Bioremediation, Environment, Federal Government, North America, United States
Delivering Progress through Innovation at Well 12A
Synergistic approach to long-term remedial actions reduces costs and time
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 to degrade contaminants in the groundwater plume. The triple treatment approach established a contaminant mass discharge reduction goal of 90 percent, with the technologies integrated to maximize synergy and overall treatment performance.
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.
Through innovation, multi-disciplined collaboration and stakeholder trust, the strategy has will allow the municipal water supply system to meet the city’s increasing water demands.