1815 13TH ST SEATTLE CHILDRENS NORTH CLINIC 2019-07-08

MAGNUSSON KLEMENCIC ASSOCIATES ■ Table 1. Existing and Proposed Impervious Surfaces Impervious Surface Area(square feet) Existing 64,695 Proposed 264,202 Interim Policy The project will discharge to the public combined sewer system (is within the combined sewer area) and creates and/or redevelops more than 2,000 square feet of impervious area, so the "Public Works Interim Policy 2-1 1: Stormwater Control in the Combined Sewer Area" (Interim Policy) will apply. See Appendix C for a copy of the Interim Policy. According to the Interim Policy, the project will be required to consider all Minimum Requirements with the following exceptions: • Minimum Requirement#6 is not applicable; • Minimum Requirement#7 can now be assessed replacing the term "a forested land cover" with "the existing site conditions." After the application of Minimum Requirement#7,the resulting stormwater flow is not anticipated to increase the Combined Sewer Overflows (CSOs) or the basement flooding in the combined sewer area. MINIMUM REQUIREMENTS The Minimum Requirements are summarized in Table 2 with further explanation of actions required provided where noted. Based on the threshold assessment above, all Minimum Requirements will apply to the project with the exception of Minimum Requirement#6. Table 2. Minimum Requirement Summary Minimum Requirement# Description Action Required Notes 1 Stormwater Site Plan Preparation Yes See below 2 Construction Stormwater Yes See IV Construction Pollution Prevention Stormwater Pollution Prevention Plan 3 Source Control of Pollution No See V Source Control Plan 4 Natural Drainage Systems and No See below Outfalls Preservation 5 On-Site Stormwater Yes See below Management Storm Drainage Report 4 Providence Regional Medical Center Everett North Site, Everett,Washington