EPA/540/MR-95/524

The ENSR Consulting and Engineering and Larsen Engineers ex-situ bioremediation technology is based on the construction of aboveground biovaults. Soil contaminated with volatile and semivolatile and semivolatile organics are placed in specifically designed soil piles, referred to as biovaults, where nutrient, moisture, and oxygen levels are controlled so that biodegradation by indigenous microbes is maximized. The Biovault treatment process was demonstrated under the SITE Program as part of the Multi-Vendor Bioremediation Demonstration of three technologies. The demonstration involved testing two side-by-side biovaults where one was operated in an aerobic mode while the other was alternated between the aerobic and anaerobic mode by controlling the availability of oxygen. A primary objective of the demonstration was to determine the effectiveness of the bioventing in reducing six target VOC contaminants (acetone, 2-butanone, 4 methyl-2-pentanone, 1,2-dichloroethene, trichloroethene, and tetrachloroethene) in the soil to below the New York State Department of Environmental Conservation soil cleanup objectives. Although removal of all critical VOCs was extensive (>65%) in both aerobic and aerobic/anaerobic vaults, the 90% goal related to the Soil Cleanup Criteria was not achieved in either plot in 5 ½ months for some compounds. Based on the demonstration, a cost of $54/yd³ was estimated for a large scale cleanup.