| Several contaminated sites in the United States have been evaluated for intrinsic bioremediation, but its application in colder temperatures has not been well addressed. The feasibility of intrinsic bioremediation of chlorinated aromatic hydrocarbons at the former landfill site at the Canadian Forces Base (CFB) Cold Lake was studied. The site was previously used for disposing of various hydrocarbon-based products such as oils, solvents and degreasers. The compounds of environmental concern that have been detected include benzene, toluene, ethylbenzene, xylenes (BTEX), 1,1,1-trichloroethane, 1,1-dichloroethane, 1,2-dichloroethane and dichlorobenzenes. The research undertaken involved four separate phases: (1) site investigation; (2) analysis of contaminant concentrations and terminal electron accepting processes across the site; (3) laboratory microbial study; and (4) computer fate and transport modeling.;Results from the geochemical and contaminant investigation, Most Probable Number (MPN) studies and screening level computer modeling suggest that reductive dechlorination and BTEX mineralisation can and is proceeding at the site, despite the colder in-situ temperatures (8°C). Although there is considerable evidence in favour of intrinsic bioremediation as a remedial option, it is believed that continued long-term monitoring should be implemented to better understand the contaminant behaviour. This has been suggested due to the anomalous findings and uncertainty concerning the possible additional source(s) of 1,1,1-trichloroethane at the site. |
