Welcome to CDM Smith.

Delivering Superfund Progress at Well 12A

​U.S. Environmental Protection Agency ​Tacoma, Washington, USA
​Well 12A's triple treatment remedial approach integrated technologies to maximize synergy and establish a contaminant mass discharge reduction goal of 90 percent.

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.

years of contamination from oil recycling
in treatment cost savings due to site modeling
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.
The presence of dense non-aqueous phase liquids...in the site’s complex subsurface hydro­ge­ol­ogy made this one of the most difficult types of Superfund clean-ups.

By applying our own research and development efforts to real life, the project is shifting the soil and groundwater treatment paradigm:

  • A robust conceptual site model, based on high-resolution characterization data and 3D visualization, accurately quantified contaminant mass and delineated discrete treatment zones and design approaches—saving more than $1 million in treatment costs.
  • The use of shear-thinning fluids and vegetable oil optimized the EAB process to improve amendment distribution in low permeability zones.
  • Passive sampling devices for long-term monitoring saved more than $100K in the first 5 years of monitoring alone.
Tamzen MacBeth Tamzen MacBeth
Through innovation, multi-disciplined collab­o­ra­tion and stakeholder trust, the strategy will allow the municipal water supply system to meet the city’s increasing water demands.

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