Location: Tacoma, Washington
Client: Thea Foss Waterway Development Authority
Contract Value: $467,000

Located on the Thea-Foss Waterway in Tacoma, Washington, the site was previously used as a metal plating facility. AEC was retained by the Thea-Foss Waterway Development Authority to perform this removal action project. The general scope of work required the excavation and offsite disposal of soil containing cadmium and chromium above site cleanup levels. Remedial excavation was performed in two areas at the site to remove material that may be a source of metals leaching to groundwater. In total, AEC excavated, handled, and transported 1,200 tons of hazardous soil and 400 tons of non-hazardous soil from the site. Hazardous soil was disposed of at a Subtitle C landfill located in Arlington, Oregon, while the non hazardous material was hauled to a Subtitle D disposal facility. The areas of excavation were then backfilled to compaction using clean import material. AEC also performed utility and storm drain improvements, as well as the construction of a tenant access roadway and resurfaced the entire area, which equated to approximately 45,000 square feet. Final capping of the source area was also performed in an effort to isolate/contain any possible remaining contamination. Capping consisted of placing clean soil fill and asphalt over the source area. Three (3) feet of clean soil fill was placed in areas where the post-remediation surface was revegetated. Sixteen (16) inches of soil base course and three (3) inches of asphalt pavement were placed where the final surface became roadway, parking, or equipment storage. Lastly, AEC performed complete restoration of the site by hydroseeding, performing various enhancements to the habitat and restoring the bank of the river. AEC completed this project on time and within budget utilizing 90% of its own forces.

Stormwater Treatment System Installation