Notes
Envirometrics Inc. report prepared for the Airport Communities Coalition (ACC) reviewing the FAA’s air quality conformity analysis for the Seattle-Tacoma International Airport Sea-Tac Master Plan Update (STMU). The report challenges the FAA’s Clean Air Act conformity finding in the FEIS, which concluded that proposed improvements would not result in new exceedances of NAAQS standards for carbon monoxide (CO) or nitrogen dioxide (NO2). Envirometrics modeled CO concentrations at surface street intersections for 2010 Do Nothing, Project, and increased-passengers scenarios, and estimated NO2 concentrations for a 33 percent increase in aircraft activity by 2020. Findings show that implementation of the third runway could increase airport operations by 33 percent annually above Master Plan projections, causing exceedances of CO and NO2 ambient air quality standards, with frequency of CO exceedances more than doubling at the S 160th St and SR 99 intersection.