TagThird Runway(1098)

A November 1999 technical letter from Northwest Hydraulic Consultants, submitted on behalf of the Airport Communities Coalition, identifies major deficiencies in the proposed stormwater management plan for Seattle-Tacoma International Airport's 3rd runway development. The review finds that the plan fails to comply with the 1998 King County Surface Water Design Manual and Washington State Department of Ecology guidelines, including requirements for large-site drainage reviews, offsite analysis, and flow control. The consultants warn that if the plan is approved as written, it could cause significant adverse impacts to downstream creek systems, including Miller Creek and Des Moines Creek.

Washington Court of Appeals Division One published opinion (No. 42306-1-I, filed November 15, 1999) in City of Des Moines, City of Burien, City of Federal Way, City of Normandy Park, City of Tukwila, Highline School District No. 401, and Airport Communities Coalition v. Puget Sound Regional Council, Executive Board of PSRC, Port of Seattle, and

Hart Crowser subsurface conditions data report (J-4978-16) prepared for HNTB and Port Of Seattle, dated November 12, 1999, regarding Phase 3 Fill for the Third Runway embankment at Seattle-Tacoma International Airport. Report covers generalized geologic and subsurface soil conditions, hydrogeologic conditions, field explorations (auger borings HC99-B61, HC99-B63, HC99-B65, HC99-B71, HC99-B73), test pits HC99-TP26 through HC99-TP44,

This October 1999 draft document outlines resolved and unresolved regulatory issues related to a Sea-Tac Airport expansion project, focusing primarily on stormwater management, wetland mitigation, and water quality concerns. Key unresolved issues include compliance with Ecology and King County Stormwater Manuals, the role of a proposed Regional Detention Facility (RDF) in wetlands, de-icing impacts on dissolved oxygen levels, and instream flow reductions in Des Moines Creek. Additional concerns involve NPDES permit compliance, clean fill criteria, legal proceedings before the Pollution Control Hearings Board, and whether a shoreline permit is needed for an Auburn mitigation site.

A October 1999 laboratory analysis report from Aquatic Research Incorporated details water sample testing conducted for Parametrix/Port of Seattle. One water sample collected on October 8-11, 1999 was tested for total suspended solids, petroleum hydrocarbons (diesel and motor oil), and total metals including cadmium, copper, lead, and zinc. Results showed low levels of contaminants, with zinc detected at 0.102 mg/l and copper at 0.0070 mg/l, while diesel and motor oil levels fell below detection limits.

In this October 1999 internal memo, Washington State Department of Ecology staffer Tom Luster describes a meeting with his supervisor Paula regarding the agency's water quality review of Sea-Tac Airport expansion. Luster explains that he cannot yet provide 'reasonable assurance' that the Port of Seattle's proposal will meet water quality standards for Des Moines Creek, citing inadequate stormwater treatment plans and the Port's removal of flow augmentation measures from its mitigation plan. He expresses concern that management pressure to approve the project quickly could compromise the integrity of the regulatory review process.

Hart Crowser memorandum from Michael Bailey, Allen Jones, and Doug Lindquist to Jim Thomson (HNTB), dated October 8, 1999, presenting probabilistic seismic hazard analysis (PSHA) results for the Sea-Tac Airport Third Runway project (J-4978-14). Reports peak horizontal acceleration (PHA) values for common design return intervals: 0.16 g (72-year), 0.36 g (475-year), 0.47 g (975-year), and

Hart Crowser subsurface conditions data report (project J-4978.02) prepared for HNTB and Port Of Seattle, dated September 24, 1999, covering Borrow Areas 1, 3, and 4 for the Sea-Tac Airport Third Runway project. Report includes generalized geologic conditions, subsurface soil conditions, hydrogeologic regime, groundwater elevation data, and perched water-bearing zone analysis. Field explorations used dual-wall

A September 20, 1999 internal memorandum from Parametrix, Inc. consultants to Scott Tobiason provides technical review comments on the first draft of the 1999 Annual Stormwater Report for Seattle-Tacoma International Airport (STIA). The memo raises concerns about consistency in water quality comparators, statistical methods for 'trimmed' data sets, and the attribution of reduced sediment levels to construction wheel wash versus other factors. It also flags regulatory issues regarding mixing zones, water quality standards language, and potential NPDES permit compliance implications of identifying pollution sources in the annual report.