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STORMWATER SITE PLAN <br />FEBRUARY 26, 2018 <br />MUKILTEO SCHOOL DISTRICT - TRANSPORTATION PAGE 1 <br />PROJECT OVERVIEW <br />This Stormwater Site Plan has been prepared for the Mukilteo School District's Transportation <br />Facility at 9001 Airport Way, Everett, WA. The site is used as an operations center and much of <br />the area is given over to the storage of buses. The project is to add paving to the southeast <br />edge of the existing parking area to provide for 6 additional bus stalls. See Figure 3: Developed <br />Conditions. <br />Project Totals: <br />New Impervious: 4,400 sf <br />Replaced Impervious: 0 sf <br />METHODOLOGY <br />The drainage design for the project has been prepared based on the requirements of the 2014 <br />Stormwater Management Manual for Western Washington, as adopted by the City of Everett. <br />With greater than 35% existing impervious, the site is considered a Redevelopment Site. <br />According to Figure 1-2.4.2 Flow Chart for Determining Requirements for Redevelopment <br />(attached in Appendix B), the development will need to meet Minimum Requirements 1-5. <br />MR 1: PREPARATION OF STORMWATER SITE PLANS <br />DRAINAGE PLAN DESCRIPTION <br />Direct precipitation is the source of runoff. The new paving will sheet flow onto the existing <br />pavement to be collected in the existing stormwater system. <br />WATER QUALITY MEASURES <br />Following is a list of the possible construction water quality BMPs. See MR 3: Water Pollution <br />Source Control for more information. The BMPs are as follows: <br />BMP C103, High Visibility Fence: <br />BMP C107, Construction Road/Parking Area Stabilization: <br />BMP C120, Temporary and Permanent Seeding: <br />BMP C121, Mulching: <br />BMP C123, Plastic Covering <br />BMP C125, Topsoil ing/Composting: <br />BMP C140, Dust Control: <br />BMP C220, Storm Inlet Protection: <br />BMP C233, Silt Fence <br />CONVEYANCE CALCULATIONS <br />Conveyance calculations will not be required as no new storm collection system is proposed. <br />The additional impervious is minor and will not significantly impact the existing collection <br />system. <br />P:\Work\Prcjects\2012\l2-185 Mukilteo SD\CODOCS\Transportation Facility Drainage 12-185.doe <br />