• Air Force Base contaminated with high levels of carbon tetrachloride due to on-site firefighting training
• 97% reduction in contaminant within three months
• Carbon tetrachloride reduced to below detection limits

Training exercises at Texas Air Force Base resulted in an impact to soil and groundwater by trichloroethylene (TCE) and carbon tetrachloride. A monitored natural attenuation study conducted indicated that chlorinated solvents at the plume would naturally decline to acceptable levels after 30 years of monitoring.

After over 14 years of monitoring, contaminant reductions were not proceeding as quickly as predicted and additional remediation was advised. It was determined that limited anaerobic activity was present and biostimulation was a viable option. A pilot test was conducted on-site.

The objective of the test was to determine the feasibility of injection into the shallow, discontinuous groundwater unit. The pilot test was also designed to determine if the residual TCE and carbon tetrachloride could be biodegraded through enhanced bioremediation and reduced to below 5 ppb (the Texas Risk Reduction Program limit). Follow-up injections were applied downgradient of the source area and also in a barrier configuration several hundred feet downgradient of the source were implemented about 6 months after the pilot test.