TagFAA(793)

This March 1994 Final Environmental Impact Statement, prepared jointly by the Federal Aviation Administration's Seattle Airports District Office and the Port of Seattle, evaluates the proposed South Aviation Support Area at Seattle-Tacoma International Airport. The document assesses the potential environmental effects of developing aviation support facilities in the southern portion of the airport, covering impacts such as noise, land use, and related concerns. It was produced as part of the federally required environmental review process before any major airport infrastructure decisions could be approved.

The Port of Seattle operates a noise information line (433-5393 or 1-800-826-1147) that allows area residents to report aircraft noise complaints, ask questions about Sea-Tac's noise abatement programs, and request evaluations of specific noise events. Calls are documented in a database, and summaries are shared with FAA air traffic officials, Port Commissioners, and the public to help monitor and improve noise programs. However, the Port cannot take immediate action — such as modifying flight tracks — based solely on phone complaints.

A 1993 letter from the Port of Seattle to a Des Moines resident explains that airline deicing at Sea-Tac Airport uses only FAA-approved ethylene or propylene glycol, and that wastewater from deicing drains to the airport's treatment system before being discharged to Puget Sound — not to Miller or Des Moines Creeks. The Port acknowledged its treatment plant was not designed to handle glycols and was evaluating upgrades. A follow-up 1996 letter challenges a contradictory statement in the airport's Final Environmental Impact Statement, which claimed most deicing fluids were contained and treated by the Port's Industrial Wastewater System.

In a November 1992 letter to the FAA's Northwest Mountain Region manager, the President of the Regional Commission on Airport Affairs urges the federal government to defer funding and detailed planning for a proposed third runway at Seattle-Tacoma International Airport (Sea-Tac). The letter argues that the Puget Sound Regional Council's ongoing regional airport system planning process must be allowed to fully evaluate all alternatives before any single project receives federal financial commitment. The author warns that proceeding prematurely with site-specific plans and an Environmental Impact Statement risks wasting federal money if the regional plan ultimately selects an alternative other than a third runway at Sea-Tac.

In 1992, the Ninth Circuit Court of Appeals upheld the FAA's decision to change flight patterns for turbine-powered aircraft at Seattle-Tacoma International Airport without preparing a full Environmental Impact Statement. The FAA had issued a Finding of No Significant Impact based on a computer noise model using the 65 decibel day-night sound level as the threshold for significant noise impact, which the court found to be a reasonable approach. The Seattle Community Council Federation had challenged the decision, arguing that the FAA failed to adequately assess the noise effects on surrounding communities.

In this 1992 letter, acoustics expert James D. Chalupník explains to attorney Richard Aramburu how aircraft noise near Seattle's Sea-Tac Airport is measured and rated, focusing on the appropriateness of the Ldn metric and the data used in the FAA's Integrated Noise Model (INM). He outlines the key physical properties of noise—intensity, frequency distribution, and fluctuation over time—and describes how various weighting schemes, particularly the A-weighting (dBA) scale, are used to approximate human perception of loudness and annoyance. The letter also notes the limitations of simpler metrics and introduces more sophisticated rating methods such as Stevens' Loudness Level and Perceived Noise Level for evaluating aircraft noise.