Publication Summary

The Port of Seattle proposes to construct a fill embankment for a third runway at Seattle-Tacoma International Airport.The volume of fill required for the embankment is reported to be 16.5 million cubic yards.The embankment is proposed to be built of fill soil derived from borrow pits located south of the airport near Des Moines Creek,and from off-site sources that would be determined in the future.A Maury Island gravel mine (about 8 miles south of the airport)has been identified as a possible off-site source of fill. Under contract with the Department of Ecology,Pacific Groundwater Group and its subconsultants,EarthTech,Inc.,and Ecology and Environment,Inc.,have evaluated some of the potential impacts of the proposed project,including effects on groundwater,streams,wetlands,and fish.The study area includes the fill area and adjoining wetlands,streams,and aquifers potentially impacted by the proposed runway project,as well as the borrow pit areas proposed for excavation near Des Moines Creek.