This project will combine the cleanup of contaminated sediments with habitat restoration in the inner half of Slip 4. Slip 4 is a 3.8-acre 'early action area' within the Lower Duwamish Waterway Superfund Site.

The partly armored/bulkheaded banks will be excavated to remove contaminated soils and laid back to create 0.1 acre of new aquatic habitat and 0.3 acres of new riparian areas. Following removal of contaminated sediments and bank soils, the subtidal, intertidal, and bank areas will be capped with clean sand, and rock, and large woody debris will be strategically placed.

The City will acquire the land, allowing conversion of land use emphasis from industrial/navigation to habitat. By eliminating deep berthing areas, the project will create new shallow subtidal habitat (0.3 acres at -10 to -4 feet) and upper intertidal habitat (0.5 acres as +4 to +12 feet), with no net change in lower intertidal habitat (-4 to +4 feet).

A concrete pier in Slip 4 will be demolished, removing over-water shading. Following the Superfund cleanup, emergent marsh and upland plants will be planted.

The City of Seattle is the Lead for this project and is partnering with King County.