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 FAQs

IN-SITU VACUUM EXTRACTION PROJECTS:
4. VACUUM EXTRACTION AND BIOVENTING

Confidential Printing Industry Client, Central Pennsylvania

A printing company removed a fuel oil underground storage tank (UST) in preparation for the construction of a new warehouse and required an investigation of the soils in the location of the former UST. The client was interested in expediting the investigation and remediation processes so that the new warehouse could be constructed above the location of the former tank without entering into a time consuming or costly remediation program.

The environmental investigation revealed that the soils in the area of the former UST had been impacted by fuel oil contamination. The constituents of primary concern were benzene, toluene, ethylbenzene, and xylene. A remedy was designed that could be implemented without delaying construction of the new warehouse. The Pennsylvania Department of Environmental Resources (PADER) approved the remediation plan.

The plan included the use of five vapor extraction wells in the oil impacted area. The wells were completed and vacuum piping was installed prior to construction of the floor slab for the new warehouse. The warehouse was then constructed and the vacuum extraction system installed on the first floor.

Throughout the remediation program the systems carbon dioxide concentrations in the extracted soil gas were monitored as in indication of biological activity. Based on the high CO2 concentrations it was calculated that the rate at which petroleum hydrocarbons were being biodegraded was as much as 10 times the rate of physical removal by the applied vacuum.

Vapor sampling confirmed that the remediation objectives had been met after just six weeks of operations. On the basis of the results, PADER issued a notice that no further action was required.