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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