUCTIONEQUIPMENT ENTRY/EXIT(FROM MONSTER RD SW)INSTALL CATCHBASIN FILTERINSTALL 168 LF (11 LF THISSHEET) PERIMETERPROTECTION PERGENERAL NOTE 1EX CURB TO BE REMOVEDFOR CONSTRUCTIONACCESSINSTALL 100'L x 25'WSTABILIZEDCONSTRUCTIONENTRANCECONSTRUCTION STAGING& STOCKPILING AREAINSTALL 512 LF (370 LFTHIS SHEET) PERIMETERPROTECTION PERGENERAL NOTE 1 CONTRACTOR TO SWEEPSTREETSDAILY OR MOREFREQUENTLY ASREQUIRED TO REMOVETRACKED SEDIMENTPROTECT EXISTINGWETLAND & 50' BUFFER.NO GRADING OR OTHERGROUND DISTURBANCE TOOCCUR WITHIN WETLANDBUFFER. FLAG WETLANDBUFFER WITH SASB TAPEDELINEATE DISTURBANCELIMITS WITHHIGH-VISIBILITY FENCE INPERVIOUS AREASINSTALL CATCH BASINFILTER IN ALL DRAINAGESTRUCTURES IN VICINITY123456789101132567981028 2 1 2 4 11 1C22401512C22401521C2240152 1C22401531C22401521C2240153 1C2240151 PP PP PP PP PP PP PP PP PP PP PP PP PP PP PP PP PP PP LI M I T S LI M I T S LI M I T S LI M I T S LI M I T S LI M I T S LI M I T S LIMITS LIMITS LIMITS LIMITS LIMITS LIMITSLIMITSLIMITSLIMITS LIMITS LIMITS L I M I T S LIMITS LIMITS LIMITS LIMITS LIMITS LIMITS L I M I T S L I M I T S L I M I T S L I M I T S L I M I T S L I M I T S GENERAL NOTES:1.INSTALL PERIMETER PROTECTION SUCH ASSILT FENCE, COMPOST SOCKS, OR STRAWWATTLES IN ACCORDANCE WITH APPENDIX DOF THE 2017 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2.INSTALL PLASTIC COVERING ON DISTURBEDAREAS REQUIRING COVER MEASURES FORLESS THAN 30 DAYS, INCLUDING STOCKPILESAND CUT AND FILL SLOPES.3.CONSTRUCTION ENTRANCES SHALL BE PHASEDAS NECESSARY THROUGHOUT CONSTRUCTIONAS REQUIRED FOR GRADING ACTIVITIES.4.CONTRACTOR TO MAINTAIN EXTRA EROSIONCONTROL AND STORMWATER POLLUTIONPREVENTION MATERIALS ON-SITE FOR REPAIR,MAINTENANCE, AND EMERGENCIESTHROUGHOUT CONSTRUCTION AS REQUIREDBY THE 2016 CITY OF RENTON SURFACE WATERDESIGN MANUAL.2C2240151 AREA SHOWN ON THIS PLAN WWTP KEY PLAN NO SCALE 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 0 5 . d w g | L a y o u t : C 2 2 4 0 1 0 5 D E M O A N D T E S C P L A N A R E A 2 2 PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 2 4 : 2 2 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; 2 2 4 - 1 1 2 3 6 2 6 E x i s t S u r v . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l E x i s t i n g B a s e m a p . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g ; W W T P K e y P l a n . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l T E S C . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l L i m i t s . d w g ; 2 2 4 - 1 1 2 3 6 2 6 C i v i l S h e e t N o t e s . d w g IM A G E S : SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 DEMO AND TESC PLAN AREA 22 C2240105 D. Saarenas E. Davido 1" = 20' 0 R. Bard MATCH LINE - SEE DWG C2240104 33723 MATCH LINE - SEE DWG C 2 2 4 0 1 0 1 KEY NOTES:CONTRACTOR TO SWEEP STREETSDAILY OR MORE FREQUENTLY ASREQUIRED TO REMOVE TRACKEDSEDIMENTINSTALL CATCH BASIN FILTER IN ALLDRAINAGE STRUCTURES IN VICINITYINSTALL CATCH BASIN FILTERREPL DECORATIVE CONC BANDIN-KINDDELINEATE DISTURBANCE LIMITSWITH HIGH-VISIBILITY FENCE INPERVIOUS AREASINSTALL 512 LF (370 LF THIS SHEET)PERIMETER PROTECTION PERGENERAL NOTE 1INSTALL 168 LF (157 LF THIS SHEET)PERIMETER PROTECTION PERGENERAL NOTE 1123456712 3 4 5 6 7 1C22401511C2240152 1C22401531C22401521C22401531C2240151 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 5 1 . d w g | L a y o u t : C 2 2 4 0 1 5 1 D E M O A N D T E S C D E T A I L S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 1 : 3 4 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g IM A G E S : 2 1 3 . 3 _ C O R P W _ P l a s t i c C o v e r i n g . t i f ; 2 1 6 . 3 _ C O R P W _ C a t c h B a s i n F i l t e r . t i f ; SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 DEMO AND TESC DETAILS C2240151 D. Saarenas E. Davido NONE 0 R. Bard 33723 SCALE:SCALE:NTS CATCH BASIN FILTER C2240101 1 NTS PLASTIC COVERING C2240101 2 C2240102 C2240103 C2240104 C2240105 C2240102 C2240103 C2240104 C2240105 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 5 2 . d w g | L a y o u t : C 2 2 4 0 1 5 2 D E M O A N D T E S C D E T A I L S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 1 : 5 1 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g IM A G E S : 2 1 4 . 0 _ C O R P W _ S i l t F e n c e . t i f ; 2 1 5 . 1 _ C O R P W _ S t a b i l i z e d C o n s t r u c t i o n E n t r a n c e . t i f ; SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 DEMO AND TESC DETAILS C2240152 D. Saarenas E. Davido NONE 0 R. Bard 33723 SCALE: SCALE: NTS SILT FENCE C2240101 1 NTS STABILIZED CONSTRUCTION ENTRANCE C2240103 2 C2240102 C2240103 C2240104 C2240105 C2240104 1 2 345 DESIGNED/DRAWN: PROJECT ENGINEER: PROJECT ACCEPTANCE: DESIGN APPROVAL: CONTRACT NO: DRAWING NO: PROJECT FILE NO:SCALE: FACILITY NUMBER: DEPARTMENT OF NATURAL RESOURCES & PARKS WASTEWATER TREATMENT DIVISION DATE: SHT NO / TOTAL REV NO: BO R D E R F I L E E D I T I O N : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r 1 2 345EFGHBCDA CHECKED: REFERENCE 1"0 P: \ C l i e n t s \ K i n g C o u n t y \ B C \ O n - C a l l B C \ S o u t h P l a n t W W T P \ _ C A D \ 0 2 - S H E E T S \ C - C I V I L \ 2 2 4 - 1 1 2 3 6 2 6 C 2 2 4 0 1 5 3 . d w g | L a y o u t : C 2 2 4 0 1 5 3 D E M O A N D T E S C D E T A I L S PL O T T E D : F e b 1 6 , 2 0 1 8 - 0 2 : 3 2 : 0 8 p m B y k r o g e r s XR E F S : K C W T D - 2 0 1 5 R 0 - D s i z e - T B - B o r d e r . d w g ; _ W A S H I N G T O N - S E A L _ E D . d w g IM A G E S : 2 1 3 . 4 _ C O R P W _ S t r a w W a t t l e s . t i f ; SOUTH TREATMENT PLANT BIOGAS AND HEAT SYSTEMS IMPROVEMENTS FEB 2018 15-xxxxxxx NO REVISION DESCRIPTION BY APVD DATE E F G HBCDA S. Hildreth D C G civil structural PRELIMINARY ISSUE DRAWING INFORMATION ONLY 90% REVIEW FEBRUARY 2018 I. McKelvey C01248C18 DEMO AND TESC DETAILS C2240153 D. Saarenas E. Davido NONE 0 R. Bard 33723 SCALE:NTS STRAW WATTLES C2240101 1 C2240102 C2240103 C2240104 C2240105 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX E Enlargement III Drainage Report F gal?“KKKKKt!'|_iI;I||||||||||||||||iP__¥iFh‘_‘|¢_W‘Ill‘!|_K‘l‘JH!v['Y"““_‘HH‘hhI[_fi__>_£____‘_>‘W‘I14|ll'“"“]”|]!________"_ufi_'_]||_“‘“UP_;‘¥_“k:H‘“hfs‘pl§K>’f[|‘l|I tatnalPtT_nI2 neI9am9lt_C_lPan GE’ GrmgQTG2aHgnOOrlirta_latnlrreenpDMREA _€/_ I\/‘llr\ I ‘I./“\£1kn’_ I I;A DRAINAGE PLAN MUNICIPALITY OF METROPOLITAN SEATTLE (METRO) ENLARGEMENT III OF METRO TREATMENT PLANT AT RENTON TABLE OF CONTENTS INTRODUCTION ............................................I CONSTRUCTION PHASE A,ENLARGEMENT III:SITE PREPARATION AND PERIMETER LANDSCAPING r .......4 CORE REQUIREMENT NO.1:DISCHARGE AT THE NATURAL LOCATION .............................5 Existing System ................................... Proposed System ................................... Underground Stormwater Sewer System .......... Stormwater Pump Station ...................... Emergency Relief Sewers ...................... _'Stormwater Quality Treatment .................-1~JO\O'\O'\U'l CORE REQUIREMENT NO.2:OFF—SITE ANALYSIS ...........9 Upstream Drainage Areas ...........................9 Downstream Drainage Areas ......................10 On—site Drainage ..................................11 Off~site Drainage .................................12 CORE REQUIREMENT NO.3:PEAK RATE RUNOFF CONTROL .'........13 Peak Rate Runoff Control Requirements .............13 Stormwater Modeling Results .......................14 Biofiltration Requirements ........................15 .Proposed Biofiltration Plan .......................15 CORE REQUIREMENT NO.4:CONVEYANCE SYSTEM ADEQUACY ......17 Adequacy of the Proposed Conveyance System ........17 Proposed Pumping Station ..........................18 CORE REQUIREMENT NO.5:TESCP ...........................21 MTPR Drainage Plan]Report I Drainpln .'doc/RCB E 1' i i. Id n 5 12ji TABLE OF CONTENTS,continued é SPECIAL REQUIREMENT NO.5:SPECIAL WATER QUALITY CONTROL ..............................22 Stormwater Quality Treatment Plan .................22 Minimum Requirements for Wetpond Facilities .......22 Proposed Oversized Wetpond Facilities .............23 SWM Wetpond Design Criteria .......................24 Compliance with SWM Design Criteria ...............24 MODIFICATIONS ...........................................26 APPENDICES Appendix A:Hydraulic Impacts of Redirecting Stormwater Runoff to the P—l Channel I Appendix B:Water Quality Impacts of Redirecting MTPR Stormwater Runoff into the P—l Channel Appendix C:Technical Support for Attaining Equivalent _Treatment with Oversized Wetponds Appendix D:Stormwater System Modeling:Hydrologic and Conveyance Capacity Analyses Appendix E:Technical Information Report (TIR)Form and _ Black River Basin Schematic E I Table Table Table Table Table Table Table 3 : (LIST OF TABLES ; 1.Drainage Basins —Proposed Development 2.Results of 100 year Storm Modeling:Pre~Development 3.Results of 100 year Storm Modeling:P0st—Development D1.Hydrograph Input Parameters:Pre—Development D2.Hydrograph Input Parameters:Post—Development D3.Existing Conveyance System Characteristics D4.Proposed Conveyance System Characteristics {i K 1 R IV i 1a1 v i FV r Figure Figure Figure Figure Figure Figure Figure LIST OF FIGURES Design Storm Hydrographs: 100 year and 1/3 of 2 year storms. Site Plan Stormwater Pumping Station Plan and Section Stormwater Pumping Station Site Plan Wetpond Facilities Schematic Existing Conveyance System Proposed Conveyance System 1 ¥ lI3 DRAINAGE PLAN MUNICIPALITY OF METROPOLITAN SEATTLE (METRO) ENLARGEMENT III OF METRO TREATMENT PLANT AT RENTON INTRODUCTION The Municipality of Metropolitan Seattle (Metro)is enlarging its regional wastewater treatment plant in Renton (MTPR)to provide treatment capacity for increased wastewater flows.These increased flows are the result of growth in the plant's service area and the transfer of flows from adjacent service areas.The proposed enlargement is a component of Metro's Comprehensive Water Pollution Abatement Plan for the Seattle~King County Metropolitan area,which implements Metro's wastewater Management Plan for the Lake Washington—Green River Basins.- The existing Metro treatment facilities in Renton will be retained and upgraded to optimize their capacity.New facilities will be added to further increase treatment capacity.The existing plant has the capacity to provide secondary treatment for 72 million gallons of sewage a day (mgd).The expanded plant will have the capacity to treat 108 mgd.The expansion from 72 to 108 mgd is referred to as Enlargement III.Phase A of Enlargement III entails site preparation and perimeter landscaping.Phase B is the liquid and solids stream upgrade and expansion.Phase C includes final landscaping and cleanup. The Drainage Plan also addresses the construction and operation of four new additional secondary clarifiers and a new additional 115—feet diameter anaerobic sludge digester.These facilities originally were part of Metro's Enlargement III project and were evaluated in the Final Supplemental Environmental Impact Statement for the Phase III Enlargement (May 24,1991).Construction of these facilities subsequently has been delayed for budget reasons but are still part of the original enlargement proposal.' New impermeable areas to be constructed in Enlargement III include paved areas for access roads,parking,a maintenance foot~trail,open channels,tanks and process structures.Most roadways and parking areas will drain to the existing underground storm sewer system which discharges to the Green River.Parking areas used to unload septage,load dewatered sludge and load grit will drain stormwater runoff to the plant's sanitary drain system.The sanitary drain system is routed through the plant for treatment and is ultimately pumped to Puget Sound through a 108-inch diameter force main —the effluent transfer system (ETS).Rainwater falling into open channels and tanks,onto covered channels and tanks,and onto process structures will be routed through the wastewater treatment plant.' MTPR Dra inage Plan/Report I Drainpln .doc/RCB ;1 5 r is —w\~\“€v'\»_\-1-_--=\-= }§‘E!s.iiii i% 2 This drainage report was prepared in accordance with Paragraph 4.22.8 of The City of Renton Code.It describes the physical aspects of the existing and proposed stormwater drain system to demonstrate compliance with applicable Core Requirements (CR),Special Requirements (SR),and design criteria of the King County Surface Water Design Manual (SWM).All _ stormwater facilities to be constructed at MTPR are sized to treat stormwater for all of the Enlargement III development, i.e.,eight new secondary clarifiers,two new dissolved air flotation tanks (DAFTS),one new aeration tank,four new primary clarifiers and one new anaerobic sludge digester.Future access roads planned for the middle of the site (to the north of the aeration tanks and between the new aeration tank and new secondary clarifiers)were considered in the calculation of peak storm runoff and stormwater quality requirements. Detention/retention facilities will not be required for Enlargement III since peak stormwater runoff will actually decrease.Biofiltration facilities and water quality control facilities will be required. Biofiltration swales will be located adjacent to newly constructed roadways and parking lots where sufficient pervious area is available.A stormwater pump station will be constructed at the confluence of the underground stormwater sewer system to . lift stormwater to a stormwater wetpond facility located on the surface.The capacity of the wetpond facility and pump station will be three times that required by the King County Surface Water Design Manual (SWM)for wetponds.The wetpond facility will be oversized to compensate for new impervious areas which will not receive treatment via biofiltration swales.Metro anticipates that the oversized wetpond facility will attain pollutant removals equal to or greater than removals attainable with a wetpond facility sized according to minimum requirements in series with the required biofiltration swales.Treated stormwater will drain from the wetponds to the P—l channel.Two new 30-inch emergency relief overflow sewers,which will also drain to the P-l channel,will provide flood protection and stormwater treatment bypass during extreme flood conditions in the Green River.‘ The stormwater pump station and biofiltration swales will be designed and constructed as part of Phase A.The wetpond facilities,associated outfall piping and the emergency relief sewers are scheduled for design and construction during Construction Phase C.Until the time when the oversized wetpond facilities are in operation,stormwater will be pumped to the wastewater treatment plant for treatment and discharge to Puget Sound.Since the pump station is planned to be in operation during Phase A,"interim"stormwater treatment is planned to begin during the winter of l992~1993. In this Drainage Plan,Metro has identified preliminary locations for the wetponds in the northern portion of the site in i (211 ___-_:;e=e===-_i; 1 l ) ) I > > \ 3 the vicinity of the wetland area.Metro is continuing to explore wetland enhancement opportunities in this area,which could utilize and incorporate some of the wetponds.Metro will obtain approval from Renton's Stormwater and wastewater Utility Engineering Supervisor if the final location of the wetponds is different from the preliminary location identified at this time. .Metro‘s proposal deviates from certain technical requirements in the SWM.Metro proposes to (1)discharge,on an interim basis,stormwater runoff through the treatment plant for treatment and discharge to Puget Sound through the ETS rather than to the Green River,and then to permanently discharge stormwater from the wetponds,and rare emergency flows,into the P~l channel rather than to the Green River (SWM CR1);(2) oversize the on-site wetpond facility because of the limited pervious area available to locate the required minimum number of biofiltration swales (SWM CR3);(3)operate a pumping system for stormwater conveyance and to use a pump storage facility (wet- well)with less than the minimum required storage volume (SWM CR4);and (4)discharge,on an interim basis,stormwater runoff through the treatment plant for treatment and discharge directly to Puget Sound through the ETS rather than treatment by the wetpond (SWM SR5). Metro previously requested and obtained approval from the City of Renton Hearing Examiner for variances with respect to items (2)and (4),and a portion of (1)allowing interim discharge of stormwater to the treatment plant.Pursuant to Renton Ordinance No.4342,effective March 9,1992,Metro is requesting,concurrent with this Drainage Plan,approval ("modification")from the Renton Director of Public works for item (1)to permanently discharge stormwater to the P—l channel, and item (3)to use a pump and smaller storage volume.See Request for Modifications,attached to this Drainage Plan. The Technical Information Report (TIR)Worksheet required with each drainage plan is attached at the end of this document in Appendix E. '1 l 1 i i ~r i E I Ll ii5: I Ir) I l 4 CONSTRUCTION PHASE A,ENLARGEMENT III: SITE PREPARATION AND PERIMETER LANDSCAPING Construction Phase A of Enlargement III includes site preparation for construction of process facilities in Phase B, civil site work including new utilities,roads and parking areas, and perimeter landscaping (grading and plantings)to allow vegetation to mature during the subsequent phases of construction. Site preparation will include excavating approximately 180,000 cubic yards of native soil and rock and placement of approximately 30,000 cubic yards of engineered fill.Excavated material will be stockpiled on—site for use in perimeter landscaping.Excess material will be distributed on~site and graded to drain to the existing underground stormwater sewer system.This first construction phase will also involve installation of concrete-drilled shafts (secant piles),stone columns,a site dewatering system,and approximately 840-feet of 48-inch diameter reinforced concrete pipe. Perimeter landscaping will involve construction of perimeter berms and fences,about 5,500 lineal feet of impervious maintenance trail,an irrigation system,and extensive tree and shrubbery planting.Approximately 120,000 cubic yards of material excavated from the secondary sedimentation area will be used for berm construction.Interior civil sitework will include " approximately 150,000 square feet of new and replaced asphalt roads and parking lots,and 6,500 lineal feet of new and replaced concrete curb and gutter. 5 CORE REQUIREMENT NO.1:DISCHARGE AT THE NATURAL LOCATION Core Requirement No.1 requires all surface and stormwater runoff from a proposed project that proposes to construct new,or modify existing drainage facilities must be discharged at the natural location so as not to be diverted onto,or away from,the adjacent downstream property.Discharge from the project must produce no significant adverse impacts to downhill property. Diversion which will correct an existing problem will be considered as a variance. This project will modify existing and construct new drainage facilities.Most of these new drainage facilities are required to comply with the SWM.This project proposes to divert surface and stormwater runoff from it's present discharge location,the Green River,to the P—l Channel.Discharge of stormwater from the MTPR site into the P—l Channel will not significantly impact downstream property,including the Black River Pumping Station and it's forebay. The interim and permanent treated stormwater discharge will be diverted from the existing outfall in the Green River.The project proposes to pump stormwater to the treatment plant with subsequent disposal to Puget Sound during the "interim"phase of construction.when the-wetponds are operational,stormwater will be pumped to the wetponds and will ultimately drain to the P—l channel.Bypass stormwater will drain to the P—l channel via new emergency overflow relief sewers when the Green River is at extreme flood stage.Metro has obtained a variance from CR1 for discharging stormwater to the treatment plant on an interim basis.Metro is applying for a modification of CR1 to discharge stormwater and emergency relief flows to the P-1 channel on an permanent basis. Existing System The total MTPR site has an area of about 84.5 acres.The existing on—site underground stormwater sewer system collects drainage from about 50 acres of impervious and pervious area. The collected stormwater drains by gravity to the Green River via a l20—inch outfall diffuser.Stormwater collected in open channels and tanks and on some process buildings,passes into the plant process stream for treatment and disposal in Puget Sound through the ETS.Runoff from the solids treatment and handling tanks,the dewatering sludge parking area and the septage unloading areas,about 3 acres in area,also drains to the plant's sanitary sewer system for treatment and discharge via the ETS. 1 Wetlands at the northern end of the site collect and store runoff from about 8 acres of pervious area.A section of Oakesdale Drive on the northern border of the MTPR site constitutes about 1.2 acres of the site.Runoff from Oakesdale 3 -Ii i V1 if 6 Drive enters the City of Renton stormwater system.A grassy swale along Longacres Drive collects and stores runoff from the southwest boundary of the site,about 2.5 acres.The swale drains eastward to the P—l channel.A narrow 3.5 acre pervious strip between the eastern property line and the east internal access road drains directly to the P—l channel. §fl The proposed Enlargement III site plan includes 49.6 acres of pervious (30.75 acres)and impervious (18.85)area draining to the underground stormwater sewer system.About 17 additional acres will drain,either directly or via the plant's sanitary sewer system,to the wastewater treatment plant.Table l presents the area of the various drainage areas of the Enlargement III site., Underground Stormwater Sewer System.The existing stormwater sewer system will be modified and extended to collect runoff from regraded landscaped areas,realigned roadways,and proposed new parking areas and roadways.The total drainage area tributary to the stormwater sewer system will not be increased in Enlargement III . Modifications to the underground storm sewer system basically consist of relocating existing catch basins to drain realigned roadways and parking lots.Realigned roads and parking lots requiring the repositioning of catch basins are as follows:the internal roads extending from the new entrance off Monster Road, roads extending from the 7th Avenue entrance and around the Dewatering building,the road realigned around the base of water tower hill,the repositioned parking lot north of the Administration Building,and the new parking lot south of the existing 12 KVA Substation.1 The stormwater sewer system will be extended to the new roads and parking lots serving the new DAFT complex and anaerobic sludge digester.Stormwater from these areas will drain to the plant's sanitary sewer system.In the proposed enlargement, stormwater draining to the grit loading ramp will be pumped to the plant sanitary sewer system in a manner similar to that serving the dewatered sludge loading area.Only when the capacity of the pumps is exceeded,such as during an extreme storm event like the 100-year storm,will stormwater from the grit area drain to the stormwater sewer system. Stormwater Pump Station.The existing underground stormwater sewer system will be augmented with a stormwater pump system at the storm sewer junction manhole.The pump station is necessary to lift stormwater flows requiring treatment from the underground storm sewer to water quality facilities located on the surface. This pump station will have the capacity to pump three times the required design storm peak flow rate for wetponds,i.e.,4.5 cfs (2.9 MGD).Flows in excess of the pump capacity will bypass the I Iv > E ! 7 II Ii i iI ;,V1 I !I i N 7 pump station and drain to the Green River via the existing 120- inch outfall diffuser.The proposed system will retain the flap gates located at the outfall manhole to prevent the influx of the Green River into the stormwater sewer system during extreme flood stage in the Green River. Emergengy Relief Sewers.Two new 30-inch emergency relief overflow sewers,one to serve each of the two stormwater sewer branches,are proposed for the underground stormwater sewer system.Stormwater entering these overflow sewers will discharge to the P—l Channel.These overflow sewers will provide relief to the plant's stormwater sewer system during extreme flood stage in the Green River,and allow flows to bypass the stormwater water quality facilities as required by the SWM.Also,these sewers will alleviate the need for another pump station while satisfying the goals of the Green River Management Group regarding discharge into the Green River during extreme flood stage. The relief sewers take advantage of the elevation difference between the Green River and Pal channel during extreme flood events,i.e.,Elevation 121 and Elevation 114,respectively, during the 100—year flood event.Emergency overflow weirs will be set at Elevation 118.0 and be located near the eastern end of the 30-inch pipe branches.Stormwater flowing over the weirs will flow by gravity to the P—l channel through 30-inch pipe. Both emergency relief sewers will be supplied with a flap gate to prohibit water in the P—l channel from entering the on—site stormwater system.4 The emergency relief overflow sewer plan will satisfy the goals of the Green River Management Group.The Green River Management Group manages the Green River Drainage Basin and controls the influx of flows to the Green River.For example, the Black River Pumping Station must start to throttle pumping when the Green River reaches 9000 cfs and must stop once the flow in the Green River reaches 12000 cfs,i.e.,about the 100—year flood stage.Overflowing MTPR's storm sewer system to the P—l channel allows the Black River pumping station to regulate the discharge of stormwater to the Green River,a preference of the Green River Management Group.Also,the stage of the Green_River will automatically throttle MTPR stormwater bypass flow draining to the Green River via the outfall diffuser. StQrmwater_Quality_$;eatment.Both biofiltration and water quality control facilities are required for this project in accordance with SWM CR3 and SR5.Biofiltration swales will be constructed alongside new roadways and parking lots where sufficient pervious area is available.Runoff from about 33%of the proposed new roadway and parking lot surface area will be treated with swales.Biofiltration swale effluent will subsequently drain to the stormwater sewer system from which it will be pumped to the water quality control facility.The swales will be constructed in accordance with Sections l.2.3,4.6.3,and 4.3.6 of the SWM. 4.:--._-=-.-_4_T;.4.m»1_T,_4;? II I 8 Because not all new roadways and parking areas can be treated by localized biofiltration due to site limitations,the required minimum volume and surface area of wetpond will be increased to three times that required by the SWM SR5.The oversized wetpond facility will impart equivalent or better treatment than biofiltration of all new impervious roads and parking lots in conjunction with wetponds sized for the minimal acceptable criteria.I The wetponds will be a series of three ponds located near the existing on—site wetlands.The ponds will be terraced to.a1low gravity flow between the wetponds,ultimately draining to the P~l channel.The wetpond facility will be designed and constructed in accordance with SWM Sections 1.3.5,4.6.2 and 4.4.4. In this Drainage Plan,Metro has identified preliminary locations for the wetponds in the northern portion of the site in the vicinity of the wetland area.Metro is continuing to explore wetland enhancement opportunities in this area,which could utilize and incorporate some of the wetponds.Metro will obtain approval from Renton's Stormwater and wastewater Utility Engineering Supervisor if the final location of the wetponds is different from the preliminary location identified at this time. The proposed stormwater pump station,the force main to the treatment plant,and the biofiltration swales will be constructed as part of Phase A Construction.The pump station should be operational for the winter of 1992-1993.The wetponds and the emergency relief overflow sewers are planned for design and construction during Phase C.Phase C design is scheduled to commence in late 1994.In the interim,the pump station will pump stormwater to the headworks of the wastewater plant for treatment and subsequently discharge to Puget Sound via the ETS. In the event of an emergency,stormwater will be routed directly to the Green River outfall.Metro currently holds a NPDES permit to discharge sewage to the Green River in such an emergency,but has never needed to do so.Also,Metro does not currently need an NPDES permit to discharge stormwater to the Green River.Stormwater pumping will be redirected to the wetpond facility when it becomes operational. II I i I I I ‘I I §I I 9 CORE REQUIREMENT NO.2:OFF—SITE ANALYSIS Core Requirement No.2 requires that all proposed projects must identify the upstream tributary drainage area and perform an analysis of the drainage system downstream from the proposed project.This analysis includes a Level 1 analysis of on—site and off—site drainage systems for the minimum distance prescribed in the SWM.This analysis also includes hydraulic and qualitative assessments of diverting MTPR l00~year 24-hour stormwater flows into the P—l Channel.Both assessments . concluded that the impacts of diverting MTPR stormwater into the P-1 Channel were insignificant. Qpstream Dgaipage Areas The King County Reconnaissance Program has placed the MTPR site within the Black River watershed.Appendix E contains a schematic of the Black River Drainage Basin.A vestige of the Black River,the P~1 channel runs along the eastern boundary of the treatment plant.Except for rainwater falling on or near the banks of the P~1 channel,all site drainage flows either to the stormwater or sanitary sewer systems.The current stormwater sewer system drains to the Green River.The sanitary sewer system discharges to the wastewater treatment plant.The treatment plant and stormwater outfall are located just upstream of the confluence of the Green River and Black River.The Green River and Black River combine to form the Duwamish River. ‘The Green~Duwamish River drains approximately 483 square miles of south and southwest King County.Flow in the main river below River Mile 64.5 is controlled by release from Howard A. Hanson Dam.The mean annual flow at Auburn is 1366 cfs (1986). The upper drainage of the Green—Duwamish system is fed by rains and snowmelt.The lower drainage —Big Soos Creek and Newaukum Creek,the two main tributaries —are fed by rain and groundwater.- The northern portion of the lower Green River basin is dominated by the commercial areas of Southcenter,surrounding commercial and light—industrial land uses,three major traffic arterials,and the shopping district north of Sea—Tac Airport. Existing and anticipated problems in the lower Green River are clearly development—related.Severe erosion along the basin's steep slopes and valley walls (Grandview Park,Kent Highlands Landfill)results in downstream sedimentation that reduces channel capacity and degrades water quality.Continued rapid development in this basin,without installation of adequate runoff controls,will exacerbate existing problems. A vestige of the Black River intersects the Green River at River Mile ll and forms the Duwamish River.The Black River used to be the primary drainage for Lake Washington before the Lake Washington Ship Canal was dug in 1917.Now the Black River I I I I I II 10 originates from storm drainage and groundwater in the center of Renton and flows west 2.65 miles to its confluence with the Duwamish.Springbrook Creek (also known as the P~l Channel) drains about 12 miles along the east valley hillside.The Black River basin has extensive areas of impervious surface and is almost wholly contained within the cities of Tukwila,Renton,and Kent . The P—l Channel conveys drainage from the Southcenter area north of I-405 into the former Black River channel.The channel generally follows the former path of Springbrook Creek and thus is referred to as both Springbrook Creek and the P-1 Channel. Drainage is impounded in the P~1 pond (The Black River Pumping Station Forebay)and pumped into the Black River channel before confluence with the Green River.The P—l channel joins the former Black River south of a forested wetland area,at the P~1 Pond,behind the Black River Pumping Station. Problems in the Black River basin stem partly from high runoff velocities from developing areas.Steep slopes and saturated soils in the ravines,garbage disposal along riverbanks,and commercial and industrial runoff have all contributed to visibly poor water quality,sedimentation, decimated fish habitat,and other complications.The King County Basin Reconnaissance Program Summary notes that Springbrook Creek,where it flows under the SW 16th Street bridge just east of Longacres (and just upstream of the MTPR)is one of the worst examples of surface water degradation in the area.Problems with this channel will continue unless storm flows are controlled where they originate,steep valley walls are protected from erosion and landslides,garbage dumping is checked,and sediment transport into the valley floor is reduced. Docwnstream 7 Drainage Areas Water quality in the Duwamish up to River Mile (RM)ll is designated "Class B"(good)due to,and in full consideration of, its industrial nature.The navigable portion of the Duwamish Waterway,below RM 5.2,is dredged almost every year to alleviate the river's heavy sediment load.The Green River from the mouth of the Black River (RM 11)to RM 42.3 is designated "Class A" (excellent).Stormwater from the MTPR discharges at RM 12.2. The lower Green River sites have relatively moderate turbidities and high suspended solids.According to the King County Sensitive Area Map Folios,the treatment site is not in the l00~ year flood plain. Discharge of treated stormwater and emergency overflow from MTPR to the P—l channel will produce no significant quantity or quality impacts to the P—l channel,Black River Pumping Station or forebay. A hydraulic modeling analysis requested by the City of Renton concluded that the l00—year 24—hour flood flow from the MTPR site I ll would raise the level of the Black River forebay only 0.07 feet (about 1-inch)assuming very conservative conditions.A one—inch rise in the forebay will not significantly impact any of the surrounding property or habitat.Appendix A contains a letter describing the results of the hydraulic/hydrologic analysis. Similarly,an analysis of the potential water quality impacts of MTPR stormwater on the P—l channel was addressed in a letter from Adolphson and Associates to Metro.Water quality in the P—l Channel generally appears turbid at the point of discharge to the Black River.The Black River,both upstream and downstream of the MTPR site,is listed among the most degraded streams in the Metro sampling area.Considering the degraded water quality of the P—l channel,the likely higher water quality of MTPR's treated stormwater,and MTPR's relatively small contribution of flow quantitatively,the conclusion is reached that “...no discernible impacts to the P~l Channel are anticipated in the short or long term future."This letter is attached in Appendix B. Qn—sita Drainaga I Table 1 presents the tributary drainage areas of the proposed Enlargement III.Of a total site area of 84.5 acres,only 49.6 acres will be tributary to the site's stormwater sewer system. The 49.6 acres will consist of about 30.7 acres of pervious surface and about 18.9 acres of impervious surfaces.Of the 18.9 acres of impervious surfaces,only 12.0 acres will be subject to vehicular use or chemical storage.About 3.6 acres of the site will drain directly to the P~l channel,about 7.8 acres will drain to the wetlands,about 2.93 acres will drain to the sanitary system from the Sludge Dewatering Facility (during non- extreme storm events)and about 17.0 acres of the site will be open tanks and channels or will drain to treatment process tanks. The existing site impervious area is approximately 16.5 acres.Enlargement III will increase the total impervious area by 2.4 acres to 18.9 acres.Only 0.4 acres of this new impervious area will drain to the stormwater system.The remaining impervious areas will drain to the plant's sanitary system. Realignments of existing roads will not significantly increase the area of impervious surfaces draining to the stormwater sewer system.Surfaces that will significantly contribute higher stormwater flows are the new road and parking lots serving the new DAFT complex,the new parking lot for the 12 KVA Substation,and the proposed roadways providing access to the new secondary clarifiers and aeration tank.However,stormwater eminating from the roads and parking areas serving the DAFTS will be pumped to the sanitary sewer.Only when the capacity of the pumps are exceeded will runoff from the DAFTS enter the stormwater sewer. I I I I I I I I I I I I III III ____w;8$ Ong_s°___g_N_M1Np_g_W__2w__§E2_ommWO_O___Q>g§___n__wvmqa$3go_>__g______n_mg“86¢O9:3“263“Q:_m___w_3e__wo6gN:2U___fl_~O>>3>_2_5_;_NEd_m_s__Eo___fl_2>__2_____’_|____ $3gO_>an_6 __g_6m__Bs___E__2mO_>___w__3_h____N_ E_m_n_Em_____$____I2_“§_fi_6 mF__a___;__g_g_____m_m _UflO_C:gsgm_¢ 0_g_wflQ__OflmCO_I_O_?_E_5_hl__6 $54____$m\$_< __1 __=QEQO_Q>QQbQWOQO__h___WE%Nm%g_EQ ‘(ppFm_O_£is HWNHaR_______w3U_____HBU____m_u3U_____OUJ53w3u1’III 12 The perimeter trail,which is about 5,500 feet long and between four and six feet wide,constitutes about 0.8 acres of impervious surfaces.This trail is hydraulically disconnected from the stormwater sewer system and should not significantly alter the existing drainage conditions along the trail.The trail will drain to the surrounding land,including the wetland, thereby receiving treatment by way of infiltration. The peak stormwater runoff during the 100-year 24-hour design storm (3.9 inches of rainfall)for Enlargement III is estimated to be 23.0 cfs.The post—development l0O—year 24-hour peak storm runoff rate at the outfall manhole is estimated to be 22.6 cfs, or 0.4 cfs less.The existing on-site stormwater sewer system has the capacity to handle the l0O—year 24-hour storm. Qff-sita Draigagg No stormwater originating off-site drains through the MTPR site.All stormwater runoff originating on-site drains to either the Green River,the P—l Channel,or to the treatment plant via open vessels or the plant's sanitary sewer system.Rain falling on the MTPR site therefore does not affect other sites.Rain falling on other sites does not flow through the MTPR site. I I I I I )I) EI I I 13 CORE REQUIREMENT NO.3:PEAK RATE RUNOFF CONTROL King County SWM Section 1.2.3,CR3 requires that all proposed projects must provide runoff control through a combination of peak rate runoff control and on-site biofiltration measures. Peak rate runoff control is provided through detention,retention or infiltration. This project will not be required to provide peak rate runoff control,i.e.,detention,retention or infiltration.Stormwater modeling indicates that the proposed Enlargement III project will not increase the peak rate runoff resulting from the 100-year 24- hour storm more than 0.5 cfs.In fact,modeling indicates that the peak rate runoff from the 100-year 24-hour storm will - decrease. This proposed project will be required to provide biofiltration to stormwater before the stormwater leaves the site since over 5000 square feet of new impervious area subject to vehicular use or chemical storage will be constructed.The proposed plan is to construct localized biofiltration swales adjacent to new roadways and parking lots where sufficient pervious area is available.About 33%of the new roads and parking lots will be served by five biofiltration swales. Not all of the new roadways and parking areas will receive biofiltration.A wetpond facility will be oversized to compensate for the inability to provide the minimum biofiltration swales.Metro has obtained a variance from CR3 to use this approach. P.eakc_Rate Runoff CD1'IL_I.'.O_l Re.s.n.u.re.ments All proposed projects must provide peak rate runoff control except for any of the following conditions: *The project includes less than 5,000 square feet of additional impervious surface *Stormwater modeling indicates that the proposed project will not increase the peak rate runoff resulting from a l0O—year,24-hour storm more than 0.5 cfs above the peak rate runoff for existing runoff conditions *The proposed project will discharge surface and stormwater runoff directly to:a regional facility;below River Mile 6.0 of the Green-Duwamish River;a lake;a wetland;or a closed depression. Stormwappr Mqdelinq Resulta The existing and proposed stormwater sewer systems were modeled to establish whether the proposed construction will increase the peak flow resulting from a 100-year storm by more than 0.5 cfs.Appendix A describes the methodology used to I. II IIIIII‘ I II I I 14 determine the peak storm runoff rates for the pre-and post- developed site.Modeling demonstrated that the calculated peak runoff for the 100-year 24-hour storm after development is less than before development —-22.99 cfs before development vs.22.61 cfs after development.Flow hydrographs at the outfall manhole are presented in Figure 1. Because modeling indicated that the peak rate runoff for the l0O—year 24-hour storm after development is less than before development,and because the MTPR site is not in a Critical Drainage Area,the proposed project is exempt from Core Requirement No.3 with respect to peak rate runoff control. The modeling results are consistent with changes in drainage that will be brought about by Enlargement III.The new additional channels,tanks,DAFTs and anaerobic digester will be constructed on over four acres of pervious area that is currently tributary to the stormwater sewer system.Stormwater from these new facilities will be directed to the wastewater treatment plant and will su sequently drain to Puget Sound via the ETS. e .... e b Propos d new impervious areas will increase the storm sewer tributary impervious area by 2.3 acres,from 16.6 to 18.9 acres. Some of th new net impervious area is a maintenance trail that meanders along the perimeter of the site.Most of the trail is separated from the impervious areas that drain directly to the stormwater sewer.Therefore,runoff from the trail must flow over pervious areas to reach a stormwater inlet.Considering that model conditions inherently assume pervious areas to be saturated or nearly saturated,the relatively small net increase in impervious area does not appear to be sufficient to offset the removal of more than four acres of pervious area from the drainage basin. Tables 2 and 3 present the flow quantities and velocities for each storm sewer pipe segment for the 100—year 24-hour storm for pre-and post-development,respectively.The tables show that flow between the northern and southern 30-inch drain lines is fairly equal.Only one pipe segment,the 30-inch pipe at node 1004,experienced flow greater than its rated capacity during this design storm.Though the peak flow at node 1004 was about 102 percent of capacity for both pre-and post—development conditions,no overflows occurred in any part of the sewer system during this hypothetical storm.Thus,the proposed stormwater sewer system is capable of conveying the peak flows generated by the 100-year 24-hour design storm. Biofiltration Reqairements Biofiltration processes runoff from impervious areas subject to vehicular use or chemical storage.Biofiltration must take place prior to discharge from the project site and be designed as described in SWM Section 4.6.3.Biofiltration facilities are I II I ZZZ:21S99000 Z‘numb9900 I m90 ‘£_l_S0 i.0090 l‘P:90 i"V90 LT“90 m___°___Z‘LS900 L_0G0 6BL9T:MyTh9Q9999900U00U0 IgDallN__ “bF5;L__Icy“_L9!_a_______ ‘_._'._‘.‘_..v._._-'._-__._._"._O“_‘_4_V_V__‘._._.__'O.D.____I_h .__._"_“_ _’_:.‘:‘________pi _5E_§§_Tfi36%D2I?‘“_aE%_g%i8n_6%O2I‘! _n__$__ ___.D~ _r_"~___\_____’__‘__. <rM I_éI_nI\K Qg8§_gemfig518*ENEE _m__:9H_ Z@2 g_m7+“ U H5E%_g%'_mR_5%N‘I'llMg"Q gQ/tr‘ Link »'TABLE 2 -Drainage Report Table 2.Results of 100 year Storm Modeling Pre-Development Total Contributing Area =48.47 Acres Peak Flow =22.99 cfs Node ID Length 1 Downstream Elevation Diameter Area 0000 ,(11) i__i__..__._iii Rim 'I“’€‘1 W (lr1)’(Acrefs)(cfs) DesVel UPS) Time (min) LatLong $ysLong 3 (71)00 10(D\JOIU’l~bf.JI\J-* 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 1101 1100 1099 1098 1097 1096 1095 1094 1093 1092 1091 1090 1089 1088 1087 1086 1085 1084 1083 1082 1081 1080 2079 1078 1079 1077 2076 1076 1075 1074 1073 1072 1071 1070 1069 1067 1000 1005 2% 58 105 324 108 77 3 40 3 70 ; es as 72 70 100 00 as 110 140 107 100 210 A 100 100 100 100 72 290 1 207 1 196 77 205 83 320 160 127 172 170 43 53 1 126.9 126.21 126.21 125.25 125.25 114.24 111 109.9 110.1 110.75 115.54 115.54 125.35 110.68 110.75 111.5 125.25 125.25 125.25 125.25 125.5 125.25 125.5 125.25 125.25 125.25 125.5 125.25 125.25 125.25 125.25 125.25 125.02 125 125 125.33 125.5 125.5 119.5 119 119 113.19 111.25 106.39 106 105.44 104.68 103.92 105.04 105.04 104.12 103.94 103.42 103.24 121 121 108.36 107.8 120.98 120.16 120.98 120.65 107.35 106.61 121 1 19.62 118.38 116.74 118.73 106.5 114.92 113.76 112.77 112.28 118.7 117 0 T 1.12 0 1.04 .0 0.04 if 10 2.40 15 3 2.40 ‘12 ‘0.20 12 0.49 12 0.90 12 1.5 12 1.05 0 1 0.00 0 0.15 0 0.51 0 0.02" 12 0.07 1 10 2.90 1 14 1 2.90 12 0.19 a0 0.00 00 1 0.00 12 0.00 1 12 0.10 ‘12 1.02 12 ‘2.17 00 0.54 30 10.71 12 2.07 12 1 2.00 12 0.04 12 0.0 12 2.41 30 16.48 a 0.14 10.0.47 0.50 0.00 ‘15 1 12 0.2 12 1 0.2 ‘1 5 0.56 0.89 0.45 1 .31 1 .24 0.26 0.43 0.86 1 .33 1 .69 0.06 0.1 1 0.39 0.51 0.77 2.66 2.55 0.22 4.81 4.75 0.08 0.1 9 0.59 0.81 4.68 5.35 0.69 0.85 0.77 1 .56 1 .1 5 7.76 0.1 7 0.46 0.56 0.77 0.23 0.23 3.28 3.18 2.51 4.23 4.16 2.02 2.56 2.91 3.3 3.55 1.32 1.53 4.96 2.36 2.52 1.92 4.35 2.88 5.65 2.9 1.52 1.94 2.57 2.06 3.91 2.99 3.16 2.77 2.82 3.46 3.15 1.61 3.19 2.56 1 .81 1 .89 5.18 3.39 1 .48 0.3 0.7 1 .28 0.43 0.63 0.26 0.4 0.48 0.45 0.91 0.85 0.51 0.21 0.58 0.95 0.54 0.62 0.31 1 .2 1 .1 0.88 0.65 0.83 0.31 1 .62 1 .09 1 .18 0.46 0.99 0.44 3.3 0.84 0.83 1 .58 1 .5 0.1 4 00% 290 348 105 429 537 77 1 17 1 87 282 377 72 78 1 53 1 83 271 1 10 250 107 1 05 31 5 1 00 203 1 00 203 72 362 207 403 77 282 B3 403 160 287 459 63 823 290 040 100 777 005 77 117 107 202 077 72 70 aos . 033 421 900 1040 107 2140 2005 100 20:1 100 203 2000 0123 207 40a 77 000 as 421 1 100 207 409 029 40 8 E 11 11- 1 1111 1? Storm Water Modeling Results Hydra &SCS:Brown and Caldwell G18 Pre-Development Conditions Renton Ill 100 yr -24 hr storm ‘‘TABLE 2 -Drainage Report Link ‘Node Length Downstream Elevation Diameter Area ID Rim Invert (in) 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 65 69 70 71 72 73 74 75 76 T7 78 79 1064 1063 1062 1061 1060 1059 1056 1051 1050 1049 1048 1047 1046 1045 1044 2021 1021 1020 1019 1018 1017 1016 1015 1014 1012 1011 1010 1009 2028 1030 1036 1035 1034 1033 1032 1031 1029 1024 1027 1026 1 025 125.33 126.5 126.5 125.25 125.25 125.25 125.25 136 133 126 130.1 130.1 129.42 130.1 129 126.8 125.5 125.5 125.5 125.94 126.2 125.94 126.5 126.5 126.4 126.5 125.5 125.6 125.2 125.2 123.5 123.4 123.3 123 123.5 125.2 125 124 123.3 123.3 123.3 112.56 110.44 120.1 109.53 106.67 100.2 107 131 121.62 122 119.79 119.79 121.73 119.79 102.59 108.2 107 107 107 106.58 122.84 106.6 106.27 106.27 117.52 117.14 106.06 105.24 116 116 119.86 119.51 118.5 117.89 116.54 116 1 15.55 114 113.8 110.5 107.8 12 21 12 24 24 24 24 B 10 6 15 6 1s 15 18 a 16 16 6 1a 10 16 21 8 8 8 24 30 12 12 12 12 12 12 12 12 1s 16 1s 15 11:» (Acres)é DesQ (¢1=) Desvel (fps) Time (min) 0.31 2.21 0.04 2.25 5.71 6.25 6.91 0.05 0.05 0.05 3.67 0.67 0.22 0.22 4.56 3.28 3.71 3.91 0.21 4.33 0.54 0.54 5.26 0.44 1 .2 1 .3 7 7.34 0.1 0.13 '0.48 .0.66 0.64 0.9 0.99 1 .30 2.26 2.26 2.40 2.62 11.1 g 0.34 1 .49 0.05 1 .39 3.01 3.09 3.44 0.06 0.06 0.06 1 .04 0.8 0.27 0.23 1 .83 1 .16 1 .48 1 .62 0.18 1.86 0.61 0.58 2.52 0.28 0.75 0.81 3.48 3.72 0.05 0.1 1 0.27 0.51 0.6 0.63 0.7 0.84 1 .6 1 .59 1 .55 1 .73 1 .9 -1.66 2.66 1.06 ‘2.64 ~6.12 3.1a 6.26 5.16 1 2.65 2.11 2.66 6.01 1 0.93 2.6 6.65 6.04 2.52 1.96 4.55 1.99 2.66 4.62 2.66 I 4.24 2.94 3.02 2.41 2.44 1 1.46 2.6 2.42 6.64 1 2.92 1 6.04 3.01 3.09 6.36 2.66 2.07 6.19 s.s1 0.22 2.7 0.6 1 .02 1 .02 0.57 1 .43 0.52 1 .04 0.26 1 .76 0.99 5.31 0.79 0.24 0.88 2.04 2.08 0.8 2.14 1 .35 0.23 0.48 1 .1 1 .75 0.26 0.71 1 .1 1 .14 1 .6 0.69 0.06 0.51 0.27 0.69 0.3 0.05 1 .88 0.8 0.41 0.29 LatLong $ysLong 16> 1 61 544 38 1 93 384 491 767 160 337 380 682 227 296 420 556 320 626 873 217 472 21 7 280 363 260 309 356 461 621 1 00 220 1 00 1 14 204 254 379 434 4-49 769 869 997 1 093 (R)- 161 1173 38 1366 155 1664 1940 160 337 360 632 227 296 420 1465 320 628 B73 217 1345 217 280 1705 2B-0 309 356 2449 2609 100 220 100 114 204 254 379 434 769 1089 1189 1317 1413 1 1 ii 1 1 1 1 i 1 §) Storm Water Modeting Results Hydra &SCS:Brown and Caldwell GIS Pre-Development Conditions Renton lll 100 yr -24 hr stonn TABLE 2 -Drainage Report R rl__1___m/en 1Ii.-._—-“-.-i Link 1 Node Length lDownstreamEleva1ion Diameter}Area 10 (11)1 1 1 (In)1 (Acres) DesQ 59'" Desvel 1'21» 80 81 82 83 B4 85 86 87 88 1 89 91 92 196 194 95 96 97 96 99 ‘H100 1024 1023 1022 1037 1042 1041 1040 1039 1038 1005 1056 1055 1052 1008 1007 1006 1004 3001 1043 1003 1002 128 244 40 45 148 1 120 100 80 140 325 252 305 284 150 482 102 156 72 112 71 125.6 125.51 125.5 125.5 125.5 126 126 128 125.5 125.5 126 129 129 125.5 125.5 126 127.5 129.5 127.5 128 129 H524 121.7 121.5 104.7 121.61 120.2 119.5 119 105.35 120.7 105.85 105.01 102.59 104.7 120.9 103.46 102.96 118.91 115.5 102.73 89.75 153 12 12 8 8 12 12 6 12 12 8888888 10 12 30 30 1 17.1 3.13 0.19 0.36 0.18 0.58 0.58 1 .76 0.21 2.31 0.45 23.39 23.39 23.39 10.47 1 1 .01 13.77 14.1 1 3.42 2.99 17.1 1 .88 0.17 0.26 0.17 0.72 0.69 1 .73 0.25 2.24 0.42 1 1 .03 10.82 10.64 5.54 5.84 8.04 8.1 9 1 .47 1 .65 9.27 9.24 4.87 1 .63 1 .76 8.04 2.87 2.74 3.21 2.42 4.75 1 .97 3.4 4.03 5.45 2.71 3.56 3 4.29 4.91 3.36 3.2 1 6.47 0.44 2.5 0.38 0.09 0.86 1 .03 0.62 0.69 0.28 1 .18 1 .59 1 .04 0.93 1 .75 0.7 2.68 0.4 0.53 0.36- 0.58 0.07 1221 244 264 -16 1 -16 611 467 100 1 60 140 626 511 662 294 464 916 102 156 72 164 255 1541 244 284 45 1 48 317 437 100 617 140 6476 6728 £9 491 3 61 52 6254 1 56 72 6438 6509 TIIHG LalL0ng SysLong ‘N 1 ("'4")1")(fl)1 1 1017 1001 999.9 89 120 A947 7 2.99 2.63 6.9;1254.9 16162.9 11 1 \ 1(l 1 1 I I i1I TABLE 3 Drainage Report Table 3.Results of 100 year Storm Post-Development Total Contributing Area =43.65 Acres Peak Flow =22.61 cfs Link Node Length 1D0wnstreamE1evati»on Diameter‘A700 ID 111)R111 .1.2'19""(in)(Acres) DasQ (cfs) DesVel ____.§“@),2_- Time 9299 1 LatLong 1 SysL0ng ‘10>A 01> (OU>\lO7(J'lA(fl1\)-* 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 1101 1100 1099 1090 1097 1090 1095 1094 1093 1092 1091 1090 1009 1000 1007 1000 1005 1004 1009 1002 1001 1000 2079 1070 1079 1077 2070 1070 1075 1074 1073 1072 1071 1070 1009 1007 1000 290 $8 105 324 108 T7 40 70 95 95 72 78 153 30 88 110 140 107 105 210 100 103 100 103 72 290 207 196 7'7 205 83 320 160 127 172 170 43 126.9 126.21 126.21 125.25 125.25 114.24 111 109.9 110.1 110.75 115.54 115.54 125.35 110.68 110.75 111.5 125.25 125.25 125.25 125.25 125.5 125.25 125.5 125.25 125.25 125.25 125.5 125.25 125.25 125.25 125.25 125.25 125.02 125 125 125.33 125.5 119.5 119 119 113.19 111.25 106.39 106 1 105.44 1 1 04.68 ‘10192 10504 10004 10412 10394 10342 10324 121 121 1 10020 1070 12090 12040 1 12090 12005 10735 1 10001 I 121 1 11902 11090 11674 11073 106.5 11492 11370 11277 ‘11220 "1107 1 0 1 072 0 1 1.44 073 247 ‘247 12 »02 12 1 0.28 12 0.77 12 1.43 12 1.86 8 1s; 151 0 1 000 8 j 0.15 8 0.62 12 0.87 14 1 3.12 12 j 049 30 7.98 12 0.05 12 1 .52 12 1.31 90 990 12 .52 12 1 220 8 '0.51 18 3.12 30 7.98 12 0.16 30 8.14 12 1.03 12 0.64 12 2.41 so 1400 0 0.14 10 1 047 15 1 050 15 0.3? 12 02 0.4 0.74 0.58 1 .29 1 .22 0.24 0.34 0.73 1 .34 1 .78 0.06 0.1 1 0.39 0.51 0.77 2.79 2.68 0.22 4.84 4.78 0.08 0.1 9 0.59 0.69 4.71 5.28 0.34 0.51 0.77 1 .29 1 .24 7.38 0.17 0.46 0.56 0.77 0.23 297 901 ‘272 421 1 415 1 1.99 1 240 1 275 *001 90 1.02 L53 ;490 290 202 195 1 442 1 200 000 291 102 194 257 £90 392 297 200 200 1 202 1 927 020 101 319 1 200 101 109 510 1 .63 0.32 0.64 1 .28 0.43 0.64 0.27 0.42 0.48 0.44 0.91 0.85 0.51 0.21 0.58 0.94 0.53 0.62 0.31 1 .2 1 .1 0.88 0.65 0.87 0.31 1 .63 1 .29 1 .39 0.46 1 .04 0.43 3.31 0.84 0.83 1 .58 1 .5 0.1 4 429 537 282 377 __W41 290 040 100 777 00s 77 117 107 202 J 077 1 72 1 70 E 000 1 300 1 421 900 *1040 1 107 ’2140 2005 100 203 100 200 2000 0129- 207 *400 §77 1 005 09 4211 100 287 459 629 1 43 1L 100 yr 24 hr stom1 Storm Water Modeling Results Hydra &SOS Post Development Conditions ''TABLE 3 -Drainage Report E ID L1nk Node ‘Length (fl) Downst Rlm ream Elevation Invert 16 Diameter‘Area D660 DasVa! (Aeres) 111116 mi l.atLong SysLor1g 1066 1064 1063 1062 1061 1060 1069 1066 1061 1060 1049 1046 1041 2047 1046 1046 1044 2021 1021 1020 1019 1016 1017 1016 1016 1014 1012 1011 1010 1009 2026 1090 1066 1066 1034 106:. 1032 1031 1029 1020 1021 53 65 363 38 155 191 107 276 160 177 43 302 140 227 296 124 136 320 308 245 217 255 217 63 83 280 309 47 105 160 100 220 100 14 90 50 125 55 15 320 126.6 126.:-1:1 126.6 126.6 126.26 126.26 126.26 126.26 136 1:16 126 130.1 132.2 100.1 129.42 100.1 _ 129 126.6 126.6 126.6 126.6 126.94 126.2 126.94 126.64 126.6 126.4 126.6 126.6 126.6 126.2 126.2 123.6 129.4 126.6 126 123.6 126.2 126 124 112.86 110.44 120.1 109.53 108.67 108.2 107 131 121.62 122 119.79 121.79 119.79 121.73 119.79 102.59 106.22 107 107 107 106.58 122.64 106.6 106.27 106.27 117.52 117.14 106.06 105.24 116 116 119.86 119.51 118.5 117.89 116.54 116 115.55 1 14 2.21 0.04 2.25 5.17 5.71 8.21 0.05 0.05 0.05 0.34 0.74 2.28 0.fl 0.22 2.84 2.47 2.9 3.1 0.1 1 3.42 0.23 0.23 4.04 0.44 1 .2 1 .3 5.78 6.12 0.1 0.13 0.42 0.62 1 .36 1 .42 1 .51 1 .9 2.76 2.78 0.31 0.95 0.27 0.23 1 .28 0.81 1.13 1.26 0.12 1.46 0.23 0.21 1 .85 0.28 0.75 0.81 2.81 3.05 0.05 0.11 0.24 0.49 0.63 0.66 1 0.93 1 1.07 1.64 ‘1.04 769 V (__Z100_129.6 1 116.6 1 161 3.01 _1.6 2.17 10.12 ;(669 M1169 2.36 1 .05 2.54 3.13 3.14 3.43 5.16 2.85 2.77 1 .77 2.56 3.26 0.93 2.6 8.77 5.41 2.31 1 .83 4.15 1 .85 2.02 3.58 2.57 4.24 2.9-4 3.02 2.33 2.3 1 .46 2.3 2.36 3.78 3.22 3.33 3.31 3.32 5.56 2.96 .22 2.7 0.6 1 .02 1 .02 0.57 1 .34 0.52 1 .04 0.26 2.64 0.91 1 .16 5.31 0.79 0.26 0.99 2.22 2.23 0.87 2.3 1 .79 0.29 0.54 1 .1 1 .75 0.26 0.75 1 .1 6 1 .14 1 .6 0.71 0.06 0.47 0.25 0.63 0.28 0.04 1 .8 ______(1!1)1 .(°__)__(1P8_)__7___(I1)___(_(fl)(f\)_ 117 12 0.2 0.26 6.69 1 0.26 1 96 96 12 031 0.64 466 0 161 161 1.49 0.06 1.99 6.04 :1.1a 4.16 1 0.06 0.06 0.06 0.16 544 36 1 93 384 491 767 1 60 337 380 682 1 40 367 296 420 556 320 628 873 21 7 472 21 7 280 363 280 309 356 4-61 621 1 00 2'20 1 00 1 14 204 254 379 434 449 1173 38 1366 1557 1664 1940 160 337 380 682 140 367 296 420 1605 320 628 873 217. 1345 217 280 1708 280 309 356 2449 2609 100 220 100 114 20-4 254 379 434 769 1089 Storm Water Modeling Results Hydra 0.scs Post-Development Conditions Renton ill 100 yr -24 hr storm 1 0 _TABLE 3 Drainage Report 10”_Rim "Invert ('41)(Acres)(<=f$) Link Node Length Downstream Elevation Diameter Aroa 1 D000 1 Desvel (195) Time (min) La1L0ng 1 SysL0ng (fl)(I1) "rs 1 1025 = 00 ~1025 01 1024 02 1020 . 00 1022 1 04 1001 1 05 1042 05 1041 01 1040 00 1000 00110005 90 1 1005 3 91 ‘1056 92 1055 93 1052 1 94 1008 ‘ 95 1007 96‘1006 9715 1004? 98 3001 99 3002 . 100 2043 ‘ 101 1043 102 10031 103 1 1002 . 123.3 123.3 125.6 125.51 125.5 125.5 125.5 126 126 126 125.5 125.5 126 129 129 125.5 125.5 126 127.5 129.75 127.5 125.5 127.5 128 129 110.5 101.0 ‘105.24 121.1 121.5 1 104.1 121.01 120.2 110.5 ‘110 105.05 120.1 105.05 1 105.01 102.50 104.1 1 120.0 ‘100.45 102.95 110.75 110.01 117.5 1 115.5 102.10 00.15 15 15 15 12 12 8 8 12 12 8 12 12 8888888 10 10 10 12 3-0 30 a.a4 0.05 0.55 0.10 0.00 ;0.10 * ’0.50 0.50 1.01 0.21 1 2.00 §0.45 1 22.00 22.00 1 22.00 1 0.17 10.51 . \13.12 10.40 1.30 . .1.01 ‘1.01 1.01 ‘ 15.01 ~_10.01 2.16 2.33 2.3 0.17 0.26 0.17 0.72 0.69 1.83 0.25 2.34 0.42 1 1.36 11.18 11.01 5.19 5.52 7.79 7.99 1.52 1.65 0.4 1.07 8.71 5.55 5.86 5.22 1 .63 1 .76 8.0-4 2.87 2.74 3.26 2.42 4.82 1 .97 3.43 4.07 5.49 2.66 3.5 2.97 4.26 4.91 5.1 4 3.65 2.94 3.1 4 1 6.45 0.38 0.27 0.41 2.5 0.36 0.09 0.86 1 .03 0.61 0.69 0.28 1 .1 8 1 .58 1 .03 0.93 1 .78 0.72 2.71 0.4 0.41 0.12 0.78 0.41 0.59 0.07 007 1000 1221 244 204 45 140 317 401 100 100 140 025 571 002 204 404 916 102 120 150 100 202 344 1317 1413 1541 244 284 45 148 317 437 100 617 140 6476 6728 7033 4434 .4913 6152 6254 120 156 160 232 6598 666192i415_0 W104 1001 (0003 00 00 1 120 40.05 1 22.51 1 2.02 0.05 1414.0115402.0 1 '1 1 1 1 15 designed based on the peak flow rate from the 2-year 24-hour storm event. One option for meeting the biofiltration requirements is to pass all of the site's stormwater through biofiltration after collection and conveyance to the storm sewer outfall manhole. This option,though meeting the intent of the SWM,bestows some practical difficulties which can be avoided with another treatment option.Most of these difficulties have to do with the capacity of the pump system,its construction and the required and available power sources and force main piping.For instance, the pump station must be sized to pump 10.2 cfs to the bioswale, i.e.,the 2-year 24—hour peak storm flow at the storm sewer outfall manhole.A wetwell could be designed to attenuate the peak flow rate.However,any increase in the size of the pump station will significantly impact the design and cost of the facility due to the extreme depth of the pump station.(The invert of the pump station wet well will be about 25 feet below ground surface.)Also,a pump station with a capacity of 10.2 cfs would require an additional source of emergency power and deny Metro the use of the to—be—abandoned 12-inch city water main. Pienefl Biofiltrazion Plan The proposed method of providing the required biofiltration is to construct swales adjacent to new roadways and parking lots where sufficient pervious area is available and to pump stormwater from the outfall manhole to an "oversized"wetpond facility.V A total of five biofiltration swales will be constructed. New impervious surfaces which will be served by local swales include the access road that starts at Monster Road and winds around water tower hill,the new parking lot north of the Administration Building,the new parking lot south the 12 KVA Substation,and the east—west road just south of the Sludge Dewatering Building.These local swales will serve 33%of the new impervious surfaces subject to vehicular use,but over 75%of the net increase in impervious road surfaces. The proposed swales will be constructed in Phase A in conjunction with the new roadways and parking lots that they will serve.The swales will be designed to handle the peak flow from the 2~year 24~hour storm event for the tributary area.All the swales will receive the l0O—year 24-hour storm from the tributary area.Treated effluent from the swales will drain to the stormwater sewer system.Roadways and parking areas not treated by localized biofiltration because of site constraints will still satisfy the requirements of SWM Section 1.2.3.Figure 2 shows the location of the five biofiltration swales planned for the Enlargement III project. 16 The proposed oversized wetpond facility,which will be three times the minimum area and volume suggested by Section 1.3.5 of the SWM,along with the locally constructed biofiltration swales, will provide equivalent or better treatment than a minimum sized wetpond facility and biofiltration facility.Over an entire year,it is anticipated that an equivalent or greater mass of pollutants will be removed by the oversized wetpond facility and local swales than by a minimum required wetpond facility and biofiltration facility.(See Appendix C which contains a letter from Metro's Technical Staff referencing technical studies of wetponds and stormwater treatment.). rk s ‘=-‘=2-='=—_’*,./‘-_-Iii;-I1‘F -~-SCALE IN FEET /’t ('4;_“"—4--~__'r:T‘-‘—--:1 .1;-7 -I '“;.é-L T rt-'//-“_____“_:_“"_“T"“_:——_-i_-.{H :3‘//\;7 VDQP 1iJiq_NNEL _j j <5?=1 f ‘,1;7"" I “@bwa\. "'‘RBI wit _J1_.u ,T _-i--.- 100 40 __-~41.14 ___Q,I _:~ NEW 3D"¢P1 CHANNEL EMERGENCY RELIEF OVERFLOW SEWER A NEW 18"¢P1 CHANNEL STDRMWATER OUTFALL EXISTING 12%cmrWATERP!PI-IUNE (TO REMAIN) NEW STORMWATER TREATMENT WET PDNDS /II*'F _ C I!,J..-'r4\%r I “-- EXISTING 2o"¢WASHINGTONNATURALGASPIPELINE(TO at ABANDONED) NEW 12"ifi CITY WATER PIPELINE NEW STORM WATER 4.5 CFS FORCE MAIN ${=me'r|=|o '4? ) ,_-*' ¢/l/~§ \/A "_-.___II":‘V \_/I ZW I ‘I "LI 'I ; .1 ,' I, 1/ EXISUNG 121»cmwneaPIPELINE(10 BE ABANDONED)(cm BE usso BYMETROTOTRANSPORT4.5 crs OF srormwme TO NEW wt?PONDS) I%. er A ________ I'll I pl I II *<**$eelii j Iii"..-'-\ I nl NEW BIOFILTRATION /j SWALE —“~<- I‘/A n|-_, 1 ‘ll?1:397’-- W..I-I '-‘‘u “Z ".I 0 “\\T ~I __’____‘-_-_|-I-..l —-":1: 1-5;.'‘*1r 4i1it tL-~‘I-1*5 __L..L-I CID q-A -.__, __Z 'I»I/4'A J Q --. IHI ‘A I _V I‘|||m-|u||L M °‘11/\‘*\I '” /fix‘:H /'\ \INEWBIOFILTRAUON_/.-“/'9,/,1"/"»//" SWALES ,'3/4 O./E»4-,cu-»/;/.—:»-- //..1 1214* ./.Q:‘,-13:"?-"' /I ,."/y’/_"*" 1 _:/;,/1;’/I /_'.';'—-ii;/-"E ~' .I /NEW 4.s<:rs (zooocsm),///;;-;-I \STORMWATER PUMPING -/"/--:>-'1/'\STATION TD \l —//.~/'\INCLUDES: __,/"'/Rn /.7//'\-CONNECTION TO ABANDONED___./‘HERN __/wnta PIPELINE FOR conver-_./“QR J,/met TO WETPONDS —' /-/’v\Gx0\*\__/-couuscnon T0 INFLUENT stwrnBondZ.//FOR TEMPORARY mm:mem-/~new or STORM wmsn ,7!’- rm ‘ E -----.f".'_. 4fT< IL)». I\@e,.v ‘-~. . / _/ "‘I i 2'1 ‘\_‘/'/\\ \I II-~\/-In I I ._¢L-. ,“ //:/,/‘\/ 'r“i4F‘liar ait _,:1'‘----_-1-._|i._____._._ Q11 I._i.Qt2___f>@y. -;z?';//’:5}.,fv ///'2'/"’,.will4/at 1 \ 'I\ 1 \X K § _- -%‘<.5 ~g’T A\/Y cum-1 _..._é_J IOFILTRATI ON /// "----E.1‘=1; lie:i -_-,e11;f;i-i>%r#-1-tr‘"‘ ‘\ I I‘u . ...--'if\" ,_.-_\‘ \_, -_.-‘~.-‘,-_/,_\ I‘,I 7/\_|_/\_ as I1;-I \/K \ \...»'h_~ __¢__._._q__ _|__|.-w-1_. _ CITY LIMITS PROPERTY LINE SHOREUNE BOUNDARY NEW FACILITIES (INCLUDING ROADS AND PARKING) EXISTING FACILITIES(wcruomc ROADS mo PARKING) EASEMENTS EXISTING STORM DRAIN FENCE LINE EXISTING WATER LINE METRO REGIONAL TREATMENT PLANT IN RENTDN Bu FIGURE 2:SITE PLAN ENLARGE)/IENT Iii M E ='rnnuwn'rro *rD|rrrurn.|1'r:.r~u mrcz 17 CORE REQUIREMENT NO.4:CONVEYANCE SYSTEM ADEQUACY Core Requirement No.4 pertains to the conveyance system's composition and adequacy,pumping stations,drainage easements, interception of interflow (near—surface groundwater)and outfall construction.CR4 only allows pumping systems on storm drainage by variance,and only if certain minimum requirements are met. The stormwater drainage and treatment plan proposed in this document requires a pump system to utilize wetponds for treatment.Thus,a variance will be required from CR4 to operate the proposed pumping system.The pump system will only have about 67%of the minimum required storage due to practical difficulties. All proposed projects must show that a conveyance system exists,or will be constructed,to adequately convey the runoff from the l0O—year 24-hour design storm.This compliance condition includes runoff that originates on the project site plus any existing runoff that will be conveyed through the project site.Surcharged conditions for pipe systems is acceptable for demonstrating the adequacy of the conveyance system provided that all runoff is contained within the conveyance system elements and does not inundate the crown of the roadway. Modeling results indicate that the existing and proposed conveyance system is adequate to convey the l00~year design storm without producing overflows.Tables 2 and 3 present flows and velocities through each stormwater pipe segment for the l0O—year 24-hour storm event for pre-and post—development,respectively. Flow between the northern and southern storm sewer branches is fairly equally split.Only one pipe segment,the 30~inch pipe at node 1004,was surcharged during the design storm simulation. Though peak flow at Node 1004 was about 102%of capacity for both pre-and post-development conditions,nowhere in the system did stormwater overflow a manhole cover.The conveyance system was analyzed using the procedure described in the section titled Core Requirement No.3. During the l0O—year flood event,bypass flows are planned to discharge to the P—l Channel via the emergency overflow relief sewers.Assuming the overflow relief sewers are about 300—foot in length and the P—l discharge invert will be Elevation 115,the capacity of the relief sewers is estimated to be about 25 cfs each.These sewers will have sufficient capacity to handle the overflow from each of the main 30-inch storm sewer branches. Proposed Pumping Station The proposed stormwater treatment system includes a pumping station.The pumping station is needed to lift stormwater to the -=¢=od-~'-\';—‘ II rI >1 18 ground surface and then to convey the stormwater to the treatment plant during the interim period and to the wetpond facility once the wetponds are constructed.Metro has obtained a variance from CR4 for use of a pumping station during the interim.Metro is requesting a modification of CR4 to operate the pumping station on a permanent basis. The pumping station allows Metro to utilize the existing and extensive system of underground piping at the MTPR site and to implement SWM's preferred method of water quality treatment ~- wetponds.The site's network of underground storm sewer pipes were originally designed to allow stormwater to drain by gravity to the Green River.The sewer pipes are located relatively deep underground because of the physical barriers created by the process facilities.For example,the depth of the ground cover at the outfall manhole (the confluence of the stormwater sewer before discharge to the Green River)is about 26 feet. A profile and plan of the proposed pumping station is presented in Figure 3A.A site plan showing the location of the pumping station and valave vault is shown in Figure 3B.The pumping station is a wet well type with submersible dual pumps, each with a capacity of 4.5 cfs.The wet well will be 12 feet 10 inches in diameter and about 40 feet deep.The invert of the pumping station will be at Elevation 92.2.An adjacent valve vault will house the pump controls and valve operators to direct flow to either the treatment plant or the wetponds.A 48-inch overflow at Elevation 113.0 will bypass flows to the existing outfall diffuser in the Green River.A backflow prevention check valve will be installed on the 48-inch overflow.New emergency overflow weirs and relief sewers,to be constructed in Construction Phase C,will bypass flows when the storm sewer backs up to Elevation 118.0. The pump system has been designed to allow the stormwater sewer to drain completely during normal operational and hydrologic conditions.Bypass of the pumping station will not occur until the water elevation in the wet well reaches 113.0. Emergency overflows will not occur until the water elevation in the storm sewer reaches 118.0.‘ Metro's proposed pump system complies with all the SWM minimum requirements to allow a pumping station on a stormwater system but one —a storage facility sized to hold 25%of the total volume of runoff for the developed tributary drainage area for the 2-year,24-hour duration design storm event.According to modeling results,a total storage volume of 314,000 gallons is required.The wetpit and stormwater sewers are estimated to have a storage capacity of about 200,000 gallons when stormwater reaches the relief overflow weirs,i.e.,about two—thirds of the required capacity.The deviation from the required storage volume is addressed through adequate safegurads incorporated into the design of the pumping system,as discussed below. I I I I I I I II I I I 1 I ~-II IQIIGJODOG1/IQ/I1SIP I I ’q -7;’/\‘-___iy _W'4..II510995/I).\£1.IJO’.IYIt\. .mm ._‘~\D . 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nu,0.0,' _Brown and Caldwell Ml LL C '°SEAC-AD 1»“Em 5 ““‘°“"EhWmm M."‘.I ___,_,_,_Consultants ‘UV Pm Ricmwfin ‘_nm,_STDRI-IWATER PUMPING sunon."N W V | "*"""*"*$8:5wlU=-Wflflhlflqlflfl '°'¢mm.u..Q SHE PL-AN ''ii "W —’"i 'mvnnvm;_ no I HD4901 ll‘out A B V V C D _‘5 F av G V R u_ 19 Considering the topography of the site and the depth of the existing stormwater sewer system,an underground well would probably be required to provide the additional required wet well volume.This wet well would be similar in construction to a wetvault and carry the same practical difficulties given the depth of the stormwater sewer system.Based on the apparent purpose of the storage volume requirement,i.e.,to provide flood protection in case of power outage or a mechanical failure, Metro suggests that the proposed stormwater pumping station, together with other measures,will satisfy the intent of the requirement.In addition to the proposed storage capacity inherent in the wet well and proposed storm sewer,the following safeguards will provide additional protection to surrounding property from flooding in case of an emergency situation such as a power outage or a mechanical failure: *Gravity overflow in excess of the pump capacity to the P—l channel during extreme storm events. *Gravity overflow in excess of the pump capacity to the Green River during non—extreme storm events. *An emergency power supply and dual power feeds to the 'treatment plant., *External controls as well as external alarms. *A 24 hour a day on-site monitoring,operations and maintenance staff. *Flap gates to prohibit the influx of the Green River y into the pumping station during extreme flood stage. Metro is requesting a modification from the required wetwell volume. If Metro cannot obtain modifications for its proposed pump system,then it likely will need to construct a large underground vault at the location of the outfall.manhole.A wetvault would not be consistent with SWM's preference for wetponds,would require a modification from SR5,and would be very costly. Constructing a wet vault would create practical difficulties,for example the depth of ground cover at the outfall manhole will be about 30 feet.Such a large structure would deprive Metro from reasonable use and development of its property;the area needed to construct a wetvault is currently dedicated to future sewage treatment purposes.Because_a modification would allow Metro to implement the preferred method of water quality treatment,it will not be detrimental to the public welfare or injurious to other property in the vicinity. I 9 i > >3 —-—-~=m.-.-.-- I1| ll 20 CORE REQUIREMENT NO.S:TESCP All engineering plans for proposed projects that propose to construct new,or modify existing drainage facilities shall ‘ include an temporary erosion and sedimentation control plan (TESCP)to prevent sediment-laden runoff from leaving the site during construction. Enlargement III meets the requirements of Section 1.2.5 of the SWM.A temporary erosion and sedimentation control plan (TESCP)has been prepared for the proposed project.The TESCP is included in Addendum No.1 of the Contract Drawings and Specifications.The TESCP was submitted to the City of Renton on July ll,1991,certified by the City of Renton,and submitted to the Hearing Examiner on July 16,1991.Subsequently,the TESCP has been revised in response to City of Renton review comments. These comments were incorporated into the contract drawings. \ 1 ! > K r I f> ; \\ 21 SPECIAL REQUIREMENT NO.5:SPECIAL WATER QUALITY CONTROL In addition to the Core Requirements,the proposed project has also been assessed for compliance with twelve Special Requirements of the SWM..Each special requirement identifies "Threshold"criteria to assess the compliance of the proposed project with the Special Requirements. Based on the threshold criteria,the proposed project is exempt from all the Special Requirements but one -—SR5:Special Water Quality Control.Because the proposed project will result in more than one acre of impervious surface that will be subject to vehicular use and runoff from the project will discharge into the P-1 channel and the Green River,a Type 1 stream,a wetpond, wetvault or water quality swale is required for water quality control. The wetponds will be designed and constructed during Phase C. In the interim,stormwater requiring treatment will be pumped to the wastewater treatment plant.A variance has been obtained to use the wastewater treatment plant,rather than wetponds,for treatment during the interim period. This project proposes to provide water quality treatment to stormwater via an oversized wetpond facility.The proposed wetpond facility will be oversized three times the required minimum surface area,volume and peak flow rate.Metro believes this treatment scheme will provide equivalent or better treatment than a minimally sized wetpond and biofiltration facility.(See Appendix D.)The wetpond facility will receive stormwater from the proposed stormwater pumping station.The preliminary location of the wetponds will be near the wetlands.Stormwater will flow by gravity through the cells of the wetpond and effluent will drain by gravity to the P—l channel. Minimum Requirements for wetpgnd Fagilities The size of the wetpond is determined as follows in accordance with SWM Section 1.3.5:- *The design water surface area shall be a minimum of one percent of the impervious surface area in the drainage sub—basin contributing to the facility. *The design volume shall be as a minimum the total runoff volume from the proposed tributary sub—basin using the total precipitation equal to one—third of the '2—year,24-hour total precipitation. Enlargement III will result in a total of 18.9 acres of impervious surfaces as shown in Table 1.Thus,the minimum \ } 22 required water surface area of the wetponds is 1%of 18.9 acres or 8200 square feet. The minimum volume requirements for the wetpond facility were calculated based on SWM Chapter 3 and as described in the section Core Requirement No.3:Runoff Control.The required wetpond volume was calculated using one-third of the total precipitation resulting from the 2-year 24-hour storm event,i.e 33%of two inches,or 0.67—inches.Based on the modelling results,the minimum required wetpond volume is 210,000 gallons.With a minimum required surface area of 8200 square feet,the wetpond must have an active depth of 3.4 feet.This depth satisfies the requirement to maintain a permanent pool in a wetpond between three to six feet (Section 4.6.2).An additional one foot of dead storage must also be provided for sediment storage,for a total depth of 4.4 feet. The wetponds must be designed to bypass flows greater than the peak flow resulting from the one-third of the 2-year 24—hour storm (Pt—wq design storm)for developed conditions (Section 4.6.2).The peak flow resulting from the Pt—wq design storm under developed conditions is 1.5 cfs based on the HYDRA4 model. All flows greater than 1.5 cfs must bypass the wetpond facilities;The pumps at the outfall manhole will be sized to only pump the required peak flow.Flows in excess of the design peak flow rate will drain by gravity to the Green River. Pienosed O_\@rsize.<;1-@_n>_ond Farilitieps. The wetpond facilities will be sized to be three times the minimum SWM requirements.The wetponds are being oversized to attain a mass removal of pollutants equivalent to,or greater than,that which can be attained with a minimum sized wetpond in series with a bioswale.Oversized wetponds with localized biofiltration swales will reduce the required pump size and will allow the use of existing on—site services (pipe,emergency power supply,etc.),thus avoiding the hardship of having to install new piping,additional emergency power capacity and flow bypass structures at the water quality facility. The oversized wetpond facility will be designed for a peak flow rate of 4.5 cfs and a volume of 630,000 gallons.The total water surface area will be at least 24,600 square feet,and the permanent pool depth will be between three and six feet with one more foot for dead storage for sediment (Section 4.6.2).The active depth will depend on the actual surface area,the slopes of the dikes,surface contours,and whether concrete walls are used in place of dikes.The stormwater pumping station will have a capacity of 4.5 cfs with flows in excess of this rate draining to the Green River.For comparison,the average 24-hour runoff flow resulting from the 2-year 24-hour storm from the entire site is about 5 cfs. SHM Wetpond Desiqn_Qriteria ) iI! 1 l I 23 The wetpond will be designed in accordance with SWM Sections 4.6.2 and 4.4.4.Section 4.6.2 controls the design if discrepancies exist between the two sections.Figure 4 is a schematic of a three celled oversized wetpond facility at its preliminary location near the wetlands on the north end of the site.Figure 2 shows the preliminary location of the proposed wetpond facility on the site plan. In this Drainage Plan,Metro has identified preliminary locations for the wetponds in the northern portion of the site in the vicinity of the wetland area.Metro is continuing to explore wetland enhancement opportunities in this area,which could utilize and incorporate some of the wetponds.Metro will obtain approval from Renton's Stormwater and Wastewater Utility Engineering Supervisor if the final location of the wetponds is different from the preliminary location identified at this time. Design criteria of specific note are reproduced: *Depth of permanent pool shall be 3 to 6 feet plus one foot of dead storage for sediment. *The lengthzwidth ratio at the design surface area shall be no less than 3:1 (preferably 5:1). *The facility will be divided into three cells.The ‘first cell shall contain about 10%of the design surface area,the second and third cells about 45%each of the design surface area. *Flows above the 2-year 24-hour peak storm flow must by- pass the facility.A mechanism must be provided to take the facility off-line. *A gravity drain one foot above the facility bottom shall drain the facility in less than four hours. C0mnlianc_e...wit_h S_wM Desicm Criteria The wetpond facility will be designed as three cells,the first cell having about 10%of the total water surface area and the other two cells with about 45%each of the total water surface area.Each cell will have a length to width ratio greater than 3:1.The total water depth will be at least 4 feet in each cell,one foot of dead storage for sediment and at least 3 feet of permanent pool.The inlet and outlet of the tanks will be designed to maximize travel time through the facility.The inlet will be designed to prevent scouring of the bottom sediments and promote sedimentation. The capacity of the stormwater pumps (4.5 cfs)prevents flows any greater than three—times the design storm peak flow rate from entering the wetponds.Thus,the pumping station will act as the required overflow system to control discharge of the l0O—year 24- hour design storm and the required emergency overflow spillway to safely pass the l0O—year 24—hour storm.A gravity drain for maintenance will be installed on each cell.The drain shall E .1,.I Il E5 \ 24 maintain one foot of depth and will drain the facility in less than four hours.The outlet drains will be controlled by valves in a control manhole(s). Berm embankments shall be constructed as recommended by a geo-technical engineer following the criteria described in Section 4.4.4 of the SWM.Retaining walls may be used instead of berms.These walls will be designed by a structural engineer registered in the State of Washington and in accordance with Section 4.4.6.Access to the wetponds will be provided for maintenance and public viewing.If located near the wetlands, the perimeter trail can serve as the necessary access.Signs will be designed,installed and located so at least one is clearly visible and legible from all adjacent streets and paths. 5 1F ; r Y i I I E i (‘IJ,__‘J|_Q_ __\_J___/Ir!llll‘]‘m__‘|lQ,||K‘’_ir___-(‘(‘_\€(1<_v_\__‘>\\\I_K_l‘\\_\\‘ (fr’_k_\‘_\\\\‘\\ K‘__\~‘\__\\\I \\‘ fr'V_X\ ‘\\\\\/I _,NJPJ/I _ ‘Q6_____A‘_\_\___\\\\\“_\_\_ ‘I1 7_____ __\~\\\V“;\~\1 J’)-"\V\ _‘IaE\\\i IW_Q“(1\‘:‘i\\\_ ‘ll\_\N_,1__,M\\A\K ll‘__‘)‘))\\N’_“Iii}:\j\‘\ £56_M_e__mvm_(__8_°‘,1!1\Am_M’f;;_i\\__\\x_W\ __'\___un__{frfrlrl_‘Y\ I6N_J_\\\\\\\_\\4H\\\\\\\\\\/ lS__I3 _I__J___ ‘__\\y__\\\\_\‘_\\\V___\\\_\ \\_\\_ _\\\_\\\\W\\I_\_\\\a\I\\\\__‘\, \__\\\( R\_I\\__\_\/N_I\II‘\\\\\\\II‘\_ I _____'‘\\\\ ___‘__\I\_\I\\\\\ v‘\//\_\_\\\ _ II‘‘ AI_Jul,’_\__II’!A__ ,1‘_\\\__\IY‘__‘___‘/'1"\\\\___‘N_v\_ 1‘__‘/IW__II’!__v\ 1‘__Ifh__‘f]|J{l‘_I\ ‘I__|||__ _‘___H_firu\_‘__"fl‘____ _\ v‘‘_' __‘T__|_r/IM‘____j0w__I_\ __ ____j‘~_ ___M‘\_\_++\+N‘_EW_‘N‘__N__K___AA_fl\‘“____\_xxJ_\_iffl___\_II‘w“'__K_____ \'"_\)__ _ fWM_f \\‘X0’_‘1'’_b 1’,‘\ /)31 k‘I‘(‘I'ii”lg ‘(I_ k _L___ _Ahv\ ___ “¥M‘\_‘ \(‘_ ___J‘’_ _/I~ _If_\_ I__ ‘_\‘__' _K_~II_‘_ _ "\__ M‘f‘ '_‘_ J,fi __'___' (If!!!_ fiApQ‘ ‘v_‘ _,_N_‘_“J“vA7\ ‘I’! _E __\IXM_I_‘AJmic’J5‘K‘F__t’,_k_____Q._’_\_,:‘.w)‘-"‘;__‘_r\__n______1-__v___’__~LL"\__I an_A‘_\_»_Np/_8“H2(_V’_‘p_k D W _\_ Ay V 1 _|VAI v“I ___Q8__'___‘‘I ‘(L_‘_ ,_fl€{\1“'f__ VJ__'_ JI___' __V__I_\_T ‘I _‘_ I ’I’\_// J_l‘___‘__I /_flD07E/I*_‘_1_/_lI______f AJJ06/M/IIIQI‘Iv_ItI I‘__ A8I\‘__ifW);_‘ '_‘II__‘I1,U PW_\___/III__ JJ; A___/F_ __\'_i’J.’'"_‘__/J’_‘___\;‘_'__'_’_;,”\__L__'I I’UX_,1Y_I_K‘_‘V,if'\‘I’/_'._I)¥_II_‘\p,1I’)iI_,‘X0r’IhfI’\__vI_.__’r_____'__,_/‘(frr//_I /I\\I__vII'__ _\ _I_\_,‘III_k /__,___A‘;l‘("(/J!___‘R\_ \ _ _K_ ’_v_M_v__’/’J‘_I ____4aI/_ VHiS‘ia__IY_Ir_l_'I“\__\“Ml"_(|§\((_%H_ _lV ‘_4N_ 0____’“Fv/_I’_]_‘Q3_‘_ 1WIJ1/‘fH__I/LV\VM _r_/IJ_I\Lvfr“J is:5: 5a __u)” __XxV __l,Z__~__AvQ‘J_t_V‘( _4‘1".VQ‘;1;___It‘II,JX__k}‘I)‘Ar‘I__'_Hf’‘__\_"_v‘_3_T‘_U__I\I_-‘H/1'JL‘r___l__!‘Iq_I,'{I\""\"I‘___mw- llMII‘:__IA‘H__H32/Ik"J‘|"H__f _,_Ww‘_‘_WW__‘W1 /IfK‘'I"v"v__"__J_7'MH____/R /\_LV'_-‘I:‘I __w>“_._I_‘_:1‘H’___p__‘_A\rF/1y_IIIV_\’\I__\rvR__N |_/______‘_i__ xI,/IJ___‘Ixl£______vIIWJ“/In\‘_n_ ,_r I_S__‘P_ h_r ”___J__')\‘ E__Z’ I M_/_\__\ ‘_5If)‘ ((§ ‘ab!’ _Lian‘('9 ‘I’ _J)_J_rHf “(M \}_h:1__\‘J__II‘ 2}"L /I M /l / 0/ °‘fi_ 8 0 ; “,C0B “MI,‘ TEH _+I‘dl_____\;_°_ 1Ixas;I 8 ll!_‘_\4U‘_ f_I(P>_\___.-I/’J_‘I ‘_1f__~__{/I,"_‘\J)\§__’f_ PL\_y‘_ _M E /I‘IJ50}W_v gW /I|_k\‘/__’_\(II’! _/‘_L__B,_{IrJ\_____I?_{_’ J/_KI_’ J I‘I3; J) r__‘ififM1/('m_f(L Ia‘_l___’;__‘___M _,__v ,I__fit“____ _____‘‘ElIa_V‘%_HWn1,‘fr‘((‘_IHU_') _w’IW_~‘$_r__v__ ‘H*1‘W_" Uv__‘I: M_’, I '2:1 “.\“_ \__ FJ'__J!A_fr’l/__I “pJ1‘;__’_\_ JJJJM___\_\__‘/__J’;;_MyOJ__JF__t__I1}fr~_/f__‘‘__ JJ4Fk_(I'1)II_4_\_ _L/‘IV_K_ JV_B‘PIY_ _F~t(__’I_‘_ ____r/I_,r\y‘_F_4r_I‘’V“omI__W‘_ifVr_“,I{P__’I J\_“ a_‘_’f L J’J“‘I__kkfr 'A '__I_kkr(ktPU_T‘_V '_(A‘|\KM'5_‘__\___Akm“V__M”_fix3‘LLW_H___AI___\“‘\__w___J_Q__J_x\‘emEa“H"R|\_ Rfir_)m\____@IrJ)M‘__tI __J‘wM__‘_r‘IWL_\+ _m?'_'__\((“’ifL:“WW‘K“ _TF‘H_Vm1 L\ _%__ump_'LLIQ“.__KI\|KrLKnv_‘L____\_xrkw‘C“Q\HM‘itq_LL_ \\A_Upkt___PH‘ kDL_A__ ___IP_kl_ IS_\_ JV_,1__’rt____u M_axA_‘_ ‘ d_\5w1%.__v_‘K FJ__‘__\\ \" ,{ __AV__2; ‘I.’__ fl_ Iv‘‘(‘V_H1 ‘J:___r_ U"__j___|_:J‘__NI“J IT‘V7‘,}\ ')\firmWICx yK_H,UV\WQW‘___}_ zA,FJ1V“C K /“_J? ’_J \,J\____ '\J\.')\MM_“ ‘JMJ_n __‘______:‘n_ lg‘_l)‘)_l""\m___“(r 1___“\F‘<1 “SN_/__J,‘£21";/J__\_Y___f‘\/I_M___’)_,___K \{l_Z__Ry_Ir__‘\’ I_I “G /tv/I //Qgv/11n“%\\\/_,fi_ IT “T_IlI// __>I .I/‘III!I1 1;III’!_m%Y.‘ / \\_\1_r‘G? ____ as\P)‘“,1I-‘W_ byQ_%NdFFL __"____) I,\“J\Vr_ IIHIf_ '_>/__r~___“lbwO/II“__‘_°tr,l_,'JI)\‘___ I__H J’/IIf____b_h'J noEW___ /0fyf3‘Km_ Ill’uG2'_fl)___\\__‘cl_v //I,2U‘I‘a\___I;?\(W2;ki“D /____‘A //I0E/_i\,>"((_‘O /IfDOM__mR 02_I _“1 E_I38I__W___“ /GB‘mu\"WW"_ __P1\m‘W__‘{Kfl‘_H___‘ ‘I III‘\\\IH_n‘1_\_I’,\\V_M_,_'_-_\/if‘ll'_|‘\IMJI__n_;_ [I],_1,“);_7 “J‘P_ 3+7\ H‘N DOEmflmw\ llA5%_ /_'5I\2°2___4_ /.&81° _‘"- ‘j/ ‘_1/J _ __ "mus\\_ A%®_,_ NOTNERWTNALPTW mummMEkmuwNTGSmNA GEF tHwDMOONWWW?HMm%_ WW ’__',_"H;_‘“_M_‘’‘fix?I M W1:‘WRVI _I/If_A\AIY‘‘Z}__“fig/F_'‘Zv7,I__‘I/‘'_PI ('7IIIJ1‘LIIJ‘dd’I ___’______ J_fI\I(_J_3I DHT___m&p_ ///W_dq 0]WC/Ifx‘\QE4M:8/,1_If m ,II_+_ mz+_‘O //T//_flVIMo_30 25 E MOD IF I CATI ONS See attached Request of Modifications:Pursuant to Ordinance No.4342,March 23,1992. § .\; i\ i- I I Ir D RAW MUNICIPALITY OF METROPOLITAN SEATTLE (METRO) ENLARGEMENT III OF METRO TREATMENT PLANT AT RENTON APPLICATION AND REQUEST FOR MODIFICATIONS PURSUANT TO ORDINANCE NO.4342 IN CONJUNCTION WITH DRAINAGE PLAN APPROVAL MARCH 25,1992 I.INTRODUCTION The Municipality of Metropolitan Seattle (Metro)has prepared a stormwater management program consistent with the City of Renton (City)drainage requirements and with Condition 7 of the building permit issued by the City for Phase A of the Metro treatment plant Enlargement III project in Renton.The program is described in detail in the Drainage Plan prepared by Brown and Caldwell,consulting engineers (attached).Metro worked closely with Randall Parsons,City of Renton Stormwater and wastewater Utility Engineering Supervisor,to develop this program. The City of Renton Municipal Code requires the preparation of a drainage plan in conformance with the Core and Special Requirements contained in sections 1.2 and 1.3 of chapter 1,and chapters 3,4,and 5 of the King County Surface Water Design Manual (SWM)and City of Renton standard drafting and design requirements. Metro's proposed program,which utilizes wetponds and swales,is consistent with applicable drainage requirements and provides adequate protection of water quality.In order to implement the program,however,Metro must obtain approval to deviate from certain technical requirements in the SWM.Metro previously obtained variances from the Renton Hearing Examiner (Hearing Examiner)with respect to some of these requirements. Metro is now requesting modifications for the other requirements pursuant to Renton Ordinance No.4342,enacted February 3,1992 and effective March 9,1992. This document constitutes Metro's application and request for modifications. II.SUMMARY OF PROPOSED STORMWATER PROGRAM The proposed stormwater facilities will consist of biofiltration swales located adjacent to newly constructed roadways and parking lots,a pump station to lift and transport stormwater,and a series of oversized wetponds.The pump station and wetponds will have three times the capacity required in the SWM.These facilities are designed to treat stormwater associated with all new impervious surfaces subject to vehicular use or storage of chemicals.r Under the proposed stormwater program,stormwater will continue to drain to the Green River outfall manhole west of the Administration Building and just east of Monster Road.The existing system will be augmented with a pump station at the outfall manhole.This pump station is necessary to lift stormwater flows to the wetpond facilities located on the surface.Flows in excess of the pump capacity,which is three times the capacity required by the SWM,will overflow into the Green River via the existing l20—inch outfall diffuser. Stormwater will be pumped to wetponds for water quality treatment.The wetponds will be a series of ponds located near existing wetlands on—site.The ponds will be terraced to allow gravity flow between the wetponds.Ultimately,the wetponds will drain to the P-1 Channel.This avoids the need for another pumping station to discharge flows directly to the Green River. The pump station and biofiltration swales are planned to be constructed as part of the Phase A construction contract during summer of 1992.The wetpond facility is scheduled to be constructed during Phase C,which is planned to begin in 1994. In the interim——while these facilities are being designed and constructed—-the pump station will pump stormwater flows to the headworks of the wastewater plant for treatment and discharge to Puget Sound via the Effluent Transfer System (ETS).Stormwater pumping will be redirected to the wetpond facility when it becomes operational. In the Drainage Plan that accompanies this modification request,Metro has identified preliminary locations for the wetponds in the northern portion of the site in the vicinity of the wetland area.Metro is continuing to explore wetland enhancement opportunities in this area,which could utilize and incorporate some of the wetponds.Metro will obtain approval from Renton's Stormwater and wastewater Utility Engineering Supervisor if the final location of the wetponds is different from the preliminary location identified at this time. III.PREVIOUS VARIANCE REQUEST BEFORE RENTON HEARING EXAMINER Metro sought variances from the following SWM requirements in an application submitted to the Director of Public Works on September 16,1991 and in a public hearing before the Renton Hearing Examiner on October 1,1991,pursuant to Renton Code 4- 2 2 "1 6 : O Core Requirement 1:Discharge at the Natural Location To allow interim discharge of stormwater runoff through the treatment plant for treatment and discharge directly to Puget Sound through the ETS rather than to K 2 the Green River.To allow permanent discharge of stormwater from wetponds,and rare emergency flows, into the P-1 Channel rather than to the Green River. 0 Core Requirement 3:Runoff Control To allow interim discharge of stormwater runoff through the treatment plant for treatment rather than on-site biofiltration facilities for all of the new impervious surface areas subject to vehicular use or storage of chemicals.To allow some new areas of impervious surface subject to vehicular use or storage of chemicals to not have biofiltration treatment on a permanent basis,but to instead provide wetpond water quality treatment up to the water quality design storm event for most of the site's new and existing impervious surface subject to vehicular use or storage of chemicals. 0 Core Requirement 4:Conveyance System To allow the use of a pump system for stormwater conveyance along with a variance from the standard size criteria for a pump storage facility (wet—well). 0 Core Requirement 5:Special Water Quality Controls To allow interim discharge of stormwater runoff through the treatment plant for treatment and discharge directly to Puget Sound through the ETS rather than treatment by a wetpond for the new impervious surface areas subject to vehicular use or storage of chemicals. In the Hearing Examiner's Decision,issued on October 14, 1991,he stated: The variance to release storm water to the treatment plant and discharge it to the Effluent Transfer System is approved for an interim until permanent facilities are constructed,but in no event shall this variance exceed four (4)years.Any extension of the time period shall be subject to a new application for variance relief. The variance to permit the use of three linked wetponds instead of biofiltration swales is approved. Decision at 8. In response to a request for reconsideration,the Hearing Examiner stated: 3 I\= \ Ii [T]his office did not intend to limit Metro's interim use of the existing facility and its non—standard (in terms of the current requirements)use of the pump and effluent transfer system.As an interim proposition, the use of the existing facility is appropriate while the system is brought up to current standards....This office intended to limit the determination of the pump variance to the permanent facilities that Metro proposes to meet the city's current stormwater requirements. Letter from Fred J.Kaufman,Renton Hearing Examiner,to Gregory Bush,Metro Manager of Environmental Compliance at 1-2 (November 5,1991). Thus,Metro has already obtained approval to:(1)deviate from Core Requirement 1 (Discharge at the Natural Location) during the interim by discharging via the treatment plant and the ETS to Puget Sound;(2)deviate from Core Requirement 3 (Runoff Control)by not utilizing biofiltration in the interim and by treating stormwater runoff from all new impervious surface areas (subject to vehicular use or storage of chemicals)on a permanent basis using oversized wetpond facilities rather than biofiltration;(3)deviate from Core Requirement 4 (Conveyance System)during the interim to allow the use of a pump system to convey stormwater to the treatment plant;and (4)deviate from Special Requirement 5 (Special Water Quality Controls)by treating stormwater from new impervious surface areas (subject to vehicular use or storage of chemicals)on an interim basis through the treatment plant. In order to implement the proposed program,Metro must still obtain approval to:(1)deviate from Core Requirement 1 (Discharge at the Natural Location)in order to permanently discharge stormwater from the wetponds,and rare emergency relief flows,into the P~l Channel rather than to the Green River;(2) deviate from Core Requirement 4 (Conveyance System)on a permanent basis in order to use a pump system (and a smaller than required wet~well)for stormwater conveyance to the wetponds. IV.MODIFICATION REQUEST . Renton recently amended its stormwater variance process to provide for administrative,rather than Hearing Examiner, approval and to replace the variance criteria with a different standard.Renton Ordinance No.4342,enacted on February 3,1992 and effective on March 9,1992,allows the Director of Public Works to approve "modifications"to requirements of the Storm and Water Drainage Code under certain circumstances.It provides: 4 >\ \ Modifications.Whenever there are practical difficulties involved in carrying out the provisions of [the Storm and Water Drainage Code],the [Director of Public Works]may grant modifications for individual cases provided he/she shall first find that a special individual reason makes the strict letter of this code impractical,that the modification is in conformity with the intent and purpose of this code,and that such modification: 1.Will meet the objectives of safety,function, appearance,environmental protection and maintainability intended by the Drainage Code requirements,based upon sound engineering judgment; and 2.Will not be injurious to other property(s)in the vicinity.. Metro requests a modification from the following requirements of the SWM,because they create practical difficulties that make compliance with the strict letter of the SWM impractical:'- 0 Core Requirement 1:Discharge at the Natural Location To allow permanent discharge of stormwater from the wetponds,and rare emergency relief flows,into the P—l Channel rather than to the Green River. O Core Requirement 4:Conveyance System To allow the use of a pump system for stormwater conveyance along with a modification from the standard size criteria for a pump storage facility (wet—well). Modification of these requirements is discussed in detail below. A.Core Requirement #1 (Discharge at Natural Locationlz Core Requirement #1 provides that All surface and storm water runoff from a proposed project that proposes to construct new,or modify existing drainage facilities must be discharged at the natural location so as not to be diverted onto,or away from the adjacent downstream property. SWM 1.2.1.Metro requests a modification from this section in order to allow stormwater,and emergency relief flows,from the site to drain to the P—l Channel,rather than to the Green River. 5 i i There are practical difficulties carrying out the provisions of Core Requirement #1.Due to the location of existing sewage treatment facilities and given the public need to preserve certain land area for potential future sewage treatment purposes, the only practical and reasonable location for the wetpond facilities is in the northern part of the site near the on-site wetlands.The plan shows that stormwater that has been treated in these wetponds will drain by borders the northern portion of Strict compliance with the flows would have to be conveyed to the Green River at the other gravity to the P-1 Channel,which the site.. SWM means that treated stormwater from the proposed wetponds back end of the site.This would involve the additional expense of discharge of stormwater by gravity flow or pumping through a separate conveyance system. This approach presents the following practical difficulties:(1) Discharge of normal flows would require the construction of a separate conveyance system which would take the storm water flows from the ponds to the Green River.This would add considerably to the public expense and would use additional property that has been set aside for sewage treatment facilities.(2)Discharge to the Green River is prohibited when the River is at flood stage. This means that peak flows would either have to go to the P—l Channel or be allowed to back up and flood the treatment plant property,which from a health and safety perspective is not acceptable. The proposed modification meets the objectives of safety, function,appearance,environmental protection,and maintainability,consistent with the Storm and Water Drainage Code.'From an engineering standpoint,the discharge of flows to the P—l Channel is workable,maintainable,and preferred to re- routing flows back to the Green River.Aesthetically,the discharge to the P—l is an element of the landscaped,terraced wetpond facility,and potentially could be incorporated into a future wetland enhancement. with respect to environmental protection,discharge of treated stormwater and emergency overflow to the P—l Channel will produce no significant quantity or quality impacts to the P—l Channel,Black River Pumping Station or forebay.A hydraulic modeling analysis requested by Renton concluded that the l0O—year 24-hour flood flow from the site would raise the level of the Black River forebay only 0.07 feet (about one inch)assuming very conservative conditions.A one-inch rise in the forebay will not significantly impact any of the surrounding property or habitat. Similarly,an analysis of the potential water quality impacts was addressed by Metro's consultant Adolfson & Associates,who concluded that Metro's proposed stormwater discharge is not anticipated to have any discernible impacts on the P—l Channel in the short or long term.Reasons for this 2 6 r I I ) I I conclusion include Metro's relatively small contribution of flow quantitatively,the likely high water quality of Metro's treated stormwater,and the degraded water quality of the P-1 Channel. Discharge to the P-1 Channel,rather than to the Green River,also is consistent with the directives of the Green River Management Agreement (July 18,1985),entered into by King County,and the Cities of Renton,Tukwila,Kent,and Auburn. While that agreement permits the discharge of additional stormwater flows to the Green River,it encourages that those flows be controllable,and it prohibits discharge of stormwater flows when the river is at flood stage.By discharging 1 stormwater to the P-1 Channel,Metro's stormwater flows are subject to control at the P-1 pump station and make use of this regional retention facility.Under Metro's proposal,no stormwater flows will be discharged to the Green River when it is at flood stage.. The modification will not be injurious to other property in the vicinity.As noted above,a one-inch rise in the forebay as a result of Metro's discharge will not significantly impact any of the surrounding property.In addition,rain falling on—site does not drain to other properties. Finally,it should be noted that approving a modification for discharge to the P—l Channel is consistent with the historical natural drainage.Since the construction of the railroad tracks located west of the site (long before Metro arrived),the natural drainage of the site has been generally toward the P—1 Channel.As part of site development for the treatment plant,the topography was altered to contain runoff on- site and stormwater was discharged with the treated wastewater effluent to the Green River.Thus,Metro's proposal to discharge stormwater to the P—l Channel will merely restore the natural drainage that existed at the time Metro occupied the site.The SWM provides that where diversion of stormwater "will correct an existing problem,"the diversion should be considered as a variance.SWM 1.2.1. For all of these reasons,we believe a modification from the natural drainage requirement is appropriate. B.Core Requirement #4 (Conveyance System): Core Requirement #4 provides that Pump systems (includes the pumps,force mains, electrical equipment,structures and appurtenances)are not allowed on storm drain systems in King County.A , variance (see section 1.4)from this requirement ... §7 may be requested.Any pump system [is required to meet certain]minimum conditions.... SWM 1.2.4.Metro is seeking a modification to allow pumping for two reasons:(1)in order to implement the SWM's preferred method of water quality treatment--wetponds-~and,(2)to utilize the existing and extensive system of underground piping at the site. There are Site~SpeCifiC reasons that make compliance with the strict letter of Core Requirement #4 impractical.The site contains an existing underground stormwater sewer system.The network of underground pipes was originally designed to allow stormwater to drain by gravity to the Green River.For hydrologic reasons at the site,the sewer pipes are located relatively deep underground.The outfall manhole (the confluence of the stormwater sewer system before discharge to the Green River)is located about 26 feet below existing grade.In the stormwater treatment system as proposed,a pump system is required to lift the stormwater flows from this manhole and to convey the flows to the wetponds located on the ground surface. The pump will be designed and operated in accordance with Metro standard specifications. If Metro does not obtain approval to pump the stormwater, then it would be unable to implement the proposed wetpond. facility which is the preferred method of treatment.Instead, Metro likely would have to construct a large underground wetvault at the location of the outfall manhole.This would create practical difficulties because the area that would be needed to construct a wetvault would involve valuable property that potentially could be used in the future for additional sewage treatment facilities.In addition,the construction of a wetvault would not be consistent with the SWM's preference for wetponds (therefore requiring a modification)and would be very large and costly. The modification meets the objectives of safety,function, appearance,environmental protection,and maintainability, consistent with the Storm and Water Drainage Code.As noted above,the pump station will be designed and operated in accordance with Metro standard specifications.The pump station is a wet~well type with submersible dual pumps,each with a capacity of 4.5 cfs.The wet—well will be 12'10"in diameter and about 40 feet deep.A 48-inch overflow at Elevation 113.0 will bypass flows to the existing outfall diffuser in the Green River.A backflow prevention check valve will be installed on the 48-inch overflow.New emergency overflow weirs and relief sewers will bypass flows when the storm sewer backs up to Elevation 118.0 1 i 8 The SWM allows a variance for use of a pump system when certain specified conditions are met.See SWM 1.2.4.Metro's proposed pump system complies with Conditions 1,2,4,5,and 6. Condition 3 requires a storage facility (wet—well)sized to hold 25%of the total volume of runoff for the developed tributary drainage area for the two year,24-hour duration design storm event.According to modeling results for the site,a total storage volume of 314,000 gallons is required.The proposed wet- well and stormwater sewers are estimated to have a storage capacity of about 200,000 gallons when stormwater reaches the relief overflow weirs (i.e.,about two—thirds of the required capacity).The proposed deviation from the required storage volume is addressed through adequate safeguards incorporated into the design of the pumping station,as discussed below. The condition requiring a large wet—well for the pump is presumably intended to provide a degree of safety for the pump station and the stormwater conveyance system in the event that the pump fails.Metro requests a modification from this Condition for such a large storage facility.Metro's proposed pump system accounts for pump failure without the need for such a large storage facility.The safety and integrity of the pump station is provided by dual pumps,an isolation gate,an overflow weir,emergency relief sewers,a 24-hour a day on-site maintenance staff,and 200,000—gall0n storage volume in the wet- well where_the pump system is located and in the stormwater sewers.These measures are consistent with the intent of Condition 3 for pump systems in section 1.2.4.It is our opinion that construction these measures is requests that the the proposed pump V.CONCLUSION of a large storage facility in addition to unnecessary and impractical.Metro therefore ‘minimum storage requirement be modified so that system can be utilized. Metro requests a modification from Core Requirement #1 (Discharge at the Natural Location),and #4 (Conveyance System) described in the Drainage Plan.Metro's proposed Drainage Plan will result in a level of control and treatment that meets or exceeds the requirements of the SWM.These modifications do not compromise the quantity or quality of stormwater control or treatment at the regional wastewater treatment facility site and are protective of the environment and surrounding property. By implementing this design rather than one which adheres strictly to the SWM,Metro will be able to preserve valuable public property which has been dedicated to potential future sewage treatment facilities and save the ratepayers considerable expense now and in the future.By utilizing the proposed design, Metro will be able to preserve the option of incorporating the 9 H of the SWM in order to implement the stormwater management system I 2 i wetpond concept into an art/wetland enhancement project for For all of the reasons set forth in this application,Metro respectfully requests that the modifications described above be granted. §10 (future public benefit.‘ \3 5! 26 APPENDIX A (Hydraulic Impacts of Redirecting Stormwater Runoff to the P- 1 Channel:l0O—year Flood Hydraulic Analysis by RW BECK) r F F II I vars-zzJBl**.?§J.'??-ls?”15=2.l...l2iliEl{.T.9“..92*§l$..IE““-R “¥‘:.~."'-T'.‘o$2‘?§?..$.‘3.4.'?."l§.9 “191 P99 vs:-"- £4 (\ /¢»\IIv». F . RW BECK masssocumzs ' 'Fwd‘!"N1 Bhnclnsd Buildlnj.suit:600 I MOI Funk Avmu I Snail.Wuhingwn 98121-1375 I USA Tulophme (105)+f1'7l'°0 I FIX (I05)‘HI.-$961 Tnln 4990401 BECKSEA ‘ WW-1421-AA1-AA 'January 22,1992 3023 2 ' Mr.’Randall Parsons,Utility Supervisor Stonn Water/Waste Water Utility Systems Division City of Renton 200 Mill Avenue South Renton,WA 98(E5 - Dear Randalltt Su bjecsz Mctro Ireatmmn Flam Expansion I‘:-ojcct Review of Storm Water Diversion at the Metro Trealsuelnt Plant.in RI-mtms We are plmod to subrnil;the rcsults of the Task 1 work for tho subject project.The analysis was pcrfulmfld by Northwest Hyclraulic Consultant:(NI-I0)and reviewed by our office- Copios of their calculations and analysis are attached.The purpose of the work was to astinmo Lhc iucntasc in runoff volumc received at the Black Rive:Pump Station (BRPS)forebay resulting from the proposed Motro diversion during an coctnemo high Grccn River flow condition.Tho analysis included using flu:HSPF hydrology developed as a.pan.of the ESGRW Plan.More specifically,tho simulation included the local 100-you flood control storage evem.under current land use conditions in Coins-idonoc with high Gsoon River flows.- Based on the work by NIIC,the pa-odioeod incmase in forebay elevations would be 0.07 foot (appcoxinnocly 1 inch).This rise in elevation corresponds to anincrcasc in V01Umc.received at tho forobay of approximately no-R"during a podod in which the forebay is filled to approximately elevation 6 (storage 132 ao-fr).We do not believe that perfiorming the work undo:‘D1-it 2 would be-bonnfldal.-Pm-forming a detailed simulation using HSPFIFEQ would more accurately estimate the elevation in the forebay,however the relative change in elevation and the increase in runoff volume at the forebay from the Metro diversion would bc ncatly the same an predicted by the HSPF analysis. ¢ 3555.015 Bnmn.HA I Cdnmlm.NE I Dian-r.CO I lmlhmpolla.IN n Mlnnwq-nlh,MN "»h~'"1-‘IN IIH-mi».PL urlmm.an Sacrunuum ca 1 sow».w.\ _.'."l§.r.n.....-...r..-."~93%.‘$€£‘u"I“dN consra rn».u_1a 01-22-92 oa=24m P002 use I vis (, (L 1 K R=93%P RENTON CONSTR TRAIIR 01-22-92 03:24PM P003 #36 -.,m--~gRN—22—’92 hED 15:22 |;>=R_£rrr"'f_L-_:wr.u'l‘-I-‘I1 raw bid“n-mu rm a -' 2 8 5 3 5 E1 5 F3@ §*~24aa mm Pno:"-r%a"'*'-U C K“E-H -r ii 2 S3.Ix C.0 .|:-LE Mr.Randall Paraona,Utility Supervisor Storm Watcxfwaste Water 2 January 22,1992 W;would be happy to meet with you to discuss the results of the analysis.If you have any quesnons,please contact our offic.-.-.. 1 Mflzcs Enclosure.>- e:Inc Fcmandea,Manage; Very truly yours, ‘R.W.BECK AND ASSOCIATES Gisebu Project Engineer Metro Treatment Plant Expansion M86013 _KW BECK L?”Iblixlaltl \I1--\--.1-=1»-M-um:-m > }F 9 iir -§~m.C.~mN-22--92 wan 15:2 lI)=RENTUN cnusra vgaxm TEl__,N?_=..<2@.6.2.sfiéréifiia “la;-55,4”-»,--.._..U n-uh |u..v 1 |-1-nu an-an aura 1uvv\Ivll"\-I_-_.:|-y~a :1 -uz nus w mmnu.1c mars _,=1-*="*1 ---- r,i‘.\ l northwest hydraulic consultants inc. -(edmonton ‘\ ?'11_?f~v-"::nw'::u vancouver ‘ K106 m-ma SOWIIB E\ January 21,1992 .Mikns.G1sebun k.W.Bfl:kindAs:I0u'au.-a 2101 Fourth Avenue,Suit:600 Seatfln,WA 981.21-2375 . | Dcarhdlrn: RIB:Renton mama 'l‘:'ca!montP!nut—I1'BI'.E'1\'f0dB!-lB.I -‘run:1 ‘nu:purpom at mu ‘mcmoxandum is to tummmiu the pmoedura fuflowed and malt: Obtaincdinrcgard to:mdc1ingt?wdlversiono£stormwa:=r£romfl1eMEI1?.OT:e.mnem Plan£(MTPJa£Ru1%nnintnSpr£ngb:ookCmelr.llnzeuulummlnatizcd h:rcpc1'ta1ntn'l‘.uk 1 of our nope of mm i --‘-_; (The Hydmloglc Simulation mm -Fértran (Ham was used no estin-me.:2»mm River 'Phmp Station (BRPS)100-your stoma:condition ‘mnuff hydrograph fmm cha MIT.Duning 1 flziscvcnt,0pu2fl0nofth.eBRPSisoonst:ainedbyflowninfl1eGranR1v::.Amnrdingm mformafimenmnte¢flomTab1o4ofmeBrownandCh1dweI1mpon,rnnoifnumzswu E ofpflvlous am and 12 ac1'a:nIimpcrv1ouslmlufi1eM'l‘Ps!1ou1dbed1va_rtod intoSpdngbroukCreek.Hyamgrapna rm spmgnrook CM:and MT?wens oompuwd using the mm multiplying hater dcdvud for tho 100-year swag:eondifiau 1'0:the BRPS,undur flu current mndiziom modeling or the E-Int Side Green River wamrshed.Enclosed you will find E fimryagn flfwmputcrprintnut wmmzrizinz flwxmlu. 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(‘I 5 E September 24,1991 SE?25 ha, Ms.Laurie Endlich H METRO ' 821 Second Avenue ” Seattle,Washington 98104-1598 RE:Fiunofi impacts to the P-1 Channel from the Metro Treatment Plant at Fienton Dear Ms.Endlich: As requested,I have evaluated the potential impact to water quality in the P-1 Channel resulting from discharge of stormwater runoft from the Metro Treatment Plant (MTP)at Flenton.l have reviewed information including the Drainage F_l_er:1oLt.,Metro_Trea_trr|ent ' Plant at B§_Ij1_0fl,Enlargement lll,September 10,1991 Draft to City (Brown and Caldwell,~ 1991);and subsequent revisions of proposed wetponds developed by Brown and Caldwell.l have also reviewed preliminary modeling results by the City of Renton (personal communication,Fl.Straka,City of Flenton,September 23,1991). Water Quantitygirgpactsi.For this evaluation,l assumed that peak stormflows in the P-1 channel at the point of discharge from the MTP are approximately 90%of the flows at the forebay of the Black River Pumping Station,where modeling results are available.This assumption was based upon the estimate (utilized for modeling by the City of Fienton) that existing peak storm flows in Springbrook Creek under I-405 are between 82%and 90%of the flows at the Pumping Station Forebay,depending upon the intensity and return frequency of the storm.For existing conditions,estimated peak storm flows in the P-1 Channel for a 2-year 24-hour storm is approximately 604 cfs.Peak discharge from the MTP stormwater system during the 2-year 24-hour storm is 4.5 cfs,or approximately ' 0.7%of peak stormflow in the P-1 Channel.Under future conditions (full buildout under existing adopted comprehensive plans),the peak flow contributed by the MTP will represent approximately 0.6%of peak flow in the P-1 Channel.This increased flow will have minimal impact to peak flows in the P—l Channel under both existing and future ' flows. Water Quality Impacts.The proposed wetpond facilities have been designed to provide maximum pollutant removal efficiency,in excess of minimum requirements tor wetponds promulgated by King County Surface Water Management Division.Based upon generally- accepted levels of treatment removal for wetponds,upwards of 80%of settleable particulates can reasonably be expected to be removed from influent stormwater entering the wetpond facility.' ADOLFSON ASSOCIATES,INC. Emirmzmental r'iH£l[_VSiS 6/10 Main Street Edmrmds,WA 98020 (206)778-4273 F.-l.\'I206)771 -5053 page 2 of 3 -'4 Stormwater from the MTP will drain from rooftop areas and paved roadways and parking areas.Although vehicle traffic on the MTP roadways will be lower than a typical public roadway,there will be some deposition of vehicular byproducts,including metals and petroleum products.The site runoff will be treated by routing this runoff through biofiltration swales (33%of proposed new roadways and parking lot areas will be routed through biofiltration swales)and the wetpond facilities.Because most of the metals commonly detected in urban runoff are associated largely with particulates (e.g.,lead, copper,and zinc),these constituents by sedimentation can be significantly reduced by the wetpond facility.Fiegular maintenance of the facilities will ensure that deposited sediments are not flushed out of the treatment facilities and into the P-1 channel.Other parameters which are typically associated with particulates will be significantly removed by the treatment facilities,including:(to some degree)total and fecal coliform;and total phosphorus.Petroleum products will be removed to an unknown extent,largely by the biofiltration swale.' Currently,water quality in the P-1 Channel is degraded,with low dissolved oxygen levels, high temperatures,high fecal coliform counts,high turbidity,and high total phosphorus and ammonia levels.The peak storm flow contributed by the MTP represents less than 1%of the total peak storm flow in the P-1 Channel,as described above.The quality of stormwater discharged from the MTP stormwater treatment facilities will likely be higher than receiving water quality for numerous parameters,and is expected to be less turbid. Because the stormwater -discharged from the MTP is such a low percentage of total flow in the P-1 Channel and thequality of discharged runoff is expected to be as high as can be provided using-accepted state-of-the-art treatment technology,no discernible impacts to the P-1 Channel are anticipated in the short or long term future. To determine the treatment effectiveness of the facilities,as well as an optimal maintenance schedule,I recommend that stormwater monitoring be conducted at the facilities.I would recommend monitoring influent and etfluent stormwater during three or four storms annually following implementation of the facilities. If you have any questions or comments,please contact me at (206)778-4273.Thank you. \._.-—--'\,'. Very truly yours/J I~I'_-'. ll _I\_'._ \ Molly olfson \, President /' ADOLFSON ASSOCIATES,INC. .._v~ page 3 of 3 cc:Mr.Flick Butler,Brown and Caldwell 1/ Mr.Jack Warburton,Brown and Caldwell 'Mr.Fiender Denson,Brown and Caldwell lll 28 APPENDIX C (Technical Support for Attaining Equivalent Treatment with Overs i zed wetponds) i l 1,7jfil|EE I RC3 Municipality of Metropolitan Seattle Exchange Building ~821 Second Ave.~Seattle,WA 98104-1598 ¢(206)684-2100 September 19,1991 Ms.Lynn Guttmann Renton Public Works Department Municipal_Building "-;; 200 Mill Avenue South Stp 2A Renton,WA 98055 -_ *‘-‘--~--:-4;“-4 _...Dear Ms.Guttmann:. This letter is to provide technical back up for Metro's letter of September 16,1991,requesting a variance to some of the specific requirements of the King County Surface Water Design Manual(KCSWDM)which has been adopted by Renton for stormwater management.Metro's proposed stormwater management system for the Renton Treatment Plant site was developed to meet the water quality objectives of the KCSWDM,and provide water quality . performanace equivalent to that expected from the core ' requirements.Metro's proposed design involves less reliance on grassy swales than specified by the core requirements,but compensates by oversizing the on—site detention wet pond.As explained in our application,this flexibility is sought because Metro is providing treatment for existing runoff as well as for the proposed expansion.*The existing site drainage pipes are placed very deep,which will necessitate pumping the water to the surface for treatment.Because of site constraints and the opportunity to use an existing line for stormwater conveyance, biofiltration would be very costly to implement over the entire site.‘ In brief,the system we are proposing involves providing biofiltration for exterior roadways and some parking areas,a constructed wetland for an isolated parking area,and treatment of the remaining stormwater in an oversized wet detention pond. About 2/3 of the new impervious area,as well as drainage from the existing site,would be treated via the detention pond. Metro believes an oversized wet pond designed to treat the full 2 year—24 hour storm flow will perform significantly better than one sized for 1/3 that flow,as the KCSWDM currently requires. Data to support this argument are taken from the Nationwide Urban Runoff Program (NURP),which studied the performance of wet detention ponds throughout the country (USEPA,1983).Walker later analyzed the NURP data,relating water quality performance to engineering design criteria (Walker,1986).Four specific design predictors were used in the EPA and Walker reports.They are as follows: r I l i (. ( \ -_- \ Ms.Lynn Guttman September 19,1991 Page 2 1)The ratio of pond surface area to the surface area of the drainage,SA/SD; 2)The ratio of pond volume to the mean storm runoff volume,VB/VR; 3)The surface overflow rate during the mean storm;and 4)Mean hydrualic residence time. In addition,pond configuration and the prevention of short circuiting are important considerations,although no quantitative indices have been developed. Each of these areas will be addressed in turn.Attachments provide numerical backup for the stated removal rates of the proposed pond._ Ratio of pond surface area to surface areatof the drainage.In general,the pond surface area should be about 1%of the contributing drainage area to achieve good pollutant removal efficiency.Modeling done for Metro in support of the Lake Sammamish Management Plan suggests that with a pond depth of about 1 meter,almost 90%removal of total suspended solids (TSS) could be expected.NURP data shows that detention ponds with surface areas greater than 1%of the watershed area achieved TSS removals of from 60%to 90%.Removal of heavy metals was also superior to that seen in smaller ponds.The proposed detention pond at the Renton site has a surface area of 1.1%of the site drainage area. Ratio of pond volume to mean storm runoff volume.Ponds having the ratio of pond volume to mean storm runoff volume greater or equal to 1 show better removal efficiencies than ponds in which the ratio is less than one.Metro!s proposed pond has a ratio of 2.3,which corresponds to TSS removals of 60%to 90%in the NURP data. Surfapefloverflow rate.This design predictor is the ratio of the mean storm runoff rate to the pond surface area.In the NURP study,ponds with overflow rates less than about 0.1 ft/hr performed best in terms of TSS and metal removals.Metro's proposed pond has an overflow rate of 0.07 ft/hr.1 ! II I »< 5. i. Ms.Lynn Guttman September 19,1991 Page_3 ~ Hydraulic residence time.The longer storm flows are detained, the greater treatment provided,both for TSS as well as for the nutrients nitrogen and phosphorus.In part,nutrient removal in wet ponds is due to biological activity in the water column,a process which is time dependent.Walker estimates that for phosphorus removal of up to 80%,a detention time in excess of 14 days is required.For about 50%phosphorus removal,detention times of 7 —14 days would be required..- TSS removals of 60%to 80%have been seen with detention times of between 6 and 7 days,according to data from NURP and Martin & Smoot (1986).As currently designed,with an active pool volume of about 1 meter,the proposed pond has a detention time of 7 days.Since the receiving waters (P-1 channel and Green River) are not particularly phosphorus sensitive in the reaches downstream of the Treatment Plant,detention times of greater than 7 days would not seem necessary.However,if determined otherwise,it would be possible to achieve a 15 day detention time by increasing the pond depth to 2 meters. Pond configuration.A laboratory scale model studied by Horner and Kortenhof (1987),found that long,narrow pond configurations with two cells achieved longer residence times than single cell configurations.The proposed detention pond design provides three cells,as per the KCSWDM,and a very elongate configuration.Use of three cells and the long,narrow configuartion serves to maximize the travel path of storm water introduced into the pond,and increase the residence time over that projected on the basis of engineering parameters alone. The attached Table indicates a range of expected annual pollutant removal effectiveness for Metro’s proposed enlarged pond size, and the smaller pond size required in the Manual.The Table also gives preliminary data about the removal efficiencies of biofiltration swales.(Biofiltration data was collected this summer as part of an inter-agency project to monitor the pollutant removal effectiveness of grassy swales,and is as yet - unpublished.) The expected pollutant removal performance is given as a range to indicate the variability seen in different parts of the country with different pond treatment systems.In general,a much higher annual average level of pollutant removal is expected from large ponds with design characteristics as described previously. 4 I '> } IV F $ i, \ i V I ! I l |1 i, i w Ms.Lynn Guttman September 19,1991 Page 4 These data indicate that with an enlarged detention pond sized as .proposed,water quality performance equal to or better than that expected from a smaller pond plus biofiltration can be achieved. Metro appreciates your willingness to consider our request for flexibility in the manner the requirements and water quality objectives of the KCSWDM can be met.If you have questions about the data presented,please contact me at 684-1551 or Louise Kulzer,at 684-2063.Additional background information can be found in Metro's publication "Considerations for the Use of Wet Ponds for Water Quality Enhancement."References cited in this letter are appended. Very truly ours, ohn F.Spencer Director Water Pollution Control Department JFS:lkk Enclosures r L>\ |1 (, ZQ -»- K References Cited in Letter Considerations for the Use of Wet Ponds for Water Quality Enhancement.1989.Office of Water Quality,Metro,Seattle,WA 98104. Martin,Edward H.and James L.Smoot.1986.Constituent-load Changes in Urban Stormwater Runoff Routed Through a Detention Pond—Wetlands System in Central Florida.U.S.Geological Survey, Water Resources Investigation Report 85-4310. Walker,William Jr.1986.Phosphorus Removal by Urban Runoff Detention Basins."Lake and Reservoir Management:Influences of Nonpoint Source Pollutants and Acid Precipitation"6th Annual International Symposium,North American Lake Management Society, Portland,Oregon.November 5 -8,1986. US Environmental Protection Agency,1983.Results of the Nationwide Urban Runoff Program.Volume 1 —Final Report.Water Planning Division,US EPA,Washington D.C.20460. i>;V,,1 I\ F 7 1 i. € K Pollutant Removal Performance of Large and Small Detention Ponds and Grassy Swales Pollutant Percent Removal Observed Large ponds Smaller ponds Grassy swales (average of 4 c storms) Total dissolved 60 —90% solids (TSS) Total phosphorus 3 —80% Total Kjeldahl neg.-30%80% U1 o\°neg.-30% nitrogen neg -60%neg.~20%neg.“ Total lead so —90%10 —60%70%# Total zinc neg.—70%O —10%60% Notes:”1* Detention pond data is from NURP,USEPA,1983. Grassy Swale data is from Biofiltration Phase II, unpublished. Large ponds and small ponds are defined as follows: Large ponds __—--—"--.---v.‘ SA/SD >1 VB/VR >1 Overflow rate <0.1 ft/hr Hydraulic resedence time >14 days Legend: Small ponds -SA/SD <1 -VB/VR <1 Overflow rate >0.1 ft/hr Hydraulic resedence time <14 days “Data for grassy swales is N02 +N03 rather than Kjeldhel Nitrogen #Lead removals were inferred from data on iron,since lead behaves simialrly in water,and lead was below detection. \ ,zw Y ( 1 {\ g \ Design Parameters for Detention Pond Water Quality Improvement (after Walker,1986). 1-‘o\°I.Pond surface area /Drainage surface area > Renton TP Site:Pond area =0.57 acres (0.23 ha), Total site area =49.6 acres (20 ha) SA/SD =1.1% II.Pond volume /Mean storm runoff volume >l Mean storm runoff volume =watershed area (ha) X runoff coefficient X mean storm size (cm) Renton TP Site:Pond volume =0.23 ha X 100 cm =2300 cubic meters Mean storm size =1.22 cm Site runoff coefficient =0.4 (40%impervious) Mean storm volume =20 ha X .4 X 1.22 cm '=976 cubic meters VB/VR Ratio =2300 cubic meters /976 cubic meters =2.36 III.Overflow rate <0.1 ft/hr Overflow rate =mean runoff rate /pond surface area =(mean storm size(cm)X runoff coefficient X drainage area(ha))/(mean storm duration(hr)X pond area(ha)) Renton TP Site:' Assumptions: Mean storm size =1.22 cm Site Runoff Coefficient =0.4 Mean storm duration =20 hours Overflow rate =(1.22 cm X 0.4 X 20 ha) '/(20 hr X 0.23 ha)Z =2.12 cm /hr =0.07 ft /hr (1 ft =30.48 cm) » >I I E 1 f 5 L: -~ '-4':a \IV.Hydraulic detention time >14 days ror 80%Phosphorus removal.k =100 X pond area(ha)X pond depth(m)/Drainage area X runoff coefficient X mean storm size /length of season (yr) Renton TP Site: Assumptions:length of season =9 mo =.75 yr Hydraulic residence time =100(0.23 ha)(1 m)(0.66 yr)/ 20 ha(0.4)(106 cm)_ =0.019 yr =7 days- é\; )5. APPENDIX D (Stormwater System Modeling:Hydrologic and Conveyance Capacity Analyses) 29 , l> E x 30 STORMWATER SYSTEM MODELING Figures D1 and D2 are schematic diagrams of the existing and proposed stormwater drain systems for MTPR.The plans show location,diameter,and node ID used in the computer modeling. Two 30—inch storm sewers,one serving the north and the other serving the south part of the plant,carry most runoff to an outfall manhole west of the Administration Building.Two smaller lines also discharge into the outfall manhole:an 18-inch line that drains the parking lot north of the administration building and the impervious areas around the grit handling facility,and a 10-inch line that accepts runoff through catch-basins located on the northern entrance road near Monster Road.The locations of the existing stormwater sewer system are based on construction drawings and inspection surveys.About 101 pipe segments were used to model the existing system;about 108 for the proposed system. p Stormwater from the dewatered sludge truck loading area,the septage disposal area,and chemical storage areas (such as the sodium hydroxide storage tank)is directed into the sanitary drain system.The sanitary drains flow to the treatment plant for processing before being discharged into Elliot Bay via the effluent transfer system.In the proposed enlargement, stormwater draining to the grit loading ramp will also be pumped to the plant sanitary sewer system in a manner similar to that serving the dewatered sludge loading area.Only when the capacity of the pumps is exceeded,such as during an extreme storm event,will stormwater from these areas drain to the stormwater sewer system.Both the sludge loading area and the grit loading area were assumed to flow into the stormwater sewer system for the l0O—year 24-hour storm event. In the proposed stormwater sewer system,several existing catch basins and inlets will be relocated to drain newly landscaped areas and realigned access roads and parking lots. Most of the realignment changes will occur near the Administration Building and the Dewatering Building.The new grades of the proposed plan will redirect some of the flows to new inlets,thus changing the site hydrology.New extensions of the stormwater system will be required to serve the new proposed roads and parking lots of the new DAFT complex and the new secondary clarifiers. Areas that do not drain to the stormwater sewer system include the wetlands,the eastern perimeter of the site,the southwest and southeast corners of the site,open process tanks and sludge processing tanks.The wetlands accept runoff from the area north of the northern access road.The P-1 channel receives flow from the eastern perimeter of the site.A swale located I I 31 just north of Longacres Drive receives stormwater from pervious areas along the southwest corner of the site.The swale operates like a retention pond,draining east to the P-1 Channel when the water accumulates to a depth of about 18 inches.Changes proposed in these areas for Enlargement III are minimal and will not significantly alter the drainage patterns or peak flow rates. Stormwater from these areas were not included in the modeling effort as agreed to by the City of Renton's Surface and Stormwater Division. Figures D1 and D2 also show the subcatchments used in the model.These subcatchments were delineated based on the contours of the site maps.The following areas do not contribute runoff to the stormwater sewer system:open vessels such as the aeration tanks,RAS channel,mixed liquor channel,chlorine contact channels,and secondary clarifiers;the primary clarifiers; solids area structures such as the DAFTs,the anaerobic digesters,and the sludge blending tank;the secondary control facilities;the influent pump building;and the area between secondary clarifiers 3-4 and 5-6.About half of the roof of the sludge dewatering building drains to the plant's sanitary system; the other part drains to the stormwater sewer system.The area around secondary clarifiers 3,4,5 and 6 drain to the chlorine contact channel. Model ins Mel;ho_c1_ol0sr The methodology used to model peak storm runoff rates and route storm flows through the stormwater sewer system complies with the requirements of the SWM.Modeling involved the following tasks: *Mathematically define the stormwater conveyance system, e.g.,pipe diameter,length,upstream and downstream invert and rim elevations. *Delineate catch basins for each stormwater inlet. *Calculate the pervious and impervious areas contributing to a stormwater inlet. *Determine the SCS curve numbers,K value,conveyance slope,and characteristic length for each catch basin. *Define the l0O—year,24-hour design storm hydrograph. *Run simulation runs for both pre-and post—developed site conditions. *Compare the peak flow rates to the 0.5 cfs exemption criterion. The 24-hour design storm hyetograph found in Figure 3.5.lA (SCS Type 1A Distribution)of the SWM was used in this analysis. The unit hyetograph was multiplied by the total l0O—year,24-hour precipitation for the MTPR site,3.9 inches according to Figures 3.5.lH of the SWM,to produce the design storm hyetograph. Adjustments for snowmelt were not required because the site l11; (* 32 elevation is below 1,000 MSL.The design storm hyetograph was input to the model using 10-minute intervals. HYDRA4,a sanitary and stormwater sewer analysis program available on Brown and Caldwell's GIS package,was used to calculate conveyance system response to storms.HYDRA4 uses the Soil Conservation Service (SCS)hydrograph method modified with the Santa Barbara Unit Hydrograph algorithm to generate runoff hydrographs.HYDRA4 routes the stormwater inflow hydrographs through the stormwater drain system.This methodology complies with Section 3.2 of the SWM,“Computation Methods". Inputs required to generate runoff hydrographs included the following: If-II-5+ Total area in acres Proportion of impervious surfaces SCS curve number for impervious areas SCS curve number for pervious areas Overland flow characteristics factor "K" Slope of the overland conveyance system The longest route surface water must flow to reach the outlet for the land segment. X-*1!- I- Tables D1 and D2 present the data used by HYDRA4 to generate runoff hydrographs for pre-and post—development stormwater systems.Soil Group C was used for all subcatchments.The majority of the pervious surfaces on the plant site are imported topsoil.These soils fall under SWM hydrologic group C.The western landscaped areas may be partly Beausite soils,although much_of that is also imported topsoil.The wetland area is also considered to be Puyallup soil,which is classified as hydrologic group B,but was modeled as soil group C.Curve numbers used in the model were as follows:- *CN for impervious areas =98 Z *CN for open spaces in good condition (grass cover on 75%or more of the area)=86 *CN for open spaces in fair condition (grass cover on S0 to 75%of the area)=90 ‘ An example of open spaces in good condition is the open field north of the Administration Building.An example of an open field in fair condition is the landscaped area lining the road just south of the solids handling facilities. K values used to calculate the time of concentration were weighted averages based on contributing area.K values used in the model were as follows:- K for short pasture and lawn =ll *K for nearly bare ground =l3 I l 33 *K for paved areas =27 The peak flow rate at the storm sewer outfall manhole was used to compare before and after development (Node 1001).Flow through the outfall was assumed to be unhindered by the Green River surface elevation. Tables D3 and D4 present the databases used in the HYDRA4 model for the pre-and post—development stormwater systems.The database files contain physical information about the conveyance systems: II-ii-3l'I(-if Downstream Node ID Downstream Invert Elevation Downstream Rim Elevation Pipe Segment Length Pipe Diameter Upstream Node ID Upstream Invert Elevation Upstream Rim Elevation>1-=(>>¥ Node IDs and pipe diameters are presented on the site plans. To orient the reader,node 1000 is the Green River outfall ~ diffuser;node 1001 is the outfall junction manhole;nodes between 1001 and 1040 are located along the southern half of the site,and nodes between 1044 and 1101 are located on the northern half of the site.Node 1055 is the overflow drain from the ETS Surge Tank west of the site.Input parameters required to produce the storm hydrographs are presented in Tables D1 and D2. E if H \ ‘x Table D1.Hydrograph Input Paramtem:Pre-Development TABLE D1 ~Drainage Report Node Total Area lmperv Area CN|mper *CNl>e|v K ‘7Si0pe Dislancewz g _(A<=re§)_,_y (%)-.I (Ft/F_LJF‘)ii.; 1101!1.12 11001‘0.12 1000 0.04 1000 1 1007 * 1000 0.20 1000 0.20 1004 0.40 1000 0.02 1002‘0.05 10011 0.00 1000 0.10 1000 0.20 1000 0.11 1001 0.20 1000 0.24 10001 - 10041,0.10 1000 2.75 1002 * 1001 0.00 1000 0.10 10701 1.02 1070;0.05 1070 0.40 1015 0.04 1074,0.10 10101 2.41 1072‘0.00 1011 0.14 1010 0.00 1009!0.11 10001 * 1 001 0.00 1000 0.20 1005 1 1004 0.11 10635 1.02 10021 0.04 I 10011 '5 _- 12% 12% 27% 88% 31% 51% 57% 75% 42% 34% 36% 100% 66% 73% 100% 0% 100% 100% 0% 9% 0% 100°/> 100% 1 0% 0% 100% 53% 81% 50% 88% 78% 11% 100% 98 86.0 98 86.7 98 88.7 98 86.0 98 86.0 98 87.1 98 87.3 98 90.0 98 86.0 98 86.0 98 88.5 98 98 90.0 98 86.0 00_ 98 86.0 98 98 98 86.0 98 86.0 98 86.0 98 98 98 86.0 98 86.0 98 I 90 00.2 98 86.0 98 86.0 98 86.0 98 86.0 98 86.0 98 13.0 13.2 16.3 25.2 15.9 19.4 20.5 23.5 17.7 16.5 17.6 27.0 22.2 22.7 27.0 11.0 27.0 27.0 11.0 12.5 11.0 27.0 27.0 12.5 11.0 27.0 20.0 24.0 19.1 25.2 23.5 12.8 27.0 0.030 0.030 0.021 0.020 0.054 0.070 0.148 0.012 0.070 0.070 0.066 0.001 0.107 0.010 0.007 0.012 0.008 0.004 0.012 0.003 0.004 0.014 0.030 0.015 0.330 0.005 0.009 0.003 0.011 0.007 0.010 0.004 0.021 220 180 200 300 80 160 220 1 00 60 60 200 160 70 60 240 320 50 160 220 260 170 260 210 160 40 100 145 90 150 140 65 180 90 E ii i *Afslsfurried no inlet at this node.C HYDRA4 Input Files Hydrograph Parameters Pre-Development Renton Ill Node 2 Total Aréi lnigen/Area CNlmper80NPew K I (%) Slope (Ft/Ft) Distance I (F1) .1000.0.40 1,1050 0.54 ‘1050 0.00 1057 * 1050 - 1055 1054. 1050 1052 1051 1050‘ 10401 * 1040 3.02 1047 0.07 1040 0.22 10451.* 10441 ' 1021 0.40 1020 0.20 1010 0.11 1010,0.21 3 1011;»0.54 ‘1010 ' 1015 0.00 1 014 0.44 1012 1.20 10115 0.10 1010‘l ' 1000 0.04 1000 0.40 1005.0.201100410.10 1003 0.00 1002 0.00 1031 0.00 1020 0.05 1020 * 1021 0.20 -1020 0.00 I I- I- O vb» U’! (Acrgs)_ 1 2% 0% 23% 100% 0% 100% 100% 71 % 76% 86% 56% 88% 52% 30% 15% 100% 83% 17% 100% 28% 15% 67% 0% 69% 0% 34% 86.0 86.0 86.0 86.0 86.0 85.0 86.0 86.0 86.0 86.9 88.3 89.8 86.0 87.1 86.0 86.0 86.0 86.0 88.3 86.0 12.9 11.0 14.7 27.0 11.0 27.0 27.0 22.3 23.2 24.7 20.0 25.1 19.6 16.6 15.0 27.0 24.2 14.2 27.0 15.5 13.5 21.7 11.0 22.4 11.0 0.080 0.045 0.045 0.002 0.000 0.007 0.010 0.006 0.003 0.005 0.003 0.005 0.007 0.006 0.005 0.005 0.005 0.004 0.005 0.006 0.086 0.002 0.008 0.005 0.006 00%j 07.5 10.0 0.005 400 180 80: 60 380 200 220 270 160 115 135 120 170 200 120 110 100 90 100 180 50 90 80 160 80 130 *Assumed no inlet at this node. 1 1'TABLE D1 -Drainage Report ’1I HYDRA4 Input Files Hydrograph Parameters Pre-Development Renton Ill TABLE D1 -Drainage Repon P -.._1°/9).- P P -Qifi3l- Node Totai Area lm en!Area CNlm er CNPew K 'Slo e ‘Distance 1 i W 1.(Aores)H (F1) 1025 1024 1000 1020 1022 1007 1007 1042 1041 1040 1000 1000 1000 1005 1004 1040 10021 1001 '10001 1000 0.31 I i 0.19 0.17 0.18 0.58 1.18 0.21 0.34 0.45 0.34 0.71 I I I t 32% 58% 23% 64% 100% 73% 100% 67% 66% 56% 85% 98 86.0 87.8 86.0 86.0 98 86.0 86.0 98 86.0 98 98 86.0 86.0 18.2 20.6 14.7 21 .2 27.0 22.7 27.0 21.7 21.5 19.9 24.6 0.005 0.011 0.005 0.005 0.010 0.011 0.012 0.005 0.010 0.016 0.026 100 150 90 130 150 420 280 1 50 190 170 160 7*Aésumed no iniet at this node.7 77 Table D2.Hydrograph input Paramters:Post-Development l ,l TABLE D2 -Drainage Report Node Total Area lmperv Area CNlmper CNPerv7 K ..,7___...._.(A°.".°.5)114?)”.__ s1<>¢€Distance<0/F1J__L 1101 0.72 1100 .0.72 10001 0.70 1000 * 1007 * 1000 0.20 1005;0.00 1004 0.40 1000 0.00 1002 0.40 1001 ..0.00 1000 0.15 1000 0.20 1000 0.11 1007.9 0.25 10001‘0.00 1005 1 1004 0.10 1000 2.50 1002 ' 1001}..0.00 1000 0.10 1070 1.02 1070 0.10 1077 * 2070 1.00 1070“0.40 1075 0.04 1074 0.10 1070..2.41 1072 0.00 1071 0.14 1070‘0.00 10001 0.11 1000 ' 1007 0.00 1000 0.20 1005 1 1004 0.11 4 1000 1.02 19% 12% 40% 100% 100% 42% 59% 65% 42% 34% 36% 100% 66% 44% 1 00% 0% 100% 100% 0% 27% 0°/0 0% 100°/0 100% 14% 0% 100% 53% 81% 50% 88% 78% 11% 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 0 98 98 98 98 98 98 98 98 98 98 00 9? 86.0 86.7 87.7 86.0 86.0 86.0 86.0 90.0 86.0 86.0 88.5 86.0 90.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 00.0 00.0 00.2 86.0 86.0 86.0 86.0 86.0 14.0 13.2 17.9 27.0 27.0 17.7 20.5 22.2 17.7 16.5 17.6 27.0 22.2 18.1 27.0 ‘11.0 27.0 27.0 11.0 15.3 11.0 11.0 27.0 27.0 13.3 11.0 27.0 20.0 24.0 19.1 25.2 23.5 _____12.8 0.030 0.030 0.021 0.020 0.054 0.070 0.148 0.012 0.070 0.070 0.066 0.001 0.107 0.010 0.007 0.012 0.008 0.004 0.012 0.003 0.001 0.004 0.014 0.030 0.015 0.330 0.005 0.009 0.003 0.011 0.007 0.010 0.004 220 1 80 200 300 80 160 220 100 60 60 200 160 70 60 240 320 50 1 60 220 260 400 170 260 210 160 40 100 145 90 150 140 65 180 "Assumed no inlet at this node. l 1 HYDRA4 lnput Files Hydrograph Parameteus Post-Development Renton ill TABLE D2 -Drainage Report 1 (-598$)-.5%) Node 7 7 T0ta7lArea7 lmperv Area]CN1mper CNPerv\7 K Slope __(Ft/Ft) Distance .(Fl) 1002 0.04 1001 ' 1000 2.02 1050 0.54 1050 2.40 1057 * 1050 * 1055 10541 1050 ‘ 1052 1051 1050 1040 * 1040 A 0.20 10471 0.74 2047 1.54 1040 0.22 1045 * 1044 '- 20211‘2.47 1021 1 0.40 1020 0.20 1010 0.11 1010 0.21 1017 0.20 1010 * 10151 0.00 10141 0.44 1012 1 .20 1 011 0.10 1010 * 1000 0.04 1000‘0.42 10053 0.20 1004.0.74 1000 0.00 1002 0.00 1001 0.00 I- I- I- CD 1'01»-u-1 100% 24% 0% 6% 1 00% 0% 3% 6% 1 00% 0% 71% 76% 86% 56% 71% 52% 30% 1 5% 1 00% 83% 19% 100% 13% 15% 80% 0% 86.0 66.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.9 88.3 89.8 86.0 86.0 86.0 86.0 86.0 86.0 86.0 86.0 27.0 14.8 11.0 12.0 27.0 11.0 11.5 12.0 27.0 11.0 22.3 23.2 24.7 20.0 22.4 19.6 16.6 15.0 27.0 24.2 14.1 27.0 13.2 13.5 23.8 11.0 0.021 0.080 0.045 0.045 0.002 0.000 0.051 0.050 0.010 0.005 0.006 0.003 0.005 0.003 0.005 0.007 0.006 0.005 0.005 0.005 0.004 0.005 0.047 0.086 0.002 0.008 ».10_20 0.05 _70%00 00.1 22.0 0.005 90 1 400 180 300 60 000 _000 400 220 050 270 100 -115 105 120 170 200 120 110 100 90 100 1 50 50 90 80 16° "Assumed no inlet at this node. HYDRA4 Input Files Hydrograph Parameters Post-Development Renton ill TABLE D2 -Drainage Repon l l,0 Node 1 Total Area lmperv Area CNlrnper CNPerv kw (Acres)}WW (%) [7K Slope (FVF1)___ Di stan (F1) CB 1027 0.20 102 1 0.00 1025 001 1024 ' 1000 * 1020‘040 10221 047 1007*010 1007 * 1042 050 1041 * 1040 1.20 1000 0.21 1000;0.04 10001 1 1005 045 1004 004 1040 000 10001 ~ 10021 1.24 1001 * 1000 * 1020 ~ 0 9% 1 00 °/1 32% 58% 23% 64% 100% 78% 100% 67% 66% 62% 82% 1 0% 86.0 86.0 86.0 87.8 86.0 86.0 86.0 86.0 86.0 86.0 86 21.50382 86 20.85235 86 24.15048 86 12.4 27.0 16.2 20.6 14.7 21.2 27.0 23.5 27.0 21.7 1 2.6037 0.006 0.010 0.005 0.011 0.005 0.005 0.010 0.011 0.012 0.005 0.010 0.016 0.026 0.011 80 120 100 150 90 130 150 420 280 150 190 170 160 400 E 1 "Assumed no inlet at this node. Tabla D3.Existing Conveyance System Parameters TABLE D3 -Drainage Report 11100010 I1 ‘Downstream l_Upstream Elevations 3‘Pipe Dimensions 7 7 Elevations 19!“ 1000 1001 1002 1000 1004 1000 1007 l 1000 1000 1010 1011 1010 1010 1015 1010 1010 1020 1010 1015 1000 1024 1025 1020 1,1027 ‘1020 1020 1001 1002 1000 1004 1 1005 1007 1007 1022 1000 1000 1000 1040 1 1041 *1 1003 1001 1044 1045 1044 1044 1 1048 1 1049 ‘1050 1001 1052 1053 1052 1055 1056 89.00 89.75 1 102.73 102.95 103.48 1 20.90 104.70 1 05.24 1 06.06 1 1 7.1 4 1 17.52 106.27 106.27 1 106.60 122.84 1 07.00 107.00 1 07.00 1 06.58 105.24 ..107.80 110.50 110.00 114.00 110.00 110.00 .110.54 117.00 110.50 110.51 110.00 104.70 121.50 121.70 105.05 110.00 ‘110.50 120.20 121.01 115.50 102.50 110.70 121.70 110.70 1 110.70 122.00 121.02 101.00 102.50 105.01 100.20 105.01 105.05 107.00 59.00 129.00 128.00 127.50 128.00 125.50 125.50 125.60 125.50 126.50 126.40 126.50 126.50 125.94 126.20 125.50 125.50 125.50 125.94 125.60 123.30 123.30 123.30 124.00 125.20 125.20 123.50 123.00 123.30 123.40 123.50 125.50 125.50 125.51 125.50 126.00 126.00 126.00 125.50 127.50 129.00 130.10 129.42 130.10 130.10 126.00 133.00 136.00 129.00 129.00 129.00 129.00 126.00 125.25 71 .0 1 12.0 102.0 482.0 1 50.0 28-4.0 160.0 105.0 47.0 309.0 280.0 83.0 63.0 217.0 245.0 308.0 217.0 255.0 1 28.0 96.0 128.0 100.0 320.0 30.0 55.0 125.0 50.0 90.0 14.0 100.0 45.0 40.0 244.0 80.0 100.0 1 20.0 1 69.0 148.0 72.0 1 36.0 1 24.0 296.0 227.0 302.0 43.0 177.0 1 60.0 305.0 191 .0 339.6 252.0 325.0 276.0 30 30 <=====<='$.’88888 21 10 10 18 18 8 18 15 15 15 15 15 12 12 12 12 12 12 12 8 12 12 12 8 12 12 8 12 18 15 15 8 15 6 10 8 30 12 12 30 30 24 0<1elD 1001 1002 1003 1004 1006 1007 1008 1009 1010 1011 1012 1014 1015 1016 1017 1020 1021 1019 1018 1024 1025 1026 1027 1028 1030 1031 1032 1033 1034 1035 1036 1037 1022 1023 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1058 A 102.70 112.05 1 100.40 104.05 121.50 105.24 105.50 100.27 117.52 A 120.00 120.00 1 106.58 100.00 124.50 107.44 100.22 124.00 1 107.00 1 107.00 110.50 113.80 114.00 ‘115.55 11 120.25 110.54 117.00 110.50 110.51 110.00 121.00 120.00 121.70 120.00 100.50 120.20 120.20 121.00 122.75 1 110.00 1 110.70 121.70 122.00 120.00 122.00 124.00 1 101.00 175.00 105.01 100.20 p 140.20 1 105.05 1 100.50 100.20 iManhol-e Rim 000910 _l01am010r1N Z _lnvert 1Mnl1olg_Ri|11 _1 ”I 5”000.0 120 0075 12000 1 1 28.00 127.50 126.00 125.50 125.50 125.60 125.50 126.50 1 26.40 1 25.74 125.50 125.94 126.20 1 28.58 125.50 128.80 1 28.80 1 25.50 123.30 123.30 123.30 124.00 1 25.00 124.25 123.50 1 23.00 123.30 1 23.40 1 23.50 1 23.50 125.46 125.50 1 28.80 1 28.80 1 26.00 1 26.00 1 25.50 1 25.50 1 25.50 130.1 O 1 29.42 1 29.42 1 27.65 1 26.00 1 33.00 1 36.00 1 89.80 129.00 1 29.00 1 56.00 126.00 1 25.25 _1_2S.25 1I l1 l Table D3.Existing Conveyance System Parameters TABLE D3 -Drainage Report Qmmsiream |77'Qpstream if .N0da|D 1 ____Elevat10ns Pipe Dimensiom}Elevations 71058 1059 1060 1061 1 1056 1061 1063 1067 10% 1064 1065 1056 1072 1072 1074 1074 1072 1077 1078 1077 1079 1080 .1079 1082 1083 1083 1085 1086 1087 1088 1089 1089 1086 1092 1093 1094 1095 1083 1097 1098 1098 1100 1069 I 1070 1001 1006 1028 1021 1029 1 1016 106.20 106.61 .1.53 120.10 110.00 110.44 112.26 i 112.11 112.66 111.00 116.10 \106.50 1 110.13 116.14 119.62 116.36 106.61 120.65 0 120.96 11 101.35 120.16 120.96 101.60 106.36 0 121.00 1 121.00 103.24 103.42 103.94 0 104.12 “106.04 105.04 103.92 104.66 105.44 106.00 106.39 111.25 ,113.19 1 119.00 119.00 119.50 113.16 114.92 116.91 120.10 »115.55 106.22 116.00 121.00 125.25 125.25 125.25 126.50 125.25 126.50 125.33 125.00 125.33 125.50 125.50 125.25 125.25 125.25 125.25 125.25 125.25 125.25 125.50 125.25 125.25 125.50 125.25 125.25 125.25 125.25 111.50 110.75 110.68 125.35 1 15.54 115.54 110.75 110.10 109.90 1 11.00 114.24 125.25 125.25 126.21 126.21 126.90 125.00 125.02 129.50 125.50 125.20 128.80 125.20 125.50 107.0 1 91 .0 1 55.0 38.0 100.0 383.0 170.0 1 72.0 65.0 53.0 43.0 320.0 83.0 205.0 196.0 77.0 290.0 103.0 1 00.0 72.0 1 03.0 100.0 210.0 105.0 1 07.0 1 4.0 1 1 0.0 88.0 30.0 1 53.0 78.0 72.0 95.0 95.0 70.0 40.0 77.0 108.0 324.0 1 05.0 58.0 290.0 127.0 160.0 180.0 1 40.0 1 5.0 320.0 100.0 207.0 069 1060 1061 1062 1067 1063 1067 1069 1064 1065 1066 1072 1073 1074 1076 1075 1077 1078 2079 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1070 1071 3001 1005 1029 2021 2028 2076 109.53 110.19 120.25 111.00 11 1.10 112.11 113.34 111.00 110.10 123.21 106.61 119.69 116.36 121.00 119.00 101.35 120.96 121.16 101.60 120.96 121.16 106.36 110.00 123.25 95.50 103.36 103.94 104.12 113.50 105.62 105.41 104.66 105.44 106.00 106.69 106.95 113.19 119.00 119.64 119.50 123.56 114.92 120.00 122.25 121.40 116.00 122.10 111.00 123.09 125.25 125.25 126.50 125.25 126.00 125.33 125.00 125.00 125.50 125.50 125.00 125.25 125.39 125.25 125.50 125.25 125.25 125.50 128.80 125.25 125.50 128.80 125.25 125.25 125.30 111.50 1 10.75 110.68 125.35 115.54 1 1 1 .00 111.00 110.10 109.90 1 1 1 .00 1 14.24 119.20 125.25 126.21 124.94 126.90 128.11 125.02 124.92 126.10 124.20 125.20 124.10 124.00 125.60 B15001:1115050155115 |Le1f1g}I1 lowmgpr 1.111066 10 %:|;_1y0r1 |ManholeRIr11_‘it **2411"106F7 1 1 1 Tabie D4.Proposed Conveyance System Parameters "TABLE D4 -Drainage Report _Dowpslreagn N9!!!lD,| __E_1_gyations \Pipe Dimensions 1 W @'1q!h.....l9l2*.1.#!=!.. .‘.N99§JP... 1 Upstream Elevations .~-l.?\’.9,"-JF§4_!!!!?9!9..'3.‘fl.....1000 1001 1002 1003 1004 1006 1007 1008 1009 1010 1011 1010 1010 1015 1016 1018 1020 1018 1015 1008 1024 1025 1026 1027 1029 1029 1031 1032 1033 1034 1035 1007 1007 1022 1006 1038 1038 1040 1041 1043 1003 1001 1044 1045 1044 1044 1044 1048 1049 1050 1001 1052 1053 1052 1055 1056 '89.75 102.73 102.95 103.46 120.90 104.70 105.24 106.06 117.14 117.52 106.27 106.27 106.60 122.84 107.00 107.00 107.00 106.58 105.24 107.80 110.50 113.80 114.00 115.00 116.00 116.54 117. 118.50 119.51 119.86 104.70 121.50 121.70 105.35 119.00 119.50 120.20 121.61 117.50 115.50 102.59 119.79 121.73 119.79 119.79 121.79 122.00 121.62 131.00 102.59 105.01 106.20 105.01 105.85 107.00 89.00 99.00 1 29.00 128.00 127.50 126.00 1 25.50 125.50 125.60 1 25.50 1 26.50 126.40 126.50 126.50 125.94 126.20 125.50 125.50 125.50 125.94 125.60 123.30 123.30 123.30 124.00 125.20 125.20 123.50 123.00 123.30 123.40 123.50 125.50 125.50 125.51 125.50 126.00 126.00 126.00 125.50 125.50 127.50 129.00 130.10 129.42 130.10 130.10 132.20 126.00 133.00 136.00 129.00 129.00 129.00 129.00‘ 126.00 1 25.25 999.9 71 .0 1 1 2.0 1 02.0 482.0 1 50.0 284.0 1 60.0 1 05.0 47.0 309.0 280.0 83.0 63.0 21 7.0 245.0 308.0 217.0 255.0 128.0 96.0 1 28.0 100.0 320.0 20.0 55.0 1 25.0 50.0 90.0 1 4.0 100.0 46.0 40.0 244.0 80.0 1 00.0 120.0 169.0 1 48.0 1 60.0 72.0 1 36.0 1 24.0 296.0 227.0 302.0 227.0 43.0 177.0 160.0 305.0 1 91 .0 339.6 252.0 325.0 276.0 120 30 30 <===<=°§88888 21 10 10 18 18 8 18 15 15 15 15 15 12 12 12 12 12 12 12 8 12 12 12 8 12 12 8 10 12L 18 151 15 a 15 a s 10 a so 12 12 so so 24. 1001 1002 1003 1004 1006 1007 1008 1009 1010 1011 1012 1014 1015 1016 1017 1020 1021 1019 1018 1024 1025 1026 1027 1028 1030 1031 1032 1033 1034 1035 1036 1037 1022 1023 1038 1039 1040 1041 1042 2043 1043 1044 10-45 1046 1047 1048 2047 1049 1050 1051 1052 1053 1054 1055 1056 1058 89.75 1 02.73 1 12.95 103.46 104.35 1 21 .50 105.24 105.56 1 06.27 1 1 7.52 120.00 120.00 106.58 109.08 124.58 107.44 108.22 124.88 107.00 107.80 110.50 113.80 114.00 115.55 120.25 116.54 117.89 118.50 119.51 119.86 121.00 123.36 121.70 123.00 106.50 120.20 120.20 121.60 122.75 121.70 116.00 119.79 121.73 122.00 123.39 122.00 1 19.79 124.00 131.00 175.00 105.01 106.20 149.20 105.85 106.50 108.20 129.00 1 28.00 127.50 126.00 1 25.50 125.50 125.60 125.50 1 26.50 126.40 125.74 125.50 125.9-4 126.20 128.58 125.50 128.80 128.80 125.50 123.30 123.30 123.30 124.00 125.00 124.25 123.50 123.00 123.30 123.40 123.50 123.50 125.46 125.50 128.80 128.80 126.00 126.00 125.50 125.50 129.50 125.50 130.10 129.42 129.42 127.65 126.00 130.10 133.00 136.00 189.80 129.00 129.00 156.00 126.00 125.25 125.25 1..E 1 Table D4.Proposed Conveyance System Parameters TABLE D4 -Drainage Report Qomstreém 1,,UP$!r9arh7 H W Ekwaflons Pl Dhn 1__;_I 1059 1060 1061 1056 1061 1063 1067 1063 1064 1065 1056 1072 1072 1074 1074 1072 1077 1078 1077 1079 1080 1079 1082 1083 1083 1085 1086 1087 1088 1089 1089 1086 1092 1093 1094 1095 1083 1097 1098 1098 1100 1069 1070 3002 3001 1006 1028 1021 1029 1°15.-. 163123‘: 109.61 109.53 120.10 110.00 110.44 112.2a 112.77 112.96 117.00 119.70 106.50 119.19 119.14 119.62 119.39 106.61 120.65 120.99 107.35 120.15 120.99 101.90 109.36 12L0O 12100 103.24 103.42 103.94 104.12 10-5.04 105.04 103.92 104.99 105.44 1os.oo 106.39 111.25 113.19 119.00 119.00 119.50 113.16 114.92 119.15 119.91 120.70 115.55 108.22 11s.oo 121.00 6123155 12125 12525 12650 12525 12650 12533 12500 12533 12550 12550 12525 12525 12525 12525 12525 12525 12525 12550 12525 12525 12550 12525 12525 12525 12525 11150 11015 11968 12535 115.54 115.54 11075 11010 10990 11L00 11424 12525 12525 12621 12621 12690 12500 12502 12915 12750 12550 12520 12880 12520 12550 GTO 19L0 1550 3&0 1000 3830 1700 1720 650 590 430 3200 830 2050 1960 770 2990 1010 1000 720 1030 1090 2100 1050 1010 140 1100 8&0 300 1530 7&0 720 950 950 700 400 770 1080 3240 1050 580 2903 1210 1600 1200 360 1400 150 320$ 1000 2070 T2 Q -4.... 1060 1061 1 1062 ‘ 1057 1063 1067 1069 1064 1 1065 1066 1072 1073 1074 1 1076 3 1075 1077 1078 2079 1079 1080 1081 . 1082 110991 1094 was 10991097 was ‘ 1099 110901091 10921093 . 1094 1 10951099 1091 1099 1 1099 1100 1 1101 1010 1071aoo1 aooz 1005 1029 i 2021 ‘ 2028 2076 169117 109.53 110.19 120.25 111.00 111.79 112.71 113.94 117.00 118.70 12321 10651 11939 11838 12L00 11900 10735 12098 121.78 10780 12098 12L78 10836 11000 12325 9550 10336 10394 10412 11350 10552 10547 10468 105A4 10600 10639 10695 11319 11900 11984 11950 12356 11492 12000 12225 11975 12L40 11600 12240 11700 12360 (_fl V___pgV feqqopgoq Eknmflons 10513 1 211“125125 12525 12650 12525 12600 12533 12500 12500 12550 12550 12500 12525 12539 12525 12550 12525 12525 12550 12880 12525 12550 12980 12525 12525 12530 11L50 11975 11058 12535 115.54 11100 11L00 11040 10990 11100 11424 11920 12525 12621 12494 12690 12841 12502 12492 126J0 12975 12420 12520 12410 12400 12560 APPENDIX E (TIR and Black River Basin Schematic} ._g _ \"<.“i_»'‘=-=?~~_--==33-FIL”-r?-"C".-..,-1-’<\\-“V-\----.-..;~w~»==».-'"*"*7:F 1 1 ;'.“'+:~';.1 A -' ii 7 7 ___V __ V v._>--;____',i\\\__;‘\'\.~-{E2}?‘:31’_;?1:_-1 1 ‘ \*'.:--’-___;__'_V_.-II BLACK mvsn BASIN "flu \7//_»f,,.=3 “""—~__.v---'A.~1 i _' III‘: .2_JQF“y:7/vf /Qfléi $1 ____'I-4-“ ___-'1')?"-_(J; .,g :,y-~1»._.4»§/P V_“_.-.-.I -__I -,bk A M I -Basin Boundary /‘\-_v -.__ --—Subcatchrnent Boundary '3 .....'_,_\$_: /‘I r__r_‘fl ‘.¢“'\:|1 } ©C0|lection Point §~—-—=3 ‘L 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TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX F Offsite Analysis Documentation Level 1 Downstream Analysis - Photos Project: King County Biogas and Heat System Improvements Photo A – Manhole B-5, 21” pipe heading West Photo B – Manhole B-5 looking West Level 1 Downstream Analysis - Photos Project: King County Biogas and Heat System Improvements Photo C – Manhole B-4A looking West (manhole could not be opened for inspection) Photo D – Manhole B-4, 24” pipe heading South Level 1 Downstream Analysis - Photos Project: King County Biogas and Heat System Improvements Photo E – Manhole B-4 looking South Photo F – Manhole B-3, 24” pipe heading South Level 1 Downstream Analysis - Photos Project: King County Biogas and Heat System Improvements Photo G – Manhole B-3 looking South Photo H – Manhole B-2 looking south (manhole could not be opened for inspection, 24” pipe heading west per plans) Level 1 Downstream Analysis - Photos Project: King County Biogas and Heat System Improvements Photo I – Manhole B-1 looking southwest (manhole could not be opened for inspection, 24” pipe heading south per plans) Photo J – Manhole 3 looking Southwest (manhole could not be opened for inspection, 30” pipe heading South per plans) Level 1 Downstream Analysis - Photos Project: King County Biogas and Heat System Improvements Photo K – Un-numbered Manhole, facing Southwest (manhole could not be opened for inspection, 30” pipe heading Southwest per plans) Photo L – Approximate location of un-numbered manhole, facing northwest (manhole could not be located, 30” pipe heading Southwest per plans) Level 1 Downstream Analysis - Photos Project: King County Biogas and Heat System Improvements Photo M – Un-numbered manhole, facing northwest (manhole could not be opened for inspection, pipe of unknown size headed northwest per plans) Photo N – Stormwater pump station OFFSITE DRAINAGE SYSTEM ANALYSIS Date: 11/21/2017 Project:1200 Monster Road SW Basin:Black River Date of Inspection:11/17/2017 Owner:King County Wastewater Treatment Division Subbasin:N/A Weather:45deg Sunny Parcel:1200 Monster Road SW Subbasin #:N/A Symbol Drainage Component Type, Name, and Size Drainage Component Description Slope Length Distance from site discharge Existing Problems Potential Problems Observations of field inspector, resource reviewer, or resident see map Type: sheet flow, swale, stream, channel, pipe, pond; Size: diameter, surface area drainage basin, vegetation, cover, depth, type of sensitive area, volume %ft ¼ ml = 1,320 ft. constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion tributary area, likelihood of problem, overflow pathways, potential impacts A MH B-5 King County Property 0 0 to 0 None None B 21" Storm King County Property 180 0 to 180 None None C MH B-4A King County Property 21" Storm King County Property 194 180 to 374 None None D MH B-4 King County Property E 24" Storm King County Property 152 374 to 526 None None F MH B-3 King County Property G 24" Storm King County Property 192 526 to 718 None None MH B-2 King County Property H 24" Storm King County Property 110 718 to 828 None None MH B-1 King County Property I 24" Storm King County Property 290 828 to 1,118 None None MH 3 King County Property J 30" Storm King County Property 255 1,118 to 1,373 None None Unlabeled MH King County Property K 30" Storm King County Property 250 1,373 to 1,623 None None L MH Not Found King County Property Manhole was unable to be field located due to heavy tree and brush cover in area shown on plans 30" Storm King County Property 265 1,623 to 1,888 None None M Unlabeled MH King County Property unlabeled storm King County Property 27 1,888 to 1,915 None None N Stormwater Pump Station King County Property 12" Force Main King County Property None None TABLE 2 Page 1 of 1 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX G WWHM Modeling Summaries (Flow Control & Water Quality) WWHM2012 PROJECT REPORT Det Vault 11/29/2017 4:43:58 PM Page 2 General Model Information Project Name:Det Vault Site Name:South Plant Biogas Site Address:1200 Monster Rd SW City:Renton Report Date:11/29/2017 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2017/04/14 Version:4.2.13 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:100 Year Det Vault 11/29/2017 4:43:58 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.65943 Pervious Total 0.65943 Impervious Land Use acre Impervious Total 0 Basin Total 0.65943 Element Flows To: Surface Interflow Groundwater Det Vault 11/29/2017 4:43:58 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 0.27231 DRIVEWAYS MOD 0.30271 SIDEWALKS MOD 0.08441 Impervious Total 0.65943 Basin Total 0.65943 Element Flows To: Surface Interflow Groundwater Vault 1 Vault 1 Det Vault 11/29/2017 4:43:58 PM Page 5 Routing Elements Predeveloped Routing Det Vault 11/29/2017 4:43:58 PM Page 6 Mitigated Routing Vault 1 Width:30.5 ft. Length:30.5 ft. Depth:10 ft. Discharge Structure Riser Height:9 ft. Riser Diameter:18 in. Orifice 1 Diameter:0.68 in.Elevation:0 ft. Orifice 2 Diameter:1.47 in.Elevation:7.903 ft. Orifice 3 Diameter:0.91 in.Elevation:8.65 ft. Element Flows To: Outlet 1 Outlet 2 Vault Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.021 0.000 0.000 0.000 0.1111 0.021 0.002 0.004 0.000 0.2222 0.021 0.004 0.005 0.000 0.3333 0.021 0.007 0.007 0.000 0.4444 0.021 0.009 0.008 0.000 0.5556 0.021 0.011 0.009 0.000 0.6667 0.021 0.014 0.010 0.000 0.7778 0.021 0.016 0.011 0.000 0.8889 0.021 0.019 0.011 0.000 1.0000 0.021 0.021 0.012 0.000 1.1111 0.021 0.023 0.013 0.000 1.2222 0.021 0.026 0.013 0.000 1.3333 0.021 0.028 0.014 0.000 1.4444 0.021 0.030 0.015 0.000 1.5556 0.021 0.033 0.015 0.000 1.6667 0.021 0.035 0.016 0.000 1.7778 0.021 0.038 0.016 0.000 1.8889 0.021 0.040 0.017 0.000 2.0000 0.021 0.042 0.017 0.000 2.1111 0.021 0.045 0.018 0.000 2.2222 0.021 0.047 0.018 0.000 2.3333 0.021 0.049 0.019 0.000 2.4444 0.021 0.052 0.019 0.000 2.5556 0.021 0.054 0.020 0.000 2.6667 0.021 0.056 0.020 0.000 2.7778 0.021 0.059 0.020 0.000 2.8889 0.021 0.061 0.021 0.000 3.0000 0.021 0.064 0.021 0.000 3.1111 0.021 0.066 0.022 0.000 3.2222 0.021 0.068 0.022 0.000 3.3333 0.021 0.071 0.022 0.000 3.4444 0.021 0.073 0.023 0.000 3.5556 0.021 0.075 0.023 0.000 3.6667 0.021 0.078 0.024 0.000 3.7778 0.021 0.080 0.024 0.000 3.8889 0.021 0.083 0.024 0.000 4.0000 0.021 0.085 0.025 0.000 4.1111 0.021 0.087 0.025 0.000 Det Vault 11/29/2017 4:43:58 PM Page 7 4.2222 0.021 0.090 0.025 0.000 4.3333 0.021 0.092 0.026 0.000 4.4444 0.021 0.094 0.026 0.000 4.5556 0.021 0.097 0.026 0.000 4.6667 0.021 0.099 0.027 0.000 4.7778 0.021 0.102 0.027 0.000 4.8889 0.021 0.104 0.027 0.000 5.0000 0.021 0.106 0.028 0.000 5.1111 0.021 0.109 0.028 0.000 5.2222 0.021 0.111 0.028 0.000 5.3333 0.021 0.113 0.029 0.000 5.4444 0.021 0.116 0.029 0.000 5.5556 0.021 0.118 0.029 0.000 5.6667 0.021 0.121 0.029 0.000 5.7778 0.021 0.123 0.030 0.000 5.8889 0.021 0.125 0.030 0.000 6.0000 0.021 0.128 0.030 0.000 6.1111 0.021 0.130 0.031 0.000 6.2222 0.021 0.132 0.031 0.000 6.3333 0.021 0.135 0.031 0.000 6.4444 0.021 0.137 0.031 0.000 6.5556 0.021 0.140 0.032 0.000 6.6667 0.021 0.142 0.032 0.000 6.7778 0.021 0.144 0.032 0.000 6.8889 0.021 0.147 0.032 0.000 7.0000 0.021 0.149 0.033 0.000 7.1111 0.021 0.151 0.033 0.000 7.2222 0.021 0.154 0.033 0.000 7.3333 0.021 0.156 0.034 0.000 7.4444 0.021 0.159 0.034 0.000 7.5556 0.021 0.161 0.034 0.000 7.6667 0.021 0.163 0.034 0.000 7.7778 0.021 0.166 0.035 0.000 7.8889 0.021 0.168 0.035 0.000 8.0000 0.021 0.170 0.053 0.000 8.1111 0.021 0.173 0.062 0.000 8.2222 0.021 0.175 0.069 0.000 8.3333 0.021 0.178 0.074 0.000 8.4444 0.021 0.180 0.079 0.000 8.5556 0.021 0.182 0.084 0.000 8.6667 0.021 0.185 0.091 0.000 8.7778 0.021 0.187 0.100 0.000 8.8889 0.021 0.189 0.106 0.000 9.0000 0.021 0.192 0.112 0.000 9.1111 0.021 0.194 0.705 0.000 9.2222 0.021 0.196 1.759 0.000 9.3333 0.021 0.199 3.009 0.000 9.4444 0.021 0.201 4.235 0.000 9.5556 0.021 0.204 5.232 0.000 9.6667 0.021 0.206 5.894 0.000 9.7778 0.021 0.208 6.393 0.000 9.8889 0.021 0.211 6.828 0.000 10.000 0.021 0.213 7.237 0.000 10.111 0.021 0.215 7.624 0.000 10.222 0.000 0.000 7.992 0.000 Det Vault 11/29/2017 4:43:58 PM Page 8 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.65943 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.65943 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.061885 5 year 0.110785 10 year 0.149222 25 year 0.204003 50 year 0.249001 100 year 0.297366 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.027404 5 year 0.043008 10 year 0.056627 25 year 0.078342 50 year 0.098336 100 year 0.122107 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.122 0.023 1950 0.137 0.026 1951 0.067 0.065 1952 0.027 0.021 1953 0.021 0.023 1954 0.044 0.024 1955 0.045 0.028 1956 0.067 0.026 1957 0.076 0.026 1958 0.045 0.024 Det Vault 11/29/2017 4:44:26 PM Page 9 1959 0.034 0.025 1960 0.072 0.035 1961 0.051 0.025 1962 0.017 0.019 1963 0.057 0.025 1964 0.058 0.024 1965 0.083 0.026 1966 0.031 0.022 1967 0.133 0.027 1968 0.076 0.023 1969 0.073 0.024 1970 0.051 0.024 1971 0.077 0.026 1972 0.117 0.030 1973 0.023 0.022 1974 0.077 0.023 1975 0.083 0.028 1976 0.054 0.025 1977 0.046 0.022 1978 0.057 0.025 1979 0.017 0.020 1980 0.162 0.032 1981 0.046 0.022 1982 0.134 0.034 1983 0.073 0.027 1984 0.035 0.020 1985 0.048 0.025 1986 0.063 0.032 1987 0.056 0.034 1988 0.020 0.022 1989 0.017 0.020 1990 0.273 0.033 1991 0.178 0.046 1992 0.047 0.022 1993 0.024 0.023 1994 0.017 0.018 1995 0.039 0.027 1996 0.128 0.056 1997 0.076 0.058 1998 0.058 0.024 1999 0.211 0.031 2000 0.061 0.027 2001 0.017 0.021 2002 0.111 0.034 2003 0.100 0.021 2004 0.144 0.229 2005 0.060 0.027 2006 0.064 0.026 2007 0.255 0.164 2008 0.170 0.173 2009 0.091 0.031 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.2731 0.2289 2 0.2555 0.1732 3 0.2112 0.1636 Det Vault 11/29/2017 4:44:27 PM Page 10 4 0.1782 0.0653 5 0.1702 0.0579 6 0.1621 0.0562 7 0.1436 0.0463 8 0.1371 0.0350 9 0.1339 0.0344 10 0.1334 0.0339 11 0.1281 0.0337 12 0.1220 0.0334 13 0.1173 0.0325 14 0.1106 0.0317 15 0.0997 0.0311 16 0.0906 0.0310 17 0.0834 0.0304 18 0.0826 0.0284 19 0.0768 0.0277 20 0.0766 0.0271 21 0.0764 0.0267 22 0.0762 0.0267 23 0.0759 0.0266 24 0.0733 0.0266 25 0.0728 0.0260 26 0.0724 0.0260 27 0.0672 0.0260 28 0.0666 0.0259 29 0.0643 0.0259 30 0.0630 0.0257 31 0.0612 0.0254 32 0.0601 0.0254 33 0.0578 0.0251 34 0.0576 0.0248 35 0.0565 0.0247 36 0.0565 0.0246 37 0.0565 0.0242 38 0.0543 0.0242 39 0.0515 0.0241 40 0.0513 0.0238 41 0.0479 0.0237 42 0.0467 0.0236 43 0.0465 0.0234 44 0.0457 0.0233 45 0.0452 0.0231 46 0.0447 0.0230 47 0.0445 0.0227 48 0.0392 0.0224 49 0.0353 0.0223 50 0.0337 0.0219 51 0.0314 0.0219 52 0.0270 0.0217 53 0.0239 0.0215 54 0.0227 0.0214 55 0.0207 0.0211 56 0.0198 0.0210 57 0.0171 0.0205 58 0.0170 0.0203 59 0.0168 0.0198 60 0.0167 0.0194 61 0.0167 0.0185 Det Vault 11/29/2017 4:44:27 PM Page 11 Det Vault 11/29/2017 4:44:27 PM Page 12 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0309 2040 1652 80 Pass 0.0336 1544 657 42 Pass 0.0363 1199 178 14 Pass 0.0390 879 168 19 Pass 0.0417 642 159 24 Pass 0.0444 493 149 30 Pass 0.0471 375 139 37 Pass 0.0498 301 134 44 Pass 0.0525 244 129 52 Pass 0.0552 194 122 62 Pass 0.0579 174 111 63 Pass 0.0605 160 105 65 Pass 0.0632 141 100 70 Pass 0.0659 122 92 75 Pass 0.0686 107 89 83 Pass 0.0713 101 85 84 Pass 0.0740 94 80 85 Pass 0.0767 85 76 89 Pass 0.0794 79 70 88 Pass 0.0821 77 65 84 Pass 0.0848 69 58 84 Pass 0.0875 67 54 80 Pass 0.0901 63 51 80 Pass 0.0928 58 48 82 Pass 0.0955 57 44 77 Pass 0.0982 54 40 74 Pass 0.1009 48 34 70 Pass 0.1036 46 31 67 Pass 0.1063 42 28 66 Pass 0.1090 41 24 58 Pass 0.1117 39 19 48 Pass 0.1144 39 19 48 Pass 0.1171 37 19 51 Pass 0.1198 36 19 52 Pass 0.1224 31 17 54 Pass 0.1251 29 17 58 Pass 0.1278 26 17 65 Pass 0.1305 23 16 69 Pass 0.1332 23 15 65 Pass 0.1359 19 15 78 Pass 0.1386 18 14 77 Pass 0.1413 18 13 72 Pass 0.1440 16 12 75 Pass 0.1467 15 10 66 Pass 0.1494 14 9 64 Pass 0.1520 14 9 64 Pass 0.1547 12 9 75 Pass 0.1574 11 8 72 Pass 0.1601 11 7 63 Pass 0.1628 10 7 70 Pass 0.1655 10 5 50 Pass 0.1682 10 5 50 Pass 0.1709 7 4 57 Pass Det Vault 11/29/2017 4:44:27 PM Page 13 0.1736 6 3 50 Pass 0.1763 6 3 50 Pass 0.1790 5 3 60 Pass 0.1816 5 3 60 Pass 0.1843 4 3 75 Pass 0.1870 4 3 75 Pass 0.1897 4 3 75 Pass 0.1924 4 2 50 Pass 0.1951 4 2 50 Pass 0.1978 4 2 50 Pass 0.2005 4 2 50 Pass 0.2032 4 2 50 Pass 0.2059 4 2 50 Pass 0.2086 4 1 25 Pass 0.2112 2 1 50 Pass 0.2139 2 1 50 Pass 0.2166 2 1 50 Pass 0.2193 2 1 50 Pass 0.2220 2 1 50 Pass 0.2247 2 1 50 Pass 0.2274 2 1 50 Pass 0.2301 2 0 0 Pass 0.2328 2 0 0 Pass 0.2355 2 0 0 Pass 0.2382 2 0 0 Pass 0.2409 2 0 0 Pass 0.2435 2 0 0 Pass 0.2462 2 0 0 Pass 0.2489 2 0 0 Pass 0.2516 2 0 0 Pass 0.2543 2 0 0 Pass 0.2570 1 0 0 Pass 0.2597 1 0 0 Pass 0.2624 1 0 0 Pass 0.2651 1 0 0 Pass 0.2678 1 0 0 Pass 0.2705 1 0 0 Pass 0.2731 0 0 0 Pass 0.2758 0 0 0 Pass 0.2785 0 0 0 Pass 0.2812 0 0 0 Pass 0.2839 0 0 0 Pass 0.2866 0 0 0 Pass 0.2893 0 0 0 Pass 0.2920 0 0 0 Pass 0.2947 0 0 0 Pass 0.2974 0 0 0 Pass Det Vault 11/29/2017 4:44:27 PM Page 14 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0 acre-feet On-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Off-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Det Vault 11/29/2017 4:44:27 PM Page 15 LID Report Det Vault 11/29/2017 4:44:35 PM Page 16 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Det Vault 11/29/2017 4:44:35 PM Page 17 Appendix Predeveloped Schematic Det Vault 11/29/2017 4:44:35 PM Page 18 Mitigated Schematic Det Vault 11/29/2017 4:44:35 PM Page 19 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Det Vault.wdm MESSU 25 PreDet Vault.MES 27 PreDet Vault.L61 28 PreDet Vault.L62 30 POCDet Vault1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 17 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 17 C, Lawn, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 17 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 17 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO Det Vault 11/29/2017 4:44:35 PM Page 20 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 17 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 17 0 4.5 0.03 400 0.1 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 17 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 17 0.1 0.25 0.25 6 0.5 0.25 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 17 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATE1 Det Vault 11/29/2017 4:44:35 PM Page 21 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 17 0.65943 COPY 501 12 PERLND 17 0.65943 COPY 501 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC Det Vault 11/29/2017 4:44:35 PM Page 22 WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN Det Vault 11/29/2017 4:44:35 PM Page 23 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Det Vault.wdm MESSU 25 MitDet Vault.MES 27 MitDet Vault.L61 28 MitDet Vault.L62 30 POCDet Vault1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 IMPLND 4 IMPLND 6 IMPLND 9 RCHRES 1 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Vault 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* END PRINT-INFO Det Vault 11/29/2017 4:44:35 PM Page 24 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 4 ROOF TOPS/FLAT 1 1 1 27 0 6 DRIVEWAYS/MOD 1 1 1 27 0 9 SIDEWALKS/MOD 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 6 0 0 1 0 0 0 9 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 0 1 9 6 0 0 4 0 0 0 1 9 9 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 4 0 0 0 0 0 6 0 0 0 0 0 9 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 4 400 0.01 0.1 0.1 6 400 0.05 0.1 0.08 9 400 0.05 0.1 0.08 END IWAT-PARM2 Det Vault 11/29/2017 4:44:35 PM Page 25 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 6 0 0 9 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 6 0 0 9 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** IMPLND 4 0.2723 RCHRES 1 5 IMPLND 6 0.3027 RCHRES 1 5 IMPLND 9 0.0844 RCHRES 1 5 ******Routing****** IMPLND 4 0.2723 COPY 1 15 IMPLND 6 0.3027 COPY 1 15 IMPLND 9 0.0844 COPY 1 15 RCHRES 1 1 COPY 501 16 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** 1 Vault 1 1 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit Det Vault 11/29/2017 4:44:35 PM Page 26 * * * * * * * * * * * * * * *** 1 0 1 0 0 4 0 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.01 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 92 4 Depth Area Volume Outflow1 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (ft/sec) (Minutes)*** 0.000000 0.021356 0.000000 0.000000 0.111111 0.021356 0.002373 0.004183 0.222222 0.021356 0.004746 0.005915 0.333333 0.021356 0.007119 0.007245 0.444444 0.021356 0.009491 0.008365 0.555556 0.021356 0.011864 0.009353 0.666667 0.021356 0.014237 0.010245 0.777778 0.021356 0.016610 0.011066 0.888889 0.021356 0.018983 0.011830 1.000000 0.021356 0.021356 0.012548 1.111111 0.021356 0.023728 0.013227 1.222222 0.021356 0.026101 0.013872 1.333333 0.021356 0.028474 0.014489 1.444444 0.021356 0.030847 0.015081 1.555556 0.021356 0.033220 0.015650 1.666667 0.021356 0.035593 0.016199 1.777778 0.021356 0.037966 0.016731 1.888889 0.021356 0.040338 0.017246 2.000000 0.021356 0.042711 0.017746 2.111111 0.021356 0.045084 0.018232 2.222222 0.021356 0.047457 0.018706 2.333333 0.021356 0.049830 0.019167 2.444444 0.021356 0.052203 0.019619 2.555556 0.021356 0.054575 0.020059 2.666667 0.021356 0.056948 0.020491 2.777778 0.021356 0.059321 0.020913 2.888889 0.021356 0.061694 0.021328 3.000000 0.021356 0.064067 0.021734 3.111111 0.021356 0.066440 0.022133 3.222222 0.021356 0.068812 0.022524 3.333333 0.021356 0.071185 0.022910 3.444444 0.021356 0.073558 0.023288 3.555556 0.021356 0.075931 0.023661 3.666667 0.021356 0.078304 0.024028 3.777778 0.021356 0.080677 0.024389 3.888889 0.021356 0.083050 0.024745 4.000000 0.021356 0.085422 0.025096 4.111111 0.021356 0.087795 0.025442 4.222222 0.021356 0.090168 0.025784 4.333333 0.021356 0.092541 0.026121 4.444444 0.021356 0.094914 0.026454 4.555556 0.021356 0.097287 0.026782 4.666667 0.021356 0.099659 0.027107 4.777778 0.021356 0.102032 0.027428 4.888889 0.021356 0.104405 0.027745 Det Vault 11/29/2017 4:44:35 PM Page 27 5.000000 0.021356 0.106778 0.028058 5.111111 0.021356 0.109151 0.028368 5.222222 0.021356 0.111524 0.028675 5.333333 0.021356 0.113897 0.028979 5.444444 0.021356 0.116269 0.029279 5.555556 0.021356 0.118642 0.029576 5.666667 0.021356 0.121015 0.029870 5.777778 0.021356 0.123388 0.030162 5.888889 0.021356 0.125761 0.030450 6.000000 0.021356 0.128134 0.030736 6.111111 0.021356 0.130506 0.031020 6.222222 0.021356 0.132879 0.031300 6.333333 0.021356 0.135252 0.031579 6.444444 0.021356 0.137625 0.031854 6.555556 0.021356 0.139998 0.032128 6.666667 0.021356 0.142371 0.032399 6.777778 0.021356 0.144744 0.032668 6.888889 0.021356 0.147116 0.032935 7.000000 0.021356 0.149489 0.033199 7.111111 0.021356 0.151862 0.033461 7.222222 0.021356 0.154235 0.033722 7.333333 0.021356 0.156608 0.033980 7.444444 0.021356 0.158981 0.034237 7.555556 0.021356 0.161353 0.034491 7.666667 0.021356 0.163726 0.034744 7.777778 0.021356 0.166099 0.034995 7.888889 0.021356 0.168472 0.035244 8.000000 0.021356 0.170845 0.053755 8.111111 0.021356 0.173218 0.062488 8.222222 0.021356 0.175591 0.069112 8.333333 0.021356 0.177963 0.074691 8.444444 0.021356 0.180336 0.079613 8.555556 0.021356 0.182709 0.084073 8.666667 0.021356 0.185082 0.091086 8.777778 0.021356 0.187455 0.100055 8.888889 0.021356 0.189828 0.106619 9.000000 0.021356 0.192200 0.112357 9.111111 0.021356 0.194573 0.705394 9.222222 0.021356 0.196946 1.759402 9.333333 0.021356 0.199319 3.009562 9.444444 0.021356 0.201692 4.235029 9.555556 0.021356 0.204065 5.232909 9.666667 0.021356 0.206437 5.894042 9.777778 0.021356 0.208810 6.393246 9.888889 0.021356 0.211183 6.828482 10.00000 0.021356 0.213556 7.237375 10.11111 0.021356 0.215929 7.624204 END FTABLE 1 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1004 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1005 STAG ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK Det Vault 11/29/2017 4:44:35 PM Page 28 <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 16 RCHRES ROFLOW COPY INPUT MEAN END MASS-LINK 16 END MASS-LINK END RUN Det Vault 11/29/2017 4:44:35 PM Page 29 Predeveloped HSPF Message File Det Vault 11/29/2017 4:44:35 PM Page 30 Mitigated HSPF Message File Det Vault 11/29/2017 4:44:35 PM Page 31 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2017; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com WWHM2012 PROJECT REPORT WQ Flowrate 11/22/2017 12:58:50 AM Page 2 General Model Information Project Name:WQ Flowrate Site Name:South Plant Biogas Site Address:1200 Monster Rd SW City:Renton Report Date:11/22/2017 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2017/04/14 Version:4.2.13 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year WQ Flowrate 11/22/2017 12:58:50 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.65225 Pervious Total 0.65225 Impervious Land Use acre Impervious Total 0 Basin Total 0.65225 Element Flows To: Surface Interflow Groundwater WQ Flowrate 11/22/2017 12:58:50 AM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre DRIVEWAYS MOD 0.38 Impervious Total 0.38 Basin Total 0.38 Element Flows To: Surface Interflow Groundwater WQ Flowrate 11/22/2017 12:58:50 AM Page 5 Routing Elements Predeveloped Routing WQ Flowrate 11/22/2017 12:58:50 AM Page 6 Mitigated Routing WQ Flowrate 11/22/2017 12:58:50 AM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.65225 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.38 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.061211 5 year 0.109579 10 year 0.147597 25 year 0.201781 50 year 0.24629 100 year 0.294128 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.168715 5 year 0.214217 10 year 0.245256 25 year 0.285646 50 year 0.316644 100 year 0.348463 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.121 0.213 1950 0.136 0.223 1951 0.067 0.127 1952 0.027 0.110 1953 0.020 0.132 1954 0.044 0.135 1955 0.044 0.162 1956 0.066 0.153 1957 0.075 0.158 1958 0.045 0.137 WQ Flowrate 11/22/2017 12:59:27 AM Page 8 1959 0.033 0.152 1960 0.072 0.145 1961 0.051 0.140 1962 0.017 0.121 1963 0.056 0.145 1964 0.057 0.146 1965 0.082 0.165 1966 0.031 0.120 1967 0.132 0.194 1968 0.075 0.259 1969 0.073 0.152 1970 0.051 0.154 1971 0.076 0.187 1972 0.116 0.187 1973 0.022 0.122 1974 0.076 0.174 1975 0.083 0.186 1976 0.054 0.140 1977 0.045 0.140 1978 0.056 0.207 1979 0.017 0.249 1980 0.160 0.258 1981 0.046 0.161 1982 0.132 0.231 1983 0.072 0.192 1984 0.035 0.124 1985 0.047 0.159 1986 0.062 0.139 1987 0.056 0.218 1988 0.020 0.146 1989 0.017 0.228 1990 0.270 0.267 1991 0.176 0.237 1992 0.046 0.124 1993 0.024 0.157 1994 0.017 0.137 1995 0.039 0.147 1996 0.127 0.188 1997 0.076 0.148 1998 0.057 0.158 1999 0.209 0.337 2000 0.061 0.155 2001 0.017 0.195 2002 0.109 0.199 2003 0.099 0.200 2004 0.142 0.328 2005 0.059 0.128 2006 0.064 0.119 2007 0.253 0.308 2008 0.168 0.218 2009 0.090 0.240 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.2701 0.3371 2 0.2527 0.3277 3 0.2089 0.3084 WQ Flowrate 11/22/2017 12:59:27 AM Page 9 4 0.1763 0.2671 5 0.1683 0.2592 6 0.1603 0.2579 7 0.1420 0.2493 8 0.1357 0.2395 9 0.1325 0.2367 10 0.1320 0.2312 11 0.1267 0.2281 12 0.1206 0.2227 13 0.1161 0.2184 14 0.1094 0.2177 15 0.0986 0.2135 16 0.0897 0.2069 17 0.0825 0.2003 18 0.0817 0.1988 19 0.0759 0.1947 20 0.0757 0.1943 21 0.0756 0.1919 22 0.0754 0.1883 23 0.0751 0.1870 24 0.0725 0.1867 25 0.0720 0.1857 26 0.0716 0.1743 27 0.0665 0.1653 28 0.0658 0.1615 29 0.0636 0.1613 30 0.0623 0.1589 31 0.0605 0.1581 32 0.0595 0.1576 33 0.0572 0.1573 34 0.0570 0.1555 35 0.0559 0.1537 36 0.0559 0.1528 37 0.0559 0.1523 38 0.0537 0.1521 39 0.0509 0.1477 40 0.0508 0.1465 41 0.0474 0.1461 42 0.0462 0.1456 43 0.0460 0.1453 44 0.0452 0.1448 45 0.0447 0.1405 46 0.0442 0.1401 47 0.0440 0.1400 48 0.0388 0.1388 49 0.0349 0.1375 50 0.0333 0.1374 51 0.0311 0.1351 52 0.0267 0.1319 53 0.0237 0.1283 54 0.0225 0.1269 55 0.0205 0.1244 56 0.0196 0.1237 57 0.0169 0.1223 58 0.0168 0.1212 59 0.0166 0.1198 60 0.0165 0.1190 61 0.0165 0.1103 WQ Flowrate 11/22/2017 12:59:27 AM Page 10 WQ Flowrate 11/22/2017 12:59:27 AM Page 11 Duration Flows Flow(cfs)Predev Mit Percentage Pass/Fail 0.0306 2041 21143 1035 Fail 0.0328 1619 18471 1140 Fail 0.0350 1312 16253 1238 Fail 0.0371 1041 14258 1369 Fail 0.0393 820 12630 1540 Fail 0.0415 629 11097 1764 Fail 0.0437 505 9811 1942 Fail 0.0459 404 8699 2153 Fail 0.0480 326 7764 2381 Fail 0.0502 281 6928 2465 Fail 0.0524 232 6203 2673 Fail 0.0546 194 5597 2885 Fail 0.0567 180 5011 2783 Fail 0.0589 165 4507 2731 Fail 0.0611 150 4051 2700 Fail 0.0633 137 3651 2664 Fail 0.0655 121 3287 2716 Fail 0.0676 108 2960 2740 Fail 0.0698 102 2686 2633 Fail 0.0720 96 2421 2521 Fail 0.0742 94 2197 2337 Fail 0.0764 82 1983 2418 Fail 0.0785 79 1789 2264 Fail 0.0807 77 1630 2116 Fail 0.0829 71 1491 2100 Fail 0.0851 68 1362 2002 Fail 0.0872 66 1251 1895 Fail 0.0894 63 1141 1811 Fail 0.0916 58 1058 1824 Fail 0.0938 57 978 1715 Fail 0.0960 57 904 1585 Fail 0.0981 52 829 1594 Fail 0.1003 48 758 1579 Fail 0.1025 46 683 1484 Fail 0.1047 42 633 1507 Fail 0.1069 41 570 1390 Fail 0.1090 40 530 1325 Fail 0.1112 39 492 1261 Fail 0.1134 39 462 1184 Fail 0.1156 38 427 1123 Fail 0.1178 36 406 1127 Fail 0.1199 33 366 1109 Fail 0.1221 30 344 1146 Fail 0.1243 29 326 1124 Fail 0.1265 26 304 1169 Fail 0.1286 23 281 1221 Fail 0.1308 23 263 1143 Fail 0.1330 21 254 1209 Fail 0.1352 19 236 1242 Fail 0.1374 18 226 1255 Fail 0.1395 18 210 1166 Fail 0.1417 17 199 1170 Fail 0.1439 15 185 1233 Fail 0.1461 14 175 1250 Fail WQ Flowrate 11/22/2017 12:59:27 AM Page 12 0.1483 14 165 1178 Fail 0.1504 14 159 1135 Fail 0.1526 12 151 1258 Fail 0.1548 11 141 1281 Fail 0.1570 11 133 1209 Fail 0.1591 11 120 1090 Fail 0.1613 10 116 1160 Fail 0.1635 10 106 1060 Fail 0.1657 10 100 1000 Fail 0.1679 9 93 1033 Fail 0.1700 6 86 1433 Fail 0.1722 6 84 1400 Fail 0.1744 6 78 1300 Fail 0.1766 5 75 1500 Fail 0.1788 5 73 1460 Fail 0.1809 5 68 1360 Fail 0.1831 4 65 1625 Fail 0.1853 4 63 1575 Fail 0.1875 4 56 1400 Fail 0.1896 4 54 1350 Fail 0.1918 4 52 1300 Fail 0.1940 4 48 1200 Fail 0.1962 4 43 1075 Fail 0.1984 4 42 1050 Fail 0.2005 4 39 975 Fail 0.2027 4 37 925 Fail 0.2049 4 36 900 Fail 0.2071 4 33 825 Fail 0.2093 2 33 1650 Fail 0.2114 2 30 1500 Fail 0.2136 2 29 1450 Fail 0.2158 2 28 1400 Fail 0.2180 2 26 1300 Fail 0.2201 2 23 1150 Fail 0.2223 2 21 1050 Fail 0.2245 2 19 950 Fail 0.2267 2 19 950 Fail 0.2289 2 18 900 Fail 0.2310 2 18 900 Fail 0.2332 2 17 850 Fail 0.2354 2 16 800 Fail 0.2376 2 15 750 Fail 0.2398 2 14 700 Fail 0.2419 2 13 650 Fail 0.2441 2 13 650 Fail 0.2463 2 13 650 Fail The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. WQ Flowrate 11/22/2017 12:59:27 AM Page 13 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0.0459 acre-feet On-line facility target flow:0.0689 cfs. Adjusted for 15 min:0.0689 cfs. Off-line facility target flow:0.0388 cfs. Adjusted for 15 min:0.0388 cfs. WQ Flowrate 11/22/2017 12:59:27 AM Page 14 LID Report WQ Flowrate 11/22/2017 12:59:53 AM Page 15 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. WQ Flowrate 11/22/2017 12:59:53 AM Page 16 Appendix Predeveloped Schematic WQ Flowrate 11/22/2017 12:59:53 AM Page 17 Mitigated Schematic WQ Flowrate 11/22/2017 12:59:53 AM Page 18 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 WQ Flowrate.wdm MESSU 25 PreWQ Flowrate.MES 27 PreWQ Flowrate.L61 28 PreWQ Flowrate.L62 30 POCWQ Flowrate1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 17 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 17 C, Lawn, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 17 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 17 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO WQ Flowrate 11/22/2017 12:59:53 AM Page 19 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 17 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 17 0 4.5 0.03 400 0.1 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 17 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 17 0.1 0.25 0.25 6 0.5 0.25 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 17 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATE1 WQ Flowrate 11/22/2017 12:59:53 AM Page 20 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 17 0.65225 COPY 501 12 PERLND 17 0.65225 COPY 501 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WQ Flowrate 11/22/2017 12:59:53 AM Page 21 WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN WQ Flowrate 11/22/2017 12:59:53 AM Page 22 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 WQ Flowrate.wdm MESSU 25 MitWQ Flowrate.MES 27 MitWQ Flowrate.L61 28 MitWQ Flowrate.L62 30 POCWQ Flowrate1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 IMPLND 6 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** WQ Flowrate 11/22/2017 12:59:54 AM Page 23 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 6 DRIVEWAYS/MOD 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 6 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 6 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 6 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 6 400 0.05 0.1 0.08 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 6 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 6 0 0 END IWAT-STATE1 END IMPLND WQ Flowrate 11/22/2017 12:59:54 AM Page 24 SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** IMPLND 6 0.38 COPY 501 15 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP WQ Flowrate 11/22/2017 12:59:54 AM Page 25 END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 END MASS-LINK END RUN WQ Flowrate 11/22/2017 12:59:54 AM Page 26 Predeveloped HSPF Message File WQ Flowrate 11/22/2017 12:59:54 AM Page 27 Mitigated HSPF Message File WQ Flowrate 11/22/2017 12:59:54 AM Page 28 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2017; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX H Conveyance Calculations 11/21/2017 RATIONAL METHOD for Conveyance Facility Sizing Project:South Treatment Plant - Biogas and Heat System Improvements Description:Rational method for SD pipe sizing Design Storm:100 yr Q=CIA Where:Q = peak flow (cfs)I = peak rainfall intensity (inches/hour) C = estimated composite runoff coefficient A = drainage subbasin area (acres) Composite Runoff Coefficient Cc = (C1*A1+C2*A2…)/At Where:Cc = composite runoff coefficient A# = area of land cover (acres) C# = runoff coefficient for Area #At = total area (acres) C #Description Area (sf) Area (acres)C A*C 1 Onsite/New Impervious Surface 11,862 0.27 0.90 0.25 2 Onsite/New Pervious Surface 0 0.00 0.25 0.00 Totals:0.27 0.25 Cc =0.90 (total C#*A#)/(total area) Time of Concentration Seg. #Description of Flow Path Segment Length (ft)kr Upper Elev Lower Elev Slope (ft/ft) Travel Time (minutes) 1 Paved Area (sheet flow) and shallow gutter flow 200 20 475 466 0.045 0.79 Totals:200 0.8 Unity Peak Intensity Factor ir = ar*Tc^-br where:Tc = time of concentration (minutes) ar and br = coefficients from Table 3.2.1.B Tc =6.30 minutes (from table above or 6.3 minimum or 100 max) ar =2.61 (from Table 3.2.1.B) br =0.63 (from Table 3.2.1.B) ir =0.82 Peak Rainfall Intensity Ir = Pr*ir where:Ir = peak rainfall intensity (inches/hour) Pr = total 24-hour precipitation for design return period (inches/24 hours) ir = unit peak rainfall intensity factor Pr =3.9 precipitation (inches) ir =0.82 unit peak intensity factor (from above) Ir =3.19 inches/hour Peak Runoff Rate Q = C*Ir*A C =0.90 Cc (unitless) from above Ir =3.19 Ir (inches/hour) from above A =0.27 total area (acres) from above Q =0.782 cfs Pipe Capacity Calculations (Manning's Equation) Full Flow (d/D = 0.90) Description ID (inches)Area (sf) Wetted Per. (ft) Hyd. Radius (ft) Manning's n Slope (ft/ft) Velocity (ft/s) Pipe Capacity (cfs) Req'd Flow (cfs) 6" for HERB Roof Runoff 6 0.196349541 1.570796327 0.125 0.011 0.02 4.79 0.940 0.782 Capacity OK Storm Drain Pipe Sizing_Rational Method_HERB.xls Calculations DCG, Inc.Page 1 of 1 11/21/2017 RATIONAL METHOD for Conveyance Facility Sizing Project:South Treatment Plant - Biogas and Heat System Improvements Description:Rational method for SD pipe sizing Design Storm:100 yr Q=CIA Where:Q = peak flow (cfs)I = peak rainfall intensity (inches/hour) C = estimated composite runoff coefficient A = drainage subbasin area (acres) Composite Runoff Coefficient Cc = (C1*A1+C2*A2…)/At Where:Cc = composite runoff coefficient A# = area of land cover (acres) C# = runoff coefficient for Area #At = total area (acres) C #Description Area (sf) Area (acres)C A*C 1 Onsite/New Impervious Surface 18,000 0.41 0.90 0.37 2 Onsite/New Pervious Surface 0 0.00 0.25 0.00 Totals:0.41 0.37 Cc =0.90 (total C#*A#)/(total area) Time of Concentration Seg. #Description of Flow Path Segment Length (ft)kr Upper Elev Lower Elev Slope (ft/ft) Travel Time (minutes) 1 Paved Area (sheet flow) and shallow gutter flow 200 20 475 466 0.045 0.79 Totals:200 0.8 Unity Peak Intensity Factor ir = ar*Tc^-br where:Tc = time of concentration (minutes) ar and br = coefficients from Table 3.2.1.B Tc =6.30 minutes (from table above or 6.3 minimum or 100 max) ar =2.61 (from Table 3.2.1.B) br =0.63 (from Table 3.2.1.B) ir =0.82 Peak Rainfall Intensity Ir = Pr*ir where:Ir = peak rainfall intensity (inches/hour) Pr = total 24-hour precipitation for design return period (inches/24 hours) ir = unit peak rainfall intensity factor Pr =3.9 precipitation (inches) ir =0.82 unit peak intensity factor (from above) Ir =3.19 inches/hour Peak Runoff Rate Q = C*Ir*A C =0.90 Cc (unitless) from above Ir =3.19 Ir (inches/hour) from above A =0.41 total area (acres) from above Q =1.187 cfs Pipe Capacity Calculations (Manning's Equation) Full Flow (d/D = 0.90) Description ID (inches)Area (sf) Wetted Per. (ft) Hyd. Radius (ft) Manning's n Slope (ft/ft) Velocity (ft/s) Pipe Capacity (cfs) Req'd Flow (cfs) 8" for Paving Areas 8 0.34906585 2.094395102 0.16666667 0.011 0.01 4.10 1.432 1.187 Capacity OK Storm Drain Pipe Sizing_Rational Method_Paving.xls Calculations DCG, Inc.Page 1 of 1 11/21/2017 RATIONAL METHOD for Conveyance Facility Sizing Project:South Treatment Plant - Biogas and Heat System Improvements Description:Rational method for SD pipe sizing Design Storm:100 yr Q=CIA Where:Q = peak flow (cfs)I = peak rainfall intensity (inches/hour) C = estimated composite runoff coefficient A = drainage subbasin area (acres) Composite Runoff Coefficient Cc = (C1*A1+C2*A2…)/At Where:Cc = composite runoff coefficient A# = area of land cover (acres) C# = runoff coefficient for Area #At = total area (acres) C #Description Area (sf) Area (acres)C A*C 1 Onsite/New Impervious Surface 18,000 0.41 0.90 0.37 2 Onsite/New Pervious Surface 0 0.00 0.25 0.00 Totals:0.41 0.37 Cc =0.90 (total C#*A#)/(total area) Time of Concentration Seg. #Description of Flow Path Segment Length (ft)kr Upper Elev Lower Elev Slope (ft/ft) Travel Time (minutes) 1 Paved Area (sheet flow) and shallow gutter flow 200 20 475 466 0.045 0.79 Totals:200 0.8 Unity Peak Intensity Factor ir = ar*Tc^-br where:Tc = time of concentration (minutes) ar and br = coefficients from Table 3.2.1.B Tc =6.30 minutes (from table above or 6.3 minimum or 100 max) ar =2.61 (from Table 3.2.1.B) br =0.63 (from Table 3.2.1.B) ir =0.82 Peak Rainfall Intensity Ir = Pr*ir where:Ir = peak rainfall intensity (inches/hour) Pr = total 24-hour precipitation for design return period (inches/24 hours) ir = unit peak rainfall intensity factor Pr =3.9 precipitation (inches) ir =0.82 unit peak intensity factor (from above) Ir =3.19 inches/hour Peak Runoff Rate Q = C*Ir*A C =0.90 Cc (unitless) from above Ir =3.19 Ir (inches/hour) from above A =0.41 total area (acres) from above Q =1.187 cfs Pipe Capacity Calculations (Manning's Equation) Full Flow (d/D = 0.90) Description ID (inches)Area (sf) Wetted Per. (ft) Hyd. Radius (ft) Manning's n Slope (ft/ft) Velocity (ft/s) Pipe Capacity (cfs) Req'd Flow (cfs) 8" for Roadway/Parking/ Sidewalks 8 0.34906585 2.094395102 0.16666667 0.011 0.02 5.80 2.025 1.187 Capacity OK Storm Drain Pipe Sizing_Rational Method_BI.xls Calculations DCG, Inc.Page 1 of 1 11/21/2017 RATIONAL METHOD for Conveyance Facility Sizing Project:South Treatment Plant - Biogas and Heat System Improvements Description:Rational method for SD pipe sizing Design Storm:100 yr Q=CIA Where:Q = peak flow (cfs)I = peak rainfall intensity (inches/hour) C = estimated composite runoff coefficient A = drainage subbasin area (acres) Composite Runoff Coefficient Cc = (C1*A1+C2*A2…)/At Where:Cc = composite runoff coefficient A# = area of land cover (acres) C# = runoff coefficient for Area #At = total area (acres) C #Description Area (sf) Area (acres)C A*C 1 Onsite/New Impervious Surface 30,000 0.69 0.90 0.62 2 Onsite/New Pervious Surface 0 0.00 0.25 0.00 Totals:0.69 0.62 Cc =0.90 (total C#*A#)/(total area) Time of Concentration Seg. #Description of Flow Path Segment Length (ft)kr Upper Elev Lower Elev Slope (ft/ft) Travel Time (minutes) 1 Paved Area (sheet flow) and shallow gutter flow 200 20 475 466 0.045 0.79 Totals:200 0.8 Unity Peak Intensity Factor ir = ar*Tc^-br where:Tc = time of concentration (minutes) ar and br = coefficients from Table 3.2.1.B Tc =6.30 minutes (from table above or 6.3 minimum or 100 max) ar =2.61 (from Table 3.2.1.B) br =0.63 (from Table 3.2.1.B) ir =0.82 Peak Rainfall Intensity Ir = Pr*ir where:Ir = peak rainfall intensity (inches/hour) Pr = total 24-hour precipitation for design return period (inches/24 hours) ir = unit peak rainfall intensity factor Pr =3.9 precipitation (inches) ir =0.82 unit peak intensity factor (from above) Ir =3.19 inches/hour Peak Runoff Rate Q = C*Ir*A C =0.90 Cc (unitless) from above Ir =3.19 Ir (inches/hour) from above A =0.69 total area (acres) from above Q =1.979 cfs Pipe Capacity Calculations (Manning's Equation) Full Flow (d/D = 0.90) Description ID (inches)Area (sf) Wetted Per. (ft) Hyd. Radius (ft) Manning's n Slope (ft/ft) Velocity (ft/s) Pipe Capacity (cfs) Req'd Flow (cfs) 8" for Paving Areas 8 0.34906585 2.094395102 0.16666667 0.011 0.02 5.80 2.025 1.979 Capacity OK Storm Drain Pipe Sizing_Rational Method_Detention Vault Outlet.xls Calculations DCG, Inc.Page 1 of 1 Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX I Stormwater BMP Adjustment Lake Forest Park 15029 Bothell Way NE Lake Forest Park, WA 98155 tel 206.523.0024 Mount Vernon 2210 Riverside Dr, Suite 110 Mount Vernon, WA 98273 tel 360.899.1110 Federal Way 31620 23rd Ave S, Suite 307 Federal Way, WA 98003 tel 206.523.0024 Whidbey Island 1796 E Main St, Suite 105 Freeland, WA 9824 tel 360.331.4131 MEMORANDUM TO:The City of Renton FROM:Erik Davido, PE Ben Iddins, PE DATE:February 15, 2018 RE:King County South Treatment Plant Biogas and Heat Systems Improvements – Core Requirement #9 Adjustment Request As stated in Section 1.2.9 of the 2016 City of Renton Surface Water Design Manual (hereafter referred to as “the Manual”), onsite BMPs are “methods of designs for dispersing, infiltrating, or otherwise reducing or preventing development-related increases in runoff at or near the sources of those increases.” Due to site conditions, documented in the Technical Information Report (TIR), the site does not infiltrate, nor is positive slope achievable for dispersion for the majority of target impervious surfaces. Because of these conditions, explained in detail below, the site is applying for an adjustment from Core Requirement #9: On-Site BMPs from the Manual. Per Core Requirement #9, all target surfaces were evaluated for BMP feasibility based on the Large Lot BMP requirements in Section 1.2.9.2.2 of the Manual. 1)Full Dispersion – Not feasible because the required native vegetated flowpath is not available onsite. 2)Full infiltration of roof runoff – Not feasible since the onsite soils are not conducive to infiltration (see Section 1.7). 3)Next, the following were evaluated for the remaining target surfaces: ·Full Infiltration – Not feasible since the onsite soils are not conducive to infiltration (see Section 1.7). ·Limited Infiltration – Not feasible since the onsite soils are not conducive to infiltration (see Section 1.7). ·Bioretention – Not feasible since the field testing indicated a measured native soil saturated hydraulic conductivity of less than 0.30 inches per hour (see Section 1.7). ·Permeable Pavement – Not feasible since the field testing indicated a measured native soil saturated hydraulic conductivity of less than 0.30 inches per hour (see Section 1.7). 4)Next, the following was evaluated for the remaining target surfaces: Basic Dispersion – Sheet flow dispersion will be utilized for approximately 407 SF of new asphalt walkway located south of the HERB and will meet the requirements listed in Section C.2.4.5 of the Manual. The width of the walkway is 6.5 feet and the associated vegetated flowpath is perpendicular to the walkway with a length greater than 10 feet. A 2’ strip of crushed rock will not be provided along the edge of the walkway since the walkway width is less than 10 feet. Basic dispersion cannot be applied to any other target impervious surfaces due to the limited pervious areas surrounding the site with positive slope needed for dispersion. 5)Next, BMPs must be implemented, at a minimum, for impervious area amounts defined by the impervious surface coverage on the buildable portion of the site/lot. Since the project will result in an impervious surface coverage on the buildable portion of the project site/lot of less than 45%, on-site BMPs must be applied to 50% of the target impervious surfaces. The 407 SF of impervious surface for which basic dispersion will be applied results in 1.24% of the target impervious surface. Therefore, one or more of the following BMPs must be implemented to achieve compliance. The BMPs were evaluated as follows: To: City of Renton Date: February 15, 2018 Davido Consulting Group, Inc. Page 2 ·Reduced Impervious Surface Credit – This credit does not apply to this project because the Restricted Footprint credit does not apply to parcels greater than 250,000 SF, the Wheel Strip Driveway credit does not apply because the only proposed driveway will be utilized as a fire access, the Minimum Disturbance Foundation credit cannot be applied because positive flow away from the building for dispersion cannot be obtained, and the Open Grid Decking Over Pervious Surface Credit does not apply since there are no proposed decks. ·Native Growth Retention Credit – This credit cannot be applied to this project because there is very little native vegetated area onsite under the current conditions. Nearly the entire site has been cleared and/or developed for the wastewater treatment plant. A majority of the native trees on the site are located around the perimeter of the site and screen the site from surrounding roads. ·Tree Retention Credit – This credit cannot be applied because all existing trees within 20 feet of the proposed impervious surfaces will be required to be removed due to excavation for the HERB and proposed utilities. Since BMPs cannot be applied to a minimum of 50% of the target impervious surfaces, the project is applying for a Standard Adjustment for relief from Core Requirement #9. The Standard Adjustment meets the criteria listed in Section 1.4.2 of the Manual and is attached in APPENDIX I. 6)All new pervious surfaces and disturbed pervious surfaces that will not be replaced with an impervious surface will be protected in accordance with the soil amendment BMP requirements listed in Appendix C, Section C.2.13 of the Manual. See the landscape plans submitted under separate cover for soil amendment details. 7)The project is not proposing a new connection to the local drainage system and therefore is not required to implement a perforated pipe connection. In addition, a perforated pipe connection would likely provide very little infiltration since the measured infiltration rate in three separate test pits were all less than 0.02 inches per hour (see Section 1.7). Due to each BMP in turn being determined as infeasible for the site (except for Basic Dispersion – Sheet Flow Dispersion for the asphalt walkway), the project is unable to apply onsite BMPs to the minimum amount of target impervious surfaces required to satisfy the Core Requirement #9. This memorandum serves as a request for a Standard Adjustment to Core Requirement #9, in accordance with Section 1.4 of the Manual, to remove the requirement that BMPs must be applied to a minimum of 50% of the target impervious surfaces and replace it with a requirement that BMPs must be applied to the maximum extent feasible. The project is proposing to apply BMPs to the maximum extent feasible with the use of Basic Dispersion. In addition, Enhanced Basic Water Quality treatment will be applied to stormwater runoff from all new plus replaced pollution generating impervious surfaces prior to being routed to a detention facility meeting the Peak Rate Flow Control Standard Area Performance Requirement. Therefore, the project proposes to implement stormwater improvements that will significantly reduce the development-related increases in runoff at the site. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX J Stormwater Facility Summary Sheet 2016 KING COUNTY SURFACE WATER DESIGN MANUAL, REFERENCE D 4/24/2016 Page 1 STORMWATER FACILITY SUMMARY SHEET DPER Permit No.___________________ (provide one Stormwater Facility Summary Sheet per Natural Discharge Location)Date ___________________ OVERVIEW:NPDES Permit No.___________________ Project Name Parcel No.____________________________ Project Location Retired Parcel No.____________________________ Downstream Drainage Basins:Project includes Landscape Management Plan?yes 2016 KING COUNTY SURFACE WATER DESIGN MANUAL, REFERENCE D 4/24/2016 Page 2 STORMWATER FACILITY SUMMARY SHEET DPER Permit No.___________________ (provide one Stormwater Facility Summary Sheet per Natural Discharge Location) Project Name Downstream Drainage Basins: Major Basin Name _______________________________ Project Location Immediate Basin Name ___________________________ FLOW CONTROL FACILITY:Basin: Facility Name/Number _______________________________________ Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX K Declaration of Covenants Page 1 of 3 Return Address: City Clerk’s Office City of Renton 1055 S Grady Way Renton, WA 98057 DECLARATION OF COVENANT AND EASEMENT FOR INSPECTION AND MAINTENANCE OF DRAINAGE FACILITIES AND ON-SITE BMPS Grantor: Grantee: City of Renton Legal Description: Assessor's Tax Parcel ID#: IN CONSIDERATION of the approved City of Renton (check one of the following) residential building permit, commercial building permit, clearing and grading permit, subdivision permit, or short subdivision permit for application file No. LUA/SWP_______________________ relating to the real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby covenants(covenant) with the City of Renton, a political subdivision of the state of Washington, that he/she(they) will observe, consent to, and abide by the conditions and obligations set forth and described in Paragraphs 1 through 9 below with regard to the Property, and hereby grants(grant) an easement as described in Paragraphs 2 and 3. Grantor(s) hereby grants(grant), covenants(covenant), and agrees(agree) as follows: 1. The Grantor(s) or his/her(their) successors in interest and assigns ("Owners ") shall at their own cost, operate, maintain, and keep in good repair, the Property's drainage facilities constructed as required in the approved construction plans and specifications __________ on file with the City of Renton and submitted to the City of Renton for the review and approval of permit(s) _____________________________. The property's drainage facilities are shown and/or listed on Exhibit A. The property’s drainage facilities shall be maintained in compliance with the operation and maintenance schedule included and attached herein as Exhibit B. Drainage facilities include pipes, channels, flow control facilities, water quality facilities, on-site best management practices (BMPs) and other engineered structures designed to manage and/or treat stormwater on the Property. On-site BMPs include dispersion and infiltration devices, bioretention, permeable pavements, rainwater harvesting systems, tree retention credit, reduced impervious surface footprint, vegetated roofs and other measures designed to mimic pre-developed hydrology and minimize stormwater runoff on the Property. 2. City of Renton shall have the right to ingress and egress over those portions of the Property necessary to perform inspections of the stormwater facilities and BMPs and conduct maintenance activities specified in this Declaration of Covenant and in accordance with the Renton Municipal Code. City of Renton shall provide at least 30 days written notice to the Owners that entry on the Property is Page 2 of 3 planned for the inspection of drainage facilities. After the 30 days, the Owners shall allow the City of Renton to enter for the sole purpose of inspecting drainage facilities. In lieu of inspection by the City, the Owners may elect to engage a licensed civil engineer registered in the state of Washington who has expertise in drainage to inspect the drainage facilities and provide a written report describing their condition. If the engineer option is chosen, the Owners shall provide written notice to the City of Renton within fifteen days of receiving the City’s notice of inspection. Within 30 days of giving this notice, the Owners, or engineer on behalf of the Owners, shall provide the engineer’s report to the City of Renton. If the report is not provided in a timely manner as specified above, the City of Renton may inspect the drainage facilities without further notice. 3. If City of Renton determines from its inspection, or from an engineer’s report provided in accordance with Paragraph 2, that maintenance, repair, restoration, and/or mitigation work is required to be done to any of the drainage facilities, City of Renton shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work (Work) required pursuant to the Renton Municipal Code. The City shall also set a reasonable deadline for the Owners to complete the Work, or to provide an engineer’s report that verifies completion of the Work. After the deadline has passed, the Owners shall allow the City access to re-inspect the drainage facilities unless an engineer’s report has been provided verifying completion of the Work. If the Work is not completed within the time frame set by the City, the City may initiate an enforcement action and/or perform the required maintenance, repair, restoration, and/or mitigation work and hereby is given access to the Property for such purposes. Written notice will be sent to the Owners stating the City’s intention to perform such work. This work will not commence until at least seven (7) days after such notice is mailed. If, within the sole discretion of the City, there exists an imminent or present danger, the seven (7) day notice period will be waived and maintenance and/or repair work will begin immediately. 4. The Owners shall assume all responsibility for the cost of any maintenance, repair work, or any measures taken by the City to address conditions as described in Paragraph 3. Such responsibility shall include reimbursement to the City within thirty (30) days of the receipt of the invoice for any such work performed. Overdue payments will require payment of interest at the maximum legal rate allowed by RCW 19.52.020 (currently twelve percent (12%)). If the City initiates legal action to enforce this agreement, the prevailing party in such action is entitled to recover reasonable litigation costs and attorney’s fees. 5. The Owners are required to obtain written approval from City of Renton prior to filling, piping, cutting, or removing vegetation (except in routine landscape maintenance) in open vegetated stormwater facilities (such as swales, channels, ditches, ponds, etc.), or performing any alterations or modifications to the drainage facilities referenced in this Declaration of Covenant. 6. Any notice or consent required to be given or otherwise provided for by the provisions of this Agreement shall be effective upon personal delivery, or three (3) days after mailing by Certified Mail, return receipt requested. 7. With regard to the matters addressed herein, this agreement constitutes the entire agreement between the parties, and supersedes all prior discussions, negotiations, and all agreements whatsoever whether oral or written. 8. This Declaration of Covenant is intended to protect the value and desirability and promote efficient and effective management of surface water drainage of the real property described above, and shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This Page 3 of 3 Declaration of Covenant shall run with the land and be binding upon Grantor(s), and Grantor's(s') successors in interest, and assigns. 9. This Declaration of Covenant may be terminated by execution of a written agreement by the Owners and the City that is recorded by King County in its real property records. IN WITNESS WHEREOF, this Declaration of Covenant for the Inspection and Maintenance of Drainage Facilities is executed this _____ day of ____________________, 20_____. GRANTOR, owner of the Property GRANTOR, owner of the Property STATE OF WASHINGTON ) COUNTY OF KING )ss. On this day personally appeared before me: , to me known to be the individual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this _____ day of ____________________, 20_____. Printed name Notary Public in and for the State of Washington, residing at My appointment expires MAINTENANCE INSTRUCTIONS FOR BASIC DISPERSION Your property contains an on-site BMP (best management practice) called “basic dispersion,” which was installed to mitigate the stormwater quantity and quality impacts of some or all of the impervious surfaces or non-native pervious surfaces on your property. Basic dispersion is a strategy for utilizing any available capacity of onsite vegetated areas to retain, absorb, and filter the runoff from developed surfaces. This on-site BMP has two primary components that must be maintained: (1) The devices that disperse runoff from the developed surfaces and (2) The vegetated area over which runoff is dispersed. Dispersion Devices The dispersion devices used on your property include the following as indicated on the site plan (CHECK THE BOX(ES) THAT APPLY): splash blocks, rock pads, gravel filled trenches, sheet flow. MAINTENANCE RESTRICTIONS The size, placement, composition, and downstream flowpaths of these devices as depicted by the site plan and design details must be maintained and may not be changed without written approval from the City of Renton or through a future development permit from the City of Renton. INSPECTION FREQUENCY AND MAINTENANCE GUIDELINES This on-site BMP has two primary components that must be maintained per Appendix A of the City of Renton’s Surface Water Design Manual: (1) The devices that disperse runoff from the developed surfaces and (2) The vegetated flowpath area over which runoff is dispersed. Maintenance of Dispersion Devices • Dispersion devices must be inspected annually and after major storm events to identify and repair any physical defects. • When native soil is exposed or erosion channels are present, the sources of the erosion or concentrated flow need to be identified and mitigated. • Concentrated flow can be mitigated by leveling the edge of the pervious area and/or realigning or replenishing the rocks in the dispersion device, such as in rock pads and gravel filled trenches. Maintenance of Vegetated Flowpaths • The vegetated area over which runoff is dispersed must be maintained in good condition free of bare spots and obstructions that would concentrate flows. Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX L Operation and Maintenance Manual APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-6 NO. 3 – DETENTION TANKS AND VAULTS 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 City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City 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. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Tank or Vault Storage Area Trash and debris Any trash and debris accumulated in vault or tank (includes floatables and non- floatables). No trash or debris in vault. Sediment accumulation Accumulated sediment depth exceeds 10% of the diameter of the storage area for ½ length of storage vault or any point depth exceeds 15% of diameter. Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than ½ length of tank. All sediment removed from storage area. 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. 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. 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 inlet/outlet pipes 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. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-7 NO. 3 – DETENTION TANKS AND VAULTS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Access Manhole (cont.) 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. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-8 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 accumulation 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 Damaged FROP-T 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. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-9 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED FROP-T Section (cont.) Damaged FROP-T (cont.) 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. Cleanout Gate Damaged or missing cleanout gate 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 orifice plate 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 to orifice plate Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Overflow Pipe Obstructions to overflow pipe 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 of overflow pipe 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 inlet/outlet pipe 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 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. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-10 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Sediment accumulation 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. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-11 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipe (cont.) Damaged inlet/outlet pipe 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 (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 Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-12 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/root growth in pipe 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 pipes 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 City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City 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. Excessive vegetation growth Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-15 NO. 9 – FENCING MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Erosion or holes under fence Erosion or holes more than 4 inches high and 12-18 inches wide permitting access through an opening under a fence. No access under the fence. Wood Posts, Boards and Cross Members Missing or damaged parts Missing or broken boards, post out of plumb by more than 6 inches or cross members broken No gaps on fence due to missing or broken boards, post plumb to within 1½ inches, cross members sound. Weakened by rotting or insects Any part showing structural deterioration due to rotting or insect damage All parts of fence are structurally sound. Damaged or failed post foundation Concrete or metal attachments deteriorated or unable to support posts. Post foundation capable of supporting posts even in strong wind. Metal Posts, Rails and Fabric Damaged parts Post out of plumb more than 6 inches. Post plumb to within 1½ inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence (including post, top rails, and fabric) more than 1 foot out of design alignment. Fence is aligned and meets design standards. Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or protective coating Part or parts that have a rusting or scaling condition that has affected structural adequacy. Structurally adequate posts or parts with a uniform protective coating. Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-16 NO. 10 – GATES/BOLLARDS/ACCESS BARRIERS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Chain Link Fencing Gate Damaged or missing members Missing gate. Gates in place. Broken or missing hinges such that gate cannot be easily opened and closed by a maintenance person. Hinges intact and lubed. Gate is working freely. Gate is out of plumb more than 6 inches and more than 1 foot out of design alignment. Gate is aligned and vertical. Missing stretcher bar, stretcher bands, and ties. Stretcher bar, bands, and ties in place. Locking mechanism does not lock gate Locking device missing, no-functioning or does not link to all parts. Locking mechanism prevents opening of gate. Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. Bar Gate Damaged or missing cross bar Cross bar does not swing open or closed, is missing or is bent to where it does not prevent vehicle access. Cross bar swings fully open and closed and prevents vehicle access. Locking mechanism does not lock gate Locking device missing, no-functioning or does not link to all parts. Locking mechanism prevents opening of gate. Support post damaged Support post does not hold cross bar up. Cross bar held up preventing vehicle access into facility. Bollards Damaged or missing bollards Bollard broken, missing, does not fit into support hole or hinge broken or missing. No access for motorized vehicles to get into facility. Bollards do not lock Locking assembly or lock missing or cannot be attached to lock bollard in place. No access for motorized vehicles to get into facility. Boulders Dislodged boulders Boulders not located to prevent motorized vehicle access. No access for motorized vehicles to get into facility. Evidence of vehicles circumventing boulders Motorized vehicles going around or between boulders. No access for motorized vehicles to get into facility. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-17 NO. 11 – GROUNDS (LANDSCAPING) 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 City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City 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. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Trees and Shrubs Hazard tree identified Any tree or limb of a tree identified as having a potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. No hazard trees in facility. Damaged tree or shrub identified Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-18 NO. 12 – ACCESS ROADS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet (i.e., trash and debris would fill up one standards size garbage can). Roadway drivable by maintenance vehicles. Debris which could damage vehicle tires or prohibit use of road. Roadway drivable by maintenance vehicles. 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. Blocked roadway Any obstruction which reduces clearance above road surface to less than 14 feet. Roadway overhead clear to 14 feet high. Any obstruction restricting the access to a 10- to 12 foot width for a distance of more than 12 feet or any point restricting access to less than a 10 foot width. At least 12-foot of width on access road. Road Surface Erosion, settlement, potholes, soft spots, ruts Any surface defect which hinders or prevents maintenance access. Road drivable by maintenance vehicles. Vegetation on road surface Trees or other vegetation prevent access to facility by maintenance vehicles. Maintenance vehicles can access facility. Shoulders and Ditches Erosion Erosion within 1 foot of the roadway more than 8 inches wide and 6 inches deep. Shoulder free of erosion and matching the surrounding road. Weeds and brush Weeds and brush exceed 18 inches in height or hinder maintenance access. Weeds and brush cut to 2 inches in height or cleared in such a way as to allow maintenance access. Modular Grid Pavement 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. Damaged or missing blocks/grids Access surface compacted because of broken on missing modular block. Access road surface restored so road infiltrates. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-31 NO. 21 – PROPRIETARY FACILITY CARTRIDGE FILTER SYSTEMS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED In addition to the specific maintenance criteria provided below, all manufacturers’ requirements shall be followed. Facility Documentation Update facility inspection record after each inspection. Maintenance records are up to date. Provide certification of replaced filter media. Filter media is certified to meet manufacturer specifications. Site Trash and debris Any trash or debris which impairs the function of the facility. Trash and debris removed from facility. Contaminants and pollution Any evidence of contaminants or pollution such as oils, 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. Life cycle Once per year. Facility is re-inspected and any needed maintenance performed. Vault Treatment Area Sediment on vault floor Varies – Refer to manufacturer’s requirements. Vault is free of sediment. Sediment on top of cartridges Varies – Refer to manufacturer’s requirements. Vault is free of sediment. Multiple scum lines above top of cartridges Thick or multiple scum lines above top of cartridges. Probably due to plugged canisters or underdrain manifold. Cause of plugging corrected, canisters replaced if necessary. 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 qualified inspection personnel determines 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 specification. Filter Media Standing water in vault Varies – Refer to manufacturer’s requirements. No standing water in vault 24 hours after a rain event. Short circuiting Flows do not properly enter filter cartridges. Flows go through filter media. Underdrains and Clean-Outs Sediment and debris Underdrains or clean-outs partially plugged or filled with sediment and/or debris. Underdrains and clean-outs free of sediment and debris. 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 inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-32 NO. 21 – PROPRIETARY FACILITY CARTRIDGE FILTER SYSTEMS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED 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 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. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-43 NO. 32 – RAINWATER HARVESTING BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Insufficient storage volume No rain water in storage unit at the beginning of the rain season. Maximum storage available at the beginning of the rain season (Oct. 1). Collection Area Trash and debris Trash of debris on collection area may plug filter system Collection area clear of trash and debris. Filter Restricted or plugged filter Filter is partially or fully plugged preventing water from getting in to the storage unit. Filter is allowing collection water into storage unit. NO. 33 – ROCK PAD BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on rock pad site. Rock pad site free of any trash or debris. Rock Pad Area Insufficient rock pad size Rock pad is not 2 feet by 3 feet by 6 inches thick or as designed. Rock pad is 2 feet by 3 feet by 6 inches thick or as designed. Vegetation growth Vegetation is seen growing in or through rock pad. No vegetation within rock pad area. Rock Exposed soil Soil can be seen through the rock pad. Full thickness of the rock pad is in place, no soil visible through rock pad. NO. 34 – SHEET FLOW BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on the sheet flow site. Sheet flow site free of any trash or debris. Sheet flow area Erosion Soil erosion occurring in sheet flow zone. Soil erosion is not occurring and rills and channels have been repaired. Concentrated flow Sheet flow is not occurring in the sheet flow zone. Sheet flow area is regraded to provide sheet flow. NO. 35 – SPLASH BLOCK BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on the splash block. Splash block site free of any trash or debris. Splash Block Dislodged splash block Splash block moved from outlet of downspout. Splash block correctly positioned to catch discharge from downspout. Channeling Water coming off the splash block causing erosion. No erosion occurs from the splash block. Downspout water misdirected Water coming from the downspout is not discharging to the dispersal area. Water is discharging normally to the dispersal area. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-47 NO. 38 – SOIL AMENDMENT BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Soil Media Unhealthy vegetation Vegetation not fully covering ground surface or vegetation health is poor. Yellowing: possible Nitrogen (N) deficiency. Poor growth: possible Phosphorous (P) deficiency. Poor flowering, spotting or curled leaves, or weak roots or stems: possible Potassium (K) deficiency. Plants are healthy and appropriate for site conditions Inadequate soil nutrients and structure In the fall, return leaf fall and shredded woody materials from the landscape to the site when possible Soil providing plant nutrients and structure Excessive vegetation growth Grass becomes excessively tall (greater than 10 inches); nuisance weeds and other vegetation start to take over. Healthy turf- “grasscycle” (mulch-mow or leave the clippings) to build turf health Weeds Preventive maintenance Avoid use of pesticides (bug and weed killers), like “weed & feed,” which damage the soil Fertilizer needed Where fertilization is needed (mainly turf and annual flower beds), a moderate fertilization program should be used which relies on compost, natural fertilizers or slow-release synthetic balanced fertilizers Integrated Pest Management (IPM) protocols for fertilization followed Bare spots Bare spots on soil No bare spots, area covered with vegetation or mulch mixed into the underlying soil. Compaction Poor infiltration due to soil compaction • To remediate compaction, aerate soil, till to at least 8-inch depth, or further amend soil with compost and re-till • If areas are turf, aerate compacted areas and top dress them with 1/4 to 1/2 inch of compost to renovate them • If drainage is still slow, consider investigating alternative causes (e.g., high wet season groundwater levels, low permeability soils) • Also consider site use and protection from compacting activities No soil compaction Poor infiltration Soils become waterlogged, do not appear to be infiltrating. Facility infiltrating properly Erosion/Scouring Erosion Areas of potential erosion are visible Causes of erosion (e.g., concentrate flow entering area, channelization of runoff) identified and damaged area stabilized (regrade, rock, vegetation, erosion control matting).For deep channels or cuts (over 3 inches in ponding depth), temporary erosion control measures in place until permanent repairs can be made Grass/Vegetation Unhealthy vegetation Less than 75% of planted vegetation is healthy with a generally good appearance. Healthy vegetation. Unhealthy plants removed/replaced. Appropriate vegetation planted in terms of exposure, soil and soil moisture. Noxious Weeds Noxious weeds Listed noxious vegetation is present (refer to current County noxious weed list). No noxious weeds present. www.modularwetlands.com Maintenance Guidelines for Modular Wetland System - Linear Maintenance Summary o Remove Trash from Screening Device – average maintenance interval is 6 to 12 months. (5 minute average service time). o Remove Sediment from Separation Chamber – average maintenance interval is 12 to 24 months. (10 minute average service time). o Replace Cartridge Filter Media – average maintenance interval 12 to 24 months. (10-15 minute per cartridge average service time). o Replace Drain Down Filter Media – average maintenance interval is 12 to 24 months. (5 minute average service time). o Trim Vegetation – average maintenance interval is 6 to 12 months. (Service time varies). System Diagram Access to screening device, separation chamber and cartridge filter Access to drain down filter Pre-Treatment Chamber Biofiltration Chamber Discharge Chamber Outflow Pipe Inflow Pipe (optional) www.modularwetlands.com Maintenance Procedures Screening Device 1. Remove grate or manhole cover to gain access to the screening device in the Pre- Treatment Chamber. Vault type units do not have screening device. Maintenance can be performed without entry. 2. Remove all pollutants collected by the screening device. Removal can be done manually or with the use of a vacuum truck. The hose of the vacuum truck will not damage the screening device. 3. Screening device can easily be removed from the Pre-Treatment Chamber to gain access to separation chamber and media filters below. Replace grate or manhole cover when completed. Separation Chamber 1. Perform maintenance procedures of screening device listed above before maintaining the separation chamber. 2. With a pressure washer spray down pollutants accumulated on walls and cartridge filters. 3. Vacuum out Separation Chamber and remove all accumulated pollutants. Replace screening device, grate or manhole cover when completed. Cartridge Filters 1. Perform maintenance procedures on screening device and separation chamber before maintaining cartridge filters. 2. Enter separation chamber. 3. Unscrew the two bolts holding the lid on each cartridge filter and remove lid. 4. Remove each of 4 to 8 media cages holding the media in place. 5. Spray down the cartridge filter to remove any accumulated pollutants. 6. Vacuum out old media and accumulated pollutants. 7. Reinstall media cages and fill with new media from manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. 8. Replace the lid and tighten down bolts. Replace screening device, grate or manhole cover when completed. Drain Down Filter 1. Remove hatch or manhole cover over discharge chamber and enter chamber. 2. Unlock and lift drain down filter housing and remove old media block. Replace with new media block. Lower drain down filter housing and lock into place. 3. Exit chamber and replace hatch or manhole cover. www.modularwetlands.com Maintenance Notes 1. Following maintenance and/or inspection, it is recommended the maintenance operator prepare a maintenance/inspection record. The record should include any maintenance activities performed, amount and description of debris collected, and condition of the system and its various filter mechanisms. 2. The owner should keep maintenance/inspection record(s) for a minimum of five years from the date of maintenance. These records should be made available to the governing municipality for inspection upon request at any time. 3. Transport all debris, trash, organics and sediments to approved facility for disposal in accordance with local and state requirements. 4. Entry into chambers may require confined space training based on state and local regulations. 5. No fertilizer shall be used in the Biofiltration Chamber. 6. Irrigation should be provided as recommended by manufacturer and/or landscape architect. Amount of irrigation required is dependent on plant species. Some plants may require irrigation. www.modularwetlands.com Maintenance Procedure Illustration Screening Device The screening device is located directly under the manhole or grate over the Pre-Treatment Chamber. It’s mounted directly underneath for easy access and cleaning. Device can be cleaned by hand or with a vacuum truck. Separation Chamber The separation chamber is located directly beneath the screening device. It can be quickly cleaned using a vacuum truck or by hand. A pressure washer is useful to assist in the cleaning process. www.modularwetlands.com Cartridge Filters The cartridge filters are located in the Pre-Treatment chamber connected to the wall adjacent to the biofiltration chamber. The cartridges have removable tops to access the individual media filters. Once the cartridge is open media can be easily removed and replaced by hand or a vacuum truck. Drain Down Filter The drain down filter is located in the Discharge Chamber. The drain filter unlocks from the wall mount and hinges up. Remove filter block and replace with new block. www.modularwetlands.com Trim Vegetation Vegetation should be maintained in the same manner as surrounding vegetation and trimmed as needed. No fertilizer shall be used on the plants. Irrigation per the recommendation of the manufacturer and or landscape architect. Different types of vegetation requires different amounts of irrigation. www.modularwetlands.com Inspection Form Modular Wetland System, Inc. P. 760.433-7640 F. 760-433-3176 E. Info@modularwetlands.com For Office Use Only (city) (Zip Code)(Reviewed By) Owner / Management Company (Date) Contact Phone ( )_ Inspector Name Date / / Time AM / PM Weather Condition Additional Notes Yes Depth: Yes No Modular Wetland System Type (Curb, Grate or UG Vault):Size (22', 14' or etc.): Other Inspection Items: Storm Event in Last 72-hours? No Yes Type of Inspection Routine Follow Up Complaint Storm Office personnel to complete section to the left. 2972 San Luis Rey Road, Oceanside, CA 92058 P (760) 433-7640 F (760) 433-3176 Inspection Report Modular Wetlands System Is the filter insert (if applicable) at capacity and/or is there an accumulation of debris/trash on the shelf system? Does the cartridge filter media need replacement in pre-treatment chamber and/or discharge chamber? Any signs of improper functioning in the discharge chamber? Note issues in comments section. Chamber: Is the inlet/outlet pipe or drain down pipe damaged or otherwise not functioning properly? Structural Integrity: Working Condition: Is there evidence of illicit discharge or excessive oil, grease, or other automobile fluids entering and clogging the unit? Is there standing water in inappropriate areas after a dry period? Damage to pre-treatment access cover (manhole cover/grate) or cannot be opened using normal lifting pressure? Damage to discharge chamber access cover (manhole cover/grate) or cannot be opened using normal lifting pressure? Does the MWS unit show signs of structural deterioration (cracks in the wall, damage to frame)? Project Name Project Address Inspection Checklist CommentsNo Does the depth of sediment/trash/debris suggest a blockage of the inflow pipe, bypass or cartridge filter? If yes, specify which one in the comments section. Note depth of accumulation in in pre-treatment chamber. Is there a septic or foul odor coming from inside the system? Is there an accumulation of sediment/trash/debris in the wetland media (if applicable)? Is it evident that the plants are alive and healthy (if applicable)? Please note Plant Information below. Sediment / Silt / Clay Trash / Bags / Bottles Green Waste / Leaves / Foliage Waste:Plant Information No Cleaning Needed Recommended Maintenance Additional Notes: Damage to Plants Plant Replacement Plant Trimming Schedule Maintenance as Planned Needs Immediate Maintenance www.modularwetlands.com Maintenance Report Modular Wetland System, Inc. P. 760.433-7640 F. 760-433-3176 E. Info@modularwetlands.com For Office Use Only (city) (Zip Code)(Reviewed By) Owner / Management Company (Date) Contact Phone ( )_ Inspector Name Date / / Time AM / PM Weather Condition Additional Notes Site Map # Comments: 2972 San Luis Rey Road, Oceanside, CA 92058 P. 760.433.7640 F. 760.433.3176 Inlet and Outlet Pipe Condition Drain Down Pipe Condition Discharge Chamber Condition Drain Down Media Condition Plant Condition Media Filter Condition Long: MWS Sedimentation Basin Total Debris Accumulation Condition of Media 25/50/75/100 (will be changed @ 75%) Operational Per Manufactures' Specifications (If not, why?) Lat:MWS Catch Basins GPS Coordinates of Insert Manufacturer / Description / Sizing Trash Accumulation Foliage Accumulation Sediment Accumulation Type of Inspection Routine Follow Up Complaint Storm Storm Event in Last 72-hours? No Yes Office personnel to complete section to the left. Project Address Project Name Cleaning and Maintenance Report Modular Wetlands System Technical Information Report King County – Biogas and Heat Systems Improvements February 2018 Davido Consulting Group, Inc. TIR_King County South Treatment Plant_Biogas and Heat Systems Improvements APPENDIX M Renton Flood Hazard Map Ren t o n Kent Newcastle Kin g C o u n t y Tu k w i l a Mercer Island Bellevu e Lake Washington Lake Youngs Panther Lake Lake Boren Cedar RiverBlack River May Creek Springbrook Creek Cougar MountainCougar Mountain Coal Creek ParkCoal Creek Park Cedar River Natural ZoneCedar River Natural Zone May Creek ParkMay Creek Park Soos Creek Park and TrailSoos Creek Park and Trail Black River Riparian ForestBlack River Riparian Forest McGarvey Open SpaceMcGarvey Open Space Maplewood Community ParkMaplewood Community Park ValleyValley BensonBenson HighlandsHighlands West HillWest Hill East PlateauEast Plateau SE 192ND STTA L B O T R D S 14 0 T H A V E S E RAI N I E R A V E S EA S T V A L L E Y R D SE 168TH ST RENTON A V E S 11 6 T H A V E S E NE 12TH ST E M E R C E R W A Y 14 8 T H A V E S E NE 7TH S T 84 T H A V E S HO Q U I A M A V E N E NEWCASTLE W AY W M E RCER WAY S 128TH ST SW 41ST ST PA R K A V E N 12 8 T H A V E S E SE JONES R D E VA L L E Y H W Y SE 72ND ST SE 164TH ST NI L E A V E N E N 10TH S T SE 183RD S T UN I O N A V E N E 15 6 T H A V E S E UN I O N A V E S E NE 2ND ST 14 8 T H A V E S E SE 164TH ST LI N D A V E S W UN I O N A V E N E 11 6 T H A V E S E SW 7TH ST N 8TH ST ED M O N D S A V E N E P UG E T D R S E NE 27TH ST 15 6 T H A V E S E RENTON AVE S B E N S O N R D S MO N R O E A V E N E 11 6 T H A V E S E NE 4TH ST S R 5 1 5 SUNS E T B L V D N E PA R K A V E N M APLE VALLEY HWY SW 43RD ST NE 3RD ST L O G A N A V E N SW SU N SET BLVD SW GRADY W A Y N 3RD ST R A I N I E R A V E N 140TH WAY S E SR 1 6 7 10 8 T H A V E S E N 6TH ST S 2ND S T 10 8 T H A V E S E SR 5 1 5 [^405 [^405 Effective FEMA FloodInsurance Rate Map µ Legend Renton City Limits Zone AE, A, AH, AO - Regulatory Zone X - Non Regulatory 0 0.5 10.25 Miles Public Works - Surface Water UtilityPrint Date: 11/05/2012 Data Sources: City of Renton, FEMA FIRM revised May 16, 1995.Cedar River flood hazard area updated with FEMA Cedar RiverLOMR (Case No. 06-10-B569P) approved December 4, 2006. This document is a graphic representation, not guaranteedto survey accuracy, and is based on the best informationavailable as of the date shown. This map is intended forCity display purposes only.