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Home My WebLink AboutRS_TIR_FINAL_20170515_Signed.pdfFinal Technical Information Report VESTED TO 2009 KCSWDM Sunset Neighborhood Park Prepared for City of Renton March 29, 2017 1100 112th Ave NE Suite 500 Bellevue, WA 98004 DEVELOPMENT ENGINEERING Ann Fowler 05/19/2017 R-3950 FINALC-17000280 PR-15000009 LUA-16000966 III Contents Section Page Acronyms and Abbreviations .................................................................................................................... v 1 Project Overview ...................................................................................................................... 1-1 1.1 Existing Site Conditions .......................................................................................................... 1-1 1.1.1 Existing Utilities ......................................................................................................... 1-2 1.1.2 Soils ........................................................................................................................... 1-2 1.2 Proposed Conditions .............................................................................................................. 1-2 2 Conditions and Requirements Summary .................................................................................... 2-1 3 Offsite Analysis ......................................................................................................................... 3-1 3.1 Upstream Analysis ................................................................................................................. 3-1 3.2 Downstream Analysis............................................................................................................. 3-1 4 Flow Control Analysis and Design .............................................................................................. 4-1 4.1 Part A - Existing Site Hydrology .............................................................................................. 4-1 4.2 Part B – Proposed Site Hydrology .......................................................................................... 4-1 4.3 Part C - Performance Standards ............................................................................................ 4-3 4.3.1 Flow Control BMPs .................................................................................................... 4-3 4.3.2 Conveyance ............................................................................................................... 4-4 5 Conveyance System Analysis and Design ................................................................................... 5-1 5.1 Existing Storm Drains ............................................................................................................. 5-1 5.2 Proposed Storm Drains .......................................................................................................... 5-1 5.3 Utilities ................................................................................................................................... 5-2 6 Special Reports and Studies ....................................................................................................... 6-1 7 Other Permits ........................................................................................................................... 7-1 8 ESC Analysis and Design ............................................................................................................ 8-1 8.1 ESC Measures ......................................................................................................................... 8-1 8.1.1 Wet Season Construction ......................................................................................... 8-2 8.1.2 Minimum ESC Requirements After Construction ..................................................... 8-3 9 Bond Quantities, Facility Summaries, and Declaration of Covenant ............................................ 9-1 10 Operations and Maintenance Manual...................................................................................... 10-1 11 References .............................................................................................................................. 11-1 Appendixes A King County Surface Water Design Manual TIR Worksheet B Design Drawings C Calculations Tables Table 4-1 Project Site Land Cover Areas .......................................................................................................... 4-2 CONTENTS, CONTINUED Section Page IV Figures 1-1 Sunset Park Vicinity Map ..................................................................................................................... 1-3 1-2 Soils Map ............................................................................................................................................. 1-4 4-1 Existing (2011) Land Cover .................................................................................................................. 4-4 4-2 Sunset Neighborhood Park Proposed Land Cover .............................................................................. 4-5 V Acronyms and Abbreviations Ac Acre BMP best management practice cfs cubic feet per second ESC erosion and sedimentation control GSI green stormwater infrastructure KCRTS King County Runoff Time Series KCSWDM 2009 King County, Washington Surface Water Design Manual NPDES National Pollutant Discharge Elimination System NRCS Natural Resources Conservation Service PGIS pollution-generating impervious surface PGPS pollution-generating pervious surface PSE Puget Sound Energy RdC Ragnar-Indianola association soil ROW right-of-way TDA threshold discharge area TIR technical information report Ur Urban Soil SECTION 1 1-1 Project Overview Located in Renton, Washington, this project includes the construction of a new Sunset Neighborhood Park and associated facilities. The technical information report (TIR) worksheet in Appendix A lists the general project elements. A project vicinity map is shown in Figure 1-1. The Sunset Neighborhood Park Project is part of a larger Sunset Terrace Redevelopment plan implemented by the City of Renton (City). The City completed and adopted the Sunset Community Plan and Planned Action Environmental Impact Statement (City of Renton, 2010a) in 2010, which included the adoption of the Sunset Area Surface Water Master Plan (City of Renton, 2011). The Sunset Area Surface Water Master Plan identifies stormwater improvements to convey, treat, detain and infiltrate runoff from the existing and future land cover conditions. The Sunset Neighborhood Park Master Plan adopted in 2014 provided a vision and layout of the park to incorporate active and passive recreation and environmental education opportunities. Park design elements include adult fitness equipment, children’s play area, a looped walking pathway system, a small water feature, picnic areas, a picnic gazebo, performance seating/open space lawn area with pergolas and benches, and a restroom building (HBB, 2014). Recent adjacent projects include the Harrington Avenue Green Connections, Sunset Terrace Regional Stormwater Facility, King County Library, and Sunset Lane NE projects. The Harrington Avenue Green Connections Project, constructed in 2014, installed roadside rain gardens along Harrington Avenue just north of the Sunset Neighborhood Park site. The Sunset Terrace Regional Stormwater Facility, completed in 2015 within the Sunset Neighborhood Park, utilizes bioretention cells and infiltration to improve the water quality of the Sunset Area Community pollution generating surfaces, which discharge to Johns Creek and Lake Washington. A new King County Branch Library was constructed in 2015 at the corner of NE 10th Street and Sunset Lane NE. The City also recently constructed the Sunset Lane NE project (also part of the larger Sunset Terrace Redevelopment Plan) which realigned the existing roadways to allow for development of the park. All these capital improvement projects mentioned above are independent projects. The Sunset Neighborhood Park will be designed and constructed in multiple phases. The design of Phase 1 is currently underway and construction is anticipated to be complete in 2017. Future phases of the design and construction will come later as funding becomes available. This Technical Information Report (TIR) reflects the fully built-out Sunset Neighborhood Park (including all future phases) project for City permitting purposes. 1.1 Existing Site Conditions Site conditions in 2011 are considered to be the project’s pre-developed (existing) conditions (back to Sunset Area Community Planned Action FEIS [City of Renton, 2010a] land cover conditions) for the City’s full drainage review purposes. The project site is located in the Sunset Community area of Renton and consists of mixed single-family and multi-family residential and commercial neighborhoods with adjacent schools and public lands. The terrain on the project site is relatively flat, with a less than 5 percent average slope toward the south. In 2011, the project site consisted of a multi-family residential neighborhood owned by the Renton Housing Authority, and included 13 residential buildings and their associated driveways, concrete walkways, utilities, and public roadway. The land to the north (upstream) of the site is a mix of single-family residential, residential roadway, and commercial lots hosting several businesses. Due to the recent completion of the Sunset Lane NE project and Sunset Terrace Regional Facility project, at the time of park construction under this project, none of the housing will remain, most of the underground utilities will have been removed, and a stabilized ground surface will be present. New utilities including SECTION 1 PROJECT OVERVIEW 1-2 water, sewer, power, telecommunication, and gas will be installed around the park by the Sunset Lane NE project. The surface water runoff from this site generally sheet flows to the southwest onto adjacent roadways, and is collected in existing storm drains in Harrington Avenue NE and Sunset Lane NE. These then connect into a 24-inch storm drain in NE Sunset Boulevard. The project area drains to Johns Creek and ultimately Lake Washington. 1.1.1 Existing Utilities Existing utilities along Harrington Ave NE, NE 10th Street and Sunset Lane NE and within the site include: • Sanitary sewer owned by the City of Renton • Water owned by the City of Renton • Underground power owned by Puget Sound Energy (PSE) • Gas main owned by PSE 1.1.2 Soils Soils at the site are mapped as Ragnar-Indianola association, sloping (RdC) and Arents, Alderwood material, 6 to 15 percent slopes (AmC) according to the Natural Resources Conservation Service (NRCS) Web Soil Survey (2014). Ragnar-Indianola association soil is classified as a Hydrologic Group A soil, which is characterized as relatively permeable outwash soils with a high capacity for infiltration. The Arents, Alderwood soil is classified as a Hydrologic Group B soil, which is characterized by low to moderately low capability to transmit water. Soils to the north and west of the site are mapped as Urban land (Ur). Urban land is classified as a Hydrological Group C soil, which is characterized as relatively impermeable glacial till overlain by weathered sand and gravel. See Figure 1-2 for the NRCS soil type map of the project area. Detailed soil information and boring locations for the northeast corner of the site (location of the regional stormwater facility) can be found in Sunset Stormwater Retrofit Low-Impact Development Project Geotechnical Data and Recommendations Report (CH2M HILL, 2012). 1.2 Proposed Conditions Proposed conditions are defined as the fully built-out conditions of the Sunset Neighborhood Park, including both Phase 1 and all future phases. Refer to Section 4.2 below for a full description of proposed site conditions. LENTOWN SBat1g0<St Tukwila Starflre Sports • V ACME Bowling, 11 Billiards & Events PROJECT-NO: 677149 S 1171hS1 S 11.tthSI .s.'120,hst Bryn Mawr-Skyway S116rhSt S 132nd St I "' t : \ PROJE£T SITE .... N 3rd St Renton , Berliner Pub s F\.vetor VICINITY MAP NOTTO SCALE FIGURE 1-1SUNSET PARK VICINITY MAP E121hSt ,e, Renton Technical College NORTH Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey Page 1 of 352608705260920526097052610205261070526112052611705260870526092052609705261020526107052611205261170561300561350561400561450561500561550561600561650561700561750561800 561300 561350 561400 561450 561500 561550 561600 561650 561700 561750 561800 47° 30' 4'' N 122° 11' 10'' W47° 30' 4'' N122° 10' 44'' W47° 29' 53'' N 122° 11' 10'' W47° 29' 53'' N 122° 10' 44'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 100 200 400 600Feet 0 35 70 140 210Meters Map Scale: 1:2,480 if printed on A landscape (11" x 8.5") sheet. Soils Map - Figure 3Figure 1-2. Soils Map MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 10, Sep 30, 2014 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 31, 2013—Oct 6, 2013 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey Page 2 of 3 Soils Map - Figure 3Figure 1-2. Soils Map Map Unit Legend King County Area, Washington (WA633) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI AmC Arents, Alderwood material, 6 to 15 percent slopes 5.2 16.8% RdC Ragnar-Indianola association, sloping 18.8 60.1% Ur Urban land 7.2 23.1% Totals for Area of Interest 31.2 100.0% Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey Page 3 of 3 Soils Map - Figure 3Figure 1-2. Soils Map SECTION 2 2-1 Conditions and Requirements Summary The City has adopted the 2017 King County, Washington, Surface Water Design Manual (KCSWDM); however, this project is vested to the 2009 KCSWDM, along with the City of Renton Amendments to the King County Surface Water Design Manual (City of Renton, 2010b) for the design of stormwater facilities. See Performance Standards in Section 4.3 of this report for information about the City’s flow control BMPs and conveyance performance standards applicable to the project. Per the 2009 City of Renton Surface Water Design Manual, the Sunset Neighborhood Park Project is subject to a full drainage review because it results in more than 2,000 square feet of new plus replaced impervious area. Typically in a full drainage review, Core Requirements 1 through 8 as well as Special Requirements 1 through 6 apply to the project. This project will be exempt from some of the core requirements and special requirements. A summary of which requirements will be required or exempt and why is provided below. Core Requirements #1 (Discharge at Natural Location): There are no exemptions to this requirement; therefore, it will apply to this project. All stormwater runoff from the project under proposed conditions will be discharged at the natural location and not diverted to or away from any other downstream areas. Core Requirement #2 (Offsite Analysis): A Level 1 analysis per the Amendments to the King County Surface Water Design Manual (City of Renton, 2010b) is considered to be sufficient because the entire downstream route within the required quarter-mile analysis area is contained in a piped conveyance system. Core Requirement #3 (Flow Control): The project is within a Basic Flow Control Area per the Sunset Area Surface Water Master Plan (CH2M HILL, 2011). Because it will reduce the amount of impervious surface area within the site, the proposed project will create less runoff than that under existing conditions. Therefore, it is assumed to meet the requirement to match existing peak runoff rates, and no flow control facilities are required. The project is subject to Large Lot Low Impervious flow control BMP requirements per the KCSWDM (2009) Section 5.2. Flow control BMPs to be implemented include rain gardens, permeable pavement (park sidewalks), and an infiltration (gravel filled) trench for restroom building rooftop runoff, as well as some limited basic dispersion provided by the park’s shrub and lawn planted areas. Core Requirement #4 (Conveyance System): A new conveyance system was designed as part of the Sunset Lane NE project, which realigned roadways adjacent to the Sunset Neighborhood Park project site. The storm drains for the Sunset Neighborhood Park will tie into this new conveyance system via a 24-inch storm drain pipe that flows to the west along the north side of NE Sunset Boulevard, after leaving the park site. The new conveyance system for the Sunset Neighborhood Park will be designed for a minimum of the 25- year design storm with a minimum of 6 inches of freeboard within each catch basin or manhole per the Amendments to the King County Surface Water Design Manual (City of Renton, 2010b). Core Requirement #5 (Erosion & Sediment Control (ESC)): There are no exemptions for this requirement; therefore, it will apply to this project. ESC plans will be included with the construction plans, and a Construction Stormwater Pollution Prevention Plan will be submitted by the contractor. Core Requirement #6 (Maintenance & Operations): There are no exemptions for the requirement; therefore, it will apply to this project. Maintenance and operations for the site stormwater conveyance used on this project will be entirely owned and operated by the City. The City’s Public Works Department will maintain the Regional Stormwater Facility infrastructure and conveyance pipes, while the City’s Community Services Department will maintain the plants in the Regional Stormwater Facility rain gardens and everything else within the park. Core Requirement #7 (Financial Guarantees & Liability): There are no exemptions for this requirement; therefore, it will apply to the contractor awarded to construct this project. SECTION 2 CONDITIONS AND REQUIREMENTS SUMMARY 2-2 Core Requirement #8 (Water Quality): There are no water quality facilities proposed for this project. This project includes just under 31,000 square feet (0.71 acre) of impervious pathway surface, including an infrequently used maintenance access driveway. Because this maintenance access driveway is not regularly used by motor vehicles, it is not considered to be a pollution-generating impervious surface (PGIS). Other impervious surface area on the project site (total of 0.80 acre) includes restroom building rooftop, curb, and picnic areas, none of which are considered PGIS. The lawn areas in the fully built park (all phases) may be considered pollution-generating pervious surface (PGPS) because they may be subject to the use of pesticides and fertilizers and loss of soil. The requirement for a basic water quality treatment facility for PGPS at the site may be waived if there is a good faith agreement with the City for a landscape management plan to control solids, pesticides, and fertilizers leaving the site. Sheet flow from the park’s lawn areas will drain to bioretention areas (swales and rain gardens) at the southwestern edge in a future phase, which will provide some water quality treatment. Special Requirement #1 (Other Adopted Requirements): This project is within the Sunset Area Surface Water Master Plan (CH2M HILL, 2011) area and subject to those requirements. Special Requirement #2 (Flood Hazard Area Delineation): The project is not located in a flood hazard area based on Figure 4-3-050Q2 of the City of Renton Municipal Code; therefore, this requirement will not apply to this project. Special Requirement #3 (Flood Protection Facilities): This project does not rely on or modify any flood protection facilities and will be exempt from Special Requirement #3. Special Requirement #4 (Source Control): This project is a public park development within City-owned property and does not require a commercial building or commercial site development permit; therefore it is exempt from Special Requirement #4. Special Requirement #5 (Oil Control): This project includes only periodic vehicle access for park maintenance, via the driveway in the northeast portion of the park. Oil control is only required for sites with high-use characteristics as defined by Chapter 1 of the Amendments to the King County Surface Water Design Manual (City of Renton, 2010b). This project does not include any high-use site characteristics and is therefore exempt from oil control requirements. Special Requirement #6 (Aquifer Protection Area): This project is located within Zone 2 of an Aquifer Protection Area based on Figure 4-3-050Q1 of the City of Renton Municipal Code. Open stormwater facilities and conveyance systems such as treatment ponds, stormwater wetlands, infiltration facilities and ditches may be required to use a liner in accordance with Section 1.2.4.3 of the City of Renton Amendments to the 2009 King County Surface Water Design Manual. However, rain gardens do not require liners, per the Amendments to the King County Surface Water Design Manual (City of Renton, 2010b), Section 6.2.4 (Facility Liners). SECTION 3 3-1 Offsite Analysis A desktop offsite analysis was performed to provide upstream and downstream analysis for the project. The study area extends to 1/4-mile downstream of the downstream discharge point on NE Sunset Boulevard. The existing drainage system consists of a buried pipe network. Refer to Section 1 for a description of existing drainage systems. 3.1 Upstream Analysis There are no offsite basins that have surface runoff flow into the Sunset Park project limits, other than the tributary areas that convey stormwater into the Regional Stormwater Facility located in the northeast corner of the park, which is a separate project that was constructed in 2016. The park does not receive any stormwater runoff from roadways and offsite basins; these discharge into the existing storm drain system within the Sunset Lane NE right-of-way. 3.2 Downstream Analysis There is a single discharge location where stormwater will leave the project site, located at Sunset Lane NE just southwest of the project site (see Drawing C-9 in Appendix B). The project is located in one Threshold Discharge Area (TDA). The following downstream analysis information is excerpted from the Sunset Lane NE Project TIR (Perteet, 2015), which includes the storm drain system immediately downstream of the Sunset Neighborhood Park Project and provides the necessary downstream analysis information for this project as well: No downstream analysis was performed in the field for this project because the entire downstream route is within a piped conveyance system with no known problem areas other than possible capacity issues addressed in the Sunset Area Storm Water Master Plan. After leaving Sunset Lane NE, runoff continues in the 24 inch diameter piped conveyance system which flows to the west along the north side of NE Sunset Boulevard. This system remains piped until it crosses under Interstate 405 and outfalls into a series of wetlands beginning near the intersection of Lake Washington Boulevard with Park Avenue N. These wetlands are connected in a series by culverts; when one wetland reaches capacity it begins to overflow to the wetland downstream of it. This series of wetlands eventually outfalls into a creek, which flows in the northwesterly direction within Gene Coulon Memorial Beach Park, and then out into Lake Washington. SECTION 4 4-1 Flow Control Analysis and Design 4.1 Part A - Existing Site Hydrology Under existing conditions, surface water runoff from this site generally drains overland via sheet flow toward the southwest and is collected in existing storm drains in Sunset Lane NE and Harrington Avenue NE. The entire Sunset Neighborhood Park Project area is within one TDA. The Sunset Terrace Regional Stormwater Facility features rain gardens already within the park that currently receive runoff from a tributary area consisting of public right of way on Sunset Boulevard (State Route [SR] 900), NE 10th Street and the proposed King County Library, and also private property on the Greater Highland Shopping Center. Runoff from the western portion of NE 10th Street is also conveyed directly to the facility. These tributary areas and drainage features were reviewed separately as part of the Sunset Terrace Regional Stormwater Facility Project, constructed in 2015. 4.2 Part B – Proposed Site Hydrology Under proposed conditions, surface water runoff will sheet flow generally to the southwest and into proposed French Drains that will convey stormwater to a series of new catch basins and storm drain pipe along the recently realigned Sunset Lane NE. In a future phase, these French Drains will be replaced with rain gardens and swales along the park’s southwestern edge. This system will connect to existing catch basin #13 (shown in Drawing C-9 in Appendix B) in Sunset Lane NE just southwest of the site boundary, which will convey stormwater through the existing piped stormwater conveyance system within the City’s right-of- way. There is no other tributary area to project site. All adjacent roadways drain directly to the existing piped conveyance system within the roadway right-of-way. Impervious surface area on the proposed site will include impervious pathways (pedestrian and maintenance vehicle access), two restroom buildings, a gazebo, picnic areas with tables, and 6-inch concrete curb along the pervious pathways. Pervious surface area will include landscaped planting areas, rain gardens, lawn, pervious pathways, and pervious rubberized safety surfacing at the playground and adult fitness areas. The pervious playground and adult fitness areas will include an underdrain to collect runoff and direct it into the piped stormwater conveyance system on Sunset Lane NE. Existing (2011) and proposed land cover areas are listed below in Table 4-1 and shown in Figures 4-1 (existing) and 4-2 (proposed). Table 4-2 shows the stormwater runoff peak flow rates based on the impervious and pervious areas listed in Table 4-1. The peak flow rates were calculated using KCRTS with 15-minutes time steps, and without any on- site stormwater BMPs. The table shows that the peak flow rates from proposed conditions will be reduced from the existing site conditions. The addition of on-site stormwater management BMPs will further reduce the peak flow rates and volume. SECTION 4 FLOW CONTROL ANALYSIS AND DESIGN 4-2 Table 4-1. Project Site Land Cover Areas Land Cover Type KCRTS Land Cover Type Existing (2011) Proposed (full park build-out) Impervious Concrete or Asphalt Pavement1 Impervious 46,709 sf Roof (Housing) Impervious 25,592 sf Impervious Paths Impervious 16,795 sf Picnic Areas Impervious 975 sf 6-inch Curb Impervious 4,498 sf 12-inch Mow Strip Impervious 414 sf Restroom Building and Gazebo Impervious 1,843 sf Porous Concrete Walkway (50% Impervious) Impervious 7,359 sf Rubberized Safety Surfacing w/ Underdrains (25% Impervious) Impervious 1,932 sf Total Impervious Surface 72,301 sf (1.66 ac) 33,816 sf (0.78 ac) Pervious Shrub/Groundcover Planting Areas Till Grass 9,697 sf Rain Gardens Till Grass 8,715 sf Lawn Areas Till Grass 67,438 sf 74,353 sf Rubberized Safety Surfacing w/ Underdrains (75% Pervious) Till Grass 5,798 sf Porous Concrete Walkway (50% pervious) Till Grass 7,359 sf Total Pervious Surface 67,438 sf (1.55 ac) 105,922 sf (2.43 ac) Total 139,738 sf (3.2 ac) 139,738 sf (3.2 ac) 1 Concrete or asphalt pavement includes existing roadway, and concrete sidewalk and pathway. Table 4-2. KCRTS Peak Flow Rates Storm Event Existing Peak Flow Rates (cfs) Proposed Peak Flow Rates (cfs) 2-year 0.79 0.51 10-year 1.16 1.08 25-year 1.84 1.23 100-year 2.74 2.15 Note: Peak flow rates generated using 15-minute time steps. SECTION 4 FLOW CONTROL ANALYSIS AND DESIGN 4-3 4.3 Part C - Performance Standards The following describe the performance standards to be used for flow control BMPs and conveyance. 4.3.1 Flow Control BMPs Existing and proposed land use types on the project site are compared in Table 4-1 above. Impervious surface area on the site is being reduced as a result of the project, and replaced with pervious pathways and vegetated areas (both lawn and shrub/landscaped). The net decrease in impervious surface area is 1.1 acres. No flow control facilities are currently required or proposed. Large Lot Low Impervious BMPs (per Section 5.2.1.2 of the KCSWDM) to be implemented include the following: • Rain Gardens: The areas upstream of the proposed rain gardens along the southwestern park boundary are mostly pervious lawn and some permeable pavement walkways; the impervious picnic gazebo will drain first to the planted areas upslope from the rain gardens. Runoff from the impervious pathways will sheet flow into lawn areas. Rain gardens and bioretention swales are proposed with 18 inches of bioretention soil, 6 inches of available ponding depth and 6-inch underdrain pipes connecting to the receiving piped conveyance system (24-inch storm drain). See Drawing C-10_P in Appendix B. • Permeable Pavement: The park will include just under 6,000 square feet (0.14 acre) of pedestrian walkways to be composed of permeable pavement (porous concrete), which is modeled as 50 percent effective impervious per the 2009 KCSWDM. Permeable pavement walkways will be composed of 6 inches of pervious cement concrete at a 1.5 percent cross slope, with 8 inches of aggregate base. Construction geotextile will be installed on the sides. Curbs will be 6-inch cement concrete curbs installed flush with the porous concrete section. As noted earlier, the pervious rubberized safety surfacing at the playground and adult fitness areas will be fitted with underdrains that will connect to the piped conveyance system at the south end of the park. Note that per the 2009 KCSWD, synthetic turf with underdrains are modeled as 75 percent grass and 25 percent effective imperious. Until these areas are installed in a future phase, these areas will be drained via sheet flow to a French Drain located adjacent to the impervious concrete pathway. See Drawings C- 8 and C-9 in Appendix B. • Gravel Filled Trench: A gravel filled trench will receive runoff from the restroom building rooftops via a Type 2 catch basin fitted with a down-turned elbow. These trenches will provide some infiltration for rooftop runoff. The Sunset Stormwater Retrofit Low-Impact Development Project Geotechnical Data and Recommendations Report (CH2M HILL, 2012) shows loamy sand soils in the vicinity of the trench (soil boring B-6-12). Per KCSWDM Section C.2.3 (Limited Infiltration), gravel filled trenches require 75 feet of length per 1,000 feet of tributary impervious surface for fine sand/loamy sand soils. The trench therefore requires a length of at least 45 feet for a tributary impervious surface of 600 square feet; the proposed trench shown on Drawing C-8 in Appendix B is 55 feet in length. The trench will be filled with at least 18 inches of washed drain rock, and will be more than 15 feet from the buildings. See details on Drawing C-10 in Appendix B. • Dispersion: Full dispersion of impervious rooftop and pathway surfaces is not possible on the park site because there are no available native (forested) vegetated areas. Some limited dispersion of runoff will occur through the shrub and groundcover areas in the park’s northeastern area, as well as in the lawn areas located throughout the park, adjacent to the pathways. Sheet flow from the lawn area in the western portion of the park will drain to a French Drain with a 6-inch underdrain pipe until bioretention swales and rain gardens are installed after Phase 1. This French Drain will discharge to the existing piped conveyance system described below in Section 4.3.2. SECTION 4 FLOW CONTROL ANALYSIS AND DESIGN 4-4 4.3.2 Conveyance The project’s stormwater conveyance facilities will consist primarily of catch basins and storm drains. The capacity of the new and existing storm drains was analyzed using the Rational Method according to Section 3.2.1 of the KCSWDM (2009). See Appendix C for pipe capacity calculations. 4.3.2.1 Proposed Storm Drains All new conveyance systems will be designed for the 25-year storm. Uniform flow conditions will be used to initially size pipes for capacity. Final pipe sizes will be verified using simple backwater analysis. Excel spreadsheets will be used in both analyses, with the following assumptions: • Pipe material – Smooth wall pipe (concrete or ductile iron pipe) with Manning’s n = 0.014 (uniform) • Minimum pipe diameter – 12 inches • Minimum cover – 2 feet; if lower cover is needed, use class 5 reinforced concrete pipe (RCP) or ductile iron pipe • Minimum velocity: 3 feet per second (fps) • Match crowns at junctions with changes in pipe diameter where possible The project will be designed to use drainage structures from the City of Renton’s Standard Plans. In general, Type 1 and 1L CBs will be used. The maximum pipe diameter for Type 1 CBs is 15 inches, and a maximum of 5 vertical feet will be allowed between the finished grade and the pipe invert. 4.3.2.2 Inlets on a Continuous Grade The new inlets used on this project are catch basins with vaned grates. Inlet capacity was not analyzed because the tributary area is relatively small and outside of vehicle travel lanes. 4.3.2.3 Sag Inlets There are no sag inlets used on this project. SECTION 5 5-1 Conveyance System Analysis and Design This section describes assumptions and site conditions to justify the conveyance design. Permanent conveyance facilities will include catch basin inlets, manholes, 12-inch-diameter storm drains, and 6-inch diameter underdrains. 5.1 Existing Storm Drains The Sunset Lane NE project analyzed the capacity of the receiving conveyance system, and sized the conveyance system for the 25-year design storm event using the King County Backwater Spreadsheet. A 24- inch HDPE storm drain (see Drawing C-9 in Appendix B) collects stormwater runoff from the park as well as the conveyance systems constructed under the Sunset Lane NE project. The following is excerpted from the Sunset Lane NE project TIR (Perteet, 2015): The first conveyance system is a series of catch basins and closed pipes which collect gutter flow from Sunset Lane NE between NE 10th Street and Harrington Avenue NE (Station 10+00 to Station 13+75) and also from NE 10th Street between Harrington Avenue NE and NE Sunset Boulevard (Station 22+50 to 27+00). This system flows to the southeast along the north side of NE 10th Street and then turns to the southwest at Sunset Lane NE and flows along the east side of Sunset Lane NE. It will intercept the emergency overflow from the regional stormwater facility, which was assumed to be in complete failure for conveyance pipe capacity analysis. At the intersection of Sunset Lane NE with Harrington Avenue NE the conveyance system will continue in a southerly direction along the west side of Harrington Avenue NE. The system will connect to the existing system in NE Sunset Boulevard. This system will also intercept offsite flow at the intersection of NE 10th Street with Sunset Lane NE, from the new library property, and the excess flows from the proposed flow splitter being installed as part of the park’s regional stormwater facility. The second conveyance system collects runoff from the rest of the Sunset Lane NE project, Station 13+75 to Station 22+50. The conveyance system follows the proposed roadway down to a low point at station 16+51. At the low point the system leaves Sunset Lane NE through a proposed utility easement on the RHA property. The pipe flows perpendicular to Sunset Lane NE and connects into the existing conveyance system on NE Sunset Boulevard. This system intercepts offsite flow north of NE 10th Street from Harrington Avenue NE, and Glennwood Avenue NE, the future developments to the southwest of Sunset Lane NE, and the park property. To be conservative, the Sunset Lane NE conveyance analysis assumed that the future developments to the southwest of Sunset Lane NE were 100% impervious. This storm drain system has calculated the 25-year peak flow rate from the park to be 5.19 cubic feet per second (cfs) based on a preliminary assumption that the park would be half impervious surface area. 5.2 Proposed Storm Drains Proposed storm drains were analyzed for the 25-year design storm according to the Rational Method as described in the KCSWDM (2009). A new storm drain system will collect and convey stormwater from the site into existing catch basin #13 in Sunset Lane NE, which discharges into the existing 24-inch storm drain described above. The new storm drain system will include eight new catch basins and 12-inch storm drain pipes along the southern site boundary under Phase 1, as well as two temporary 6-inch French Drains. Stormwater runoff from the eastern portion of the park will drain to a temporary 6-inch French Drain located along the main central pathway, then into a series of catch basins and 12-inch storm pipes. Runoff from the western portion of the site will sheet flow across the mainly lawn-covered slope into a temporary French Drain, then into another 12-inch storm drain. Both of these systems will discharge to the existing 24- inch storm drain that runs southwest toward NE Sunset Boulevard via an existing catch basin in Sunset Lane NE. In a future phase, the temporary French Drains will be replaced with a system of swales and rain gardens SECTION 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 5-2 along the southwestern boundary of the park (capturing runoff from the western park area) and a pervious rubberized playground surface with an underdrain. The Sunset Lane NE project analyzed the capacity of the receiving conveyance system in Sunset Lane NE, assuming a park with half impervious, half pervious land cover and calculated a basin flow rate of 5.19 cfs. The actual land cover of the fully built Sunset Neighborhood Park will be approximately 24% impervious. To be conservative, the Rational Method used to calculate the flow rate from the fully developed park assumed that the entire park drained into one catch basin and one discharge point. Based on this conservative assumption, the 25-year design peak flow rate is 3.55 cfs. The new 12-inch storm drains will have adequate capacity for this flow rate. See calculations provided in Appendix C. Also, because the calculated basin flow rate from the park (see Appendix C) is less than that estimated by the Sunset Lane NE project for the 25-year design storm for the purpose of analyzing the receiving conveyance system, the downstream storm drain system is known to have adequate capacity. The proposed storm drain configuration is shown and detailed on plan sheets in Appendix B. 5.3 Utilities An existing gas main traverses the park site from north to south, just west of the proposed restroom buildings. This gas main will be protected in-place. A new water line and sanitary sewer line will be installed during Phase 1 to serve the park restroom buildings as well as the water feature that will be installed in a future phase. These utilities will connect to existing water mains and sanitary sewers in NE 10th Street, which is the park site’s northern boundary. Electrical service will also connect to the park’s restroom buildings from the northeastern corner (NE 10th Street). Pedestrian lights will have been installed along the pathways next to the park boundary under the Sunset Lane NE project or will be installed during Phase 1 construction. The preference is to place new storm drains under the curb/gutter line along Sunset Lane NE. This is proposed where no utility conflicts are noted. Potholing will be performed to identify the location and depth of the utilities. The design may work around the existing utilities or the utilities will be relocated. SECTION 6 6-1 Special Reports and Studies The Sunset Area Surface Water Master Plan (CH2M HILL, 2011) discusses constructing green stormwater infrastructure (GSI) in key areas within the Sunset Study Area. Harrington Avenue NE as well as the planned park located in the center of the proposed Sunset Lane NE loop were identified as locations to construct GSI. The Harrington Avenue NE GSI project was constructed in 2014. The Sunset Terrace Regional Stormwater Facility within the Phase 1 park area was constructed in 2015, and utilized the Sunset Stormwater Retrofit Low-Impact Development Project Geotechnical Data and Recommendations Report (CH2M HILL, 2012). These related projects do not affect the drainage requirements for the Sunset Neighborhood Park Project, but are good to be aware of as design and construction move forward. The Master Plan proposes to construct a new storm drain under Glennwood Avenue NE where there are currently no stormwater conveyance facilities. The Master Plan shows the proposed Glennwood Avenue NE storm drain system connecting into the storm drain system along Harrington Avenue NE which is being removed as part of the Sunset Lane NE project. Runoff from the area that this proposed storm drain system along Glennwood Avenue NE will most likely collect was accounted for in the backwater analysis used to size the proposed new conveyance system along Sunset Lane NE (Perteet, 2015). The Sunset Neighborhood Park project is partially located within a Zone 2 Aquifer Protection Area. The City of Renton Amendments to the King County Surface Water Design Manual states that if a project is within a Zone 2 aquifer protection area, flow control and water quality treatment facilities may require lining. This requirement is not applicable for the proposed project, because no flow control or water quality facilities are proposed. There are steep slopes to the west of the Sunset Lane NE project, however construction activities and stormwater infrastructure will remain at least 80 feet from the top of the slope. There will be a Temporary Erosion and Sediment Control (ESC) plan as part of the project plan set, and the contractor will be required to prepare a project Stormwater Pollution Prevention Plan (SWPPP). Proposed drainage facilities for this project do not rely on soil properties; therefore, no geotechnical investigation is needed at this time. No other special reports or studies apply to this project. SECTION 7 7-1 Other Permits The following permits are anticipated for the project: • General Construction Stormwater Permit and Notice of Intent – Washington Department of Ecology • Civil Construction Permit (includes a Clearing and Grading Permit) – City of Renton SECTION 8 8-1 ESC Analysis and Design An Erosion and Sedimentation Control (ESC) plan will be developed for the final contract plans in accordance with the City of Renton Amendments to the King County Surface Water Design Manual and KCSWDM Appendix D. ESC plans are shown in Drawings C-1, C-2 and C-3 in Appendix B. To avoid erosion and the transport of sediment offsite, the contractor will implement temporary control measures during the construction phase of the project. During construction, stormwater runoff will be conveyed in the existing conveyance systems, which are primarily storm drains. ESC measures will be needed to prevent runoff from causing erosion and discharging sediment into the existing drainage system during and after construction. Appropriate ESC measures will be needed for construction activities on existing storm drain systems. The contractor will be responsible for the phasing of erosion and sediment control measures so that they are coordinated with the staging of construction activities. Additionally, the contractor will be responsible for inspection and maintenance of temporary controls during construction, including removal of accumulated sediment, and for the removal of the controls and remaining accumulated sediment at the end of construction. The project will follow the requirements listed in the National Pollutant Discharge Elimination System (NPDES) General Construction Stormwater Permit. The contractor will prepare a stormwater pollution prevention plan (SWPPP) following the 12 elements listed in the KCSWDM, and the SWPPP will be updated as site conditions change. Permanent measures will be implemented where needed to stabilize disturbed soils at project completion. 8.1 ESC Measures The following ESC measures will be provided, as further detailed on ESC plan sheets in Appendix B: • Clearing Limits – Clearing limits will be delineated on the construction plans. Silt fence or wattles will be installed down slope of any fill slopes to prevent offsite sediment migration. • Cover Measures – The contractor will provide temporary and permanent cover measures where needed to protect disturbed areas. Mulching will be used in accordance with the KCSWDM’s Erosion and Sediment Control Standards Appendix D to provide immediate, temporary protection from erosion and to enhance plant growth. Nets and blankets may be used according to Erosion and Sediment Control Standards Appendix D to provide additional protection and to hold seed and mulch in place on slopes. Disturbed areas will be seeded as a permanent cover measure to reduce erosion. • Perimeter Protection – To reduce the transport of sediment off site, the contractor will provide catch basin filters and street sweeping as indicated on the final construction drawings and as needed. • Traffic Area Stabilization – Stabilized construction entrances will be installed at all construction vehicle access locations. • Sediment Retention – Catch basin filters (inlet protection) will provide sediment retention at the locations shown on the final construction drawings. • Surface Water Collection – Surface water control will be provided by using the existing and new drainage conveyance systems. Surface water will not be discharged into the existing bioretention cells, which are to be protected with silt fences as shown on Drawing C-2 in Appendix B. • Dewatering Control – Groundwater is not expected to be encountered during construction because the site sits at the top of a steep slope and the soils in the area have high infiltration capacity. If SECTION 8 ESC ANALYSIS AND DESIGN 8-2 groundwater is encountered during construction, it may be pumped to an onsite sediment trap or to a catchment created by sandbags with an overflow into a catch basin containing a catch basin insert. • Dust Control – If necessary, the contractor will use water according to KCSWDM Section 3.8 to prevent wind transport of soil. Exposed soils will be sprayed until wet and resprayed as needed. When using water for dust control, the contractor will spray exposed soils until they are wet, but runoff should not be generated by spraying. Oil shall not be used for dust control. At the contractor’s option, a tackifier may be used with approval from the Engineer and the City. • Flow Control – A sediment trap is proposed during construction at the southwest portion of the site, and will provide sediment retention and possible flow control as needed. See Drawing C-2 in Appendix B. Construction activities will remove and permanently reduce the amount of impervious surface area on the site. Excessive runoff during construction is not anticipated, because the site will be mostly pervious. • ESC Implementation - All ESC measures will be inspected and maintained on a regular basis following the maintenance requirements listed for each BMP, as described in KCSWDM Erosion and Sediment Control Standards Appendix D. The contractor will designate a certified ESC Supervisor and will give his or her name, address, and phone number to the City before construction begins. The ESC Supervisor will inspect the site at least once a month during the dry season, weekly during the wet season, and within 24 hours of each runoff-producing storm. If the City of Renton requires a written record of maintenance activities, a standard ESC maintenance report will be used as a written record of all maintenance. The proposed ESC measures for the project will be further detailed in the final contract plans. Construction for this project will not be located within a stream buffer, a wetland or associated buffer, or within 50 feet of a lake. 8.1.1 Wet Season Construction If soils are exposed between October 1 and March 31, the contractor will mulch and seed as much disturbed area as possible by the first week of October to provide grass cover for the wet season. The contractor will also conform to the following wet season special provisions: 1. Apply cover measures to disturbed areas that are to remain unworked for more than 2 days. 2. Protect stockpiles that are to remain unworked for more than 12 hours. No area is to be left uncovered/denuded longer than 12 hours. 3. Provide onsite supplies of cover materials sufficient to cover all disturbed areas. 4. Seed all proposed lawn areas that are to be unworked during the wet season by the end of the first week of October. 5. Apply mulch to all other areas that are unworked for protection. 6. Maintain a minimum of 50 linear feet of silt fence (and the necessary stakes) on site for every acre of disturbed area. 7. Provide construction road and parking lot stabilization areas for all sites, unless underlain by coarse grain soil. 8. Provide sediment retention as required. 9. Provide additional surface water controls as required. 10. Implement construction phasing and more conservative BMPs for construction activity near surface waters (to be evaluated by contractor). SECTION 8 ESC ANALYSIS AND DESIGN 8-3 11. Runoff generated from dewatering activities is to be treated using suitable methods for the site. Review and maintain ESC measures on a weekly basis and within 24 hours after any runoff-producing event. 8.1.2 Minimum ESC Requirements After Construction Before obtaining final construction approval, the following conditions must be met: 1. All disturbed areas of the site should be vegetated or otherwise permanently stabilized. At a minimum, disturbed areas will be seeded and mulched to provide a high likelihood that sufficient cover will develop shortly after final approval. If seeded during the dry season, the seeded area will be irrigated as necessary to maintain the sprouted vegetation until the start of the wet season. 2. Temporary ESC measures such as silt fences, pipe slope drains, construction entrances, and storm drain inlet protection will be removed. 3. All permanent surface water facilities including catch basins, manholes, pipes, ditches, and channels will be cleaned of silt and debris. SECTION 9 9-1 Bond Quantities, Facility Summaries, and Declaration of Covenant This is a Public Works project to be entirely owned and maintained by the City of Renton. As such, a bond quantities worksheet and Declaration of Covenant are not required for this project. Also, because no flow control or water quality facilities are included in the project, Flow Control and Water Quality Summary Sheets are not required. SECTION 10 10-1 Operations and Maintenance Manual An operations and maintenance manual is not provided here, because this is a Public Works project and the City will assume maintenance and operation of all systems. 11-1 References CH2M HILL. 2011. Sunset Area Surface Water Master Plan. Prepared for the City of Renton, Washington. April. CH2M HILL. 2012. Sunset Stormwater Retrofit Low-Impact Development Project Geotechnical Data and Recommendations Report. Prepared for the City of Renton, Washington. August. City of Renton. 2010a. Draft Sunset Area Community Planned Action NEPA/SEPA Environmental Impact Statement. Prepared for City of Renton and Renton Housing Authority. http://rentonwa.gov/uploadedFiles/Business/CED/planning/2010/Vol1_SunsetArea-PA_DraftEIS.pdf. City of Renton Community and Economic Development, Renton, Washington. December. City of Renton. 2010b. Amendments to King County Surface Water Design Manual. http://rentonwa.gov/uploadedFiles/Government/PW/UTILITIES/Surface_Water/City%20Amendments%20to %20the%20King%20County%20Surface%20Water%20Design%20Manual.pdf. City of Renton, Public Works Department, Surface Water Utility, Washington. February. HBB. 2014. Sunset Neighborhood Park Master Plan Report. Prepared for City of Renton, Washington. December 2014. King County Department of Natural Resources. 2009. King County, Washington Surface Water Design Manual. Perteet. 2015. Sunset Lane NE Draft Stormwater Technical Information Report. Prepared for City of Renton, Washington. October. United States Department of Agriculture (USDA). 2014. Soil Survey, Natural Resources Conservation Service, Web Soil Survey. http://websoilsurvey.nrcs.usda.gov/. September. Appendix A TIR Worksheet March 29, 2017March 2017 Appendix B Design Drawings SUNSET NEIGHBORHOOD PARK GENERAL REQUIREMENTS TEMPORARY EROSION/SEDIMENT CONTROL (TESC) GENERAL NOTES 1.BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTIVITY OCCURS, A PRECONSTRUCTION MEETING MUST BE HELD WITH THE CITY OF RENTON, PUBLIC WORKS DESIGN ENGINEER. THE ESC FACILITIES SHOWN ON THIS PLAN MUST BE CONSTRUCTED PRIOR TO OR IN CONJUNCTION WITH ALL CLEARING AND GRADING ACTIVITIES IN SUCH A MANNER AS TO ENSURE THAT SEDIMENT- LADEN WATER DOES NOT ENTER THE DRAINAGE SYSTEM OR VIOLATE APPLICABLE WATER QUALITY STANDARDS. 2.THE ESC FACILITIES SHALL BE INSPECTED BY THE PERMITTEE/CONTRACTOR DAILY DURING NON-RAINFALL PERIODS, EVERY HOUR (WORKING HOURS) OR EVERY EIGHT HOURS (NON-WORKING HOURS) DURING A RAINFALL EVENT AND AT THE END OF EVERY RAINFALL, AND MAINTAINED AS NECESSARY TO ENSURE THEIR CONTINUED FUNCTIONING. IN ADDITION, TEMPORARY STORAGE TANK/POND AND ALL TEMPORARY SILTATION CONTROLS SHALL BE MAINTAINED IN A SATISFACTORY CONDITION UNTIL SUCH TIME THAT CLEARING AND/OR CONSTRUCTION IS COMPLETED, PERMANENT DRAINAGE FACILITIES ARE OPERATIONAL, AND THE POTENTIAL FOR EROSION HAS PASSED. WRITTEN RECORDS SHALL BE KEPT DOCUMENTING THE REVIEWS OF THE ESC FACILITIES. 3.THE ESC FACILITIES ON INACTIVE SITES SHALL BE INSPECTED AND MAINTAINED A MINIMUM OF ONCE A MONTH OR WITHIN 48 HOURS FOLLOWING A STORM EVENT. 4.THE ENGINEER HAS THE AUTHORITY TO HALT CONSTRUCTION IF EROSION CONTROLS ARE NOT MAINTAINED PROPERLY OR IF A VIOLATION HAS NOT BEEN CORRECTED. THE CONTRACTOR SHALL BEAR ALL RISK AND ALL COSTS OF ANY WORK DELAYS CAUSED BY THESE ACTIONS. 5.THE CONTRACTOR SHALL COMPLY THE NPDES PERMIT REQUIREMENTS, MONITOR AND REPORT THE STORM WATER DISCHARGE IN ACCORDANCE WITH THE GENERAL PERMIT. 6.FOR TURBIDITY NONCOMPLIANCE ISSUES, THE CONTRACTOR SHALL CONTACT DEPARTMENT OF ECOLOGY WATER QUALITY MANAGER. FOR SPILL OF IMMEDIATE DANGER TO LIFE AND HEALTH, THE CONTRACTOR SHALL CONTACT DEPARTMENT OF ECOLOGY HOT LINE (425-649-7000) AND CITY OF RENTON SPILL AND DISCHARGE 24-HOUR CONTACT (425-430-7400). 7.AN EROSION CONTROL AND SEDIMENTATION CONTROL ESC LEAD SHALL BE DESIGNATED. THE ESC LEAD SHALL BE RESPONSIBLE FOR THE PERFORMANCE, MAINTENANCE AND REVIEW OF ESC MEASURES. FOR PROJECTS THAT DISTURB ONE ACRE OR MORE OF LAND, THE ESC SUPERVISOR MUST BE A CERTIFIED PROFESSIONAL IN EROSION AND SEDIMENT CONTROL OR A CERTIFIED EROSION AND SEDIMENT CONTROL LEAD WHOSE CERTIFICATION IS RECOGNIZED BY DEPARTMENT OF ECOLOGY OR KING COUNTY. 8.ALL LIMITS OF CLEARING AND AREAS OF VEGETATION PRESERVATION AS PRESCRIBED ON THE PLAN(S) SHALL BE CLEARLY FLAGGED IN THE FIELD AND OBSERVED DURING CONSTRUCTION. 9.ALL REQUIRED SEDIMENT/EROSION CONTROL FACILITIES MUST BE CONSTRUCTED AND IN OPERATION PRIOR TO LAND CLEARING AND/OR CONSTRUCTION TO ENSURE THAT SEDIMENT LADEN WATER DOES NOT ENTER THE NATURAL DRAINAGE SYSTEM. ALL EROSION AND SEDIMENT FACILITIES SHALL BE MAINTAINED IN A SATISFACTORY CONDITION UNTIL SUCH TIME THAT CLEARING AND/OR CONSTRUCTION IS COMPLETE AND POTENTIAL FOR ON-SITE EROSION HAS PASSED. THE IMPLEMENTATION, MAINTENANCE, REPLACEMENT, AND ADDITIONS TO EROSION/SEDIMENTATION CONTROL SYSTEMS SHALL BE THE RESPONSIBILITY OF THE PERMITEE. 10.THE EROSION AND SEDIMENTATION CONTROL SYSTEMS DEPICTED ON THIS DRAWING ARE INTENDED TO BE MINIMUM REQUIREMENTS TO MEET ANTICIPATED SITE CONDITIONS. AS CONSTRUCTION PROGRESSES AND UNEXPECTED OR SEASONAL CONDITIONS DICTATE, THE PERMITEE SHALL ANTICIPATE THAT MORE EROSION AND SEDIMENTATION CONTROL FACILITIES WILL BE NECESSARY TO ENSURE COMPLETE SILTATION CONTROL ON THE PROPOSED SITE. DURING THE COURSE OF CONSTRUCTION, IT SHALL BE THE OBLIGATION AND RESPONSIBILITY OF THE PERMITEE TO ADDRESS ANY NEW CONDTIONS THAT MAY BE CREATED BY THE ACTIVITIES AND TO PROVIDE ADDITIONAL FACILITIES, OVER AND ABOVE MINIMUM REQUIREMENTS, AS MAY BE NEEDED, TO PROTECT ADJACENT PROPERTIES AND WATER QUALITY OF THE RECEIVING DRAINAGE SYSTEM. BMP INSTALLATION, MAINTENANCE, AND DISCHARGES 1.INLET PROTECTION SHALL BE INSTALLED IN ANY ROAD OR PARKING LOT DRAINAGE SYSTEM INLETS, EXISTING OR NEWLY INSTALLED, WHICH ARE LIKELY TO RECEIVE RUNOFF FROM THE DISTURBED AREAS DURING CONSTRUCTION. INLET PROTECTION SHOWN ON THE TESC PLANS ARE APPROXIMATE LOCATIONS. THE CONTRACTOR SHALL ADD INLET PROTECTION AS NECESSARY TO ALL CATCH BASINS THAT RECEIVE STORM WATER RUNOFF WITHIN THE PROJECT AREA AND THAT MAY OR MAY NOT BE SHOWN ON THE TESC PLANS. 2.AT NO TIME SHALL MORE THAN 1 FOOT OF SEDIMENT BE ALLOWED TO ACCUMULATE WITHIN A CATCH BASIN. ALL CATCH BASINS AND CONVEYANCE LINES SHALL BE CLEANED AT THE COMPLETION OF THE PROJECT IF IT IS DETERMINED BY THE PROJECT REPRESENTATIVE THAT THIS IS NEEDED. THE LEANING OPERATION SHALL NOT FLUSH SEDIMENT-LADEN WATER INTO THE DOWNSTREAM SYSTEM. 3. THE CONTRACTOR SHALL NOT CONVEY RUNOFF TO THE EXISTING BIORETENTION CELL. 4.WHERE HYDROSEEDING FOR TEMPORARY EROSION CONTROL IS USED, FAST GERMINATING GRASSES SHALL BE APPLIED AT AN APPROPRIATE RATE (EXAMPLE: ANNUAL OR PERENNIAL RYE APPLIED AT APPROXIMATELY 80 POUNDS PER ACRE). 5.WHERE STRAW MULCH IS USED FOR TEMPORARY EROSION CONTROL, IT SHALL BE APPLIED AT A MINIMUM THICKNESS OF 2͟, AND BE CERTIFIED WEED FREE. 6.ALL WORK AND MATERIALS SHALL BE IN ACCORDANCE WITH CITY OF RENTON STANDARDS AND SPECIFICATIONS. 7.THE ESC FACILITIES SHALL BE CONSTRUCTED IN ACCORDANCE WITH THE DETAILS ON THE APPROVED PLANS. LOCATIONS MAY BE MOVED TO SUIT FIELD CONDITIONS, SUBJECT TO APPROVAL BY THE ENGINEER AND THE CITY OF RENTON INSPECTOR. 8.A COPY OF THE APPROVED EROSION CONTROL PLANS MUST BE ON THE JOB SITE WHENEVER CONSTRUCTION IS IN PROGRESS. 9.CONSTRUCTION LIMITS SHALL BE DELINEATED WITH A HIGH VISIBILITY FENCE AND 6FT. CHAIN LINK FENCE. 10.OFF-SITE STREETS MUST BE KEPT CLEAN AT ALL TIMES. IF DIRT OR MUD IS DEPOSITED ON THE PUBLIC STREET SYSTEM, THE STREET SHALL BE IMMEDIATELY CLEANED WITH POWER SWEEPER OR OTHER EQUIPMENT. ALL VEHICLES SHALL LEAVE THE SITE BY WAY OF THE CONSTRUCTION ENTRANCE AND SHALL BE CLEANED OF ALL DIRT THAT WOULD BE DEPOSITED ON THE PUBLIC STREETS. FLUSHING WITH WATER WILL NOT BE ALLOWED. 11.CONTRACTOR SHALL PROTECT PREVIOUS CONCRETE PATHWAYS DURING CONSTRUCTION ACTIVITIES. 12.ALL DENUDED SOILS OR STOCKPILES MUST BE STABILIZED WITH AN APPROVED TESC COVER METHOD (E.G. SEEDING, MULCHING OR PLASTIC COVER). 13.IF ANY PART(S) OF THE CLEARING LIMIT BOUNDARY OR TEMPORARY EROSION/SEDIMENTATION CONTROL MEASURE(S) IS/ARE DAMAGED, IT SHALL BE REPAIRED IMMEDIATELY. 14.ALL PROPERTIES ADJACENT TO THE PROJECT SITE SHALL BE PROTECTED FROM SEDIMENT DEPOSITION AND RUNOFF. 15.DO NOT FLUSH CONCRETE BY-PRODUCTS INTO THE STORM DRAINAGE SYSTEM. IF EXPOSED AGGREGATE IS FLUSHED INTO THE STORM SYSTEM, IT COULD MEAN RE-CLEANING THE ENTIRE DOWNSTREAM STORM SYSTEM, OR POSSIBLY RE-LAYING THE STORM LINE. 16.THE CONTRACTOR SHALL NOT DISCHARGE TURBID WATER GENERATED FROM CONSTRUCTION ACTIVITIES, DIRECTLY TO ANY STREAMS, STORM WATER SYSTEM INLETS, OR DRAINAGE DITCHES IN ACCORDANCE WITH THE GENERAL PERMIT. 17.THE CONTRACTOR SHALL NOT DISCHARGE ANY CLEANING SOLVENTS OR CHEMICALS UTILIZED FOR TOOL OR EQUIPMENT CLEANING TO THE GROUND. REFUELING OF EQUIPMENT SHALL BE CONDUCTED AWAY FROM THE DRAINAGE FACILITIES AND DONE IN SUCH A MANNER AS TO PREVENT SPILLS FROM ENTERING THE GROUNDWATER OR WATER BODIES (INCLUDING WETLANDS). SPILLS SHOULD BE PREVENTED FROM HITTING THE GROUND PER CSWPPP. 18.THE CONTRACTOR SHALL SET ASIDE A SEPARATE AREA FOR THE WASH-OUT OF CONSTRUCTION EQUIPMENT AND TOOLS. 19.THE CONTRACTOR SHALL PROPERLY DISPOSE OF ALL CONSTRUCTION DEBRIS IN AN APPROVED AND PERMITTED LANDFILL FACILITY. 20.CONTRACTOR SHALL VERIFY THE FEASIBILITY, OBTAIN AN INDUSTRIAL WASTE DISCHARGE AUTHORIZATION PERMIT AND SEEK APPROVAL FROM THE CITY OF RENTON UTILITY DISTRICT PRIOR TO DISCHARGE OF ANY CONSTRUCTION RUNOFF TO THE SANITARY SEWE BMP INSTALLATION, MAINTENANCE, AND DISCHARGES (CONTINUED) SEQUENCE OF CONSTRUCTION THE TYPICAL CONSTRUCTION SEQUENCE SHALL BE AS FOLLOWS: 1.CONDUCT PRE-CONSTRUCTION MEETING. 2.POST SIGN WITH NAME AND PHONE NUMBER OF TESC SUPERVISOR. 3.UPDATE TESC PLAN. 4.PREPARE STORMWATER POLLUTION PREVENTION PLAN & UPDATE AS REQUIRED. 5.SUBMIT NOTICE OF INTENT TO WA STATE DEPARTMENT OF ECOLOGY. 6.INSTALL CATCH BASIN INLET PROTECTION. 7.INSTALL PERIMETER PROTECTION (HIGH VISIBILITY FENCE, ETC.). 8.INSTALL PROTECTION AROUND ALL ITEMS TO REMAIN. 9.INSTALL TEMPORARY STORAGE TANKS, SEDIMENT POND(S), FILTRATION SYSTEM(S), ETC. AS REQUIRED PRIOR TO GROUND DISTURBANCE. 10.CLEAR AND GRUB THE SITE. 11.MAINTAIN EROSION CONTROL MEASURES IN ACCORDANCE WITH PLANS AND MANUFACTURER'S RECOMMENDATIONS. 12.PERFORM GRADING EARTHWORK. 13.INSTALL BUILDING AND UTILITIES. 14.PLACE HARDSCAPE. 15.RESTORE ROADWAY AND SIDEWALKS. 16.INSTALL IRRIGATION SYSTEM. 17.INSTALL PLANTS. 18.RELOCATE EROSION CONTROL MEASURES OR INSTALL NEW MEASURES SO THAT AS SITE CONDITIONS CHANGE, THE EROSION AND SEDIMENT CONTROL IS ALWAYS IN ACCORDANCE WITH THE CITY TESC MINIMUM REQUIREMENTS. 19.STABILIZE ALL AREAS THAT REACH FINAL GRADE WITHIN 7 DAYS. 20.SEED ANY AREAS TO REMAIN UNWORKED FOR MORE THAN 30 DAYS. 21.UPON COMPLETION OF THE PROJECT, ALL DISTURBED AREAS MUST BE STABILIZED AND BEST MANAGEMENT PRACTICES BE APPLIED TO REMOVAL OF CONTROLS IF APPROPRIATE. 1 LEGEND: INLET PROTECTION, SEE CITY OF RENTON STD. PLAN 216.30 6' TEMPORARY CHAINLINK FENCE AND HIGH VISIBILITY FENCE SILT FENCE, SEE CITY OF RENTON STD. PLAN 214.00 INTERCEPTOR SWALE, SEE CITY OF RENTON STD. PLAN 217.10 PROTECT IN PLACE EXISTING GAS MAIN X INSTALL INLET PROTECTION, TYP. SUNSET NEIGHBORHOOD PARK PEDESTRIAN LIGHTS INSTALLED DURING SUNSET LANE NE CONSTRUCTION, DO NOT DISTURB. TYP (NIC) EXISTING RAIN GARDENS - DO NOT DISCHARGE SURFACE WATER INTO GARDENS. SEE NOTE 5 NOTES: 1.THE IMPLEMENTATION OF ALL TESC AND THE CONSTRUCTION, MAINTENANCE, REPLACEMENT, AND UPGRADING OF THESE TESC PLAN FACILITIES IS THE RESPONSIBILITY OF THE CONTRACTOR UNTIL ALL CONSTRUCTION IS APPROVED. 2.THE BOUNDARIES OF THE CONSTRUCTION LIMITS SHOWN ON THIS PLAN SHALL BE CLEARLY FLAGGED WITH HIGH VISIBILITY FENCING IN THE FIELD PRIOR TO CONSTRUCTION. DURING THE CONSTRUCTION PERIOD, NO DISTURBANCE AND/OR MATERIAL/EQUIPMENT STAGING SHALL BE PERMITTED BEYOND THE FLAGGED CONSTRUCTION LIMITS. THE FLAGGING SHALL BE MAINTAINED BY THE CONTRACTOR FOR THE DURATION OF CONSTRUCTION. 3.TESC FACILITIES AND MEASURES SHALL BE CONSTRUCTED AND/OR INSTALLED PRIOR TO ANY GRADING, EARTH-DISTURBING ACTIVITY, OR EXTENSIVE LAND CLEARING IN ACCORDANCE WITH THE APPROVED TEMPORARY EROSION SEDIMENTATION CONTROL PLAN. THESE FACILITIES MUST BE SATISFACTORILY MAINTAINED. 4.SEE DRAWING C-1 FOR TEMPORARY EROSION/SEDIMENT CONTROL (TESC) GENERAL NOTES. 5.CONTRACTOR SHALL USE CARE WHEN WORKING NEAR THE EXISTING RAIN GARDENS TO PROTECT THE EXISTING UNDERDRAIN SYSTEM FROM DAMAGE DURING CONSTRUCTION. INSTALL SILT FENCE INSTALL CHAINLINK AND HIGH VISIBILITY FENCE AROUND PERIMETER INTERCEPTOR SWALE (2' BOTTOM 2H:1V SIDE SLOPE) TEMPORARY SEDIMENT TRAP, SEE CITY OF RENTON STD. PLAN 211.00 3:1 3:1 12" TEMPORARY DISCHARGE DRAIN PIPE 0 20 40 60 1"=20' 1 PROTECT EXISTING IRRIGATION METER AND DCVA INSTALL SILT FENCE, PROTECT IRRIGATION SYSTEM CHECK DAMS, SEE CITY OF RENTON STD. PLAN 217.40 BLOCK CURB INLET PROTECTION, SEE CITY OF RENTON STD. PLAN 216.40 BLOCK CURB INLET PROTECTION CHECK DAM, TYP. >> SUNSET NEIGHBORHOOD PARK LEGEND: INLET PROTECTION, SEE CITY OF RENTON STD. PLAN 216.30 6' TEMPORARY CHAINLINK FENCE AND HIGH VISIBILITY FENCE SILT FENCE, SEE CITY OF RENTON STD. PLAN 214.00 INTERCEPTOR SWALE, SEE CITY OF RENTON STD. PLAN 217.10 CONSTRUCTION ENTRANCE, SEE CITY OF RENTON STD. PLAN 215.10 X PROTECT IN PLACE EXISTING GAS MAIN INSTALL INLET PROTECTION, TYP. INSTALL CHAINLINK AND HIGH VISIBILITY FENCE AROUND PERIMETER INSTALL CONSTRUCTION ENTRANCE PLACE STEEL PLATES IN ROADWAY AT CONSTRUCTION ENTRANCE TO PROTECT EXISTING UTILITIES (VALVES) IN ROADWAY NOTES: 1.THE IMPLEMENTATION OF ALL TESC AND THE CONSTRUCTION, MAINTENANCE, REPLACEMENT, AND UPGRADING OF THESE TESC PLAN FACILITIES IS THE RESPONSIBILITY OF THE CONTRACTOR UNTIL ALL CONSTRUCTION IS APPROVED. 2.THE BOUNDARIES OF THE CONSTRUCTION LIMITS SHOWN ON THIS PLAN SHALL BE CLEARLY FLAGGED WITH HIGH VISIBILITY FENCING IN THE FIELD PRIOR TO CONSTRUCTION. DURING THE CONSTRUCTION PERIOD, NO DISTURBANCE AND/OR MATERIAL/EQUIPMENT STAGING SHALL BE PERMITTED BEYOND THE FLAGGED CONSTRUCTION LIMITS. THE FLAGGING SHALL BE MAINTAINED BY THE CONTRACTOR FOR THE DURATION OF CONSTRUCTION. 3.TESC FACILITIES AND MEASURES SHALL BE CONSTRUCTED AND/OR INSTALLED PRIOR TO ANY GRADING, EARTH-DISTURBING ACTIVITY, OR EXTENSIVE LAND CLEARING IN ACCORDANCE WITH THE APPROVED TEMPORARY EROSION SEDIMENTATION CONTROL PLAN. THESE FACILITIES MUST BE SATISFACTORILY MAINTAINED. 4.SEE DRAWING C-1 FOR TEMPORARY EROSION/SEDIMENT CONTROL (TESC) GENERAL NOTES. PEDESTRIAN LIGHTS INSTALLED DURING SUNSET LANE NE CONSTRUCTION, TYP. (NIC) INTERCEPTOR SWALE 0 20 40 60 1"=20' TEMPORARY DRAIN PIPE CHECK DAMS, SEE CITY OF RENTON STD. PLAN 217.40 CHECK DAM, TYP. >> 1 SUNSET NEIGHBORHOOD PARK LEGEND: CONCRETE PATHWAY PERVIOUS CONCRETE PATHWAY PLANTING, SEE PLANTING PLAN NOTE: 1.SEE URBAN DESIGN PLANS FOR SCORING PATTERN, JOINTING PATTERN AND DETAILS, LIGHT FIXTURES, BOLLARDS, TRASH RECEPTACLES, AND OTHER FURNISHINGS. PEDESTRIAN LIGHTS INSTALLED DURING SUNSET LANE NE CONSTRUCTION, TYP. (NIC) MOW STRIP, SEE LANDSCAPE DRAWINGS CONCRETE PATHWAY, SEE DETAIL 1/C7 PERVIOUS CONCRETE PATHWAY, SEE DETAIL 2/C7 EXST RAIN GARDEN EXST RAIN GARDEN CONCRETE CURB, SEE DETAIL 2/C7 CONCRETE CURB, SEE DETAIL 2/C7 CONCRETE CURB, SEE DETAIL 2/C7 DETECTABLE WARNING SURFACE PER WSDOT STD PLAN F-45.10-01 (TYP). SEE TYPICAL DETECTABLE WARNING SURFACE PLACEMENT AND GRADING DETAIL 4 ON SHEET C-7 (TYP) PEDESTRIAN LIGHTS, TYP OF 2. SEE ELECTRICAL DRAWINGS 0 20 40 60 1"=20' MATCH EXISTING DEPRESSED CURB LOCATION 1 SUNSET NEIGHBORHOOD PARK SUNSET NEIGHBORHOOD PARK LEGEND: CONCRETE PATHWAY PERVIOUS CONCRETE PATHWAY PLANTING, SEE PLANTING PLAN NOTE: 1.SEE URBAN DESIGN PLANS FOR SCORING PATTERN, JOINTING PATTERN AND DETAILS, LIGHT FIXTURES, BOLLARDS, TRASH RECEPTACLES, AND OTHER FURNISHINGS. CONCRETE CURB, TYP SEE DETAIL 2/C7 PERVIOUS CONCRETE PATHWAY, TYP. SEE DETAIL 2/C7 CONCRETE PATHWAY, SEE DETAIL 1/C7 0 20 40 60 1"=20' 1 DETECTABLE WARNING SURFACE PER WSDOT STD PLAN F-45.10-01 (TYP). SEE TYPICAL DETECTABLE WARNING SURFACE PLACEMENT AND GRADING DETAIL 4 ON SHEET C-7 (TYP) DETECTABLE WARNING SURFACE PER WSDOT STD PLAN F-45.10-01 (TYP). SEE TYPICAL DETECTABLE WARNING SURFACE PLACEMENT AND GRADING DETAIL 4 ON SHEET C-7 (TYP) SUNSET NEIGHBORHOOD PARK 1 SUNSET NEIGHBORHOOD PARK SDCO RIM = 330.70 IE = 327.70 FRENCH DRAIN SEE DETAIL ON C-10 REMOVE EX. CLEANOUT, INSTALL TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 329.20 IE = 323.85 (EX 12") IE = 324.70 (6") IE = 324.20 (12") SDCO RIM = 329.20 IE = 329.70 TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 336.60 IE = 332.80 (6") CONNECTS TO INFILTRATION TRENCH TO SOUTH NOTE: 1.SEE C-3 AND C-4 FOR HARDSCAPE PLANS 2.CLEANOUTS FOR STORM DRAIN SHALL BE PER CITY OF RENTON STD PLAN 403.1, EXCEPT CLEANOUT COVER SHALL BE LABELED "DRAIN" INSTEAD OF "SEWER". 3.BEDDING AND BACKFILL FOR STORM DRAIN PIPE SHALL CONFORM TO CITY OF RENTON STD PLAN 220.00. 4.UNLESS STATED OTHERWISE, INTENT OF HARDSCAPE GRADING IS TO PRODUCE CROSS-SLOPE BETWEEN 0.5% AND 1.5%, AND LONGITUDINAL SLOPE BETWEEN 0% AND 4%. CONFIRM FORMWORK WILL PRODUCE SLOPES IN THIS RANGE AT LEAST 2 BUSINESS DAYS BEFORE POURING CONCRETE; NOTIFY PROJECT REPRESENTATIVE OF ANY DISCREPANCY. EX 12" SD PEDESTRIAN LIGHTS INSTALLED DURING SUNSET LANE NE CONSTRUCTION, TYP. (NIC) 6" PVC SD @ 1% MIN TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 337.50 IE = 333.55 (6") 6" PVC SD @ 1% MIN SD POC FOR FUTURE WATER FEATURE (PER CITY OF RENTON STD PLAN 403.2, SEE NOTE 6) RIM = 337.80 IE = 334.00 SEE INSET GRADING DETAIL ON SHEET C-9 ABBREVIATIONS CO CB CL DI EL FL IE LT MJ POC SD SS STD CLEANOUT CATCH BASIN CENTERLINE DUCTILE IRON ELEVATION FLANGE INVERT ELEVATION LINEAL FEET, LEFT MECHANICAL JOINT POINT OF CONNECTION STORM DRAIN SANITARY SEWER, STANDARD TYPE 2 CB PER CITY OF RENTON STD PLAN 201.00 W/ SOLID COVER PER 204.50 RIM = 338.1 IE = 335.6 (6" IN) IE = 335.1 (6" OUT) SDCO RIM = 337.9 IE = 335.4 340.89 341.05 340.89 341.05 0 20 40 60 1"=20' 5.GRADING IN PLANTED AREAS SHALL BE SMOOTH. ANGLE POINTS ARE PROVIDED IN CONTOURS FOR EASE OF STAKING; CONSTRUCT WITH SMOOTH TRANSITIONS. 6.SD POINT OF CONNECTION (POC) FOR WATER FEATURE SHALL BE PER CITY OF RENTON STD. PLAN 403.2, EXCEPT CLEANOUT COVER SHALL BE LABELED "DRAIN" INSTEAD OF "SEWER" INFILTRATION TRENCH, SEE A/C-10 AC-9 A C- 9 MOW STRIP, TYP. TOP OF CROWN, TYP. 6" TEE IE = 324.70 1 EXISTING IRRIGATION METER AND DCVA SEE SHEET C-7 FOR PROFILE SUNSET NEIGHBORHOOD PARK TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 336.6 IE = 332.80 (6") IE = 332.30 (12") TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 336.80 IE = 331.80 (12") FRENCH DRAIN SEE DETAIL D/C-10 TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 329.90 IE = 324.90 (12") EXISTING CB 13 NOTE: 1.SEE C-3 AND C-4 FOR HARDSCAPE PLANS 2.CLEANOUTS FOR STORM DRAIN SHALL BE PER CITY OF RENTON STD PLAN 403.1, EXCEPT CLEANOUT COVER SHALL BE LABELED "DRAIN" INSTEAD OF "SEWER". 3.BEDDING AND BACKFILL FOR STORM DRAIN PIPE SHALL CONFORM TO CITY OF RENTON STD PLAN 220.00. 4.THE INTENT OF HARDSCAPE GRADING IS TO PRODUCE CROSS-SLOPES BETWEEN 0.5% AND 1.5%, AND LONGITUDINAL SLOPES BETWEEN 0% AND 4%. CONFIRM FORMWORK WILL PRODUCE SLOPES IN THIS RANGE AT LEAST 2 BUSINESS DAYS BEFORE POURING CONCRETE; NOTIFY PROJECT REPRESENTATIVE OF ANY DISCREPANCY. 5.GRADING IN PLANTED AREAS SHALL BE SMOOTH. ANGLE POINTS ARE PROVIDED IN CONTOURS FOR EASE OF STAKING. CONSTRUCT WITH SMOOTH TRANSITIONS. LEGEND: FINISHED GRADE ELEVATIONS GRADE BREAK 329.40 FRENCH DRAIN SEE DETAIL D/C-10 TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 331.15 IE = 326.15 (12") TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 333.70 IE = 328.70 (12") TYPE 1 CB (PER CITY OF RENTON STD PLAN 200.00) RIM = 336.10 IE = 331.10 (12") 12" SD @ 1% MIN. (TYP)PEDESTRIAN LIGHTS INSTALLED DURING SUNSET LANE NE CONSTRUCTION, TYP. (NIC) 338.35 338.45 338.20 338.00 338.76 338.80 338.75 338.00 339.00 338.75 338.70 338.55 338.69338.67 338.70 338.50 338.53 338.39 338.45 338.62 338.62 338.48 338.53 338.70 338.48 338.67 338.55 338.41 338.21 338.14338.20 337.98 337.88 337.84 337.72 337.68 337.60 337.64 337.75 GRADING DETAIL 1" = 10' ABBREVIATIONS CO CB CL DI EL FL IE LT MJ POC SD SS STD CLEANOUT CATCH BASIN CENTERLINE DUCTILE IRON ELEVATION FLANGE INVERT ELEVATION LINEAL FEET, LEFT MECHANICAL JOINT POINT OF CONNECTION STORM DRAIN SANITARY SEWER, STANDARD 0 20 40 60 1"=20' 0 10 20 30 1"=10' 336.60 336.50 CROWN GRADING TYPICAL SECTION A C-8 MOW STRIP TOP OF CROWN CONCRETE PATHWAY 1 4 TYP 14 TYP SLOPE ROUNDING TOE OF SLOPE PER CONTOURS CONCRETE PATHWAY 1" TYP ABOVE LAWN VARIES 1' 0 10 20 30 1"=10' 0 10 20 30 1"=10' SEE C-8 FOR DETAILS SEE C-8 FOR DETAILS SDCO RIM = 329.95 IE = 326.95 1 C C-10 SEE SHEET C-7 FOR PROFILE SUNSET NEIGHBORHOOD PARK C - 1 SUNSET NEIGHBORHOOD PARK SURFACE WATER DRAINAGE NOTES AND SPECIFICATIONS SURFACE WATER STANDARD NOTES 1.BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTIVITY, A PRECONSTRUCTION MEETING MUST BE HELD BETWEEN THE DDES'S LAND USE INSPECTION SECTION, THE APPLICANT, AND THE $33/,&$17 6&216758&7,215(35(6(17$7,9( 2.ALL CONSTRUCTION SHALL BE IN ACCORDANCE WITH THE 2016 STANDARD SPECIFICATIONS FOR ROAD, BRIDGE AND MUNICIPAL CONSTRUCTION PREPARED BY WSDOT AND THE AMERICAN PUBLIC WORKS ASSOCIATION (APWA), AS AMENDED BY THE CITY OF RENTON PUBLIC WORKS DEPARTMENT. 3.THE SURFACE WATER DRAINAGE SYSTEM SHALL BE CONSTRUCTED ACCORDING TO THE APPROVED PLANS, WHICH ARE ON FILE IN THE PUBLIC WORKS DEPARTMENT. ANY DEVIATION FROM THE APPROVED PLANS WILL REQUIRE WRITTEN APPROVAL FROM THE CITY OF RENTON PUBLIC WORKS DEPARTMENT, SURFACE WATER UTILITY SECTION. 4.A COPY OF THESE APPROVED PLANS MUST BE ON THE JOB SITE WHENEVER CONSTRUCTION IS IN PROGRESS. 5.DATUM FOR VERTICAL CONTROL SHALL BE NORTH AMERICAN VERTICAL DATUM 1988 METERS, AND FOR HORIZONTAL CONTROL SHALL BE NORTH AMERICAN DATUM 1983/1991 METERS UNLESS OTHERWISE APPROVED BY THE CITY OF RENTON PUBLIC WORKS DEPARTMENT. REFERENCE BENCHMARK AND ELEVATIONS ARE NOTED ON THE PLANS. 6.ALL SEDIMENTATION/EROSION FACILITIES MUST BE IN OPERATION PRIOR TO CLEARING AND BUILDING CONSTRUCTION, AND THEY MUST BE SATISFACTORILY MAINTAINED UNTIL CONSTRUCTION IS COMPLETED AND THE POTENTIAL FOR ON-SITE EROSION HAS PASSED. 7.ALL RETENTION/DETENTION FACILITIES MUST BE INSTALLED AND IN OPERATION PRIOR TO OR IN CONJUNCTION WITH ALL CONSTRUCTION ACTIVITY UNLESS OTHERWISE APPROVED BY THE PUBLIC WORKS DEPARTMENT, SURFACE WATER UTILITY SECTION. 8.NOT USED. 9.ALL PIPE AND APPURTENANCES SHALL BE LAID ON A PROPERLY PREPARED FOUNDATION IN ACCORDANCE WITH SECTION 7-02.3(1) OF THE CURRENT STATE OF WASHINGTON STANDARD SPECIFICATION FOR ROAD AND BRIDGE CONSTRUCTION. THIS SHALL INCLUDE NECESSARY LEVELING OF THE TRENCH BOTTOM OR THE TOP OF THE FOUNDATION MATERIAL, AS WELL AS PLACEMENT AND COMPACTION OF REQUIRED BEDDING MATERIAL, TO UNIFORM GRADE SO THAT THE ENTIRE LENGTH OF THE PIPE WILL BE SUPPORTED ON A UNIFORMLY DENSE, UNYIELDING BASE. $//3,3(%('',1*6+$//%($3:$&/$66³&´:,7+7+((;&(37,212)39&3,3($//75(1&+ BACKFILL SHALL BE COMPACTED TO MINIMUM 95% FOR PAVEMENT AND STRUCTURAL FILL AND 90% OTHERWISE PER ASTM D-1557-70. PEA GRAVEL BEDDING SHALL BE 6 INCHES OVER AND UNDER PVC PIPE. 10.GALVANIZED STEEL PIPE AND ALUMINIZED STEEL PIPE FOR ALL DRAINAGE FACILITIES SHALL HAVE ASPHALT TREATMENT #1 OR BETTER INSIDE AND OUTSIDE. 11.STRUCTURES SHALL NOT BE PERMITTED WITHIN 10 FEET OF THE SPRING LINE OF ANY STORM DRAINAGE PIPE, OR 15 FEET FROM THE TOP OF ANY CHANNEL BANK. 12.ALL CATCH BASIN GRATES SHALL BE DEPRESSED 0.10 FEET BELOW PAVEMENT LEVEL. 13.OPEN CUT ROAD CROSSINGS THROUGH EXISTING PUBLIC RIGHT OF WAY WILL NOT BE ALLOWED UNLESS SPECIFICALLY APPROVED BY CITY OF RENTON PLANNING/BUILDING/PUBLIC WORKS ADMINISTRATOR. 14.ROCK FOR EROSION PROTECTION OF ROADSIDE DITCHES, WHERE REQUIRED, SHALL BE OF SOUND QUARRYROCK PLACED TO A DEPTH OF ONE (1) FOOT AND MUST MEET THE FOLLOWING SPECIFICATIONS: 4 - 8 INCH ROCK / 40 - 70% PASSING; 2 - 4 INCH ROCK / 30 - 40% PASSING; AND LESS THAN 2 INCH ROCK / 10 - 20% PASSING. 15.ALL BUILDING DOWNSPOUTS AND FOOTING DRAINS SHALL BE CONNECTED TO THE STORM DRAINAGE SYSTEM, UNLESS APPROVED BY THE CITY PLAN REVIEWER OR SURFACE WATER UTILITY SECTION. AN ACCURATELY DIMENSIONED, CERTIFIED AS-BUILT DRAWING OF THIS DRAINAGE SYSTEM WILL BE SUBMITTED TO THE CITY UPON COMPLETION. 16.ISSUANCE OF THE BUILDING OR CONSTRUCTION PERMITS BY THE CITY OF RENTON DOES NOT RELIEVE THE OWNER OF THE CONTINUING LEGAL OBLIGATION AND/OR LIABILITY CONNECTED WITH STORM SURFACE WATER DISPOSITION. FURTHER, THE CITY OF RENTON DOES NOT ACCEPT ANY OBLIGATION FOR THE PROPER FUNCTIONING AND MAINTENANCE OF THE SYSTEM PROVIDED DURING CONSTRUCTION. 17.THE CONTRACTOR SHALL BE RESPONSIBLE FOR PROVIDING ADEQUATE SAFEGUARD, SAFETY DEVICES, PROTECTIVE EQUIPMENT, FLAGGERS, AND ANY OTHER NEEDED ACTIONS TO PROTECT THE LIFE, HEALTH, AND SAFETY OF THE PUBLIC, AND TO PROTECT PROPERTY IN CONNECTION WITH THE PERFORMANCE OF WORK COVERED BY THE CONTRACT. ANY WORK WITHIN THE TRAVELED RIGHT OF WAY THAT MAY INTERRUPT NORMAL TRAFFIC FLOW SHALL REQUIRE A TRAFFIC CONTROL PLAN APPROVE BY THE PUBLIC WORKS DEPARTMENT, TRANSPORTATION SYSTEMS DIVISION. ALL SECTIONS OF THE WSDOT STANDARD SPECIFICATIONS 1-07-23 TRAFFIC CONTROL SHALL APPLY. 18.SPECIAL DRAINAGE MEASURES WILL BE REQUIRED IF THE PROJECT LOCATION IS WITHIN THE AQUIFER PROTECTION AREA (APA). 19.ALL DESIGN AND CONSTRUCTION SHALL BE IN ACCORDANCE WITH PERMIT CONDITIONS, THE KING COUNTY CODE (KCC), WASHINGTON STATE DOT (WSDOT) STANDARD SPECIFICATIONS AND THE CONDITIONS OF PRELIMINARY APPROVAL. IT SHALL BE THE SOLE RESPONSIBILITY OF THE APPLICANT AND THE PROFESSIONAL CIVIL ENGINEER TO CORRECT ANY ERROR, OMISSION, OR VARIATION FROM THE ABOVE REQUIREMENTS FOUND IN THESE PLANS. ALL CORRECTIONS SHALL BE AT NO ADDITIONAL COST OR LIABILITY TO THE CITY OF RENTON. 20.THE DESIGN ELEMENTS WITHIN THESE PLANS HAVE BEEN REVIEWED ACCORDING TO THE KING COUNTY DEPARTMENT OF DEVELOPMENT AND ENVIRONMENTAL SERVICES (DDES) ENGINEERING REVIEW CHECKLIST. SOME ELEMENTS MAY HAVE BEEN OVERLOOKED OR MISSED BY THE DDES PLAN REVIEWER. ANY VARIANCE FROM ADOPTED STANDARDS IS NOT ALLOWED UNLESS SPECIFICALLY APPROVED BY KING COUNTY PRIOR TO CONSTRUCTION. 21.APPROVAL OF THIS GRADING AND DRAINAGE PLAN DOES NOT CONSTITUTE AN APPROVAL OF ANY OTHER CONSTRUCTION (E.G. DOMESTIC WATER CONVEYANCE, SEWER CONVEYANCE, GAS, (/(&75,&$/(7& 22.GRADING ACTIVITIES (SITE ALTERATION) ARE LIMITED TO THE HOURS OF 7 A.M. TO 7 P.M. MONDAY THROUGH SATURDAY AND 10 A.M. TO 5 P.M. ON SUNDAY, UNLESS OTHERWISE $33529(':,7+$:5,77(1'(&,6,21%<7+(5(9,(:,1*$*(1&< 22.IT SHALL BE THE APPLICANT'S/CONTRACTOR'S RESPONSIBILITY TO OBTAIN ALL CONSTRUCTION ($6(0(1761(&(66$5<%()25(,1,7,$7,1*2))6,7(:25.($6(0(1765(48,5(5(9,(: $1'$33529$/35,2572&216758&7,21 23.DEWATERING SYSTEM (UNDERDRAIN) CONSTRUCTION SHALL BE WITHIN A RIGHT-OF-WAY OR APPROPRIATE DRAINAGE EASEMENT, BUT NOT UNDERNEATH THE ROADWAY SECTION. ALL 81'(5'5$,16<67(060867%(&216758&7(',1$&&25'$1&(:,7+:6'2767$1'$5' SPECIFICATIONS. 24.ALL UTILITY TRENCHES AND ROADWAY SUBGRADE SHALL BE BACKFILLED AND COMPACTED TO 95 PERCENT DENSITY, STANDARD PROCTOR. 25.THE CONTRACTOR SHALL BE RESPONSIBLE FOR PROVIDING ADEQUATE SAFEGUARDS, SAFETY DEVICES, PROTECTIVE EQUIPMENT, FLAGGERS, AND ANY OTHER NEEDED ACTIONS TO 3527(&77+(/,)(+($/7+$1'6$)(7<2)7+(38%/,&$1'723527(&73523(57<,1 CONNECTION WITH THE PERFORMANCE OF WORK COVERED BY THE CONTRACTOR. ANY WORK WITHIN THE TRAVELED RIGHT-OF-WAY THAT MAY INTERRUPT NORMAL TRAFFIC FLOW SHALL REQUIRE AT LEAST ONE FLAGGER FOR EACH LANE OF TRAFFIC AFFECTED. MANUAL ON UNIFORM TRAFFIC CONTROL DEVICES (MUTCD) SHALL APPLY. WORK IN RIGHT-OF-WAY IS NOT AUTHORIZED UNTIL A TRAFFIC CONTROL PLAN IS APPROVED BY THE CITY OF RENTON. 26.PROOF OF LIABILITY INSURANCE SHALL BE SUBMITTED TO DDES PRIOR TO THE CONSTRUCTION OF THE DRAINAGE FACILITIES, PREFERABLY AT THE PRECONSTRUCTION MEETING. 27.ALL PIPE AND APPURTENANCES SHALL BE LAID ON A PROPERLY PREPARED FOUNDATION IN ACCORDANCE WITH WSDOT SPECIFICATIONS. THIS SHALL INCLUDE LEVELING AND COMPACTING THE TRENCH BOTTOM, THE TOP OF THE FOUNDATION MATERIAL, AND ANY REQUIRED PIPE BEDDING, TO A UNIFORM GRADE SO THAT THE ENTIRE PIPE IS SUPPORTED BY A UNIFORMLY DENSE UNYIELDING BASE. 28.ALL DRAINAGE STRUCTURES, SUCH AS CATCH BASINS AND MANHOLES, NOT LOCATED WITHIN A TRAVELED ROADWAY OR SIDEWALK, SHALL HAVE SOLID LOCKING LIDS. ALL DRAINAGE STRUCTURES ASSOCIATED WITH A PERMANENT RETENTION/DETENTION FACILITY SHALL HAVE 62/,'/2&.,1*/,'6 29.ALL CATCH BASIN GRATES SHALL CONFORM TO KCRS, WHICH INCLUDES THE STAMPING "OUTFALL TO STREAM, DUMP NO POLLUTANTS" AND "PROPERTY OF KING COUNTY", EXCEPT THAT PRIVATE DRAINAGE SYSTEMS SHALL NOT HAVE THE WORDS "PROPERTY OF KING COUNTY". 30.ALL DRIVEWAY CULVERTS LOCATED WITHIN KING COUNTY RIGHT-OF-WAY SHALL BE OF SUFFICIENT LENGTH TO PROVIDE A MINIMUM 3:1 SLOPE FROM THE EDGE OF THE DRIVEWAY TO THE BOTTOM OF THE DITCH. CULVERTS SHALL HAVE BEVELED END SECTIONS TO MATCH THE SIDE SLOPE KCRS. 31.ALL DISTURBED PERVIOUS AREAS (COMPACTED, GRADED, LANDSCAPED, ETC.) OF THE DEVELOPMENT SITE MUST DEMONSTRATE ONE OF THE FOLLOWING: THE EXISTING DUFF LAYER SHALL BE STAGED AND REDISTRIBUTED TO MAINTAIN THE MOISTURE CAPACITY OF THE SOIL, 25$0(1'('62,/6+$//%($''('720$,17$,17+(02,6785(&$3$&,7< 32.SEASONAL CLEARING IS LIMITED BETWEEN OCTOBER 1 AND MARCH 30 INCLUSIVE, UNLESS OTHERWISE APPROVED WITH A WRITTEN DECISION BY THE REVIEWING AGENCY. 33.,03529(0(176$1'25%8,/',1*66+$//127%(,167$//('817,/'5$,1$*()$&,/,7,(6$5( "IN OPERATION", (KCC 9.04). 1 SUNSET NEIGHBORHOOD PARK NOTES: 1.SEE ELECTRICAL PLAN FOR ELECTRICAL AND TELECOMMUNICATIONS UTILITIES. 2.SEE BUILDING MECHANICAL DRAWINGS FOR WATER SERVICE, VENTING AND OTHER PLUMBING INFORMATION. 3.SANITARY SIDE SEWER SHALL BE 35 SDR PVC (ASTM 3034). 4.POINT OF CONNECTIONS FOR SITE UTILITIES SHALL BE WITHIN 5 FEET OF STRUCTURE FOUNDATIONS. 5.WATER SERVICE SHALL BE TYPE K COPPER. 6.WATER SERVICE LINE SHALL BE INSTALLED A MINIMUM OF 5 FEET HORIZONTALLY FROM THE EXISTING GAS LINE AND 12 INCHES VERTICALLY REPLACE EXISTING 8" SS CLEANOUT PER CITY OF RENTON STD. PLAN NO. 403.1 FUTURE PHASE STORAGE TANK TEMPORARY CAP FOR FUTURE CONNECTION IE = 329.81 PROTECT IN PLACE EXISTING GAS MAIN LEGEND: WATER LINE SANITARY SEWER LINE W SS 4" SS PROVIDE TEMPORARY CAP AT FINISHED FLOOR FOR FUTURE CONNECTION TO WATER FEATURE 4" SS (TYP. OF 3) (/%2: IE = 328.26 (/%2: IE = 328.96 6" SS CLEANOUT PER CITY OF RENTON STD. PLAN NO. 403.1 85 LF OF 6" SS AT 1% SLOPE 70 LF OF 6" SS AT 1.0% SLOPE 2" WATER SERVICE EXISTING 8" DI WATER MAIN EXISTING 12" DI WATER MAIN INSTALL 1.5" OUTLET SERVICE SADDLE FOR CONNECTION TO INDOOR PLUMBING. SEE NOTE 6 6" PVC CASING FOR FUTURE WATER FEATURE. PROVIDE TEMPORARY CAPS AT BOTH ENDS 8"x6" REDUCER PEDESTRIAN LIGHTS INSTALLED DURING SUNSET LANE NE CONSTRUCTION, TYP. (NIC) ABBREVIATIONS IE SS STD LT DI MJ FL CL EL INVERT ELEVATION SANITARY SEWER STANDARD LINEAL FEET DUCTILE IRON MECHANICAL JOINT FLANGE CENTERLINE ELEVATION STA LT STATION LEFT STA 21+60 EXISTING 2" WATER METER INSTALL 2" DCVA OUTSIDE OF ROW PER CITY OF RENTON STD. PLAN 340.8 EXISTING 2" IRRIGATION METER AND DCVA EX. RAIN GARDEN EX. RAIN GARDEN 0 20 40 60 1"=20' 1 Appendix C Calculations BASIN FLOW Calculations Project:Sunset Neighborhood Park Proj. No:677149 Date:3/29/2017 Rational Method Catch Basin Rainfall Intensity IR Impervious C Impervious Area (ac) a Pervious C Pervious Area (ac)Cc 01 2.733941 0.9 0.77 0.25 2.43 0.405823 PR iR aR bR s0 Tc L 3.4 0.8041 2.66 0.65 0.0273 6.3 330 Basin Flow Rate (cfs) 3.55 a Excludes bathroom building roof area (600 sf) that drains directly to an infiltration trench. Page 2 of 2 STORM PIPE Calculations Project:Sunset Neighborhood Park Proj. No:677149 Date:3/29/2017 Location U/S D/S I.E. Adjusted L Diam.Available Q Finished Grade U/S D/S Cal'd Slope of of Q Q V From To Slope of Pipe Pipe Full Check Full Cover ID#ID#(cfs)(ft)(ft)(ft)(ft)%Pipe (ft)(n=)(in)(cfs)cfs (fps)check 1 2 3 14 15 16 17 18 19 22 23 24 25 26 27 28 7 6 3.55 336.60 336.80 332.30 331.80 1.67%1.67%30 0.014 12 4.28 ok 5.45 4.30 6 5 3.55 336.80 336.10 331.80 331.10 1.27%1.27%55 0.014 12 3.74 ok 4.76 5.00 5 4 3.55 336.10 333.70 331.10 328.70 3.43%3.43%70 0.014 12 6.14 ok 7.82 5.00 4 3 3.55 333.70 331.15 328.70 326.15 4.25%4.25%60 0.014 12 6.84 ok 8.71 5.00 3 2 3.55 331.15 329.90 326.15 324.90 2.08%2.08%60 0.014 12 4.79 ok 6.10 5.00 2 1 3.55 329.90 329.20 324.90 324.20 2.00%2.00%35 0.014 12 4.69 ok 5.97 5.00 1 13 3.55 329.20 328.24 323.85 323.60 1.15%1.15%21.8 0.014 12 3.55 ok 4.52 5.35 Sunset Park – KCRTS Peak Flow Rates (15-minutes Time Step) Existing Conditions Flow Frequency Analysis Time Series File:snp1_ex15.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.791 6 8/27/01 18:00 2.74 1 100.00 0.990 0.592 8 1/05/02 15:00 1.84 2 25.00 0.960 1.84 2 12/08/02 17:15 1.16 3 10.00 0.900 0.637 7 8/23/04 14:30 1.12 4 5.00 0.800 1.16 3 11/17/04 5:00 0.986 5 3.00 0.667 0.986 5 10/27/05 10:45 0.791 6 2.00 0.500 1.12 4 10/25/06 22:45 0.637 7 1.30 0.231 2.74 1 1/09/08 6:30 0.592 8 1.10 0.091 Computed Peaks 2.44 50.00 0.980 Proposed Conditions Flow Frequency Analysis Time Series File:snp_pp15.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.508 6 2/09/01 12:45 2.15 1 100.00 0.990 0.362 7 1/06/02 1:00 1.23 2 25.00 0.960 1.23 2 12/08/02 17:15 1.08 3 10.00 0.900 0.324 8 8/26/04 0:45 0.583 4 5.00 0.800 1.08 3 11/17/04 5:00 0.576 5 3.00 0.667 0.576 5 10/27/05 10:45 0.508 6 2.00 0.500 0.583 4 10/25/06 22:45 0.362 7 1.30 0.231 2.15 1 1/09/08 6:30 0.324 8 1.10 0.091 Computed Peaks 1.84 50.00 0.980