Application of bioventing at a fuel oil impacted site

Misdelivery of approximately 8,700 gallons of fuel oil into an underground storage tank compliance monitoring well at a manufacturing facility in the Piedmont Physiographic Province of Virginia resulted in contamination of site soils and ground water. Attempts to remediate the site using conventional ground-water pump and treat technology succeeded in containing the fuel oil within the site boundaries, but did little to remove soil residual and dissolved phase hydrocarbon. Bioventing was considered as an option to address the residual hydrocarbon in the vadose zone. Results of a pilot test suggested that a viable indigenous population of heterotrophic organisms capable of utilizing hydrocarbon as a cell growth and energy source was present in the subsurface. Based on this conclusion and the data generated in the pilot test, a bioventing system was designed and installed at the site. At the conclusion of six months of operation, 6,097 kg of hydrocarbon were removed by in situ biodegradation, 30 kg by vacuum extraction, and 4 kg by separate recovery.