TagThird Runway(157)

This report ducdtns Envirometri,a’ review and analysb of the Federal Aviation AdmbtbtIation’s air quality study of the implementation of the Master Plan Update for the Seattle-Tacoma International Airport in its draft Clean Air Act Conformity findin& the FAA concludu that, based on the FEIS modeling, “with mitigation, the proposed improvements would not ruult in any new exceedanca, nor increase the frequency or severity of any existing violations of the ambient ah quality standaais for cartx>n monoHde (CO) or niH>gen dioxide(NOD at any modeled eceptor JBVU6d• %HbV ZBU• The FAA’s conclusion is based on the assumption that avbtion traffic will tn the same regardless of whether or not the Master Plan projects are completed. In fact, implementation of the thiN runway could mean an incnase in airport operations by as much as an annual average 33 penent aIx>ve that projected by the Master Plan UFxiate by a)a), which could translate into an increase of up to 50 percent atxive the projections for the peak hour. Therefore, to test the impact and validity of this assumption, Envhometda atimated NO2 and modeled CO concentrations based on the alternate assumption that the expanded airport would ruult in increased ainraft and passenger vehicle traffic. Our analysis providu pndktions of the effect of aN) percent increase hI passengers in the peak hour in a)10 on CO concentrations at surface street intersections from increased vehicle traffic and the effect on NO2 concentrations fn>m a 33 percent increase ainraft activity by 2020 r We conducted our intersection modeling…