TagStormwater(373)

Letter dated August 3, 2001 from King County Department of Natural Resources Director Pam Bissonnette to Ann Kenny, Senior Permit Specialist, Washington Department of Ecology Northwest Regional Office, transmitting King County’s technical review comments on the Port Of Seattle’s Low Flow Impact Analysis – Low Flow Impact Offset Facility Proposal (July 2001). The enclosure provides

This August 2001 King County review evaluates the Port of Seattle's Low Flow Impact Analysis and proposed Flow Impact Offset Facility, which aims to mitigate reductions in stream flows in local creeks—including Des Moines, Miller, and Walker creeks—caused by future airport development. The review finds that while the proposed water storage and augmentation measures substantially offset low-flow impacts during the critical late-summer period, there are significant gaps in documentation, biological assessment, and design details that need to be addressed. Recommendations include professional engineering certification, enhanced biological monitoring, improved calibration documentation, and refinements to the reserve storage facility designs.

A declaration by civil engineer William A. Rozeboom, filed with Washington's Pollution Control Hearings Board, raises concerns about the environmental impact of Seattle-Tacoma International Airport's Third Runway construction project. Rozeboom, a stormwater and hydraulics expert retained by the Airport Communities Coalition, warns that the project will reduce low streamflows in Des Moines, Miller, and Walker Creeks during summer months due to increased impervious surfaces and changes to the industrial wastewater system. While the July 2001 Stormwater Management Plan addresses peak flood flows, Rozeboom argues it fails to adequately assess or mitigate the project's impact on low-flow stream conditions.

Draft Water Quality Certification #1996-4-02325, pages 16-17 of 23, dated August 2001, issued by Washington State Department of Ecology regarding Port Of Seattle Seattle-Tacoma International Airport (STIA). Covers operational stormwater requirements including the approved Comprehensive Stormwater Management Plan (CSMP) Volumes 1-4 December 2000 as revised July 2001, retrofitting of stormwater management facilities, discharge of operational

Washington State Department of Ecology Water Quality Program publication numbers 99-11 through 99-15, August 2001. Stormwater Management Manual for Western Washington covering five volumes: Volume I Minimum Technical Requirements and Site Planning, Volume II Construction Stormwater Pollution Prevention, Volume III Hydrologic Analysis and Flow Control Design/BMPs, Volume IV Source Control BMPs, Volume V Runoff Treatment

Exhibit AR032547 from Washington State Department of Ecology (Ecology), Volume V – Runoff Treatment BMPs, August 2001. Covers phosphorus removal treatment trains (Table 3.1), Enhanced Treatment Menu (Section 3.4) and Basic Treatment Menu (Section 3.5) for stormwater management. Specifies requirements for industrial, commercial, multi-family project sites, arterials and highways discharging to fish-bearing streams or lakes.

Sand and Gravel Stormwater Pollution Prevention Plan (SWPPP) prepared by Parametrix, Inc. for Port of Seattle, covering Borrow Areas 3 and 4 of the Third Runway Project at Seattle-Tacoma International Airport. Prepared August 2001, approved by Michael Feldman, Director of Aviation Facilities, Port of Seattle. Document checked by Paul Fendt, P.E. and prepared by Julie