City of Des Moines Comment Letter on Seattle-Tacoma SAMP Draft Environmental Assessment

The City of Des Moines submitted formal comments to the Port of Seattle in December 2024, expressing serious concerns about the Seattle-Tacoma International Airport's Sustainable Airport Master Plan and its projected growth in flight operations. The letter warns that by 2032, a nearly 20% increase in annual flights will significantly expand noise exposure for Des Moines residents, with the population affected by harmful noise levels rising by roughly 37% even without the proposed expansion. The city calls on the Port and FAA to extend public review periods, develop meaningful noise mitigation measures such as sound insulation programs, and collaborate more genuinely with neighboring communities rather than treating public input as a regulatory checkbox.

Notes

December 12, 2024 letter from the City of Des Moines to Steve Rybolt, Port of Seattle Aviation Environment and Sustainability, submitting formal comments on the Seattle-Tacoma International Airport (Sea-Tac Airport) Sustainable Airport Master Plan (SAMP) Draft Environmental Assessment (EA). Raises concerns about the inadequate public comment period, aircraft noise impacts including DNL 65 dBA contour expansion, projected 20% increase in annual operations to 511,800 by 2032, a 25% increase in nighttime arrivals, and the estimated increase in population exposed to significant noise from 14,061 (2022) to nearly 22,000 (2032). Notes that most of the expanded DNL 65 dBA contour falls within Des Moines, WA. Calls for Part 150 study updates, sound insulation for eligible homes and schools, noise abatement measures, ongoing noise monitoring, and proactive collaboration between Port of Seattle and City of Des Moines. References community meeting held December 3, 2024, with approximately 90 attendees. Cites NEPA, CFR Part 150, and SAMP Draft EA Appendix A data.

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