TagSEPA(233)

The City of Des Moines, WA issued a public notice in July 2024 for a proposed 402,380-square-foot industrial building on a 30-acre site near S. 216th St. and 20th Ave. S., submitted by Panattoni Development Corporation. The project, which involves filling wetlands and rerouting a stream, was granted a Mitigated Determination of Nonsignificance (MDNS) under SEPA, meaning city officials determined it would not cause significant adverse environmental impacts. Public comments and appeals of the environmental decision were accepted through late July and early August 2024.

The City of Des Moines issued a Mitigated Determination of Nonsignificance (MDNS) for a proposed 402,380-square-foot industrial building near Seattle-Tacoma International Airport, finding no significant environmental impact provided certain conditions are met. Key mitigation requirements include wetland and stream protections, long-term environmental monitoring, and compliance with FAA Advisory Circular 150/5200-33C standards to ensure the project's stormwater detention pond does not attract hazardous wildlife that could pose risks to aircraft operations. The decision, issued July 8, 2024, was open for public comment through July 23, 2024, with an appeal deadline of August 2, 2024.

The Federal Aviation Administration (FAA) issued a Negative Determination in July 2024, concluding that planned near-term construction and equipment relocation projects at Seattle-Tacoma International Airport (SEA) are not reasonably likely to cause effects on Washington State's coastal zone. The 31 Near-Term Projects, which include taxiway extensions, blast pad expansions, and relocation of navigational aids, are part of the airport's Sustainable Airport Master Plan and are scheduled to begin construction in 2026. The FAA requested written concurrence from the Washington State Department of Ecology, while the Port of Seattle remains responsible for separate consistency certification for any projects requiring Clean Water Act permits.

This technical report, prepared by Landrum & Brown for the Port of Seattle in June 2024, outlines the purpose and need for near-term construction and improvement projects identified in the Sustainable Airport Master Plan for Seattle-Tacoma International Airport. It is part of a broader set of supporting documents that also covers alternatives analysis, terminal needs, and air cargo facility requirements. The report provides the foundational justification for planned airport development decisions.

Appendix C of the Sea-Tac Sustainable Airport Master Plan covers air quality and greenhouse gas emissions analyses prepared for the Port of Seattle by Landrum & Brown. It includes technical reports on emissions from aircraft, ground support equipment, construction, and other airport sources, as well as a human health risk assessment focused on ultrafine particles. Note that some climate-related sections originally included in the Draft Environmental Assessment were later removed following changes to federal executive orders and a 2025 Supreme Court ruling.

This Noise Technical Report, prepared by Landrum & Brown for the Port of Seattle in March 2024, analyzes noise impacts associated with near-term construction and development projects outlined in the Sustainable Airport Master Plan for Seattle-Tacoma International Airport. The report is part of Appendix J, which covers noise and noise-compatible land use, and was developed to satisfy both federal (NEPA) and state (SEPA) environmental review requirements. It provides technical findings to help assess how proposed airport improvements may affect noise levels in surrounding communities.

This technical memorandum from Landrum & Brown (February 2024) explains that noise modeling for the Seattle-Tacoma Airport (SEA) Sustainable Airport Master Plan (SAMP) Environmental Review was updated from AEDT Version 3e to the newer AEDT Version 3f, released December 13, 2023. The upgrade allowed modelers to use actual aircraft data for the Boeing 737-7 and Cessna 408 SkyCourier rather than substitute aircraft, improving modeling accuracy. The document details the specific airframe, engine, and Aircraft Noise and Performance (ANP) data changes made between the two software versions.