Designing Effective Solutions For TCE and Other Contaminants in Superfund Site Soil and Groundwater 

Sitting on a 36-acre former dairy farm, the Ellis Superfund Site in Evesham Township, New Jersey, was used for drum storage and reconditioning until the 1970s, leading to residual contaminants, most notably an industrial solvent called trichloroethylene, or TCE, in the soil and groundwater. Our team has assisted the Environmental Protection Agency, through a U.S. Army Corps of Engineers contract, with cleanup, accelerating the process by researching, designing and overseeing cost-effective contamination remedies on the site.

About 100 55-gallon plastic drums — many filled with liquid and actively leaking — were discovered on the 4-acre site. Levels of TCE in the groundwater were as high as 1,000,000 parts per billion. After removing the containers, the New Jersey Department of Environmental Protection began to treat the area in 1998 using pumps to extract contaminated groundwater to a surface treatment system. The subsurface soil was very tight, limiting the method’s effectiveness to remove groundwater.

Understanding and Implementing Remediation Treatments 

Our team was first brought on in 2014 by the USACE to help accelerate the cleanup process for the EPA. We conducted extensive research to understand the status of the site, including:

• Advancing 16 soil borings.
• Collecting groundwater and soil samples to characterize the contamination.
• Installing a new pumping well and six piezometers, which measure static water elevations.
• Conducting a 72-hour pumping test to measure water pressure under dynamic conditions.

We discovered the largest hinderance to remediation was low hydraulically conductive soil and designed two cleanup phases using different technological approaches:

1. Traditional excavation of a third of the project area, with disposal at an off-site facility.
2. In-situ thermal treatment, addressing the rest of the site.

Thermal remediation heats subsurface soil and groundwater, volatilizing contamination into a vapor that can be collected above the water table and treated at the surface. We prepared detailed design documents for the USACE and helped in the contractor bidding process. The USACE selected a contractor that leveraged resistive heating, which passes an electrical current through the soil to create heat.

Several metal rod conductors were placed in the ground within groundwater contamination, and collection pipes were installed above the water tables to extract contaminated vapors. The ground surface was lined with a vapor barrier to improve insulation and prevent contaminants from escaping. Our team provided oversight of the treatment.

With the successful implementation of these remedies, the EPA has already achieved one of the project goals by reducing TCE levels in the soil to one part per million. The remediation has also made significant progress on the next project goal: reducing TCE levels in groundwater to 5 parts per billion.

After initial treatment, the site had less than 82 parts per billion TCE, a 99.99% reduction from highest levels. The site will be monitored until natural attenuation reduces TCE levels to the clean-up goal.