Brief

An environmental consultant hired by the landowner characterized the site and determined that the groundwater was still impacted with carbon tetrachloride (CTET). Located in a shallow aquifer, the CTET plume covered an area of approximately 750 m2 and penetrated the aquifer to approximately 2 m below the water table. IRSL was retained by the client based on their innovative design and successful approach at other sites impacted with chlorinated compounds.

To treat the remaining dissolved phase impacts, IRSL designed a Direct Push Injection program that used Emulsified Vegetable Oil (EVO) to provide a carbon donor that would enhance the anaerobic bioremediation reactions already occurring within the aquifer.

Process

To remediate the carbon tetrachloride (CTET) within the groundwater to below the remedial targets, IRSL worked with the manufacturer of the donor solution to create the most effective formula to stimulate Anaerobic Bioremediation, based on site data input into their proprietary analytic equipment.

IRSL completed one injection of Emulsified Vegetable Oil (EVO) enhanced with nutrients and buffering agents:

• EVO stimulated the natural attenuation reactions already occurring in the aquifer by providing a carbon donor to the native bacteria, which fed on the contaminants, breaking them down into harmless by-products.


• Nutrients helped the native bacteria to build cell mass, thereby overcoming limiting reactions.


• Carbonate Buffering Reagent kept the pH of the system within the bacteria’s preferred range.

Results

The remedial program was executed in three weeks.

The CTET was treated to below the remedial targets developed for the program.

Long-term monitoring indicated that the groundwater concentration remained below the remedial targets for the one-and-half years since remediation.

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