The Port of Seattle began planning a third runway expansion for Sea-Tac International Airport in 1988. Over the years the plan met many legal challenges from community and environmental groups fearing the runway’s impacts on the area surrounding the airport.
Among the many permits that the Port was required to obtain during the lengthy federally mandated period of public input and debate on the third runway issue was a 401 certification. The nomenclature refers to the fact that the certification addresses Section 401 of the federal Clean Water Act relating to water quality. The U.S. Environmental Protection Agency charges states with providing this certification.
The Port of Seattle and Federal Aviation Administration issued their draft Environmental Impact Statement for the third runway on April 27, 1995. It proposed a third runway of up to 8,500 feet in length located 1,700 feet west of the existing second runway. This in turn would require the westward extension of the airport plateau atop some 17 million cubic yards of fill dirt secured by retaining walls averaging 74 feet high on the west, 54 feet high on the north, and 27 feet high on the south. The Draft Environmental Impact Statement identified the need to acquire about 400 homes and cited potential effects on nearby Miller Creek and on several acres of wetland habitat.
The Port had prepared two earlier applications but withdrew them to address new information on wetlands impacts. On August 10, 2001, the Washington State Department of Ecology issued the 401 permit to the Port of Seattle. The Airport Communities Coalition (a group strongly opposed to third runway construction) appealed the issuance of the 401 permit to the Washington State Pollution Control Hearings Board, which stayed issuance of the permit pending a hearing on March 18, 2002.
Following the issuance of the Board’s conditional permit approval, the Port of Seattle decided to appeal the Hearings Board's findings. Although the 401 permit was long sought, the Port found the conditions extreme. On September 26, 2002, the Port of Seattle appealed eight of the newly mandated conditions. On September 18, 2002, the Washington State Department of Ecology also appealed three of these eight contested conditions. In addition, the Airport Communities Coalition (opposed to the runway), filed an appeal.
The Port alleged that the Hearings Board had exceeded the boundaries of its authority, and also that it had improperly limited the evidence heard prior to making the decision. The primary issue for both the Port's appeals and those of the Department of Ecology involved the Hearing Board’s criteria for fill dirt quality, which the agencies felt set a higher standard than even those found in nature. The State Legislature voided the new criteria in April 2003.
In August 2004, the Airport Communities Coalition dropped its appeals following an adverse State Supreme Court decision. Construction resumed on the third runway, which was completed in 2008 at a cost of more than $1 billion.