TagEnvironmental Impact Statement(400)

The City of Des Moines, WA provided its City Council with an update on the Sustainable Airport Master Plan (SAMP) for Seattle-Tacoma International Airport, following the FAA's September 2025 approval of 31 near-term expansion projects — including 19 new gates, a second terminal, and cargo facilities. The Port of Seattle launched a state-level environmental review (SEPA) in May 2026, releasing a Draft Environmental Impact Statement with a 60-day public comment period. Des Moines is collaborating with the cities of Burien and SeaTac through an Interlocal Agreement to submit coordinated comments, with the final report expected in 2027.

Des Moines resident Jeffrey Bogen submitted a formal comment arguing that the Sea-Tac Airport Master Plan (SAMP) Environmental Impact Statement fails to adequately analyze cumulative health effects on nearby communities. He contends that the EIS must go beyond examining individual pollution sources and instead assess the combined burden of aircraft ultrafine particles, roadway traffic emissions, chronic noise, and other stressors together, since scientific research shows these exposures interact and compound one another. Bogen calls for a comprehensive cumulative-risk framework, backed by ten peer-reviewed studies, to be incorporated into the EIS before any accurate public health or policy conclusions can be drawn.

A Des Moines resident's formal comment on the Seattle-Area Metroplex Environmental Impact Statement argues that Sea-Tac Airport's official planning assumption — that average aircraft size will grow by only 0.5% per year — is mathematically incompatible with the airport's own goal of 56 million annual passengers by 2032. The comment shows that reaching that passenger target under the current assumption would require roughly 880,000 flights per year, far exceeding the airport's infrastructure ceiling of about 517,000 operations. The author contends that airlines like Alaska and Delta are already ordering larger aircraft and expanding international routes at Sea-Tac, meaning faster fleet upgauging is not a worst-case scenario but a necessity for the plan to make sense.