An Environmental Impact Statement (EIS) is a detailed analysis of the likely effects of a proposed plan or project, including reasonable alternatives, on the natural and “built” environment, and outlines measures to “mitigate” (soften or compensate for) negative impacts. The federal requirement for EIS preparation, which typically evolves through draft and final stages of publication, was established by the National Environmental Policy Act of 1970, which has since been emulated by most states and local governments. The findings of an EIS do not necessarily dictate final policy decisions, but the “adequacy” of its analysis can be challenged by opponents in court to delay and/or modify a project.
Not Cleared For Takeoff
Publication of the Final Environmental Impact Statement for the third runway was a major -- but far from final -- step in a regional planning process that began in 1988 with forecasts that Sea-Tac could reach its maximum efficient capacity by the year 2000. Because the airport's first two parallel runways were built only 800 feet apart, only one could be used when cloud cover was lower than 5,000 feet or when pilot visibility falls below five miles. This condition prevails approximately 44 percent of the time at Sea-Tac and resulted in flight delays and higher costs for airlines and their passengers.
The Port of Seattle and Puget Sound Regional Council conducted a public study of this problem between 1989 and 1992. Known as "Flight Plan," the three-year effort entailed extensive citizen outreach and technical analysis of numerous options for meeting regional air travel needs through 2020. The Regional Council narrowed its “preferred alternative” to the third runway in 1996.
The Final Sea-Tac Environmental Impact Statement also found that the Port’s existing noise and pollution reduction programs were sufficient to address the impacts of new construction and expanded airport operation. The Final EIS cautioned that the Seattle-Tacoma region would experience increasing demand for air services due to explosive growth in both the region’s population and income level during the 1990s.
Critics and opponents of the third runway, including Sea-Tac-area cities (organized in 1995 as the Airport Communities Coalition), institutions, and environmental groups challenged the Final Environmental Impact Statement's findings with administrative and legal appeals.
Despite these objections, the Puget Sound Regional Council blessed the third runway by adding it to the federally mandated Regional Transportation Plan on July 11, 1996. The Port of Seattle Commission made the project official by adopting its Master Plan Update for Sea-Tac on August 1, 1996.
The original analysis was confirmed by a Supplemental Environmental Impact Statement published on May 13, 1997. The FAA, as the lead responsible agency for airport construction, filed its final “record of decision” supporting the third runway on July 3, 1997. That same year, Sea-Tac aircraft operations topped its maximum efficient capacity of 380,000 landings and takeoffs. (They would rise to nearly 446,000 operations in 2000, then decline with the economy and post-9/11 air travel slump to about 365,000 operations in 2002.)
In May 2004, the State Supreme Court largely cleared the way for construction to resume, and on August 19, 2004, the Airport Communities Coalition dropped litigation, after having spent $15 million over 10 years campaigning and litigating against the third runway.
Construction resumed and the 8,500-foot runway was completed four years later for a total cost of just over $1 billion. It opened on November 20, 2008.