1410 SEINER DR FISHERMAN JACKS 2025-08-21

WATERFRONT PLACE CENTRAL PORT OF EVERETT — PSA 1-2015-005 HYDROLOGIC AND HYDRAULIC REPORT PND No. 154016 — 005.01 and conveyed to the Fisherman's Harbor A (FHA) stormwater system. Surface runoff for the southern portion of the project site, sub -basin's B1-12, is to be collected and conveyed to the Fisherman's Harbor B (FHB) stormwater system. 8.4. STORMWATER FLOW CONTROL PLAN Per COESMM Volume 1, Section 2.2.7, the Fisherman's Harbor project is exempt from flow control requirements, as it discharges directly into Snohomish River Basin, and meets listed restrictions. 8.5. STORMWATER TREATMENT PLAN Per section 2.2.6 of the COESWMM, the proposed project site includes a total effective area of new and/or replaced pollution -generating impervious surface (PGIS) greater than 5,000 square feet. As such stromwater treatment shall be provided for all pollution generating impervious/pervious surfaces. Both systems FHA and FHB shall include a new stormwater Modular Wetland treatment vault which is to provide a minimum basic level of treatment for all pollution generating surfaces prior to discharge through existing stomwater outfalls. These systems shall be designed in accordance with the following: • Emerging Technologies approved by the Washington State Department of Ecology (DOE), and allowed per COESMM Volume III, Chapter 13 will be used to provide "Basic Treatment". The Waterfront Place Central Team has worked Directly with BioClean to utilize the Modular Wetland Treatment Systems to provide design requirements for developers. • The water quality design treatment flowrate will be the 91 st percentile of the 24 —hour runoff volume as developed by MGSFlood Version 4, an approved continuous simulation runoff model by the Department of Ecology. • The volume calculations developed using MGSFlood Version 4, utilizes a large open channel as the point of compliance. A summary of the treatment design parameter information is provided in Table 1. Backup for MGSFlood analysis can be found in Appendix B. Additional information on the treatment class of the systems provided can be found in the Stormwater Treatment Alternatives Analysis — Port of Everett Waterfront Place Central at Fisherman Harbor Keport, (Herrara 2016.) Table 1: Treatment System Summary ODC