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STORMWATER SITE PLAN <br />COMPASS HEALTH PHASE <br />AUGUST 5, 2022 <br />PAGE 1 <br />PROJECT OVERVIEW <br />This Stormwater Site Plan has been prepared for the Compass Health Phase 2 project located to <br />the west of Broadway Avenue between 33rd and 34th at 3322 Broadway, Everett, Washington, <br />see Figure 1: Vicinity Map. The site is part of the larger Compass Health property in the area <br />and currently contains the main Compass Health support building. The project is to remove the <br />existing improvements and construct a new multistory behavioral health services building in its <br />place. The proposed building covers most of the northern section of the site. See Figure 3: <br />Developed Conditions. The area ultimately will contain Phase 2 as well as Phase 3 (the addition <br />of a building to the south of Phase 2). The drainage calculations have been prepared based on <br />the expected Ph 2 buildout alone. Future Phases will follow their own drainage review process. <br />Project Totals: <br />The impervious surface count within the property boundary is as follows: <br />Existing Impervious <br />Roof 23,500 sf <br />Other impervious surface 18,900 sf <br />Total Impervious 42,400 sf <br />This will all be removed. <br />Phase 2 Impervious <br />Roof 18,100 sf (deducting 4,200 sf roof planters) <br />Other impervious surface 5,500 sf <br />Total Phase 2 Impervious 23,600 sf <br />Reduction in impervious by demolishing existing building and replacing with Phase 2 <br />(18,800 sf) <br />Temporary Gravel 13,000 sf <br />Total Reduction (5,800 sf) <br />METHODOLOGY <br />As the site is in the combined sewer area of Everett, the drainage design for the project has <br />been prepared based on the requirements of the City of Everett Design Standards and <br />Specifications Section 6-10 for the Combined Sewer Basin. The City currently uses the 2019 <br />Department of Ecology Stormwater Manual for Western Washington. The design is based on <br />the following parameters: <br />• The site has greater than 35% existing impervious. <br />• The project results in a reduction of impervious surface for the Phase 2 work. <br />• The project results in greater than 5,000 sf of new plus replaced impervious and <br />the value exceeds 50% of the existing. <br />Therefore, the project needs to meet Minimum Requirements 1-9 the new hard surfaces and <br />converted pervious areas. <br />P:\Work\Projects\2021\21-056 Ankrom Compass Health\CE\DOCS\Final Drainage Report.doc <br />