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Stamped approved F_Technical Information Report_601 Monster Road C18006309.pdf
Page 1 of 407 TECHNICAL INFORMATION REPORT Prologis Renton 9 PARCEL NO: 242304-9008 601 Monster Road SW Renton, WA PREPARED FOR: Prologis 12720 Gateway Dr., Suite 110 Tukwila, WA 98168 REVISED April 2019 November 2018 (Job No.:17-045) Steve T. Nelson, Senior Civil Engineer 253-572-4903 - snelson@innovaarchitects.com Brian Ludwig Project Manager 253-572-4903 – bludgwig@innovaarchitects.com Reviewed by Paul B. McCormick, PE, SE 253-572-4903 - paul@innovaarchitects.com INNOVA Architects 950 Pacific Ave., Suite 450 Tacoma, WA 98402 April 4, 2019 R-4042 C18006309 DEVELOPMENT ENGINEERING rnair 06/26/2019 SURFACE WATER UTILITY jfarah 06/26/2019 Page 2 of 407 Table of Contents SECTION 1 – PROJECT OVERVIEW ............................................................................................. 3 SECTION 2 – CONDITIONS AND REQUIREMENTS SUMMARY ........................................................17 Core Requirement #1: Discharge at the Natural Location .................................................17 Core Requirement #2: Offsite Analysis .............................................................................17 Core Requirement #3: Flow Control ..................................................................................17 Core Requirement #4: Conveyance System .....................................................................18 Core Requirement #5: Construction Stormwater Pollution Prevention ...............................18 Core Requirement #6: Maintenance and Operations ........................................................18 Core Requirement #7: Financial Guarantees and Liability .................................................18 Core Requirement #8: Water Quality Facilities ..................................................................18 Core Requirement #9: On-Site BMPS ...............................................................................18 Special Requirements: .......................................................................................................19 SECTION 3 – OFF-SITE ANALYSIS .............................................................................................21 SECTION 4 – FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN..................26 Existing Site Hydrology (Part A) .........................................................................................26 Developed Site Hydrology (Part B).....................................................................................26 Performance Standards (Part C) ........................................................................................28 Flow Control Standards (Part D) ........................................................................................28 Water Quality System (Part E) ...........................................................................................30 SECTION 5 – CONVEYANCE SYSTEM ANALYSIS AND DESIGN ......................................................64 SECTION 6 – SPECIAL REPORTS AND STUDIES ........................................................................ 100 Geotechnical Report by Terra Associates Inc. ................................................................. 100 Monster Road Basin Study .............................................................................................. 135 SECTION 7 – OTHER PERMITS ................................................................................................ 271 SECTION 8 – CONSTRUCTION STORMWATER POLLUTION PREVENTION AND SPILL CONTROL (CSWPP) PLAN ANALYSIS AND DESIGN ................................................................................. 275 SECTION 9 – BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ........ 367 SECTION 10 – OPERATIONS AND MAINTENANCE MANUAL ........................................................ 382 Figures Page 1 Technical Information Worksheet 6 - 11 2 Site Location Map 12 3A Existing Basin Exhibit 13 3B Developed Basin Exhibit 14 4 Soils Map 15 5 Offsite Analysis Downstream Drainage System Description 22 6 Offsite Analysis Drainage System Map 23 7 Site Map & Overall Drainage Basin 24 8 Tree Retention Credit Worksheet 30 9 Modular Wetland Detail 52 Tables Page 1 Onsite Drainage Basin 27 2 Offsite Drainage Basin 27 3 Offsite Parks Department Property Drainage Basin 27 4 Increase/Decrease of Differing Surface Areas 27 5 Total Flows Onsite and Offsite 28 6 Developed Onsite Flows (Conveyance) 65 Page 3 of 407 Section 1 – Project Overview Project Name: Prologis 601 Monster Road SW Permit Applied for: Site Development Project Address: 601 Monster Road SW, Renton Parcel: 242304-9008 Parcel Area: 418,768 sf (9.61 acres) Project Disturbance Area: Total onsite and offsite – 407,161 SF (9.35 acres) Onsite: 382,864 SF (8.79 acres) Offsite: 12,122 SF (0.28 acres) – Existing ROW East Side 12,175 SF (0.28 acres) – Existing Park Dept. Property Zoning: Industrial Medium (IM) Prologis is proposing to demolish the existing structures, site amenities, onsite utilities and construct a new warehouse facility with truck dock. In addition, the project will construct associated parking, utilities, landscaping, necessary utility revisions and frontage improvements as required by the City of Renton. The project site is fully developed with an existing structure of approximately 145,593 square feet, a smaller out building of 1,626 square feet and corresponding parking and drive aisles of about 89,053 sq. ft. The balance of the property is landscaped with land cover consisting primarily of grass areas on the north and east sides of the building with a few sparse trees. There is a stand of trees with underbrush along the southern property line; this area is classified as a regulated slope. Stormwater for the existing site is collected by an existing on-site storm drainage system which is conveyed to an Existing Regional Stormwater Facility located immediately east of the subject parcel. Currently stormwater for the existing site is released at three separate locations. The existing north parking area conveys stormwater, via sheet flow, directly to Monster Road SW with no on- site collection. An existing catch basin at the northeast corner of the site picks up a small amount of flow and directs it to the existing conveyance system along Monster Road SW on the east side of the site. The rest of the impervious surfaces, parking, driveways and the roof area are collected in a conveyance system that first flows south from the building’s northeast corner then west along the south side of the site and on to an existing off-site conveyance system which directs flows to the existing regional stormwater system about 200 feet west of this site. All flows from the existing site flow to the regional stormwater pond which is located within ¼-mile downstream of the project site. For ease of explanation the proposed stormwater management system may be considered to be divided into three sub-collection systems which converge at the existing stormwater structure near the southwest corner of the site. One system will collect stormwater runnoff from normal use parking areas; one will be for heavy truck use areas and one for clean roof water. As noted, the first system collects stormwater from impervious surfaces that are subject to normal traffic use as well as the landscape areas. It starts at the northwest parking lot and drains east collecting water from the two entrances along the north property line; continues south collecting flows from the two parking areas on the east side of the site before turning west collecting flows from the parking and driveway along the south side of the building. The second stormwater collection system will collect flows from the truck dock area. This water will be directed to an oil/water separator near the southeast corner of the building, which after treatment, will be conveyed to the first Page 4 of 407 conveyance system. Both systems flow to a proposed water quality facility at the southwest corner of the site where enhanced treatment occurs before discharging to an existing structure and conveyance system. The third stormwater collection system will convey the clean roof waters around the building and then discharge to the same existing manhole at the southwest corner of the site as the other two systems. From this point, stormwater releases to the existing downstream piping which flows to the existing regional stormwater facility. A small area of 0.16 acres which is currently part of an existing driveway on the west side of the building will remain an asphalted driveway in the developed condition. Developed drainage of this area will maintain stormwater flows similar to the existing condition. Of note, the project will remove one existing catch basin located immediately south of the current site entrance located inside of the Monster Road SW right-of-way near the north-east corner of the project. As replacement for the single storm structure the project will install two new structures inside the flow line of the proposed curb as well as approximately 135 lineal feet of 12” storm drainage pipe. A maximum spacing of 300 feet between the new and nearest existing structure to the south will be maintained. The subject site is situated within an overall storm water drainage basin about 45 acres in size and includes a total of six (6) properties, five (5) private and one (1) public as well as drainage from a portion of Monster Road SW. With the exception of Monster Road SW all six (6) parcels are mentioned in the “Regional Detention Facility Pump Station Agreement and Reciprocal Easements” which is the recorded agreement that defines how much each property owner is to contribute toward the construction and maintenance of the pond/pump system. This agreement allows for future development on these sites. Stormwater from this drainage basin is discharged via the pump station to a drainage swale flowing to the P1 Channel (Black River). A copy of this regional facilities agreement and an Investigational Report on this Existing Regional Stormwater Facility and the original TIR for this facility is provided in Section 6.0 of this report. This site’s redevelopment will consist of increasing the building footprint area by about 18,887 square feet and the pollution generating impervious surfaces will be expanded by about 44,654 square feet (includes run-on from approximately 4,803 sf of sidewalk). Sewer for the existing building is connected to the City of Renton’s sanitary sewer system at the northeast corner of the building. Existing 8” and 3” service lines drain to an existing on-site sanitary sewer manhole at this location. The 8” sewer line continues north to the main trunk line which runs west to east along Monster Road SW. This line continues to the regional sanitary sewer plant just east of this site. The project is proposing to continue utilizing a portion of the existing on-site sanitary sewer system. Domestic water service and fire loop currently supply the existing building from the water main located in Monster Road SW to the north of the project site. The existing domestic water service connection to this building will continue to be used. A proposed 12” fire loop will circle the building with fire hydrants spaced at required distances Connection of the proposed fire loop will occur at the existing location to the north and a new connection is proposed near the north east corner of the project. The DDCVA will be located in the northwest corner of the building, within the proposed fire riser room. Demolition of the existing site will require removal of the existing buildings. A large portion of the existing concrete slab will be saved and used as flooring for the new structure. Existing utilities will be removed and or abandoned in place in accordance with the approved plans and City of Renton requirements. Page 5 of 407 Clearing and grading will include removing some trees and grass areas and minor grading around the site. No major import or export of soil is anticipated for the site, with only a minor amount of structural fill expected for the building and paved areas. A small amount of remediation work is required. The areas of this work are mentioned on the TESC Plan. Remediation for these areas is addressed by plans prepared by Floyd Snider and submitted separately. During construction, silt fencing, BMP’s for existing catch basins, soil cover BMPs such as seeding or mulching for sediment and erosion control will be used along with creating collection points for stormwater which will be pumped to on-site portable sedimentation tanks to manage sediment laden waters before discharging into the existing downstream conveyance system. Refer to plans provided by Floyd-Snider for media treatment, if required, of onsite stormwater during construction activities. The majority of the site is generally flat with slopes ranging between 1 and 5-percent except for steep slopes along the southern property line where the slopes are approximately 30-percent. The site slopes from a high elevation of approximately 60-feet along the southern property line where it is the site’s high point. It drops quickly down to elevation 30-feet where the site improvements start. Slopes continue in a north to northwesterly and westerly directions where it ends at the westerly property line at elevation 26-feet, and the northwesterly corner of the site at elevation 24-feet. Topographic data shown on the Civil Plans is taken from an on-site existing conditions survey. Test pit data has been provided as part of the soil investigation developed by Terra Associates Inc. which identifies site soils for most of the site as fill material, averaging about 5 feet deep; it’s underlain by soft to dense interbedded alluvial soils. Page 6 of 407 Figure 1 Page 7 of 407 Page 8 of 407 Page 9 of 407 Page 10 of 407 Page 11 of 407 Page 12 of 407 Page 13 of 407 Page 14 of 407 Page 15 of 407 Page 16 of 407 SECTION 2.0 CONDITIONS AND REQUIREMENTS SUMMARY Page 17 of 407 Section 2 – Conditions and Requirements Summary Project Determination of Non-Significance Mitigated (DNS-M) was received on August 31, 2018. Enclosed within this Section is the August 31, 2018 Environmental Threshold (SEPA) Determination for this project. According to the DNS-M: “The project would be subject to Full Drainage Review in accordance with the 2017 Renton Surface Water Design Manual (RSWDM). All nine core requirements and the six special requirements are required to be met. The proposal would be required to provide flow control and enhanced basic water quality in compliance with the 2017 RSWDM.” This storm drainage report and the Civil Site Plans address the above-mentioned requirement. The existing site is a fully developed with a commercial building, surrounding parking, driveway surfaces. According to the City of Renton Surface Water Design Manual Amendment: Figure 1.1.2.A Flow Chart for Determining Type of Drainage Review Required the proposed project requires a “Full Drainage Review.” Section 1.1.2.3 Full Drainage Review o All eight core requirements in Section 1.2 o All six special requirements in Section 1.3 Analysis of the Eight Core Requirements is as follows: Core Requirement #1: Discharge at the Natural Location Existing outfall for this property is entirely man-made which is an 18” diameter storm drainage pipe located near the south west corner of the site. This discharge location shall remain and be utilized by the proposed stormwater conveyance system. Core Requirement #2: Offsite Analysis Please refer to Section 3 of this report for discussion of the Off-Site Analysis. Core Requirement #3: Flow Control The existing site is a fully developed with a commercial building, surrounding parking, and driveway surfaces. According to the RSWDM: In accordance with Section 1.2.3.1 Area-Specific Flow Control Facility Requirement and the City of Renton Flow Control Applications Map (Reference 15-A of the RSWDM) the project is located in the “Peak Rate Flow Control Standard (Existing Site Conditions).” o Peak Rate Flow Control Standard: Matching Existing 2, 10 and 100-year peak rate runoff for areas draining to constructed (man-made) or highly modified drainage systems so as not to create a downstream flooding problem. Proposed surfaces for this project will continue to flow to the existing regional storm water facility which is adequate to mitigate the small increase in water volume created by the additional impervious surface area. As part of the Administrative Site Plan approval and Environmental (SEPA) Review, Innova Architects submitted a report titled Investigation of the Shared Facility Drainage Plan. According to this investigation the existing regional Page 18 of 407 storm water facility has adequate stormwater storage capacity to mitigate for the additional impervious surface created by the proposed building. Therefore, no onsite detention system is proposed. For analysis and further discussion please refer to Section 4 of this report and the Investigation of the Shared Facility Drainage Plan Report provided in the Appendix. Core Requirement #4: Conveyance System The on-site conveyance system has been sized to convey the 100-year runoff from the proposed developed site. WWHM 2012 Continuous Runnoff Modeling was utilized to determine the anticipated flows. Sizing for the stormwater piping is generally 12” in diameter and 18” diameter and where possible 8” diameter was used for runs of pipe 100-feet and less between structures. Please refer to Section 5 of this report for further discussion of the conveyance system. Core Requirement #5: Construction Stormwater Pollution Prevention The proposed project will comply with the requirements set forth in the 2017 RSWDM. Core Requirement #6: Maintenance and Operations A Maintenance and Operations Manual has been prepared and complies with the City of Renton Requirements as set forth in the 2017 RSWSDM. Please refer to Section 10 of this report. Core Requirement #7: Financial Guarantees and Liability Financial and Liability Guarantees will be provided and comply with the City of Renton requirements. Please refer to Section 9 of this report. Core Requirement #8: Water Quality Facilities According to the 2017 RSWSDM the project must provide Enhanced water quality treatment for the Pollution Generating Impervious Surfaces (PGHIS) and if applicable Pollution Generating Pervious Surfaces (PGPS). Stormwater quality mitigation will be provided utilizing a Modular Wetland System (MWS). This type of system has received a General Use Level Designation (GULD) from the Department of Ecology for Basic, Enhanced and Phosphorus water quality treatment. Core Requirement #9: On-Site BMPS According to Section 1.2.9 of the 2017 RSWSDM, “All proposed projects, including redevelopment projects, must provide on-site BMPs to mitigate the impacts of storm and surface water runoff generated by new impervious surface, new pervious surface, existing impervious surfaces, and replaced impervious surface targeted for mitigation as specified in the following sections.” The intent of Core Requirement #9 according to the storm manual is “To provide mitigation of hydrologic impacts that are not possible/practical to mitigate with a flow control facility. Such impacts include increases in runoff volumes and peak discharges and decreases in groundwater recharge.” Finally, since the site is fully developed without the ability to infiltrate stormwater onsite most Low Impact Development methodologies are not feasible. However, the project will provide amended soils in the landscaped and disturbed areas that will not receive hardscape and the steep slope area along the southern property line will remain undisturbed and be placed inside of a Native Vegetation Tract. Page 19 of 407 Special Requirements: 1. Other Adopted Area-Specific Requirements: This project is part of a “Shared Facility Drainage Plan” created in 1994. There are special requirements for upkeep, maintenance and cost sharing for this facility. (See Appendix A). There are no other known adopted area specific requirements for the project. 2. Flood Hazard Area Delineation: This project is not in a flood hazard area. 3. Flood Protection Facilities: This project site will not modify any existing flood protection facilities. 4. Source Control: This project is a speculative building and the future tenant is not known. Any specific source control BMP’s would be defined when the tenant has been defined and that companies specific source control requirements are known and can be addressed at that time. However as required by the 2017 RSWDM the project will provide an oil-water separator for the truck dock area as well as a Modular Wetland System to provide Enhanced stormwater runoff quality treatment. 5. Oil Control: An area of the proposed project is a high-use area; therefore, this special requirement would apply. A coalescing plate oil/water separator facility is proposed for this specific area. 6. Aquifer Protection Area: This project is not located an aquifer protection area. Page 20 of 407 SECTION 3.0 OFF-SITE ANALYSIS Page 21 of 407 Section 3 – Off-Site Analysis The existing conditions at this site show the majority of the site’s drainage flows in a south, and then in the west direction exiting the site at the west and southwest corner. The northerly parking area does drain directly onto Monster Road SW with no controlled drainage conveyance system in-place. There is also a small impervious surface area at the northeast corner of the building, which flows to an 8” conveyance system, and then discharges to the existing 12” drain line that is located at this corner of the site. This 12” line collects roadway drainage from Monster Road SW, which is located along the east property line. Drainage then flows in a northwesterly direction to Monster Road SW along this property’s northern property line, where it discharges to an 18” line. This line continues along the south side of this roadway, collecting drainage from the south half the roadway, continuing along the road alignment for about 1,000-ft to the middle of an existing building to the west of the project site. This 18” line continues west along the north side of this building to the northwest corner, where it turns south along this building in a 24” line. Drainage continues to the southwest corner of the building where it turns east, and then, south discharging into an existing 200-foot-long biofiltration swale and into the regional storm water facility noted previously. Along the east side of this building there is a drainage system that starts near the northeast corner of the building, flowing south collecting drainage from several catch basins in the two parking areas on this side of the site. Drainage flows to the southeast corner of the building. Drainage continues west in an 18” drain line, picking up drainage from this driveway and parking areas along with the existing building’s roof areas until it leaves the project site and continues to an existing storm water manhole about 60 feet west of this site. Drainage continues north in a 24” line, where it then turns west in a 24” line for about 250 feet where it empties into an existing 200- foot-long biofiltration swale. This biofiltration swale discharges to the regional storm water facility noted previously. Based on a site visit and the designed drawings for the “Shared Facility Drainage Plan” which this project site drains to, this is a description of this system which is downstream of this project. From the north pond area, which this site drains to, there is a 12” outlet pipe that drains to a pump manhole at the northwest corner of the pond area. It is then pumped into an 8” PVC forced main (about 480-ft long) where it then discharges into a biofiltration swale about 150 feet long. It continues in a 30-ft 12” culvert under a service road and then it continues about 35-feet to a gravel outfall into the P1 Channel (Black River). See the plans titled “Regional Retention Pond Pump Outfall Facility” in Section 6 of this report. Page 22 of 407 Figure 5 Page 23 of 407 Figure 6 Page 24 of 407 Figure 7 Page 25 of 407 SECTION 4.0 FLOW CONTROL, LOW IMPACT DEVELOMENT & WATER QUALITY FACILITY ANALYSIS & DESIGN Page 26 of 407 Section 4 – Flow Control and Water Quality Facility Analysis and Design Existing Site Hydrology (Part A) The project parcel is developed, generally level, with an existing warehouse structure, small shop building to the southwest of the main structure, along with paved parking areas to the north and east. Landscaping consisting of grass and ornamental trees and plants is provided in and around the paved areas. A steep vegetated slope descends from the south to the north for approximately 35 feet high and runs the entire length of the southern property line. The majority of the site is generally flat with slopes ranging between 1 and 5-percent except for steep slopes along the southern property line where the slopes are approximately 30-percent. The site slopes from a high elevation of approximately 60-feet along the southern property line where it is the site’s high point. It drops quickly down to elevation 30-feet where the site improvements start. Slopes continue in a north to northwesterly and westerly directions where it ends at the westerly property line at elevation 26-feet, and the northwesterly corner of the site at elevation 24-feet. Topographic data shown on the Civil Plans is taken from an on-site existing conditions survey. Test pit data has been provided as part of the soil investigation developed by Terra Associates Inc. (dated September 26, 2017) which identifies site soils for most of the site as fill material, averaging about 5 feet deep; it’s underlain by soft to dense interbedded alluvial soils. Currently, stormwater is collected by an existing storm water conveyance system along the east and south sides of the site which drains to an existing regional stormwater facility with a “Shared Facility Drainage Plan.” The existing system on the east side of the site starts with a 6” storm line increasing to an 18” line, gathering other drainage lines, turning west at the southeast corner of the building continuing west collecting roof drainage and roadway drainage. The 18” existing storm line connects to a structure located off the parcel near southwest corner of the building. From this structure a 24-inch diameter storm line flows northward eventually discharging into a bio-swale which flows into the existing regional pond. The private regional shared stormwater facility contains two cells of which the bio-swale drains to the northern cell. Release from the facility is through a 12” outlet pipe which conveys stormwater to an existing manhole near the northwest corner of the pond and which contains a duplex pump system. Stormwater is pumped through an existing 8” PVC force main (approximately 480-ft long), discharges into an existing 150-foot long biofiltration swale, flows through an existing 30-ft long, 12” diameter culvert located under a service road and then it continues about 35-feet to a gravel outfall into the P1 Channel also known as the Black River (See the plans titled “Regional Retention Pond Pump Outfall Facility” in Section 6.0). According the approved design documents for this facility the maximum peak discharge from the pump system is 3.90 cfs (1750 gallons per minute). Developed Site Hydrology (Part B) After construction of the proposed structure and site work the property will continue to flow to the existing private regional storm water facility as it currently does. Since the regional detention facility was designed and constructed to include development of this parcel no additional water quantity mitigation is proposed. Page 27 of 407 Table 1 – Onsite Drainage Basin Surface Type Exist. Areas, sf / ac Dev. Areas, sf / ac Roof 147,219 / 3.38 164,480 / 3.78 Paving/Gravel/SW 104,590 / 2.40 154,950 / 3.56 Lawn/Landscape 131,054 / 3.01 59,907 / 1.37 Native Vegetation** 45,313 / 1.04 45,313 / 1.04 Total Area 428,176 / 9.83 424,650 / 9.75* Table 2 – Offsite City Right-of-Way Drainage Basin Surface Type Exist. Areas, sf / ac Dev. Areas, sf / ac Dev. Dedicated ROW sf /ac Paving/Gravel/SW 8,612 / 0.20 8,612 / 0.20 0 Lawn/Landscape 3,510 / 0.08 3,510 / 0.08 3,526 / 0.08 Total Area 12,122 / 0.28 12,122 / 0.28* 3,526 / 0.08* Table 3 – Offsite Parks Dept. Property Drainage Basin Surface Type Exist. Areas, sf / ac Dev. Areas, sf / ac Paving/Gravel/SW 5,031 / 0.12 6,362 / 0.15 Lawn/Landscape 7,144 / 0.16 5,813 / 0.13 Total Area 12,175 / 0.28 12,175 / 0.28* *The total drainage basin area (on-site and off-site), under consideration, is 452,473 square feet (10.39 acres). It is worth noting that the project is proposing to deed to the City of Renton approximately 3,526 sf/0.08 ac for additional right-of-way along Monster Road on the north side of the parcel which accounts for the reduction in the on-site developed basin area. ** The Native Vegetation area contributary to the storm conveyance system includes a small area of run-on from the neighboring property to the south. Increases/decreases in the differing surface areas from Table 1 has been tabulated in Table 2 below. Table 4 – Note: decreases in area between the developed and existing are shown in ( ). Surface Type Developed – Existing sf / ac Roof (NPGIS) 17,261 / 0.40 Paving/Gravel/SW (PGIS) 50,360 / 1.16 Lawn/Landscape (71,147) / (1.63) Native Vegetation 0 In addition, the project is providing new parking in the existing parks department property located at the extreme north east corner of the project site. Table 4 below provides a breakdown of the existing conditions and post development conditions for the Park Department Property. Page 28 of 407 Where no quantity mitigation for the new impervious surfaces is required as that is addressed by the existing private shared regional facility, the project is required to provide quality treatment for the new plus replaced pollution generating impervious surfaces (PGIS) and the pollution generating pervious surfaces (PGPS). This treatment requirement is required for both on-site and off-site new and replaced pollution generating hard surfaces. The project has proposed to “over-treat” the PGIS and PGPS on site therefore the stormwater quality facility has been sized by including the flows from the offsite portions of the project New Row, Ex. ROW (Dev), and Ex. Park Dept. Prop. Basin (Dev). Please refer to the Developed Basin Map for a description of these areas. Performance Standards (Part C) In accordance with Section 1.2.3.1 Area-Specific Flow Control Facility Requirement and the City of Renton Flow Control Applications Map the project is located in the “Peak Rate Flow Control Standard (Existing Site Conditions).” o Peak Rate Flow Control Standard: Matching Existing 2, 10 and 100-year peak rate runoff for areas draining to constructed (man-made) or highly modified drainage systems so as not to create a downstream flooding problem. This parcel is part of a Private Shared Facility Drainage Plan in which stormwater runoff quantity mitigation is provided by an existing regional stormwater detention facility. The area specific water quality treatment menu to be followed, for this project site, is the Enhanced Basic Water Quality Menu, which is met with a linear modular wetland system for the site’s PGHS. Additionally, an oil/water separator with a coalescing plate will be added to remove oils from the truck dock area of the site. Flow Control Standards (Part D) Quantity mitigation for stormwater runnoff from the proposed project will continue to flow to the existing regional storm water facility. In a report, previously provided to the City, titled “Investigation of the Shared Facility Drainage Plan” it is shown that the existing stormwater facility has sufficient volume to address the increase in impervious surfaces from the proposed project. It is worth noting that the pond release is via an existing dual pump system therefore there will be no increase in downstream peak flow release from the pond. Since the project’s quantity mitigation is met by the existing regional storm water facility then it is important for the quantity stormwater calculations, provided in this report, to demonstrate the overall impact of the entire developed project (onsite and offsite). Therefore, based upon the Performance Standard mentioned above, the following Table, outlines the flow difference between the existing and developed conditions for the project site including the offsite improvements. Table 5 – Total flow onsite and offsite (Refer to pages 38 and 39 of this report) Return Period Peak Flow Existing Condition (cfs) Developed Condition (cfs) 2-year 2.56 3.07 10-year 3.86 4.50 100-year 5.67 6.44 Page 29 of 407 According to the original design for the Regional Drainage Facility the existing dual pump system has a peak flow of 3.90 cfs. The project will not impact this release rate; therefore, the flow standard criteria has been met. There will be no increase to the downstream peak flows releasing from the facility due to this project. For discussion of On-Site BMPs please see Core Requirement #9 mentioned above in Section #2: Conditions and Requirements Summary. On-site BMP’s, for the project are determined using Section C.1.3.2 “Large Lot BMP” requirements and Table C.1.3.A “On-Site BMP Application Rates”. It is important to note that according to the Geotechnical Engineer on-site infiltration is not feasible thereby making many of the required BMPs infeasible. The following list shows the BMP selection based upon feasibility. On-Site BMP Requirements Overview C.2.1. Full Dispersion – Not Feasible Full dispersion is not feasible for this site since there is no native vegetated surfaces, on site, to disperse runoff from the target surfaces. C.2.2. Full Infiltration – Not Feasible According to the geotechnical report “low permeability” of on-site soils “combined with the presence of fill material and a shallow groundwater table would preclude the ability of the site soils to infiltrate development stormwater.” Therefore, this BMP is not feasible. C.2.3. Limited Infiltration – Not Feasible See note above under C.2 Full Dispersion. C.2.4. Basic Dispersion – Not Feasible Basic dispersion is not feasible for this site since there is no native vegetated surfaces, on site, to disperse runoff from the target surfaces. C.2.6. Bioretention – Not Feasible Bioretention relies on infiltration, which is not recommended on this site (see C.2 above). C.2.7. Permeable Pavement – Not Feasible The subject parcel has known soil and groundwater contamination thereby making this BMP infeasible according to section C.2.7. C.2.9. Reduced Impervious Surface Credit – Not Available The site is greater than 250,000 square feet so no restricted footprint credit is available. C.2.10. Native Growth Retention Credit – Not Feasible This site contains no native growth retention areas that meet the requirements set forth in Section C2.10.1 of the RSWDM to allow for this credit. C.2.11. Perforated Pipe Connection – Not Feasible As noted above; infiltration is not recommended for this site, due to poor infiltrative soils, the fact that this site has known contaminants, and due to the possibility, that a perforated pipe could saturate the underlining fill soils and creating an unstable condition for the building and site. C.2.13. Soil Amendment -- Feasible The proposed project will apply soil amendments to all areas less than 33% slope and which have been disturbed by the construction. C.2.14. Tree Retention Credit - Feasible A few trees 6” in diameter and larger at 4.5’ breast height are located within the Native Growth Retention Area and within 20-feet of the proposed paving. A total of 17 trees with an estimated canopy of 13,220 sf are available for application of the Tree Retention Credit. All trees are deciduous therefore a multiplier of 0.10 is used. Page 30 of 407 Total allowed mitigated area is 1,322 sf (0.03 acres). Therefore, the WWHM2012 calculations reflect a reduction of 0.03 acres in the developed condition. It is worth noting that the Native Growth Retention Area is not being used for any other stormwater credits. Figure 8 Although many of the BMPs, listed above, are not feasible the project is utilizing certain BMPs to the maximum extent possible. Water Quality System (Part E) Water quality for the new impervious surfaces subject to vehicular traffic will be managed in two ways. First, the truck dock area will be treated by an oil/water separator facility. Discharge from the oil/water separator will flow to the on-site conveyance system which collects stormwater from the other impervious surfaces subject to vehicular traffic (PGHS). This combined flow will be directed to a water quality facility before leaving the site at the existing discharge location. According to Section 1.2.8.1, A. Land Use-Specific Water Quality Facility Requirement, since this Tree Retention Credit Worksheet (C.2.1.14) Estimated Canopy (SF) [Minimum 500]Mitigated Area (0.10 x Est. Canopy) 2820 282 800 80 800 80 450 50 600 60 450 50 450 50 800 80 800 80 450 50 800 80 450 50 450 50 600 60 600 60 800 80 800 80 Total Trees: 17 12920 1322 (=0.03 Acres Mitigated) Note: Minimum canopy area for decidious trees is 50 sf per RSWDM 8" Deciduous 6" Deciduous 30" Birch 8" Birch 8" Deciduous 6" Birch 7" Birch 6" Birch Tree 6" Deciduous 8" Deciduous 8" Deciduous 6" Deciduous 6" Deciduous 7" Deciduous 7" Deciduous 8" Birch 8" Deciduous Page 31 of 407 project is a commercial facility and more than 50% of the runoff will flow to the proposed water quality facility, enhanced water quality treatment is required. Water quality mitigation will be provided by a Modular Wetland System. Modular Wetland Systems are compact but provide outstanding Enhance Water Quality Treatment. This system was sized using WWHM2012 with a 15-minute time-step and in an offline capacity as a flow splitter is proposed to divert the larger flows. According to the calculations, the Off-line Facility Target Flow is required to treat a flow of 0.3575 cfs. Sizing for the oil/water separator was determined using flows provided by WWHM2012 and the City’s Table 6.2.1 A. The Developed Basin Map shows the area subject to treatment by the oil/water separator. This area is approximately 0.70 acres in size and is located in front of the proposed truck loading docks. Page 32 of 407 Total Project Stormwater Basin Calculation The following calculation shows the total quantity impact to the downstream private regional drainage facility including both onsite and offsite improvements. Page 33 of 407 WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: 20190305 Total Calc Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 3/5/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : EXISTING BASIN Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Steep 1.04 C, Lawn, Flat 3.01 Pervious Total 4.05 Impervious Land Use acre ROADS FLAT 2.4 ROOF TOPS FLAT 3.38 Impervious Total 5.78 Basin Total 9.83 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : Ex ROw Bypass: No Page 34 of 407 GroundWater: No Pervious Land Use acre C, Lawn, Steep .08 Pervious Total 0.08 Impervious Land Use acre ROADS FLAT 0.2 Impervious Total 0.2 Basin Total 0.28 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : Ex Park Prop Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .16 Pervious Total 0.16 Impervious Land Use acre ROADS FLAT 0.12 Impervious Total 0.12 Basin Total 0.28 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : DEV A Bypass: No GroundWater: No Pervious Land Use acre Page 35 of 407 C, Lawn, Flat .19 Pervious Total 0.19 Impervious Land Use acre ROADS FLAT 0.42 Impervious Total 0.42 Basin Total 0.61 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : DEV B Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Steep 1.04 C, Lawn, Flat .86 Pervious Total 1.9 Impervious Land Use acre ROADS FLAT 2.92 SIDEWALKS FLAT 0.03 Impervious Total 2.95 Basin Total 4.85 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : EX ROW DEV Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Steep .08 Pervious Total 0.08 Page 36 of 407 Impervious Land Use acre ROADS MOD 0.2 Impervious Total 0.2 Basin Total 0.28 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : DEV C Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .32 Pervious Total 0.32 Impervious Land Use acre SIDEWALKS FLAT 0.03 Impervious Total 0.03 Basin Total 0.35 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : Roof Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 3.78 Impervious Total 3.78 Page 37 of 407 Basin Total 3.78 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : DEV D Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 0.16 Impervious Total 0.16 Basin Total 0.16 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : NEW ROW Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .08 Pervious Total 0.08 Impervious Land Use acre Impervious Total 0 Basin Total 0.08 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater Page 38 of 407 ___________________________________________________________________ Name : Ex Park Dept Prop Dev Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .13 Pervious Total 0.13 Impervious Land Use acre ROADS FLAT 0.15 Impervious Total 0.15 Basin Total 0.28 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:4.29 Total Impervious Area:6.1 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:2.7 Total Impervious Area:7.69 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 2.563638 5 year 3.32975 10 year 3.861559 25 year 4.563117 50 year 5.108073 100 year 5.672772 Page 39 of 407 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 3.072656 5 year 3.921184 10 year 4.502278 25 year 5.260732 50 year 5.844404 100 year 6.444809 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 3.544 4.112 1950 3.334 4.156 1951 2.226 2.582 1952 1.711 2.130 1953 1.850 2.311 1954 2.098 2.513 1955 2.310 2.798 1956 2.289 2.763 1957 2.755 3.232 1958 2.064 2.520 1959 1.973 2.501 1960 2.319 2.682 1961 2.304 2.725 1962 1.856 2.292 1963 2.232 2.652 1964 2.071 2.484 1965 2.850 3.324 1966 1.794 2.169 1967 3.189 3.721 1968 3.517 4.252 1969 2.583 3.018 1970 2.406 2.882 1971 2.855 3.423 1972 3.228 3.671 1973 1.618 2.050 1974 2.671 3.158 1975 2.791 3.434 1976 2.088 2.470 1977 1.985 2.506 1978 2.502 3.095 1979 3.374 4.230 1980 3.666 4.123 1981 2.643 3.190 1982 3.911 4.562 1983 2.909 3.589 1984 1.932 2.318 1985 2.634 3.168 1986 2.274 2.701 1987 3.350 4.152 1988 1.968 2.487 1989 2.461 3.142 1990 5.525 6.012 1991 4.169 4.675 1992 1.922 2.305 Page 40 of 407 1993 1.588 1.950 1994 1.642 2.083 1995 2.320 2.816 1996 2.743 3.178 1997 2.586 3.017 1998 2.365 2.911 1999 5.277 6.191 2000 2.568 3.058 2001 2.591 3.239 2002 3.470 4.000 2003 2.734 3.175 2004 4.914 5.799 2005 2.297 2.683 2006 2.073 2.396 2007 4.919 5.443 2008 4.094 4.585 2009 3.016 3.795 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 5.5252 6.1908 2 5.2774 6.0125 3 4.9186 5.7990 4 4.9139 5.4427 5 4.1691 4.6747 6 4.0941 4.5854 7 3.9113 4.5624 8 3.6662 4.2515 9 3.5437 4.2303 10 3.5169 4.1560 11 3.4698 4.1521 12 3.3738 4.1235 13 3.3496 4.1117 14 3.3338 3.9999 15 3.2280 3.7946 16 3.1889 3.7212 17 3.0161 3.6712 18 2.9092 3.5886 19 2.8548 3.4343 20 2.8502 3.4225 21 2.7909 3.3238 22 2.7554 3.2387 23 2.7435 3.2322 24 2.7344 3.1905 25 2.6710 3.1777 26 2.6434 3.1749 27 2.6338 3.1681 28 2.5911 3.1581 29 2.5862 3.1415 30 2.5828 3.0954 31 2.5682 3.0577 32 2.5017 3.0183 33 2.4613 3.0171 34 2.4060 2.9110 35 2.3654 2.8815 Page 41 of 407 36 2.3197 2.8164 37 2.3190 2.7978 38 2.3096 2.7634 39 2.3035 2.7252 40 2.2973 2.7009 41 2.2887 2.6828 42 2.2741 2.6815 43 2.2322 2.6519 44 2.2257 2.5820 45 2.0982 2.5205 46 2.0876 2.5134 47 2.0732 2.5063 48 2.0710 2.5007 49 2.0644 2.4866 50 1.9849 2.4840 51 1.9728 2.4697 52 1.9680 2.3965 53 1.9325 2.3179 54 1.9217 2.3111 55 1.8564 2.3048 56 1.8498 2.2924 57 1.7937 2.1686 58 1.7111 2.1297 59 1.6422 2.0835 60 1.6178 2.0496 61 1.5876 1.9505 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 42 of 407 WATER QUALITY SIZING CALCULATION Page 43 of 407 WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: 20190301 WQ Unit Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 3/4/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : EXISTING BASIN WQ Page 44 of 407 Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Steep 1.04 C, Lawn, Flat 2.61 Pervious Total 3.65 Impervious Land Use acre ROADS FLAT 2.4 Impervious Total 2.4 Basin Total 6.05 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : Ex ROW Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Steep .08 Pervious Total 0.08 Impervious Land Use acre ROADS MOD 0.2 Impervious Total 0.2 Basin Total 0.28 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : Ex Park Prop Basin Bypass: No GroundWater: No Page 45 of 407 Pervious Land Use acre C, Lawn, Flat .16 Pervious Total 0.16 Impervious Land Use acre ROADS FLAT 0.12 Impervious Total 0.12 Basin Total 0.28 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : DEV A Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .19 Pervious Total 0.19 Impervious Land Use acre ROADS FLAT 0.42 Impervious Total 0.42 Basin Total 0.61 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : DEV B Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Steep 1.04 C, Lawn, Flat .86 Page 46 of 407 Pervious Total 1.9 Impervious Land Use acre ROADS FLAT 2.92 SIDEWALKS FLAT 0.03 Impervious Total 2.95 Basin Total 4.85 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : EX ROW DEV Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Steep .08 Pervious Total 0.08 Impervious Land Use acre ROADS MOD 0.2 Impervious Total 0.2 Basin Total 0.28 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : DEV C Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .32 Pervious Total 0.32 Impervious Land Use acre Page 47 of 407 SIDEWALKS FLAT 0.03 Impervious Total 0.03 Basin Total 0.35 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : Ex Park Prop Basin Dev Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Steep .13 Pervious Total 0.13 Impervious Land Use acre ROADS FLAT 0.15 Impervious Total 0.15 Basin Total 0.28 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : DEV D Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 0.16 Impervious Total 0.16 Basin Total 0.16 Page 48 of 407 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : New ROW Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .08 Pervious Total 0.08 Impervious Land Use acre Impervious Total 0 Basin Total 0.08 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:3.89 Total Impervious Area:2.72 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:2.7 Total Impervious Area:3.91 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 1.269026 5 year 1.698905 10 year 2.004328 Page 49 of 407 25 year 2.414678 50 year 2.738582 100 year 3.07847 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 1.637934 5 year 2.116591 10 year 2.447559 25 year 2.882827 50 year 3.22002 100 year 3.56869 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 1.830 2.258 1950 1.711 2.144 1951 1.153 1.421 1952 0.797 1.094 1953 0.853 1.193 1954 1.037 1.347 1955 1.109 1.473 1956 1.103 1.458 1957 1.396 1.755 1958 0.989 1.326 1959 0.896 1.280 1960 1.222 1.489 1961 1.142 1.461 1962 0.866 1.190 1963 1.120 1.432 1964 1.008 1.318 1965 1.444 1.802 1966 0.868 1.150 1967 1.719 1.993 1968 1.723 2.257 1969 1.304 1.634 1970 1.190 1.546 1971 1.407 1.828 1972 1.688 2.026 1973 0.767 1.049 1974 1.344 1.703 1975 1.428 1.778 1976 1.062 1.343 1977 0.978 1.282 1978 1.195 1.599 1979 1.554 2.182 1980 1.950 2.293 1981 1.279 1.690 1982 2.037 2.470 1983 1.359 1.864 1984 0.940 1.230 1985 1.267 1.670 1986 1.180 1.463 1987 1.548 2.146 1988 0.884 1.268 Page 50 of 407 1989 1.137 1.617 1990 3.083 3.453 1991 2.257 2.633 1992 0.941 1.229 1993 0.747 1.017 1994 0.746 1.066 1995 1.114 1.484 1996 1.498 1.767 1997 1.318 1.641 1998 1.111 1.515 1999 2.665 3.344 2000 1.272 1.640 2001 1.204 1.677 2002 1.778 2.180 2003 1.449 1.767 2004 2.482 3.134 2005 1.172 1.464 2006 1.078 1.320 2007 2.760 3.066 2008 2.208 2.578 2009 1.421 1.933 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 3.0831 3.4530 2 2.7605 3.3435 3 2.6648 3.1344 4 2.4820 3.0661 5 2.2567 2.6326 6 2.2081 2.5780 7 2.0365 2.4702 8 1.9495 2.2929 9 1.8302 2.2576 10 1.7782 2.2570 11 1.7228 2.1816 12 1.7193 2.1796 13 1.7108 2.1460 14 1.6882 2.1443 15 1.5541 2.0259 16 1.5482 1.9927 17 1.4981 1.9335 18 1.4493 1.8639 19 1.4442 1.8278 20 1.4282 1.8019 21 1.4212 1.7784 22 1.4066 1.7672 23 1.3956 1.7670 24 1.3588 1.7550 25 1.3436 1.7030 26 1.3181 1.6900 27 1.3041 1.6773 28 1.2789 1.6698 29 1.2718 1.6406 30 1.2666 1.6404 31 1.2218 1.6338 Page 51 of 407 32 1.2036 1.6173 33 1.1949 1.5987 34 1.1904 1.5456 35 1.1800 1.5147 36 1.1717 1.4889 37 1.1532 1.4841 38 1.1423 1.4729 39 1.1374 1.4636 40 1.1199 1.4625 41 1.1140 1.4607 42 1.1106 1.4585 43 1.1087 1.4318 44 1.1029 1.4207 45 1.0777 1.3469 46 1.0625 1.3430 47 1.0366 1.3262 48 1.0077 1.3196 49 0.9889 1.3184 50 0.9779 1.2821 51 0.9408 1.2804 52 0.9402 1.2675 53 0.8964 1.2300 54 0.8839 1.2293 55 0.8675 1.1928 56 0.8660 1.1903 57 0.8534 1.1501 58 0.7972 1.0937 59 0.7674 1.0661 60 0.7467 1.0488 61 0.7459 1.0167 ___________________________________________________________________ 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. ___________________________________________________________________ Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0.5643 acre-feet On-line facility target flow: 0.6379 cfs. Adjusted for 15 min: 0.6379 cfs. Off-line facility target flow: 0.3575 cfs. Target water quality flow. Adjusted for 15 min: 0.3575 cfs. Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 52 of 407 FIGURE 9 Page 53 of 407 WQ Flow Splitter Calculation Orifice Sizing Water Quality Diversion Structure Given d Q = c[(pi)d^2/4][(2gh)^1/2] d = 2.625 IN. Orifice diameter c = 0.62 Sharp edged orifice constant g = 32.2 Ft/Sec^2 gravitation constant h = 3.66 FT. head on orifice Q = 0.3575 CFS Required Water quality flow 0.3575 cfs provided from WWHM WQ Calc. Invert elevation outlet 6" to Modular Wetland: 19.76 FT Total 100-year flow to diversion structure: 3.124 cfs Flow over weir: 2.766 cfs Flow to Water Qual Unit 0.3575 cfs Total flows provided from the 100-year Backwater Analysis and conveyance calculations Weir Calcs. based on King County SWM FIGURE 4.4.7B INCHES FEET CFS C L H P Q 3.30 33.00 5.57 6.15 2.77 L = length of concrete weir Rim Elevation: 26.68 FT Invert Elevation: 19.76 FT Overflow Weir Elevation: 22.95 FT Water Elevation over weir during 100-year event: 23.42 FT Page 54 of 407 Project Name: DCT Industries Monster Road Date: 10/03/2018 Project Number: 17-045 Oil/Water Separator Coalescing Plate Calculation Ref: 2017 City of Renton Surface Water Design Manual Area to Proposed Oil/Water Separator = 30,500 sf or 0.700 acres Ah= horizontal surface are of the plate (ft2) Vt=rise rate of the oil droplet (ft/min) Q=design flowrate (ft3/min) Sw=specific gravity of water at the design temperature - use 1.0 So=specifice gravity of oil at design temperature - use 0.85 mw=absolute viscosity of the water (poise) - use 0.015674 for 39 degrees k value from Table 6.2.1.A for Off-Line 6 month precip of 1.44" = 3.53 1. Calculate plate minimum effective separation area Ah Ah=k*Q/vt=Q/[(.00386)*((Sw-So)/mw))] Q= 0.06 cfs WQ offline design flow from WWHM2012 Q= 3.6 cfm WWHM2012 Off-Line flow x 60 Ah= 344.0 ft2 2. Calculate collective projected surface area Ah=Aa*cos H H= angle of plates - use 45 degrees Aa=actual collective plate area of plate configuration (sf) Aa=Ah/cos 45 => 486.51 sf Use Utililty Vault model 577-CPS with 592 sf plate area, Max 555 GPM WWHM2012 Output Using 0.70 acres of PGHS Page 55 of 407 Oil Water Separator Flow Calculation Page 56 of 407 Page 57 of 407 WWHM2012 PROJECT REPORT Oil/Water Separator flow calculation ___________________________________________________________________ Project Name: 20181003 O-W Sep Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 10/3/2018 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Oil-Water Sep Basin Pre Bypass: No GroundWater: No Pervious Land Use acre C, Pasture, Flat .7 Pervious Total 0.7 Impervious Land Use acre Impervious Total 0 Basin Total 0.7 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : Oil-Water Sep Basin Dev Bypass: No Page 58 of 407 GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 0.7 Impervious Total 0.7 Basin Total 0.7 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.7 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.7 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.024534 5 year 0.042123 10 year 0.056214 25 year 0.07682 50 year 0.094229 100 year 0.113427 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.266885 5 year 0.337107 10 year 0.384818 25 year 0.446706 50 year 0.494073 100 year 0.542591 Page 59 of 407 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.033 0.346 1950 0.039 0.374 1951 0.049 0.216 1952 0.016 0.192 1953 0.014 0.207 1954 0.020 0.217 1955 0.031 0.246 1956 0.026 0.242 1957 0.024 0.275 1958 0.023 0.222 1959 0.019 0.226 1960 0.039 0.222 1961 0.019 0.235 1962 0.013 0.204 1963 0.019 0.227 1964 0.025 0.223 1965 0.018 0.283 1966 0.015 0.189 1967 0.040 0.326 1968 0.022 0.371 1969 0.021 0.258 1970 0.017 0.249 1971 0.023 0.297 1972 0.038 0.306 1973 0.018 0.185 1974 0.022 0.271 1975 0.029 0.312 1976 0.021 0.210 1977 0.006 0.227 1978 0.017 0.278 1979 0.011 0.380 1980 0.062 0.341 1981 0.016 0.279 1982 0.042 0.393 1983 0.026 0.320 1984 0.016 0.202 1985 0.009 0.278 1986 0.040 0.241 1987 0.037 0.372 1988 0.016 0.226 1989 0.010 0.282 1990 0.123 0.476 1991 0.049 0.380 1992 0.020 0.200 1993 0.018 0.173 1994 0.008 0.188 1995 0.025 0.247 1996 0.063 0.263 1997 0.046 0.256 1998 0.019 0.259 1999 0.076 0.530 2000 0.018 0.264 Page 60 of 407 2001 0.005 0.290 2002 0.028 0.338 2003 0.038 0.263 2004 0.039 0.496 2005 0.026 0.227 2006 0.027 0.200 2007 0.100 0.463 2008 0.086 0.373 2009 0.038 0.345 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.1226 0.5300 2 0.0998 0.4959 3 0.0858 0.4756 4 0.0762 0.4635 5 0.0626 0.3933 6 0.0617 0.3800 7 0.0494 0.3799 8 0.0488 0.3735 9 0.0463 0.3733 10 0.0416 0.3721 11 0.0402 0.3707 12 0.0397 0.3457 13 0.0394 0.3450 14 0.0393 0.3409 15 0.0391 0.3381 16 0.0383 0.3260 17 0.0380 0.3201 18 0.0378 0.3116 19 0.0368 0.3061 20 0.0335 0.2965 21 0.0309 0.2898 22 0.0294 0.2829 23 0.0275 0.2823 24 0.0269 0.2789 25 0.0265 0.2783 26 0.0261 0.2776 27 0.0256 0.2747 28 0.0246 0.2705 29 0.0245 0.2638 30 0.0236 0.2632 31 0.0231 0.2627 32 0.0229 0.2590 33 0.0218 0.2577 34 0.0217 0.2556 35 0.0214 0.2486 36 0.0213 0.2473 37 0.0200 0.2461 38 0.0200 0.2421 39 0.0195 0.2412 40 0.0190 0.2347 41 0.0189 0.2271 42 0.0188 0.2270 43 0.0185 0.2266 Page 61 of 407 44 0.0180 0.2261 45 0.0179 0.2258 46 0.0177 0.2227 47 0.0173 0.2219 48 0.0169 0.2217 49 0.0163 0.2170 50 0.0159 0.2159 51 0.0158 0.2096 52 0.0156 0.2074 53 0.0154 0.2045 54 0.0137 0.2019 55 0.0128 0.2002 56 0.0109 0.2000 57 0.0099 0.1921 58 0.0095 0.1892 59 0.0078 0.1884 60 0.0060 0.1854 61 0.0047 0.1732 ___________________________________________________________________ Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0.086 acre-feet On-line facility target flow: 0.1137 cfs. Adjusted for 15 min: 0.1137 cfs. Off-line facility target flow: 0.0642 cfs. Oil Water Separator Target Flow Adjusted for 15 min: 0.0642 cfs. ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2018; All Rights Reserved. Page 62 of 407 Oil Water Flow Splitter Calculation Orifice Sizing Oil/Water Diversion Structure Given d Q = c[(pi)d^2/4][(2gh)^1/2] d = 1.750 IN. Orifice diameter c = 0.62 Sharp edged orifice constant g = 32.2 Ft/Sec^2 gravitation constant h = 0.50 FT. head on orifice Q = 0.06 CFS Required maximum flow oil/water sep 0.06 cfs provided from WWHM calculation Invert elevation outlet 8" to Oil Water Separator: 23.94 FT Total 100-year flow to diversion structure: 0.54 cfs Flow over weir: 0.48 cfs Flow to Oil/Water Separator: 0.06 cfs Total flows provided from the 100-year Backwater Analysis and conveyance calculations Weir Calcs. based on King County SWM FIGURE 4.4.7B INCHES FEET CFS C L H P Q 3.28 28.26 1.90 6.45 0.48 L = 1/2 circumference of 18" diam. overflow baffle Rim Elevation: 26.68 FT Invert Elevation: 23.94 FT Weir Elevation: 24.28 FT Water Elevation over weir during 100-year event: 24.44 FT Page 63 of 407 SECTION 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN Page 64 of 407 Section 5 – Conveyance System Analysis and Design Design of the proposed conveyance system is in accordance with Chapter 4 of the 2017 RSWDM. It is worth noting that all conveyance piping was designed to convey the 100-year storm event. No backwater condition is expected for the project. The following information provides confirmation that the proposed piping system is adequate to carry the anticipated flows. Backwater Flow Analysis: Minimum 10 and 25 year: 100-year was used Manning’s n value = 0.012(backwater analysis) Backwater condition is not anticipated for the project; however, backwater has been provided in accordance with the City of Renton requirements to prove capacity. Roof runoff connects downstream of the flow splitter and quality mitigation therefore, according to the WWHM2012 storm calculations (15-minute timestep) the maximum anticipated 100-year flow for the site (not including the roof) is approximately 3.124 cfs (see table below). Flows were determined using WWHM2012 and are referred to in the 25 and 100-year backwater analysis on pages 96 and 97, respectively. Table 6 – Developed Onsite Flows (conveyance): Return Period Peak Flow Developed flow to diversion structure (cfs) Developed flows to downstream storm conveyance 2-year 1.420 2.861 5-year 1.839 3.659 10-year 2.131 4.209 25-year 2.515 4.927 50-year 2.815 5.483 100-year 3.124 6.054 Roof drainage connects downstream of the flow splitter and quality mitigation at CB#17. Downstream of CB#17 is an existing 18” diameter pipe at 1.25% slope. Total stormwater runoff for the project site to the downstream conveyance system is 6.054 cfs. According to the backwater analysis this existing 18” pipe is more than adequate to convey the anticipated 100- year release. Please refer to the following Existing and Developed Basin Maps for a description of the site drainage basins (Figures 3A and 3B). In addition, a short run of 12” storm pipe is proposed to be installed in Monster Road along the side of the project. Conveyance calculations may be found beginning on page 91 of this report. Total anticipated flow through this new for the 25-year and 100-year recurrence interval is 0.150 cfs and 0.183 cfs, respectively. The backwater analysis for this section of piping may be found on page 98 of this report. Page 65 of 407 DEVELOPED BASIN A CONVEYANCE CALC WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: monsterProl DevAConv Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 2/25/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : DEV A Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .19 Pervious Total 0.19 Impervious Land Use acre ROADS FLAT 0.42 Impervious Total 0.42 Page 66 of 407 Basin Total 0.61 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : DEV A Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .19 Pervious Total 0.19 Impervious Land Use acre ROADS FLAT 0.42 Impervious Total 0.42 Basin Total 0.61 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.19 Total Impervious Area:0.42 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.19 Total Impervious Area:0.42 ___________________________________________________________________ Page 67 of 407 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.172305 5 year 0.222388 10 year 0.256985 25 year 0.302452 50 year 0.337652 100 year 0.374031 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.172305 5 year 0.222388 10 year 0.256985 25 year 0.302452 Backwater Analysis 50 year 0.337652 100 year 0.374031 Backwater Analysis ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.235 0.235 1950 0.229 0.229 1951 0.146 0.146 1952 0.117 0.117 1953 0.127 0.127 1954 0.140 0.140 1955 0.156 0.156 1956 0.155 0.155 1957 0.183 0.183 1958 0.140 0.140 1959 0.136 0.136 1960 0.152 0.152 1961 0.154 0.154 1962 0.127 0.127 1963 0.149 0.149 1964 0.139 0.139 1965 0.190 0.190 1966 0.120 0.120 1967 0.210 0.210 1968 0.239 0.239 1969 0.173 0.173 1970 0.161 0.161 1971 0.192 0.192 1972 0.214 0.214 1973 0.111 0.111 1974 0.179 0.179 1975 0.187 0.187 1976 0.139 0.139 1977 0.137 0.137 1978 0.170 0.170 1979 0.232 0.232 1980 0.243 0.243 1981 0.178 0.178 1982 0.260 0.260 Page 68 of 407 1983 0.199 0.199 1984 0.130 0.130 1985 0.179 0.179 1986 0.150 0.150 1987 0.229 0.229 1988 0.135 0.135 1989 0.169 0.169 1990 0.357 0.357 1991 0.273 0.273 1992 0.129 0.129 1993 0.108 0.108 1994 0.113 0.113 1995 0.157 0.157 1996 0.181 0.181 1997 0.172 0.172 1998 0.162 0.162 1999 0.356 0.356 2000 0.172 0.172 2001 0.178 0.178 2002 0.231 0.231 2003 0.180 0.180 2004 0.330 0.330 2005 0.152 0.152 2006 0.136 0.136 2007 0.319 0.319 2008 0.268 0.268 2009 0.207 0.207 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 69 of 407 DEVELOPED BASIN B CONVEYANCE CALC WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: monsterProl DevBConv Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 2/25/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : DEV B Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Steep 1.04 C, Lawn, Flat .86 Pervious Total 1.9 Impervious Land Use acre ROADS FLAT 2.92 SIDEWALKS FLAT 0.03 Impervious Total 2.95 Page 70 of 407 Basin Total 4.85 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : DEV B Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Steep 1.04 C, Lawn, Flat .86 Pervious Total 1.9 Impervious Land Use acre ROADS FLAT 2.92 SIDEWALKS FLAT 0.03 Impervious Total 2.95 Basin Total 4.85 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:1.9 Total Impervious Area:2.95 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:1.9 Total Impervious Area:2.95 Page 71 of 407 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 1.203242 5 year 1.543091 10 year 1.776711 25 year 2.082543 50 year 2.318512 100 year 2.561743 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 1.203242 5 year 1.543091 10 year 1.776711 25 year 2.082543 Backwater Analysis 50 year 2.318512 100 year 2.561743 Backwater Analysis ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 1.634 1.634 1950 1.594 1.594 1951 1.042 1.042 1952 0.819 0.819 1953 0.885 0.885 1954 0.990 0.990 1955 1.092 1.092 1956 1.080 1.080 1957 1.287 1.287 1958 0.981 0.981 1959 0.954 0.954 1960 1.086 1.086 1961 1.079 1.079 1962 0.884 0.884 1963 1.044 1.044 1964 0.975 0.975 1965 1.313 1.313 1966 0.856 0.856 1967 1.441 1.441 1968 1.637 1.637 1969 1.188 1.188 1970 1.134 1.134 1971 1.337 1.337 1972 1.463 1.463 1973 0.782 0.782 1974 1.237 1.237 1975 1.314 1.314 1976 0.980 0.980 1977 0.958 0.958 1978 1.181 1.181 1979 1.617 1.617 1980 1.650 1.650 1981 1.247 1.247 Page 72 of 407 1982 1.800 1.800 1983 1.380 1.380 1984 0.910 0.910 1985 1.230 1.230 1986 1.076 1.076 1987 1.596 1.596 1988 0.952 0.952 1989 1.190 1.190 1990 2.481 2.481 1991 1.892 1.892 1992 0.907 0.907 1993 0.755 0.755 1994 0.794 0.794 1995 1.097 1.097 1996 1.273 1.273 1997 1.202 1.202 1998 1.120 1.120 1999 2.408 2.408 2000 1.202 1.202 2001 1.239 1.239 2002 1.585 1.585 2003 1.265 1.265 2004 2.266 2.266 2005 1.079 1.079 2006 0.964 0.964 2007 2.187 2.187 2008 1.861 1.861 2009 1.456 1.456 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 73 of 407 DEVELOPED BASIN C CONVEYANCE CALC WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: monsterProl DevCConv Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 2/25/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : DEV C Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .32 Pervious Total 0.32 Impervious Land Use acre SIDEWALKS FLAT 0.03 Impervious Total 0.03 Basin Total 0.35 ___________________________________________________________________ Page 74 of 407 Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : DEV C Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .32 Pervious Total 0.32 Impervious Land Use acre SIDEWALKS FLAT 0.03 Impervious Total 0.03 Basin Total 0.35 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.32 Total Impervious Area:0.03 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.32 Total Impervious Area:0.03 _________________________________________________________________ Page 75 of 407 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.035386 5 year 0.058084 10 year 0.076089 25 year 0.102337 50 year 0.124509 100 year 0.148996 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.035386 5 year 0.058084 10 year 0.076089 25 year 0.102337 Backwater Analysis 50 year 0.124509 100 year 0.148996 Backwater Analysis ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.066 0.066 1950 0.071 0.071 1951 0.037 0.037 1952 0.019 0.019 1953 0.015 0.015 1954 0.027 0.027 1955 0.027 0.027 1956 0.032 0.032 1957 0.042 0.042 1958 0.021 0.021 1959 0.019 0.019 1960 0.041 0.041 1961 0.032 0.032 1962 0.016 0.016 1963 0.031 0.031 1964 0.030 0.030 1965 0.047 0.047 1966 0.020 0.020 1967 0.072 0.072 1968 0.044 0.044 1969 0.042 0.042 1970 0.031 0.031 1971 0.043 0.043 1972 0.064 0.064 1973 0.016 0.016 1974 0.040 0.040 1975 0.045 0.045 1976 0.031 0.031 1977 0.027 0.027 1978 0.031 0.031 1979 0.022 0.022 1980 0.079 0.079 1981 0.030 0.030 1982 0.073 0.073 1983 0.036 0.036 Page 76 of 407 1984 0.024 0.024 1985 0.032 0.032 1986 0.036 0.036 1987 0.035 0.035 1988 0.014 0.014 1989 0.012 0.012 1990 0.141 0.141 1991 0.091 0.091 1992 0.026 0.026 1993 0.016 0.016 1994 0.012 0.012 1995 0.025 0.025 1996 0.061 0.061 1997 0.042 0.042 1998 0.032 0.032 1999 0.102 0.102 2000 0.035 0.035 2001 0.019 0.019 2002 0.063 0.063 2003 0.049 0.049 2004 0.076 0.076 2005 0.036 0.036 2006 0.036 0.036 2007 0.130 0.130 2008 0.089 0.089 2009 0.049 0.049 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 77 of 407 Developed Basin D Conveyance WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: monsterProl DevDConv Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 2/25/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : DEV D Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 0.16 Impervious Total 0.16 Basin Total 0.16 Page 78 of 407 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : DEV D Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 0.16 Impervious Total 0.16 Basin Total 0.16 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.16 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.16 ___________________________________________________________________ Page 79 of 407 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.061002 5 year 0.077053 10 year 0.087958 25 year 0.102104 50 year 0.112931 100 year 0.124021 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.061002 5 year 0.077053 10 year 0.087958 25 year 0.102104 50 year 0.112931 100 year 0.124021 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.079 0.079 1950 0.085 0.085 1951 0.049 0.049 1952 0.044 0.044 1953 0.047 0.047 1954 0.050 0.050 1955 0.056 0.056 1956 0.055 0.055 1957 0.063 0.063 1958 0.051 0.051 1959 0.052 0.052 1960 0.051 0.051 1961 0.054 0.054 1962 0.047 0.047 1963 0.052 0.052 1964 0.051 0.051 1965 0.065 0.065 1966 0.043 0.043 1967 0.075 0.075 1968 0.085 0.085 1969 0.059 0.059 1970 0.057 0.057 1971 0.068 0.068 1972 0.070 0.070 1973 0.042 0.042 1974 0.062 0.062 1975 0.071 0.071 1976 0.048 0.048 1977 0.052 0.052 1978 0.063 0.063 1979 0.087 0.087 1980 0.078 0.078 1981 0.064 0.064 1982 0.090 0.090 1983 0.073 0.073 Page 80 of 407 1984 0.046 0.046 1985 0.064 0.064 1986 0.055 0.055 1987 0.085 0.085 1988 0.052 0.052 1989 0.065 0.065 1990 0.109 0.109 1991 0.087 0.087 1992 0.046 0.046 1993 0.040 0.040 1994 0.043 0.043 1995 0.057 0.057 1996 0.060 0.060 1997 0.058 0.058 1998 0.059 0.059 1999 0.121 0.121 2000 0.060 0.060 2001 0.066 0.066 2002 0.077 0.077 2003 0.060 0.060 2004 0.113 0.113 2005 0.052 0.052 2006 0.046 0.046 2007 0.106 0.106 2008 0.085 0.085 2009 0.079 0.079 _____________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 81 of 407 Exist Developed ROW on East side of project tributary to site conveyance. WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: monsterProl EXROWConv Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 3/5/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 (adjusted) Precip Scale: 0.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Basin 3 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Steep .08 Pervious Total 0.08 Impervious Land Use acre Impervious Total 0 Basin Total 0.08 ___________________________________________________________________ Page 82 of 407 Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : EX ROW DEV Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Steep .08 Pervious Total 0.08 Impervious Land Use acre Impervious Total 0 Basin Total 0.08 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.08 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.08 Total Impervious Area:0 ___________________________________________________________________ Page 83 of 407 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.009646 5 year 0.016189 10 year 0.021097 25 year 0.027859 50 year 0.033261 100 year 0.038947 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.009646 5 year 0.016189 10 year 0.021097 25 year 0.027859 Backwater Analysis 50 year 0.033261 100 year 0.038947 Backwater Analysis ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.019 0.019 1950 0.018 0.018 1951 0.010 0.010 1952 0.005 0.005 1953 0.003 0.003 1954 0.008 0.008 1955 0.007 0.007 1956 0.010 0.010 1957 0.011 0.011 1958 0.007 0.007 1959 0.005 0.005 1960 0.011 0.011 1961 0.007 0.007 1962 0.003 0.003 1963 0.009 0.009 1964 0.009 0.009 1965 0.012 0.012 1966 0.006 0.006 1967 0.019 0.019 1968 0.011 0.011 1969 0.012 0.012 1970 0.009 0.009 1971 0.011 0.011 1972 0.018 0.018 1973 0.004 0.004 1974 0.011 0.011 1975 0.013 0.013 1976 0.008 0.008 1977 0.008 0.008 1978 0.009 0.009 1979 0.004 0.004 1980 0.024 0.024 1981 0.008 0.008 1982 0.019 0.019 1983 0.011 0.011 Page 84 of 407 1984 0.005 0.005 1985 0.008 0.008 1986 0.010 0.010 1987 0.009 0.009 1988 0.003 0.003 1989 0.003 0.003 1990 0.035 0.035 1991 0.025 0.025 1992 0.007 0.007 1993 0.004 0.004 1994 0.003 0.003 1995 0.006 0.006 1996 0.019 0.019 1997 0.011 0.011 1998 0.009 0.009 1999 0.027 0.027 2000 0.010 0.010 2001 0.004 0.004 2002 0.015 0.015 2003 0.016 0.016 2004 0.022 0.022 2005 0.009 0.009 2006 0.009 0.009 2007 0.033 0.033 2008 0.024 0.024 2009 0.013 0.013 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0355 0.0355 2 0.0329 0.0329 3 0.0273 0.0273 4 0.0246 0.0246 5 0.0240 0.0240 6 0.0238 0.0238 7 0.0217 0.0217 8 0.0193 0.0193 9 0.0189 0.0189 10 0.0187 0.0187 11 0.0186 0.0186 12 0.0185 0.0185 13 0.0175 0.0175 14 0.0161 0.0161 15 0.0155 0.0155 16 0.0135 0.0135 17 0.0127 0.0127 18 0.0124 0.0124 19 0.0120 0.0120 20 0.0115 0.0115 21 0.0114 0.0114 22 0.0114 0.0114 23 0.0112 0.0112 24 0.0111 0.0111 25 0.0108 0.0108 26 0.0107 0.0107 Page 85 of 407 27 0.0103 0.0103 28 0.0103 0.0103 29 0.0103 0.0103 30 0.0099 0.0099 31 0.0094 0.0094 32 0.0094 0.0094 33 0.0093 0.0093 34 0.0091 0.0091 35 0.0091 0.0091 36 0.0091 0.0091 37 0.0087 0.0087 38 0.0086 0.0086 39 0.0084 0.0084 40 0.0080 0.0080 41 0.0077 0.0077 42 0.0076 0.0076 43 0.0076 0.0076 44 0.0075 0.0075 45 0.0073 0.0073 46 0.0072 0.0072 47 0.0067 0.0067 48 0.0063 0.0063 49 0.0055 0.0055 50 0.0055 0.0055 51 0.0053 0.0053 52 0.0047 0.0047 53 0.0042 0.0042 54 0.0039 0.0039 55 0.0039 0.0039 56 0.0036 0.0036 57 0.0035 0.0035 58 0.0035 0.0035 59 0.0029 0.0029 60 0.0028 0.0028 61 0.0026 0.0026 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 86 of 407 Conveyance Calculation Roof Flows WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: monsterProl RoofConv Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 2/25/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Roof Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 3.78 Impervious Total 3.78 Basin Total 3.78 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater Page 87 of 407 ___________________________________________________________________ MITIGATED LAND USE Name : Roof Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 3.78 Impervious Total 3.78 Basin Total 3.78 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:3.78 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:3.78 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 1.441181 5 year 1.820378 10 year 2.078017 25 year 2.412211 50 year 2.667995 100 year 2.92999 Page 88 of 407 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 1.441181 5 year 1.820378 10 year 2.078017 25 year 2.412211 Backwater Analysis 50 year 2.667995 100 year 2.92999 Backwater Analysis ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 1.867 1.867 1950 2.017 2.017 1951 1.166 1.166 1952 1.037 1.037 1953 1.120 1.120 1954 1.172 1.172 1955 1.329 1.329 1956 1.307 1.307 1957 1.483 1.483 1958 1.197 1.197 1959 1.221 1.221 1960 1.198 1.198 1961 1.267 1.267 1962 1.104 1.104 1963 1.227 1.227 1964 1.203 1.203 1965 1.528 1.528 1966 1.022 1.022 1967 1.761 1.761 1968 2.002 2.002 1969 1.391 1.391 1970 1.343 1.343 1971 1.601 1.601 1972 1.653 1.653 1973 1.001 1.001 1974 1.461 1.461 1975 1.683 1.683 1976 1.132 1.132 1977 1.226 1.226 1978 1.499 1.499 1979 2.052 2.052 1980 1.841 1.841 1981 1.506 1.506 1982 2.124 2.124 1983 1.728 1.728 1984 1.090 1.090 1985 1.503 1.503 1986 1.302 1.302 1987 2.009 2.009 1988 1.219 1.219 1989 1.525 1.525 1990 2.568 2.568 1991 2.052 2.052 Page 89 of 407 1992 1.080 1.080 1993 0.935 0.935 1994 1.017 1.017 1995 1.336 1.336 1996 1.421 1.421 1997 1.380 1.380 1998 1.399 1.399 1999 2.862 2.862 2000 1.424 1.424 2001 1.565 1.565 2002 1.826 1.826 2003 1.419 1.419 2004 2.678 2.678 2005 1.224 1.224 2006 1.081 1.081 2007 2.503 2.503 2008 2.016 2.016 2009 1.863 1.863 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 2.8618 2.8618 2 2.6776 2.6776 3 2.5682 2.5682 4 2.5026 2.5026 5 2.1237 2.1237 6 2.0521 2.0521 7 2.0516 2.0516 8 2.0170 2.0170 9 2.0158 2.0158 10 2.0094 2.0094 11 2.0018 2.0018 12 1.8666 1.8666 13 1.8628 1.8628 14 1.8411 1.8411 15 1.8259 1.8259 16 1.7605 1.7605 17 1.7285 1.7285 18 1.6829 1.6829 19 1.6531 1.6531 20 1.6013 1.6013 21 1.5652 1.5652 22 1.5279 1.5279 23 1.5246 1.5246 24 1.5060 1.5060 25 1.5026 1.5026 26 1.4991 1.4991 27 1.4833 1.4833 28 1.4607 1.4607 29 1.4245 1.4245 30 1.4211 1.4211 31 1.4186 1.4186 32 1.3988 1.3988 33 1.3915 1.3915 34 1.3801 1.3801 Page 90 of 407 35 1.3425 1.3425 36 1.3355 1.3355 37 1.3289 1.3289 38 1.3075 1.3075 39 1.3024 1.3024 40 1.2672 1.2672 41 1.2266 1.2266 42 1.2255 1.2255 43 1.2236 1.2236 44 1.2208 1.2208 45 1.2191 1.2191 46 1.2028 1.2028 47 1.1980 1.1980 48 1.1969 1.1969 49 1.1720 1.1720 50 1.1660 1.1660 51 1.1316 1.1316 52 1.1200 1.1200 53 1.1041 1.1041 54 1.0903 1.0903 55 1.0809 1.0809 56 1.0798 1.0798 57 1.0372 1.0372 58 1.0216 1.0216 59 1.0174 1.0174 60 1.0011 1.0011 61 0.9352 0.9352 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 91 of 407 Conveyance calculation for Monster Road (East side of project). WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: 20190308 MonRdEastConv Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 3/8/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Ex ROw Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Page 92 of 407 Impervious Land Use acre ROADS MOD 0.2 Impervious Total 0.2 Basin Total 0.2 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : EX ROW DEV Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS MOD 0.2 Impervious Total 0.2 Basin Total 0.2 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.2 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.2 ___________________________________________________________________ Page 93 of 407 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.088797 5 year 0.112746 10 year 0.129082 25 year 0.15034 50 year 0.166655 100 year 0.183402 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.088797 5 year 0.112746 10 year 0.129082 25 year 0.15034 Backwater Analysis 50 year 0.166655 100 year 0.183402 Backwater Analysis ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.112 0.112 1950 0.117 0.117 1951 0.067 0.067 1952 0.058 0.058 1953 0.069 0.069 1954 0.071 0.071 1955 0.085 0.085 1956 0.080 0.080 1957 0.083 0.083 1958 0.072 0.072 1959 0.080 0.080 1960 0.076 0.076 1961 0.074 0.074 1962 0.064 0.064 1963 0.076 0.076 1964 0.077 0.077 1965 0.087 0.087 1966 0.063 0.063 1967 0.102 0.102 1968 0.136 0.136 1969 0.080 0.080 1970 0.081 0.081 1971 0.098 0.098 1972 0.098 0.098 1973 0.064 0.064 1974 0.092 0.092 1975 0.098 0.098 1976 0.074 0.074 1977 0.074 0.074 1978 0.109 0.109 1979 0.131 0.131 1980 0.136 0.136 1981 0.085 0.085 1982 0.122 0.122 Page 94 of 407 1983 0.101 0.101 1984 0.065 0.065 1985 0.084 0.084 1986 0.073 0.073 1987 0.115 0.115 1988 0.077 0.077 1989 0.120 0.120 1990 0.141 0.141 1991 0.125 0.125 1992 0.065 0.065 1993 0.083 0.083 1994 0.072 0.072 1995 0.077 0.077 1996 0.099 0.099 1997 0.078 0.078 1998 0.083 0.083 1999 0.177 0.177 2000 0.082 0.082 2001 0.102 0.102 2002 0.105 0.105 2003 0.105 0.105 2004 0.172 0.172 2005 0.068 0.068 2006 0.063 0.063 2007 0.162 0.162 2008 0.115 0.115 2009 0.126 0.126 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.1774 0.1774 2 0.1724 0.1724 3 0.1623 0.1623 4 0.1406 0.1406 5 0.1364 0.1364 6 0.1358 0.1358 7 0.1312 0.1312 8 0.1261 0.1261 9 0.1246 0.1246 10 0.1217 0.1217 11 0.1200 0.1200 12 0.1172 0.1172 13 0.1149 0.1149 14 0.1146 0.1146 15 0.1124 0.1124 16 0.1089 0.1089 17 0.1054 0.1054 18 0.1046 0.1046 19 0.1025 0.1025 20 0.1022 0.1022 21 0.1010 0.1010 22 0.0991 0.0991 23 0.0984 0.0984 24 0.0983 0.0983 25 0.0977 0.0977 Page 95 of 407 26 0.0917 0.0917 27 0.0870 0.0870 28 0.0850 0.0850 29 0.0849 0.0849 30 0.0836 0.0836 31 0.0832 0.0832 32 0.0830 0.0830 33 0.0828 0.0828 34 0.0818 0.0818 35 0.0809 0.0809 36 0.0804 0.0804 37 0.0801 0.0801 38 0.0800 0.0800 39 0.0777 0.0777 40 0.0771 0.0771 41 0.0769 0.0769 42 0.0767 0.0767 43 0.0765 0.0765 44 0.0762 0.0762 45 0.0739 0.0739 46 0.0737 0.0737 47 0.0737 0.0737 48 0.0731 0.0731 49 0.0724 0.0724 50 0.0723 0.0723 51 0.0711 0.0711 52 0.0694 0.0694 53 0.0675 0.0675 54 0.0668 0.0668 55 0.0655 0.0655 56 0.0651 0.0651 57 0.0644 0.0644 58 0.0638 0.0638 59 0.0631 0.0631 60 0.0626 0.0626 61 0.0580 0.0580 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. ___________________________________________________________________ Page 96 of 407 Design Q’s for the 25-year Backwater analysis: (Basin A) (Basin B + Basin Dev Offsite Tributary) (Basin C) (Roof) Page 44 ADD (Page 48 + Page 60) ADD Page 52 ADD Page 65 Pipe Segments Pipe Segments Pipe Segments Pipe Segments 4 through 2 5 through 7 13 through 15 17 through Ex. SDMH 5 through 4 7 through 9 15 through 17 9 through 13 13 through 15 Site stormwater piping was designed to convey the 100-year event under Manning’s Equation. The Backwater Analysis confirms that the project is capable of conveying the 25 and 100-year events. Page 97 of 407 Design Q’s for the 100-year Backwater analysis: (Basin A) (Basin B + Basin Dev Offsite Tributary) (Basin C) (Roof) Page 44 ADD (Page 48 + Page 60) ADD Page 52 ADD Page 65 Pipe Segments Pipe Segments Pipe Segments Pipe Segments 4 through 2 5 through 7 13 through 15 17 through Ex. SDMH 5 through 4 7 through 9 15 through 17 9 through 13 13 through 15 Site stormwater piping was designed to convey the 100-year event under Manning’s Equation. The Backwater Analysis confirms the project is capable of conveying the 25 and 100-year events. Page 98 of 407 Design Q’s for the 25 and 100-year Backwater analysis may be found on page 94 of this report. Page 99 of 407 SECTION 6.0 SPECIAL REPORTS AND STUDIES Page 100 of 407 Section 6 – Special Reports and Studies Geotechnical Report by Terra Associates Inc. Monster Road Basin Study Page 101 of 407 Page 102 of 407 Page 103 of 407 Page 104 of 407 Page 105 of 407 Page 106 of 407 Page 107 of 407 Page 108 of 407 Page 109 of 407 Page 110 of 407 Page 111 of 407 Page 112 of 407 Page 113 of 407 Page 114 of 407 Page 115 of 407 Page 116 of 407 Page 117 of 407 Page 118 of 407 Page 119 of 407 Page 120 of 407 Page 121 of 407 Page 122 of 407 Page 123 of 407 Page 124 of 407 Page 125 of 407 Page 126 of 407 Page 127 of 407 Page 128 of 407 Page 129 of 407 Page 130 of 407 Page 131 of 407 Page 132 of 407 Page 133 of 407 Page 134 of 407 Page 135 of 407 Monster Road Basin Study Page 136 of 407 Page 137 of 407 Page 138 of 407 Page 139 of 407 Page 140 of 407 Page 141 of 407 Page 142 of 407 Page 143 of 407 Page 144 of 407 Page 145 of 407 Page 146 of 407 Page 147 of 407 Page 148 of 407 Page 149 of 407 Page 150 of 407 Page 151 of 407 Page 152 of 407 Page 153 of 407 Page 154 of 407 Page 155 of 407 Page 156 of 407 Page 157 of 407 Page 158 of 407 Page 159 of 407 Page 160 of 407 Page 161 of 407 Page 162 of 407 Page 163 of 407 Page 164 of 407 Page 165 of 407 Page 166 of 407 Page 167 of 407 Page 168 of 407 Page 169 of 407 Page 170 of 407 Page 171 of 407 Page 172 of 407 Page 173 of 407 Page 174 of 407 Page 175 of 407 Page 176 of 407 Page 177 of 407 Page 178 of 407 Page 179 of 407 Page 180 of 407 Page 181 of 407 Page 182 of 407 Page 183 of 407 Page 184 of 407 Page 185 of 407 Page 186 of 407 Page 187 of 407 Page 188 of 407 Page 189 of 407 Page 190 of 407 Page 191 of 407 Page 192 of 407 Page 193 of 407 Page 194 of 407 Page 195 of 407 Page 196 of 407 Page 197 of 407 Page 198 of 407 Page 199 of 407 Page 200 of 407 Page 201 of 407 Page 202 of 407 Page 203 of 407 Page 204 of 407 Page 205 of 407 Page 206 of 407 Page 207 of 407 Page 208 of 407 Page 209 of 407 Page 210 of 407 Page 211 of 407 Page 212 of 407 Page 213 of 407 Page 214 of 407 Page 215 of 407 Page 216 of 407 Page 217 of 407 Page 218 of 407 Page 219 of 407 Page 220 of 407 Page 221 of 407 Page 222 of 407 Page 223 of 407 Page 224 of 407 Page 225 of 407 Page 226 of 407 Page 227 of 407 Page 228 of 407 Page 229 of 407 Page 230 of 407 Page 231 of 407 Page 232 of 407 Page 233 of 407 Page 234 of 407 Page 235 of 407 Page 236 of 407 Page 237 of 407 Page 238 of 407 Page 239 of 407 Page 240 of 407 Page 241 of 407 Page 242 of 407 Page 243 of 407 Page 244 of 407 Page 245 of 407 Page 246 of 407 Page 247 of 407 Page 248 of 407 Page 249 of 407 Page 250 of 407 Page 251 of 407 Page 252 of 407 Page 253 of 407 Page 254 of 407 Page 255 of 407 Page 256 of 407 Page 257 of 407 Page 258 of 407 Page 259 of 407 Page 260 of 407 Page 261 of 407 Page 262 of 407 Page 263 of 407 Page 264 of 407 Page 265 of 407 Page 266 of 407 Page 267 of 407 Page 268 of 407 Page 269 of 407 Page 270 of 407 SECTION 7.0 OTHER PERMITS Page 271 of 407 Section 7 – Other Permits A demolition, clearing and grading permit and building will be required for the project. A NPDES permit has been obtained, DOE Permit: WAR306628-20181017-CSWGP A Building permit is anticipated for the project. Page 272 of 407 Page 273 of 407 Page 274 of 407 SECTION 8.0 CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN ANALYSIS AND DESIGN Page 275 of 407 Section 8 – Construction Stormwater Pollution Prevention and Spill Control (CSWPP) Plan Analysis and Design ESC Plan Analysis and Design (Part A) The ESC Plan Analysis and Design is part of this application and is part of the construction drawings. SWPPP Plan Design (Part B) The project proposes clearing more than 1-acre for commercial use; therefore, it is anticipated that a NPDES Permit will be required (DOE Permit No. WAR306628-20181017-CSWGP. Temporary and erosion control (TESC) measures are provided as part of this TIR and construction documents. The SWPPP has been provided with the site development submittal as a separate stand-alone document as well as being included with this report. Page 276 of 407 04Construction Stormwater General Permit Stormwater Pollution Prevention Plan (SWPPP) for Prologis Renton 9 Prepared for: Prologis Permittee / Owner Developer Operator / Contractor Prologis Prologis Prologis City of Renton Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD TBD TBD SWPPP Prepared By Name Organization Contact Phone Number S Nelson Innova Architects 253-572-4903 SWPPP Preparation Date 4/2/2019 Project Construction Dates Activity / Phase Start Date End Date Demolition/Reconstruction 6/25/19 6/25/20 Page 277 of 407 Table of Contents 1 PROJECT INFORMATION 280 1.1 EXISTING CONDITIONS 280 1.2 PROPOSED CONSTRUCTION ACTIVITIES 280 2 CONSTRUCTION STORMWATER BEST MANAGEMENT PRACTICES (BMPS) 282 2.1 THE 13 ELEMENTS 282 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits 282 2.1.2 Element 2: Establish Construction Access 283 2.1.3 Element 3: Control Flow Rates 284 2.1.4 Element 4: Install Sediment Controls 285 2.1.5 Element 5: Stabilize Soils 286 2.1.6 Element 6: Protect Slopes 287 2.1.7 Element 7: Protect Drain Inlets 288 2.1.8 Element 8: Stabilize Channels and Outlets 289 2.1.9 Element 9: Control Pollutants 290 2.1.10 Element 10: Control Dewatering 292 2.1.11 Element 11: Maintain BMPs 293 2.1.12 Element 12: Manage the Project 294 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs 296 3 POLLUTION PREVENTION TEAM 297 4 MONITORING AND SAMPLING REQUIREMENTS 298 4.1 SITE INSPECTION 298 4.2 STORMWATER QUALITY SAMPLING 298 4.2.1 Turbidity Sampling 298 4.2.2 pH Sampling 300 5 DISCHARGES TO 303(D) OR TOTAL MAXIMUM DAILY LOAD (TMDL) WATERBODIES 301 5.1 303(D) LISTED WATERBODIES 301 5.2 TMDL WATERBODIES 301 6 REPORTING AND RECORD KEEPING 302 6.1 RECORD KEEPING 302 6.1.1 Site Log Book 302 6.1.2 Records Retention 302 6.1.3 Updating the SWPPP 302 6.2 REPORTING 303 6.2.1 Discharge Monitoring Reports 303 6.2.2 Notification of Noncompliance 303 Page 278 of 407 List of Tables Table 1 – Summary of Site Pollutant Constituents .................................................................. 280 Table 2 – Pollutants ................................................................................................................ 290 Table 3 – pH-Modifying Sources ............................................................................................. 290 Table 4 – Dewatering BMPs .................................................................................................... 292 Table 5 – Management ........................................................................................................... 294 Table 6 – BMP Implementation Schedule ............................................................................... 295 Table 7 – Team Information .................................................................................................... 297 Table 8 – Turbidity Sampling Method ...................................................................................... 298 Table 9 – pH Sampling Method ............................................................................................... 300 List of Appendices Appendix/Glossary A. Site Map B. BMP Detail C. Correspondence D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information G. Contaminated Site Information H. Engineering Calculations Page 279 of 407 List of Acronyms and Abbreviations Acronym / Abbreviation Explanation 303(d) Section of the Clean Water Act pertaining to Impaired Waterbodies BFO Bellingham Field Office of the Department of Ecology BMP(s) Best Management Practice(s) CESCL Certified Erosion and Sediment Control Lead CO2 Carbon Dioxide CRO Central Regional Office of the Department of Ecology CSWGP Construction Stormwater General Permit CWA Clean Water Act DMR Discharge Monitoring Report DO Dissolved Oxygen Ecology Washington State Department of Ecology EPA United States Environmental Protection Agency ERO Eastern Regional Office of the Department of Ecology ERTS Environmental Report Tracking System ESC Erosion and Sediment Control GULD General Use Level Designation NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Units NWRO Northwest Regional Office of the Department of Ecology pH Power of Hydrogen RCW Revised Code of Washington SPCC Spill Prevention, Control, and Countermeasure su Standard Units SWMMEW Stormwater Management Manual for Eastern Washington SWMMWW Stormwater Management Manual for Western Washington SWPPP Stormwater Pollution Prevention Plan TESC Temporary Erosion and Sediment Control SWRO Southwest Regional Office of the Department of Ecology TMDL Total Maximum Daily Load VFO Vancouver Field Office of the Department of Ecology WAC Washington Administrative Code WSDOT Washington Department of Transportation WWHM Western Washington Hydrology Model Page 280 of 407 1 Project Information Project/Site Name: Prologis Renton 9 Street/Location: 601 Monster Road SW City: Renton State: WA Zip code: Subdivision: N/A Receiving waterbody: Regional Stormwater Facility 1.1 Existing Conditions Total acreage (including support activities such as off-site equipment staging yards, material storage areas, borrow areas). Total acreage: 10.39 acres Offsite ROW Imp. 0.28 acres Disturbed acreage: 9.35 acres Existing structures: 3.37 acres Landscape topography: 1.45 acres Drainage patterns: One Basin Existing Vegetation: About 1.04 acres of existing landscape will not be disturbed Critical Areas (wetlands, streams, high erosion risk, steep or difficult to stabilize slopes): Steep slope located on the south side of the site which will be placed in a dedicated protection easement List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: Regional Stormwater Facility then to the Black River Category 5 Table 1 includes a list of suspected and/or known contaminants associated with the construction activity. Table 1 – Summary of Site Pollutant Constituents Constituent (Pollutant) Location Depth Concentration See DOE's Cleanup Site ID 11481 AOC1 & AOC2 4 to 8 feet Trichloroethylene (TCE) AOC4 (NE bldg. corner) 6.5 to 14 feet 188 (µg/m3) 1.2 Proposed Construction Activities Description of site development (example: subdivision): Existing commercial site/building redevelopment; new building and site improvements. Description of construction activities (example: site preparation, demolition, excavation): Site prep, demolition,preload; excavation, utility installation and reconstruction Page 281 of 407 Description of site drainage including flow from and onto adjacent properties. Must be consistent with Site Map in Appendix A: The entire site flows to an existing off-site regional stormwater facility. A portion of the site flows onto Monster Road which drains to the same facility. A small vegetated portion of the developed right of way along the east side of the project site drains onto the site. Likewise a small paved portion of the property along the west side will sheet flow uncaptured. This is true in the existing and developed condition. Otherwise the majority of the site will be captured and conveyed via tightline to the regional private facility. Description of final stabilization (example: extent of revegetation, paving, landscaping): New Building, parking and landscaping. Site will continue to flow to the existing off-site regional stormwater facility Contaminated Site Information: Proposed activities regarding contaminated soils or groundwater (example: on-site treatment system, authorized sanitary sewer discharge): The site has been assigned Cleanup Site ID 11481 by the Dept of Ecology. Three Areas of Concern (AOC1, AOC2, AOC4) were indicated by Floyd | Snider in their 2017 Phase 1 ESA which necessitate further action. AOC4 requires excavation and removal of the contaminated material and has been addressed in the Floyd | Snider Fill and Grade Plans which have been submitted to the City. AOC1 and AOC2 have been addressed in the site development plans prepared by Innova Architects. Any soil excavated in these area will be directly loaded into trucks and hauled to a Subtitle D facility. Additionally, all stormwater and groundwater that enters these areas during excavation will be pumped to a portable sediment tank, filtered and pumped into the sanitary sewer system. Page 282 of 407 2 Construction Stormwater Best Management Practices (BMPs) The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e., hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. 2.1 The 13 Elements 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits List and describe BMPs: Locate property lines, silt fencing, orange construction fencing to indicate areas to be protrected (steep slopes will not be disturbed). Installation Schedules: Prior to construction activity Inspection and Maintenance plan: Inspect daily and maintain as needed Responsible Staff: Contractor and CESCL Page 283 of 407 2.1.2 Element 2: Establish Construction Access List and describe BMPs: A standard rock construction entrance will be implermented and has been outlined on the Erosion Control plans. Installation Schedules: Prior to to construction activity. Inspection and Maintenance plan: In accordance with the approved plans, jurisdictional requirements and as requested per CESCL Responsible Staff: Contractor and CESCL Page 284 of 407 2.1.3 Element 3: Control Flow Rates Will you construct stormwater retention and/or detention facilities? Yes No Will you use permanent infiltration ponds or other low impact development (example: rain gardens, bio-retention, porous pavement) to control flow during construction? Yes No List and describe BMPs: Temporary flow control, during construction, will be addressed by a sediment pond, sediment trap, silt fencing and straw wattles. Sediment trap and pond sizing calculations have been provided in Appendix H of this report. As part of this project the owner will be sawcutting the existing concrete slab in order to save and reuse as much of the existing concrete floor as is practicable to be used for the new structure. Since the existing concrete slab is level, direct conveyance and capture of storm water from the slab is not feasible. Minimal sediment is expected to be on the slab therefore we have proposed the placement of straw wattles around the permiter of the slab to minimize runoff onto the surrounding soils. Additionally, we are proposing to leave an opening near the south- east corner of the slab where stormwater would drain to a rip rap pad and drain into the existing storm system. Please refer to the Civil Plans or the Site Plan section of this report for more information. Permanent stormwater runoff control, for this parcel, is addressed by an existing private regional stormwater facility. Water Quality is being addressed using stormwater modular wetland and oil water seperator. Installation Schedules: Temporary BMP's to be installed prior to construction work Inspection and Maintenance plan: No maintenance is expected, but the CESCL should inspect the existing facility Responsible Staff: CESCL Page 285 of 407 2.1.4 Element 4: Install Sediment Controls List and describe BMPs: Silt fencing, bioswales, wheel wash facilities if warranted, Temporary Construction Stormwater Sedimentation Tank for stormwater that comes into contact with contaminated soils. Installation Schedules: Install prior to construction work. Inspection and Maintenance plan: Inspect daily or as directed by the on-site CESCL. Responsible Staff: Contractor and CESCL Page 286 of 407 2.1.5 Element 5: Stabilize Soils West of the Cascade Mountains Crest Season Dates Number of Days Soils Can be Left Exposed During the Dry Season May 1 – September 30 7 days During the Wet Season October 1 – April 30 2 days Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Anticipated project dates: Start date: 6/25/2019 End date: 6/25/2020 Will you construct during the wet season? Yes No List and describe BMPs: Silt fencing, plastic covering, straw mulch, sediment pond, sediment trap, straw wattles, portable sediment tank and filter system pumped to sewer for runoff that contacts contaminated soils. Installation Schedules: Prior to construction Inspection and Maintenance plan: Daily or as directed by the on-site CESCL Responsible Staff: Contractor and CESCL Page 287 of 407 2.1.6 Element 6: Protect Slopes Will steep slopes be present at the site during construction? Yes No The site contains existing steep slopes along the southern property line. These steep slopes will not be disturbed by the construction and are located outside of the clearing area. List and describe BMPs: Orange construction fencing. Installation Schedules: Prior to construction. Inspection and Maintenance plan: As directed by the CESCL Responsible Staff: Contractor and CESCL Page 288 of 407 2.1.7 Element 7: Protect Drain Inlets List and describe BMPs: Catch Basin Filters, wattles Installation Schedules: Prior to Construction Inspection and Maintenance plan: As required by jurisdictional requirements or as directed by the on-site CESCL Responsible Staff: Contractor and CESCL Page 289 of 407 2.1.8 Element 8: Stabilize Channels and Outlets Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all conveyance systems. List and describe BMPs: Rip rap pads will be installed at inlet and outlet locations on sediment pond and trap. Installation Schedules: Prior to construction activity Inspection and Maintenance plan: As required by jurisdictional requirements or as directed by the on-site CESCL Responsible Staff: Contractor and CESCL Page 290 of 407 2.1.9 Element 9: Control Pollutants The following pollutants are anticipated to be present on-site: Table 2 – Pollutants Pollutant (List pollutants and source, if applicable) Sediment during reconstruction Building debris during demolition will be transported to an approved disposal facility Pollutants managed by remedial action work plan (AOC4) - See Floyd Snider Plans Concrete Handling Pollutants in AOC1 and AOC2 Sawcutting List and describe BMPs: Sediment fencing, wattles, sediment pond, sediment trap, plastic covering, and other as directed by the on-site CESCL in conjunction with the Floyd Snider Plans Installation Schedules: Prior to and during site construction Inspection and Maintenance plan: As required by jurisdictional requirements or as directed by the on-site CESCL Responsible Staff: Contractor and CESCL Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? Yes No List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: N/A Will wheel wash or tire bath system BMPs be used during construction? Yes No List and describe BMPs: Standard Construction Entrance Installation Schedules: Prior to Construction or as directed by the on-site CESCL Inspection and Maintenance plan: As required by jurisdictional requirements or as directed by the on-site CESCL Responsible Staff: Contractor and CESCL Will pH-modifying sources be present on-site? Yes No If yes, check the source(s). Table 3 – pH-Modifying Sources None Bulk cement Cement kiln dust Fly ash Other cementitious materials New concrete washing or curing waters Waste streams generated from concrete grinding and sawing Exposed aggregate processes Dewatering concrete vaults Concrete pumping and mixer washout waters Recycled concrete Page 291 of 407 Recycled concrete stockpiles Other (i.e., calcium lignosulfate) [please describe: ] Describe BMPs you will use to prevent pH-modifying sources from contaminating stormwater. List and describe BMPs: Concrete Washout Area, Sediment Pond, Sediment Trap Installation Schedules: Prior to connstruction or as directed by the on-site CESCL Inspection and Maintenance plan: Daily or as directed by the on-site CESCL Responsible Staff: CESCL Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches, streets, or streams. Excess concrete must not be dumped on-site, except in designated concrete washout areas with appropriate BMPs installed. Will uncontaminated water from water-only based shaft drilling for construction of building, road, and bridge foundations be infiltrated provided the wastewater is managed in a way that prohibits discharge to surface waters? Yes No N/A If yes, provide BMPs to contain the wastewater during infiltration. Prior to infiltration, water from water- only based shaft drilling that comes into contact with curing concrete must be neutralized until pH is in the range of 6.5 to 8.5 (su). List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: N/A Responsible Staff: Contractor and CESCL Page 292 of 407 2.1.10 Element 10: Control Dewatering Control and disposal for the dewatering under the remedial action (AOC4) will be defined by the plans and reports prepared by Floyd Snider. Dewatering methods for AOC1 and AOC2 have been addressed in this report and the civil plans. Check treatment of disposal option for dewatering water, if applicable: Table 4 – Dewatering BMPs Infiltration Transport off-site in a vehicle (vacuum truck for legal disposal) Ecology-approved on-site chemical treatment or other suitable treatment technologies Sanitary or combined sewer discharge with local sewer district approval (last resort) Use of sedimentation bag with discharge to ditch or swale (small volumes of localized dewatering) X Utilize the proposed on-site sedimentation facility List and describe BMPs: Stormwater and groundwater that enters AOC1 and AOC2 during excavation will be pumped to a portable sediment tank, filtered and pumped into the sanitary sewer system. Installation Schedules: As needed or as directed by the on-site CESCL Inspection and Maintenance plan: Dailiy of as directed by on-site CESCL Responsible Staff: Contractor and CESCL Page 293 of 407 2.1.11 Element 11: Maintain BMPs All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained and repaired as needed to ensure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMP specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW). Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to once every calendar month. All temporary ESC BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal of either BMPs or vegetation shall be permanently stabilized. Additionally, protection must be provided for all BMPs installed for the permanent control of stormwater from sediment and compaction. BMPs that are to remain in place following completion of construction shall be examined and restored to full operating condition. If sediment enters these BMPs during construction, the sediment shall be removed and the facility shall be returned to conditions specified in the construction documents. Page 294 of 407 2.1.12 Element 12: Manage the Project The project will be managed based on the following principles: Projects will be phased to the maximum extent practicable and seasonal work limitations will be taken into account. Inspection and monitoring: o Inspection, maintenance and repair of all BMPs will occur as needed to ensure performance of their intended function. o Site inspections and monitoring will be conducted in accordance with Special Condition S4 of the CSWGP. Sampling locations are indicated on the Site Map. Sampling station(s) are located in accordance with applicable requirements of the CSWGP. Maintain an updated SWPPP. o The SWPPP will be updated, maintained, and implemented in accordance with Special Conditions S3, S4, and S9 of the CSWGP. As site work progresses the SWPPP will be modified routinely to reflect changing site conditions. The SWPPP will be reviewed monthly to ensure the content is current. Table 5 – Management Design the project to fit the existing topography, soils, and drainage patterns Emphasize erosion control rather than sediment control Minimize the extent and duration of the area exposed Keep runoff velocities low Retain sediment on-site Thoroughly monitor site and maintain all ESC measures Schedule major earthwork during the dry season Other (please describe) Page 295 of 407 Table 6 – BMP Implementation Schedule Phase of Construction Project Stormwater BMPs Date Wet/Dry Season [Insert construction activity] [Insert BMP] [MM/DD/YYYY] [Insert Season] Initial start of construction Silt Fencing 6/25/2019 Dry and maintain during Interception swale 10/1/19 Wet construction Construction Entrance 6/25/2019 Dry Catch Basin Filters 6/25/19 Dry Wattles 6/25/19 Dry Sedimentation Tank Facilities 6/25/19 Dry Sediment Pond 10/1/19 Wet Sediment Trap 10/1/19 Wet Earth Berms 10/1/19 Wet Page 296 of 407 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs Low Impact BMP’s are not proposed for this project due to the underlying fill soils. No infiltration is recommended by the geotechnical engineer. Page 297 of 407 3 Pollution Prevention Team Table 7 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD [Insert Number] Resident Engineer TBD Emergency Ecology Contact Spills Manager - Rob Walls 425-649-7130 Emergency Permittee/ Owner Contact TBD Non-Emergency Owner Contact TBD Monitoring Personnel TDB Ecology Regional Office Bellevue Office 425-649-7000 Page 298 of 407 4 Monitoring and Sampling Requirements Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: A record of the implementation of the SWPPP and other permit requirements Site inspections Stormwater sampling data File a blank form under Appendix D. The site log book must be maintained on-site within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See CSWGP Special Condition S8 and Section 5 of this template. 4.1 Site Inspection Site inspections will be conducted at least once every calendar week and within 24 hours following any discharge from the site. For sites that are temporarily stabilized and inactive, the required frequency is reduced to once per calendar month. The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with the applicable requirements of the CSWGP. 4.2 Stormwater Quality Sampling 4.2.1 Turbidity Sampling Requirements include calibrated turbidity meter or transparency tube to sample site discharges for compliance with the CSWGP. Sampling will be conducted at all discharge points at least once per calendar week. Method for sampling turbidity: As directed by the on-site CESCL Table 8 – Turbidity Sampling Method Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size) Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size) The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency less than 33 centimeters. If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to or greater than 6 cm, the following steps will be conducted: 1. Review the SWPPP for compliance with Special Condition S9. Make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. Page 299 of 407 3. Document BMP implementation and maintenance in the site log book. If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following steps will be conducted: 1. Telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) within 24 hours. Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, Yakima): (509) 575-2490 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/CRO_nerts_online.html Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/ERO_nerts_online.html Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/NWRO_nerts_online.html Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/SWRO_nerts_online.html 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period 3. Document BMP implementation and maintenance in the site log book. 4. Continue to sample discharges daily until one of the following is true: Turbidity is 25 NTU (or lower). Transparency is 33 cm (or greater). Compliance with the water quality limit for turbidity is achieved. o 1 - 5 NTU over background turbidity, if background is less than 50 NTU o 1% - 10% over background turbidity, if background is 50 NTU or greater The discharge stops or is eliminated. Page 300 of 407 4.2.2 pH Sampling pH monitoring is required for “Significant concrete work” (i.e., greater than 1000 cubic yards poured concrete over the life of the project). The use of recycled concrete or engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD] or fly ash) also requires pH monitoring. For significant concrete work, pH sampling will start the first day concrete is poured and continue until it is cured, typically three (3) weeks after the last pour. For engineered soils and recycled concrete, pH sampling begins when engineered soils or recycled concrete are first exposed to precipitation and continues until the area is fully stabilized. If the measured pH is 8.5 or greater, the following measures will be taken: 1. Prevent high pH water from entering storm sewer systems or surface water. 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate technology such as carbon dioxide (CO2) sparging (liquid or dry ice). 3. Written approval will be obtained from Ecology prior to the use of chemical treatment other than CO2 sparging or dry ice. Method for sampling pH: pH meter or as directed by the on-site CESCL Table 9 – pH Sampling Method pH meter pH test kit Wide range pH indicator paper Page 301 of 407 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies 5.1 303(d) Listed Waterbodies Circle the applicable answer, if necessary: Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? Yes No List the impairment(s): Category 5 waters Black River; impairments are Dissolved Oxygen, Bioassessment and Bacteria If yes, discharges must comply with applicable effluent limitations in S8.C and S8.D of the CSWGP. 5.2 TMDL Waterbodies Waste Load Allocation for CWSGP discharges: Not Applicable Describe the method(s) for TMDL compliance: List and describe BMPs: During construction storm water will be collected and pumped to Bakers Tanks, filtered and pumped into the natural release point for the site and flow to the regional facility. Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water Body form is included in Appendix F. Page 302 of 407 6 Reporting and Record Keeping 6.1 Record Keeping 6.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: A record of the implementation of the SWPPP and other permit requirements Site inspections Sample logs 6.1.2 Records Retention Records will be retained during the life of the project and for a minimum of three (3) years following the termination of permit coverage in accordance with Special Condition S5.C of the CSWGP. Permit documentation to be retained on-site: CSWGP Permit Coverage Letter SWPPP Site Log Book Permit documentation will be provided within 14 days of receipt of a written request from Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP. 6.1.3 Updating the SWPPP The SWPPP will be modified if: Found ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. There is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine additional or modified BMPs are necessary for compliance. An updated timeline for BMP implementation will be prepared. Page 303 of 407 6.2 Reporting 6.2.1 Discharge Monitoring Reports Cumulative soil disturbance is less than one (1) acre; therefore, Discharge Monitoring Reports (DMRs) will not be submitted to Ecology because water quality sampling is not being conducted at the site. Or Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given monitoring period the DMR will be submitted as required, reporting “No Discharge”. The DMR due date is fifteen (15) days following the end of each calendar month. DMRs will be reported online through Ecology’s WQWebDMR System. To sign up for WQWebDMR go to: http://www.ecy.wa.gov/programs/wq/permits/paris/webdmr.html 6.2.2 Notification of Noncompliance If any of the terms and conditions of the permit is not met, and the resulting noncompliance may cause a threat to human health or the environment, the following actions will be taken: 1. Ecology will be notified within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number (Regional office numbers listed below). 2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or correct the noncompliance. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6 cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as required by Special Condition S5.A of the CSWGP. Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, or Yakima County Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman County Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum Include the following information: 1. Your name and / Phone number 2. Permit number Page 304 of 407 3. City / County of project 4. Sample results 5. Date / Time of call 6. Date / Time of sample 7. Project name In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water. Page 305 of 407 Appendix/Glossary A. Site Map Page 306 of 407 Page 307 of 407 Page 308 of 407 Page 309 of 407 Page 310 of 407 B. BMP Detail Page 311 of 407 Page 312 of 407 Page 313 of 407 Page 314 of 407 Page 315 of 407 Page 316 of 407 Page 317 of 407 Page 318 of 407 Page 319 of 407 Page 320 of 407 Page 321 of 407 Page 322 of 407 C. Correspondence Page 323 of 407 Page 324 of 407 Page 325 of 407 Page 326 of 407 Page 327 of 407 Page 328 of 407 D. Site Inspection Form Page 329 of 407 Page 330 of 407 Page 331 of 407 Page 332 of 407 Page 333 of 407 Page 334 of 407 E. Construction Stormwater General Permit (CSWGP) Page 335 of 407 Page 336 of 407 Page 337 of 407 F. 303(d) List Waterbodies / TMDL Waterbodies Information Not Applicable Page 338 of 407 G. Contaminated Site Information Page 339 of 407 Page 340 of 407 Page 341 of 407 Page 342 of 407 Page 343 of 407 Page 344 of 407 Page 345 of 407 Page 346 of 407 Page 347 of 407 Page 348 of 407 Page 349 of 407 Page 350 of 407 Page 351 of 407 Page 352 of 407 Page 353 of 407 Page 354 of 407 Page 355 of 407 Page 356 of 407 H. Engineering Calculations Page 357 of 407 SEDIMENT TRAP SIZING CALCULATIONS - NORTH This sediment trap has been sized to address the expected flow from the developed 10-year recurrence interval at a 15-minute timestep. The design is conservative as we have based it upon the 10-year recurrence and the entire Developed Drainage Basin A plus a portion of the future roof area. It is not feasible to collect all of the Developed Basin A so a portion of this area will be controlled utilizing silt fence, straw wattles, and catch basin inserts. WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: TESC Dev AplusRoof Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 3/29/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : DEV A Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .19 Pervious Total 0.19 Impervious Land Use acre ROADS FLAT 0.42 Impervious Total 0.42 Basin Total 0.61 Element Flows To: Surface Interflow Groundwater Page 358 of 407 ___________________________________________________________________ Name : Future Roof Area Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 1 Impervious Total 1 Basin Total 1 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : DEV A Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .19 Pervious Total 0.19 Impervious Land Use acre ROADS FLAT 0.42 Impervious Total 0.42 Basin Total 0.61 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : Future Roof Area Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 1 Impervious Total 1 Basin Total 1 Element Flows To: Page 359 of 407 Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.19 Total Impervious Area:1.42 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.19 Total Impervious Area:1.42 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.553588 5 year 0.703418 10 year 0.805684 25 year 0.938816 50 year 1.041034 100 year 1.145993 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.553588 5 year 0.703418 10 year 0.805684 Flow for Sediment Trap Sizing 25 year 0.938816 50 year 1.041034 100 year 1.145993 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 360 of 407 Page 361 of 407 Size Sediment Trap (Renton) Prologis Renton 9 Q2 = 0.81 cfs (Peak Flow , 10-year recurrence, 15-min time step) Vsed = 0.00096 ft/s (Particle Settling Velocity) FS = 2 (Factor of Safety) SA = 2*Q2 / Vsed =1679.17 sf, (Surface area at Weir) Surface Area at Weir Provided = 1,751 sf Berm Elev. 28.0 Weir Elev. 27.0 2.5' Settling Zone Elev. 24.5 1.0' Sediment storage Elev. 23.5 Surface Area = FS(Q2/Vsed) (Per 2017 City of Renton Surface Water Manual Section D.2.1.5.1 Sediment Trap) Page 362 of 407 SEDIMENT POND SIZING CALCULATIONS – SOUTH (DEVELOPED BASIN B CONVEYANCE CALC) This sediment pond has been sized to address the expected flow from the developed 10-year recurrence interval at a 15-minute timestep. The design is based upon the 10-year recurrence and the entire Developed Drainage Basin B. In addition, the project will install silt fence, straw wattles, and catch basin inserts to additionally minimize sediment laden water from leaving the site. WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: monsterProl DevBConv Site Name: Monster Road Site Address: 601 Monster Rd City : Renton Report Date: 2/25/2019 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2018/03/02 Version : 4.2.14 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : DEV B Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Steep 1.04 C, Lawn, Flat .86 Page 363 of 407 Pervious Total 1.9 Impervious Land Use acre ROADS FLAT 2.92 SIDEWALKS FLAT 0.03 Impervious Total 2.95 Basin Total 4.85 Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : DEV B Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Steep 1.04 C, Lawn, Flat .86 Pervious Total 1.9 Impervious Land Use acre ROADS FLAT 2.92 SIDEWALKS FLAT 0.03 Impervious Total 2.95 Basin Total 4.85 Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:1.9 Total Impervious Area:2.95 Mitigated Landuse Totals for POC #1 Total Pervious Area:1.9 Total Impervious Area:2.95 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 1.203242 5 year 1.543091 Page 364 of 407 10 year 1.776711 25 year 2.082543 50 year 2.318512 100 year 2.561743 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 1.203242 5 year 1.543091 10 year 1.776711 Flow for Sediment Pond Sizing 25 year 2.082543 50 year 2.318512 100 year 2.561743 ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Page 365 of 407 Size Sediment Pond (Renton) Prologis Renton 9 Surface Area = FS(Q2/Vsed) Sub Basin Dev B area flowing to proposed sediment pond. Q10 =1.777 cfs (Peak Flow Developed , 10-yr recurrence, 15-min time step) Vsed = 0.00096 ft/s (Particle Settling Velocity) FS = 2 (Factor of Safety) SA = 2*Q2 / Vsed =3702.08 sf, (Surface area at Top of Riser) (Per 2017 City of Renton Surface Water Manual Section D.2.1.5.2 Sediment Pond) Elev. 28.0 berm Surface Area at Top of Riser Provided = 4511 Elev. 27.0 overflow weir Elev. 26.0 top of riser 2.5' Settling Zone Elev. 23.5' 1' Sediment storage Elev. 22.5' Principal Spillway (Riser) Diameter Sizing (Peak Flow Developed, 10-yr recurrence, 15-min time step) Q10 = 1.777 cfs (Peak Flow, 10yr Developed ) H = 1.00 ft (Head measured from Top of Riser to Crest of emergency spillway) Diameter = 8"= 12.0 Q = c[(pi)d^2/4][(2gh)^1/2] d =12.00 IN. Orfice diameter c =0.62 Sharp edged orfice constrant g =32.2 Ft/Sec^2 gravitation constant h =1.000 FT. head on orfice Q = 3.91 CFS Principal Spillway Diameter is Acceptable Dewatering Orifice Sizing Ao =(As(2*h)0.5)/(10.6*3600*T*g0.5) Ao= 0.001885 (Orifice Area , Square Feet ) As= 3702.08 (Pond surface Area, Square Feet) h =3.5 (Height of Riser in Feet) T = 24 (Dewatering Time, HRs g = 32.2 (Acceleration of gravity ft/sec 2) Dewatering Orifice Diameter D = 24 * (Ao / 3.14)^.5 = 0.59 in (9/16" orifice) Q = ca 2gh Page 366 of 407 SECTION 9.0 BOND QUANITITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT Page 367 of 407 Section 9 – Bond Quantities, Facility Summaries, and Declaration of Covenant A Bond Quantity Worksheet and Facility Summary has been provided for review. Page 368 of 407 Page 369 of 407 Page 370 of 407 Page 371 of 407 Page 372 of 407 Page 373 of 407 Page 374 of 407 Page 375 of 407 Page 376 of 407 Page 377 of 407 Page 378 of 407 Page 379 of 407 Page 380 of 407 Page 381 of 407 SECTION 10.0 OPERATIONS AND MAINTENANCE MANUAL Page 382 of 407 Section 10 – Operations and Maintenance Manual An operations and maintenance manual has been provided for review. Page 383 of 407 Prologis Renton 9 601 Monster Road SW Maintenance and Source Control Manual For: Prologis 12720 Gateway Dr., Suite 110 Tukwila, WA 98168 By: Innova Architects 950 Pacific Avenue, Suite 450 Tacoma, Washington 98402 253-572-4903 Date: April 2019 Job No: 17-045 Parcel: 2423049008 Permit No: Engineer: Steve T. Nelson, P.E. Contact: Steve T. Nelson, P.E. Innova Architects 950 Pacific Avenue, Suite 450 Tacoma, Washington 98402 253-572-4903 SNelson@INNOVAarchitects.com April 3, 2019 Page 384 of 407 Table of Contents Section 1 – Project Description Section 2 – Maintenance Importance and Intent Section 3 – Responsible Parties Section 4 – Facilities Requiring Maintenance Section 5 – Vegetation Maintenance Section 6 – Pollution Source Control Measures Section 7 – Annual Cost of Maintenance Appendix A: Maintenance Checklists Appendix B: Stormwater Plan Page 385 of 407 Section 1 – Project Description The proposed project site is located at 601 Monster Road SW, Renton, Washington in King County on Parcel Number 242304-9008. The property is located inside the city of limits of the City of Renton. The total parcel area is 9.61 acres. This site’s redevelopment will consist of expanding the existing building’s footprint by about 0.367 acres to about 3.75 acres and the pollution generating impervious surfaces will be expanded by about 1.102 acres to about 3.29 acres. The proposal is for three accesses off Monster Road SW (one new) and using the existing sidewalk along most of Monster Road SW but adding a new section of curb, gutter and sidewalk along the east side of the site. The landscape buffer will be added to. Sewer, water and other utilities common to this type of project (power, cable, phone, etc.) are available in along Monster Road SW. Currently this properly has an existing commercial building, access and parking which is generally around the site. The general ground cover is mostly grasses, a few brushes and a few trees. Grades across the property generally slope from southeast corner to northwest corner with slopes ranging between 1 to 5 percent ending next to Monster Road SW. There is a small much steeper area next to the south property line that runs around 30 percent. Total vertical relief across the site, not counting this steep section is approximately 15-feet from an elevation of 39 along the existing parking area at the southeast corner to an elevation of 24 at the northwest property corner next to Monster Road SW. The project is bounded on the west and south by existing commercial buildings, on the east by Monster Road SW and then King County sewage treatment facility, and on the north by Monster Road SW and then a city park and then Black River. For stormwater quantity, this property, along with the surrounding properties, is part of a private shared regional stormwater facility which is just west of this site. Utilizing this stormwater facility eliminates the need for an on-site detention facility. Stormwater quality will be to provide enhanced basic water quality treatment along with utilizing an oil/water separator for the truck dock area and then further cleaning water by using a linear modular wetland system which meets the enhanced basic water quality treatment. New storm connections will be made to the existing storm line which runs along the south side of the existing building. The project is proposing to connect the roof drains (clean water) directly to the last manhole on this existing storm lines that continues to the existing stormwater facilities just west of this site. Page 386 of 407 Section 2 – Maintenance Importance and Inlet The importance of maintenance for the proper functioning of stormwater control facilities cannot be over-emphasized. A substantial portion of failures (clogging of filters, re-suspension of sediments, loss of storage capacity, etc.) are due to inadequate maintenance. Stormwater BMP maintenance is essential to ensure that BMPs function as intended throughout their life cycle. The fundamental goals of maintenance activities are to insure the entire flow regime and treatment train designed for this site continue to fully function. For this site these include: Maintain ability of storm facility to attenuate flow rates Maintain the oil/water separator facility Maintain ability to safely convey design stormwater flows Maintain the Linear Modular Wetland System Preserve soil and plant health, as well as stormwater flow contact with plant and soil system Clearly identify systems so they can be protected Keep maintenance costs low Prevent large-scale or extensive stormwater system failures Prevent water quality violations or damage to downstream properties The intent of this section and manual is to pass on to the responsible party(s) all the information critical to understand the design of the system, risks and consideration for proper use, suggestions for maintenance frequencies, and const so that realistic budgets can be established. Section 3 – Responsible Party DCT Industrial will responsible for the maintenance and operations of the onsite storm system. Section 4 – Facilities Requiring Maintenance All stormwater structures, oil/water separator facility, linear modular wetland system, cleanouts and conveyance piping will require regular maintenance. Section 5 – Vegetation Maintenance Plant Maintenance All required landscaping shall be maintained for the life of the project. Plants shall be maintained in a vigorous and healthy condition, free from diseases, pests and weeds. All landscape areas shall be kept free of trash. Plants maintenance standards apply for the life of the project and to all future property owners. Tree Pruning Pruning of Significant and Legacy trees shall be done by a professional tree service only. Page 387 of 407 All plant materials shall be pruned and trimmed as necessary to maintain a healthy growing condition or to prevent primary limb failure. Pruning of trees shall be limited to thinning, windowing, or skirting, unless otherwise restricted by critical area regulations. o Thinning: Removal of foliage evenly through the tree crown maintaining tree form and health. Not more than one quarter of the total leaf area is removed. o Windowing: The practice of creating a “window” within the tree crown. The overall crown remains intact. When windowing one side of a tree, it may be necessary to prune the opposite side of the tree to maintain balance. o Skirting: The practice of opening up views by removing the lower limbs of a tree. As a rule, do not limb up more than one-their of the tree’s visible height. Section 6 – Pollution Source Control Measures Pollution source control measures will be provided for individual lots during the building permit phase of the project. Section 7 – Annual Cost of Maintenance Annual maintenance costs are estimated to be approximately $5,000 per year. Page 388 of 407 Appendix A: Maintenance Checklists Page 389 of 407 Page 390 of 407 Page 391 of 407 Page 392 of 407 Page 393 of 407 Page 394 of 407 Page 395 of 407 Page 396 of 407 Page 397 of 407 Page 398 of 407 Page 399 of 407 Page 400 of 407 Page 401 of 407 Page 402 of 407 Page 403 of 407 Page 404 of 407 Page 405 of 407 Page 406 of 407 Appendix B Stormwater Plan Page 407 of 407