Delivering Superfund Progress at Well 12A

Polluted from 40 years of oil recycling, and despite decades of treatment, groundwater at the Commence­ment Bay – South Tacoma Channel Well 12A Superfund site remained cont­a­m­i­nated with chlorinated solvents that continued to affect Tacoma, Washington’s municipal water supply. The presence of dense non-aqueous phase liquids, including trichloroeth­yl­ene, in the site’s complex subsurface hydro­ge­ol­ogy made this one of the most difficult types of clean up within the Superfund program.

CDM Smith assisted the U.S. Envi­ron­men­tal Protection Agency (EPA) with a program re-evaluation to accelerate site cleanup. Our compre­hen­sive, multi-component remedial strategy includes excavation to remove sludge filter cakes buried at shallow depth, in-situ thermal remediation to heat subsurface soil and collect cont­a­m­i­nants through soil vapor extraction, and in-situ enhanced anaerobic biore­me­di­a­tion (EAB) to degrade cont­a­m­i­nants in the groundwater plume. The triple treatment approach established a contaminant mass discharge reduction goal, with the tech­nolo­gies integrated to maximize synergy and overall treatment performance.