TagDes Moines Creek(169)

A water resources consultant raised concerns in a July 2001 letter to the U.S. Army Corps of Engineers and Washington State Department of Ecology about the Port of Seattle's stormwater management plans for Sea-Tac Airport expansion. The letter challenged the effectiveness of proposed biofiltration swales, noting they can actually increase bacterial levels rather than reduce them, and warned that releasing stored stormwater from detention vaults into nearby Class AA streams could discharge pollutant-laden, oxygen-depleted water into already stressed waterways. The consultant concluded that the Port's plans fell short of providing reasonable assurance that water quality standards would be met.

This table from a July 2001 Comprehensive Stormwater Management Plan summarizes drainage area measurements and changes in impervious surfaces (such as pavement and rooftops) across Miller Creek, Walker Creek, and Des Moines Creek watersheds at Seattle-Tacoma International Airport (STIA). It compares 1994 baseline conditions to projected 2006 future conditions, showing a total increase of approximately 305.7 acres of impervious area across all drainage basins. The data was compiled from GIS coverage to support stormwater management planning for the airport's master plan update.

This document describes the Integrated Water System (IWS) stormwater management configuration at Seattle-Tacoma International Airport (Sea-Tac), detailing storage lagoons totaling 76.9 million gallons and a treatment rate of 4.0 million gallons per day across approximately 435 acres. Simulations over a 50-year period confirmed zero overflow events under proposed conditions, with overflows only beginning to occur if treatment rates dropped below 3.1 million gallons per day. The system experienced only one historical overflow during an extreme rain-on-snow event in December 1996–January 1997, with no petroleum hydrocarbons detected downstream.

Email dated May 17, 2001 from Raymond Hellwig (Ecology) to Thomas Fitzsimmons and Tom Fitzsimmons, cc Ann Kenny, transmitting an ‘updated’ discussion paper marked deliberative and not yet available for public disclosure. The attached discussion paper (issuelink-1.doc) addresses three key issues carried forward from a September 2000 paper: (1) Stormwater Management Plan (SMP) led by

Final draft meeting notes prepared by Rachel McCrea of Floyd & Snider Inc. for a 401 Permit Decision-Making technical meeting held April 23, 2001, regarding Sea-Tac International Airport Third Runway. Attendees included representatives from Washington State Department of Ecology (John Drabek, Ann Kenny), Port of Seattle (Keith Smith), King County (Kelly Whiting), HNTB (Alan Black),

Final draft meeting notes from April 16, 2001 technical meeting on 401 Permit Decision-Making for Sea-Tac Airport Third Runway, prepared by Rachel McCrea of Floyd & Snider Inc. Attendees included John Drabek and Ann Kenny (Dept. of Ecology), Keith Smith (Port of Seattle), Kelly Whiting (King County), Alan Black (HNTB), Paul Fendt and Tom Atkins

In this April 11, 2001 letter, Washington State Department of Ecology Director Tom Fitzsimmons responds to attorney Kevin Stock regarding concerns raised by the Airport Communities Coalition (ACC) about the Port of Seattle's proposed Third Runway. Ecology agrees to host a technical meeting with ACC experts to examine whether Third Runway infrastructure could create pathways for contaminants from the Airport Operations and Maintenance Area (AOMA) to proposed runway sites, but declines to halt the 401 water quality certification process pending completion of a separate groundwater study. Ecology assures the ACC that it will not approve or deny the Third Runway projects until a 'pathway' analysis addressing contamination concerns is completed.

In an April 2001 letter to the Washington State Department of Ecology, Northwest Hydraulic Consultants raised serious concerns about the adequacy of a low streamflow analysis conducted for the proposed third runway expansion at Seattle-Tacoma (Sea-Tac) Airport. The firm argued that Ecology's March 2001 review memo effectively endorsed the study's methods and conclusions without addressing significant technical flaws, including the use of future rather than existing basin conditions and the failure to account for impacts from gravel mining, lagoon lining programs, and embankment seepage. The consultants, representing the Airport Communities Coalition, requested that Ecology revisit its review, consider all submitted technical comments, and require the airport's applicant to formally respond to outstanding concerns before any regulatory certification was granted.

This 2001 draft report by Parametrix, Inc. describes a water quality study conducted for the Port of Seattle to assess the feasibility of meeting state water quality standards following construction of a third runway at Seattle-Tacoma International Airport. The study focused on developing a site-specific water-effect ratio (WER) for copper in Miller, Walker, and Des Moines Creeks by conducting toxicity bioassays on stormwater samples collected during storm events. The report summarizes results from initial screening and range-finding phases, with the final site-specific water quality standard still pending completion at the time of publication.