TagSea-Tac Airport(2023)

This appendix from Seattle-Tacoma International Airport's Final Supplemental Environmental Impact Statement evaluates potential environmental impacts through the year 2020 under three scenarios, including the new Port forecast and cases where aviation demand grows 10% faster than projected. Key findings indicate that noise impacts are expected to remain below current levels in all scenarios, with 'With Project' improvements producing roughly 53% of current noise conditions by 2020. The analysis also examines air quality, enplanement levels, and aircraft operations across both Do-Nothing and preferred alternatives to guide long-term airport planning.

A April 1997 memo and progress report from Hellmuth, Obata + Kassabaum, Inc. (HOK) summarizes the near-complete Sea-Tac Area Mitigation Study, which assessed environmental, traffic, and socio-economic impacts related to Sea-Tac Airport. The memo outlines scheduling recommendations for a series of public and stakeholder meetings planned for May 1997 in Burien, Washington, including suggestions to consolidate citizen meetings and limit City Council sessions. As of the report date, all major project tasks were at 100% completion except the Mitigation Plan, which stood at 99%, with the consultant team preparing to present final findings to the community.

A 1997 Agreed Order issued by the Washington State Department of Ecology directed the Port of Seattle to address hazardous substance contamination at Seattle-Tacoma International Airport. Jet fuel, gasoline, industrial solvents, and other chemicals had been released across twelve separate sites within a half-square-mile Aircraft Operations and Maintenance Area, impacting both soil and groundwater. The order established a framework for ongoing environmental investigation and cleanup while acknowledging the operational challenges of working in an active airport environment.

In December 1996, the Port of Seattle submitted a Section 404 permit application to the U.S. Army Corps of Engineers to place fill material in waters of the United States as part of Sea-Tac Airport's Master Plan Update, which included construction of a third parallel runway. The application explains that the new runway, located 2,500 feet west of the existing 16R/34L runway, was needed to reduce severe arrival delays during poor weather conditions, which were costing airlines approximately $42 million annually. The project was the outcome of nearly a decade of regional planning, including the PSRC's Flight Plan Study, which evaluated numerous alternatives before recommending the runway expansion as the best solution for the region's long-term air travel needs.

This 1996 plan by Parametrix, Inc. outlines the proposed relocation of Miller Creek to accommodate expansion improvements at Seattle-Tacoma International Airport. It assesses the creek's existing ecological conditions—including fish habitat, hydrology, and riparian vegetation—and identifies the construction impacts the relocation would cause. The document then presents mitigation goals, site selection rationale, and engineering details for redesigning the creek channel to offset environmental impacts.

Annual Stormwater Monitoring Report for Seattle-Tacoma International Airport (STIA) covering the period July 1, 1995 through June 30, 1996, AR 027767–027769. Prepared by Scott Tobiason, Environmental Management Specialist, Port Of Seattle Environmental Services. Reviewed by Tom Hubbard (Port of Seattle) and Gary Minton (Resource Planning Associates). Document concerns NPDES stormwater monitoring at Sea-Tac Airport.

HNTB-prepared Final Draft Phase I study (November 1996) for Sea-Tac Airport Third Runway fill material alternative delivery methods. Evaluates transport corridors including Corridor 1 (Des Moines Creek barge transfer and land conveyor), Corridor 2 (SR 509 conveyor, truck, rail), and Corridor 3 (SR 518 conveyor, truck, rail). Covers technical viability, construction/environmental permitting (local, state, federal),

In August 1996, community groups CASE and RCAA formally appealed the Port of Seattle's Resolution No. 3212, which approved construction of a third runway at Seattle-Tacoma International Airport. The appeal argued that newer navigation technologies such as Localizer Directional Aid (LDA) and GPS, combined with demand management strategies, could provide equivalent airport capacity at far lower cost and with less environmental harm. The groups requested a Supplemental Environmental Impact Statement to evaluate these technology-based alternatives and reconsider the third runway decision.

A 1996 Seattle Times article details the massive earth-moving challenge facing Sea-Tac Airport's planned third runway, which required importing approximately 14.25 million cubic yards of fill dirt at an estimated cost of $120 million to level a corridor of dips and valleys as deep as 145 feet. Port of Seattle planners were exploring multiple options for sourcing and transporting the dirt, including conveyor belts, barges, and rail spurs, while facing legal opposition from nearby cities who argued the project understated environmental and community harm.