1815 13TH ST SEPA 016 - 013 - PRMC NEW CLINIC BUILDING Land Use Decision Documents 2025-04-21

EVALUATION FOR AGENCY USE ONLY There would be no waste materials discharged into the ground. All existing and proposed restrooms would be connected to the City of Everett municipal sewer system. c. Water Runoff (including stormwater): 1) Describe the source of runoff (including storm water) and method of collection and disposal, if any (include quantities, if known). Where will this water flow? Will this water flow into other waters? If so, describe. The City of Everett stormwater system serving this site is a combined storm and sanitary sewer system. Rainwater is the source of runoff onsite. Roof runoff will be collected and conveyed down through the building's plumbing system until it is picked up by a dedicated stormwater system outside. Runoff from pavement will sheet flow to catch basin structures, while runoff within landscaped areas will either infiltrate or be collected through area drains, see Figure 3 — SEPA Civil Sheet C1.01 and Figure 4 — SEPA Civil Sheet C1.02. Water will be conveyed through dedicated stormwater pipe to the onsite stormwater detention vault. The vault's flow control structure will then release the water to the City's combined sewer system. In accordance with City of Everett's 2010 Stormwater Management Manual and the Interim Policy 2-11, the developed discharge durations will match pre - developed durations for the range of pre -developed discharge rates from 50% of the 2-year recurrence interval to the full 50-year recurrence interval. 2) Could waste materials enter ground or surface waters? If so, generally describe. No, there will be no waste materials entering the ground or surface waters. Where accidental fuel spills are possible from fuel tank filling operations, fuel is kept isolated from the stormwater system (by means of an oil stop valve) and immediately cleaned up. 3) Does the proposal alter or otherwise affect drainage patterns in the vicinity of the site? If so, describe. The proposal would not alter or otherwise impact drainage patterns in the vicinity of the site. d. Proposed measures to reduce or control surface, ground, and runoff water, and drainage pattern impacts, if any: The project will comply with City of Everett drainage regulations that regulate stormwater runoff from all new development and redevelopment. BMPs would be used throughout construction to reduce potential impacts. Environmental Checklist — Providence Regional Medical Center Everett — North Site Page 10 © SHOC�KEY