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2014 SWMMWW MINIMUM RE UIREMENTS SUMMARY <br /> MR : MINIMUM REQUIREMENT <br /> SSP : STORMWATER SITE PLAN <br /> MR#1 PREPARATION OF STORMWATER SITE PLAN: <br /> Stormwater site plan follows the 2014 Stormwater Management Manual for Western <br /> Washington. <br /> MR#2 CONSTRUCTION OF STORMWATER POLLUTION PREVENTION <br /> PLAN (SWPPP): <br /> Refer to section IV for SWPPP. <br /> MR#3 SOURCE CONTROL OF POLLUTION: <br /> NA. No source control pollutants pertains to the proposed project,therefore no BMP's are <br /> required for the proposed project. <br /> MR#4 PRESERVATION OF NATURAL DRAINAGE SYSTEMS AND <br /> OUTFALLS: <br /> The developed site drainage will be discharged towards an existing drainage system along <br /> the Seahurst Ave to continue its natural drainage path. The runoff from the pervious areas <br /> in Basin-2 will continue to the flow towards east. <br /> MR#5 ONSITE STORMWATER MANAGEMENT: Per Minimum Requirement 45, <br /> the following BMP's shall be applied to provide onsite stormwater management and must <br /> be considered in the following order: Full Dispersion or Full Infiltration,Rain Gardens, <br /> Downspout Dispersion and Perforated Stub out Connections. Full Dispersion is infeasible <br /> because the required native vegetation preservation could not be achieved. <br /> Infiltration/Bioretention is not recommended because as per the Geotech Report the site <br /> contains hard pan at shallow depth. Downspout Dispersion is not feasible because the <br /> required vegetated flow path required by the BMP could not be met. Perforated stub out <br /> connection is also not feasible as the hardpan would interfere with the trench bottom. The <br /> roof drains will be tightlined to the existing drainage system. along Seahurst Ave. The <br /> following BMP's shall be applied to the other hard surfaces: Full dispersion, Permeable <br /> Pavement, Bioretention, and then Dispersion. Full dispersion is not feasible per explanation <br /> above. Permeable pavement is not a feasible option because the soil is not good. Basic <br /> Dispersion is not feasible because the required vegetated flow path could not be met. Post- <br /> Construction Soil Quality and Depth BMP T.5.13 is proposed to provide onsite stormwater <br /> management for the pervious areas of the site. <br /> Insight Engineering Co. -Stormwater Site Plan 07/24/19 <br /> -4 - <br />