Case study: Vacuum extraction harnessed for emergency cleanup

A routine groundwater quality investigation conducted by the Louisiana Department of Environmental Quality in 1993 revealed water supply contamination in a municipal well. Underground gasoline storage tanks, which had been removed in 1990, were the suspected source of the contamination. Through soil analysis it became clear that the site of the former USTs was in fact the source of the hydrocarbons; that significant quantities of hydrocarbons were still present in the shallow soil and groundwater; that those hydrocarbons were likely to migrate towards the well; and that cleanup of the source area was essential to restore groundwater quality. BCM Engineers recommended a one-month emergency response action at the site, using Two-Phase Vacuum Extraction (TPVE) to remove hydrocarbons from the shallow subsurface and to minimize the potential for continued migration to the deeper portion of the aquifer. One month`s operation resulted in the removal of 450,000 gallons of contaminated groundwater and more than 1,000 pounds of hydrocarbons. The speedy removal of contaminated water and the bulk of the hydrocarbons and quick restoration of groundwater quality exceeded all expectations. Analysis of water samples showed no detectable benzene more than a year after the cleanup ended.