Gas Station located in Stuart, Florida
Bioremediation utilized with air sparging

Oculus Number 8511601

Site Summary

Underground storage tank (UST) leaks from a gas station contaminated shallow ground water under the property. Following the removal of the leaking USTs and impacted soils around the tank cavity, combined air sparging and bioremediation was implemented to remediate the ground water.

Geology and Hydrogeology

The setting of the site is a coastal beach complex dominated by sands and calcified deposits. The shallow subsurface including the perched ground water zone were dominantly sand.

Ground Water Flow Characteristics

The size of ground water plume that resulted from leaking USTs was estimated to be 8,500 square feet. The contamination was a wide range of petroleum constituents including benzene, ethylbenzene, toluene, xylenes, MTBE and naphthalene.

Remediation Design

Petrox bioremediation was implemented in conjunction with air sparging. The combined approach takes advantage of the stripping action of sparging to remove dissolved volatile contaminants and the availability of oxygen to support aerobic bioremediation. Forty units of Petrox (2,200 gallons) were injected into the contaminated ground water through vertical injection wells for three consecutive months.

Results

After the Petrox inoculations, the contaminant concentrations were reduced across the property. The following table shows the overall contaminant reductions in three monitoring wells.

The cost for Petrox treatment was less than $25,000.