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Drainage Report—Revision 1 <br /> Boeing Everett—Rail Spur Parking Lot September 26,2013 <br /> Ultimately, all site runoff from the north and south subbasins is conveyed to Japanese Gulch to <br /> the west of the Boeing plant and runoff from the central subbasin is conveyed to an existing <br /> detention pond to the west of Perimeter Road prior to discharge to Japanese Gulch. TABLE 1 <br /> summarizes existing site conditions and land cover. <br /> TABLE 1 Project Site Area and Size of Improvements <br /> Project Site Areas <br /> Existing Develoled <br /> SF Acres SF Acres <br /> IMPERVIOUS AREAS <br /> North Subbasin—Tributary 80,615 1.85 80,615 1.90 <br /> South Subbasin-Tributary 12,035 0.28 12,035 0.28 <br /> Central Subbasin-Proposed - - 104,823 2.41 <br /> Total Impervious Surface: 92,650 2.13 197,473 4.58 <br /> Total New Impervious Surface: - - 104,823 2.41 <br /> Total Pollution Generating 92,650 2.13 197,473 4.58 <br /> Impervious Surface: <br /> Total New Pollution Generating - - 104,823 2.41 <br /> Impervious Surface: <br /> PERVIOUS AREAS <br /> Lawn 104,823 2.41 - - <br /> Total Pervious Surface 104,823 2.41 - - <br /> TOTAL 197,473 4.53 197,473 4.53 <br /> The areas in TABLE 1 were determined by area measurements in AutoCAD from a topographic <br /> survey performed on March 26, 2013. As shown in TABLE 1, the developed-site impervious <br /> surfaces total 197,473 SF, with 104,823 SF of new impervious surface/PGIS. There is 92,650 SF <br /> of pollution-generating impervious surface tributary to the developed site comprised of the north <br /> and south subbasins. <br /> 3.1 Minimum Requirements <br /> Per the requirements in Volume I, Chapter I-2, Section I-2.4 of the Stormwater Manual, <br /> Minimum Requirements 1 through 11 must be addressed for this project. These requirements are <br /> addressed below: <br /> 3.1.1 Minimum Requirement#1:Erosion and Sediment Control <br /> The project is new development including more than 1 acre of land disturbing activities and <br /> therefore requires a Large Parcel Erosion and Sediment Control Plan (ESC plan) per Volume I, <br /> Chapter I-2, Section 1-2.5 of the Stormwater Manual. Additionally, a Permanent Stormwater <br /> Quality Control Plan (PSQC)which meets Minimum Requirements 2 through 11 is required. The <br /> ESC and PSQC plans have been developed to meet the requirements in Volume I, Chapter I-2, <br /> Section 1-2.5 and are included in Section 9 of this report. <br /> DCG, Inc. Page 3 of 11 <br />