TagThird Runway(206)

This engineering cross-section diagram from Sea-Tac International Airport illustrates the dramatic 179-foot elevation drop adjacent to the proposed Third Runway, showing how a massive retaining wall and new embankment would be constructed alongside Miller Creek. The exhibit depicts key infrastructure features including a permanent chain-link security fence, rock underdrain, silt fence, inner collection swale, and a minimum 50-foot creek buffer zone designed to protect the existing waterway. The drawing is part of the Miller Creek Instream and Buffer Enhancements project documentation associated with the Third Runway expansion.

This document explains the regulatory approval process required for filling wetlands as part of Sea-Tac Airport's third runway expansion, which requires both a federal permit under Section 404 of the Clean Water Act and a state certificate under Section 401. The Port of Seattle filed its third application in October 2000 after two previous attempts failed, facing significant environmental obstacles including contaminated fill material, threats to stream flow and salmon habitat, destruction of nearly 20 acres of wetlands, flooding risks, embankment stability concerns in an earthquake-prone area, and existing pollution levels that already exceed allowable limits. The U.S. Army Corps of Engineers must also weigh the public need for the project against these environmental harms, raising broader questions about whether the expansion is justified at all.

This document explains the Washington State Department of Ecology's review process for Sea-Tac Airport's applications to fill wetlands as part of its third runway project. Sea-Tac submitted three separate applications between 1996 and 2000, with the third ultimately receiving a Section 401 water-quality certificate that was later put on hold after the Airport Communities Coalition appealed. The Pollution Control Hearings Board identified three key concerns driving the stay: contaminated fill material, insufficient water rights for dry-season stream flow, and inadequate wetlands mitigation plans.

The U.S. Army Corps of Engineers has been reviewing a permit application related to a proposed third runway at Sea-Tac Airport, described as the largest Section 404 proceeding the Corps had handled and the biggest public works project in Washington State since the Grand Coulee Dam. Key issues under consideration include the replacement of lost wetlands, streamflow impacts, and the seismic stability of the proposed runway embankment. No deadline exists for the Corps to render its final decision, though draft permit conditions were reportedly being prepared by civilian technicians in the Seattle District Office.

This U.S. Army Corps of Engineers document reviews the environmental impact of construction projects at Seattle-Tacoma International Airport, including the Third Runway and related Master Plan Update improvements, focusing on impacts to wetlands and waterways. The Corps conducted an independent assessment of wetland functions and evaluated whether the Port of Seattle's proposed mitigation plans adequately compensated for the destruction or alteration of aquatic resources. After finding the Port's initial December 2000 mitigation plan insufficient, the Corps worked with the Port to develop a revised plan, accepted in November 2001, that better addressed the loss of wetland functions caused by airport construction.

This document summarizes the environmental wetland impacts associated with airport expansion projects near Sea-Tac Airport, detailing acreage affected across four creek basins — Miller Creek, Walker Creek, Des Moines Creek, and Green River. It breaks down impacts by wetland vegetation type (forested, shrub, emergent, and open water) and hydrological classification (depressional, riverine, and slope), with total impacts ranging from 4% of the Walker Creek project area to 100% of the Green River area. The tables also distinguish between temporary and permanent wetland impacts as determined by the U.S. Army Corps of Engineers, covering features such as the Third Runway and Runway Safety Area extensions.

The Airport Communities Coalition (ACC) filed an emergency motion asking the Washington Supreme Court to temporarily halt construction of a proposed third runway at Seattle-Tacoma International Airport. ACC sought to prevent the Port of Seattle from filling wetlands and the Department of Ecology from approving embankment construction while the court's decision on related appeals remained pending. The motion was prompted by reports that the Port planned to begin depositing fill material in April, before the court had issued its ruling.

The Airport Communities Coalition filed an emergency motion asking the Washington Supreme Court to block the Port of Seattle from filling wetlands and rerouting Miller Creek in preparation for a third runway at Sea-Tac Airport. The Coalition argued that the Pollution Control Hearings Board's order is legally binding on the Port and the Department of Ecology, and that the Port cannot alter the site's status quo while the appeal is pending. The motion sought an injunction to preserve existing conditions until the court issued a final ruling on whether the project complies with state water quality standards.

The Airport Communities Coalition (ACC) filed an emergency motion seeking to stop the Port of Seattle from moving forward with its Third Runway Project without complying with conditions set by the Pollution Control Hearings Board. This supplemental brief, submitted to the Washington Supreme Court, addresses whether the Administrative Procedure Act's stay provisions apply to ACC's request to enjoin the Port from violating the Board's order. ACC argues that the relevant APA provisions do not directly govern its motion, but that an injunction is especially warranted because the Port failed to obtain a stay of the Board's order.

The Airport Communities Coalition (ACC) appealed a federal court decision regarding the U.S. Army Corps of Engineers' approval of a third runway at Seattle-Tacoma International Airport. At issue was whether the Corps was required to incorporate all water quality conditions set by Washington State's Pollution Control Hearings Board (PCHB) into its Clean Water Act Section 404 permit, including protections against polluted fill and wetland impact mitigation measures. The case, heard by the Ninth Circuit Court of Appeals, centered on whether the Corps acted unlawfully by selectively excluding key state-mandated environmental safeguards from the construction permit.