Fueling Station- Aquifer Air Sparging

This project site is an active gasoline station situated over an EPA-designated sole-source aquifer system. Soil underlying the site consisted of uniform medium sand. Groundwater is unconfined at a depth of approximately six feet.

In response to a gasoline release, SES Environmental completed an investigation to delineate the extent of groundwater contamination. Based on these results, a remediation system consisting of air sparging and soil vapor extraction was designed and implemented. Initiated in 1991, SES Environmental was one of the first environmental contractors in Indiana to design, receive regulatory approval, and implement an aquifer air sparging groundwater remediation system.

The combined air sparging and soil vapor extraction system utilized at this site resulted in an average 98% reduction in groundwater contaminant concentrations within a 6 month period. Subsequent long term groundwater monitoring indicated groundwater contaminant concentrations remained below regulatory MCLs....until another fuel release occurred approximately two years later.

The original system was utilized again to reduce groundwater contaminant levels to MCLs. Due to the high vulnerability of shallow groundwater, the system remains in place as a standby in case future problems arise.

On behalf of the client, SES prepared an application for cost recovery through the Indiana Excess Liability Trust Fund, which resulted in nearly 99.5% cost reimbursement for the project.

Truck Stop Facility

This project involved a large truck stop facility located in southern Indiana. A shallow, unconfined aquifer beneath the site was impacted by years of fuel handling operations. The contaminant plume was fairly large, measuring approximately 190 wide by 270 feet long.

Based on the soil formation characteristics, air sparging was chosen for remediation.

Rather than install single sparge points across the entire plume, SES utilized a proprietary method to install multiple sparge points from a single location using angled placement methods. This approach reduced project costs by 45% from original estimates. Construction costs were reduced by minimizing trenching, vault installation, and sparge installation time. By incorporating bio-venting, SES was capable of remediating both gasoline and distillate fuel contaminants.