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HomeMy WebLinkAboutRS_Drainage Assessment Lot 17_190402_v3 425.455.2900 15900 SE Eastgate Way, Suite 300, Bellevue WA 98006 quadranthomes.com 1/4/19 City of Renton Community Development Services 1055 S Grady Way Renton, Washington 98057 RE: Written Drainage Assessment Lakeview Crest Lot 17 3939 Park Ave N Lakeview, Lot 17 is a single family residential project, which will be used as a Model Home for Lakeview Crest. This lot is 8,955 square feet and is currently vacant. The proposed improvements will include the addition of a new single-family residence. The area of disturbance will not exceed the lot lines and will be equal to the house footprint, driveway, patio and walkway construction. There are no wetlands or any steep slope hazard areas on this lot. The lot is less than 22,000 square feet, so it is subject to the Small Lot BMP Requirements in Appendix C of the 2009 Renton Surface Water Design Manual. The drainage requirement for this lot will be met by using C.2.3.4 Drywells for limited infiltration to mitigate an impervious area equal to at least 10% of the site/lot for site/lot sizes up to 11,000 square feet. The soil type is sandy loam and therefore the required volume is 380 cubic feet per every 1,000 square feet, based on the stormwater manual C.2.3.4. Lot 17 is 8,955 SF with the drywell design to mitigate 895.5 SF for stormwater runoff. The drywell on lot 17 will be 8.5’ in diameter and 6’ deep, holding a volume of 340 cubic feet. There is also a 10’ section of perforated pipe connection to the storm line as shown on the BMP site plan. Perforated pipe connections are intended to convey concentrated runoff from impervious surfaces (usually roof runoff) directly to a local drainage system while providing some infiltration of that runoff in the process per C.2.11. EROSION AND SEDIMENT CONTROL MEASURES: In order to prevent erosion and trap sediments within the project site, the following BMP’s will be used approximately as shown in the ESC details on the CSWPP plan: · Clearing limits will be marked by fencing or other means on the ground. · The driveway will be constructed and graveled immediately. A rocked construction entrance will be placed at the end of the driveway. Dispersion trenches will be placed according to flow control requirements. · Runoff will not be allowed to concentrate, and no water will be allowed to point discharge onto the slopes. Silt fencing will be placed along slope contours at the down slope limit of clearing. · Mulch will be spread over all cleared areas of the site when they are not being worked. Sincerely, Tatyana Sirotinsky Assistant Product Development Manager 425-646-8309 tatyana.sirotinsky @quadranthomes.com REVISION Received: 04/15/2019 / aalexander BUILDING DIVISION PR16000315 B18006356 V3 APPROVED BUILDING DIVISION THIS SET OF APPROVED PLANS MUST BE ON THE JOB AT ALL TIMES DURING CONSTRUCTION. THIS BUILDING IS NOT TO BE OCCUPIED UNTIL AFTER FINAL INSPECTION BY THE RENTON BUILDING DIVISION AND RECEIPT OF CERTIFICATE OF OCCUPANCY. APPROVAL SHALL NOT BE CONSTRUED AS THE AUTHORITY TO VIOLATE OR CANCEL ANY PROVISIONS OF CODES, ORDINANCES, OR OTHER REGULATIONS ENFORCED BY THIS CITY. DATE: 04/24/2019 PLAN VIEW OF PARCEL TO STORM DRAINSYSTEMRIGHT- OF-WAYGENERAL NOTES:1.INFILTRATION TRENCHES LIMITED TO ROOF RUNOFF FROM SINGLE-FAMILY OR DUPLEX HOMES OR TO CONTROL BASEMENT FLOODING. CONSULT WA DEPARTMENT OF ECOLOGY REGULATIONS FOR UNDERGROUND INJECTION CONTROL PROGRAM (UIC) FOR OTHER TYPES OF RUNOFF MANAGEMENT.2.IMPERVIOUS AREAS LARGER THAN 10,000 SF AND NON-NATIVE PERVIOUS AREAS LARGER THAN 35,000 SF MAY REQUIRE LARGER PIPE AND SHOULD BE DESIGNED BY A CIVIL ENGINEER.3.THE PERFORATED PIPE MAY NOT BE PLACED IN A CRITICAL AREA BUFFER OR ON SLOPES STEEPER THAN 25%.4.SEE CONSTRUCTION PLANS FOR SPECIFIC PROJECT REQUIREMENTS.24" MIN.18" MIN.MIN. 1' ABOVE SEASONAL HIGH GROUNDWATER TABLE 6" MIN.1 1/2" - 3/4" WASHED DRAIN ROCK NON-WOVEN GEOTEXTILE FOR SEPARATION ON TOP AND SIDES OF TRENCH PER WSDOT SPECIFICATIONS SECTION 9-33.2(1) TABLE 3 COMPACTED TOPSOIL OR OTHER CLEAN FILL 6" MIN. PVC PERFORATED PIPE PER ASTM D1785 10' MIN. LEVEL TRENCH WITH PERFORATED PIPE, SEE NOTE 1 DOWNSPOUT WITH CLEANOUT FILTER, SEE DETAIL ASECTION A NOTES:1.TRENCH LENGTH TO BE 10 FEET IN LENGTH FOR EVERY 5,000 SF OF CONTRIBUTING IMPERVIOUS SURFACE, OR 35,000 SF OF NON-NATIVE PERVIOUS SURFACE, OR PORTION THEREOF. 5' MIN. 5' MIN.TO STORM DRAIN SYSTEM 5' MIN. 5' MIN. A DOWNSPOUT WITH CLEANOUT FILTER, SEE DETAIL 10' MIN. LEVEL TRENCH WITH PERFORATED PIPE, SEE NOTE 1 CONFIGURATION ON FLAT GROUND CONFIGURATION ON SLOPING GROUND UNDISTURBED NATIVE SOIL CLEANOUT PER STD. PLAN 226. 00 CLEANOUT PER STD. PLAN 226. 00 FILTER SCREEN 2'-5' TO GROUND SOLIDS/ LEAVES TYPICAL DOWNSPOUT FILTER DETAIL FOOTING DRAIN BYPASS CLEANOUT PER STD. PLAN 226. 00 PERFORATED STUB- OUT CONNECTION PUBLIC WORKS DEPARTMENT APPROVED:DATEGregg Zimmerman Public Works Administrator UNLESS OTHERWISE NOTED, DRAWING IS NOT TO SCALE ( NTS)STD. PLAN - 263. 40 DocuSign Envelope ID: 6EECF5B6-602A-4E4A-B436- A317AA638878 9/28/2018 | 9:45 AM 102 SF