A release of hydrocarbons, ketones, and semi-volatile mixed-organic wastes from a chemical manufacturing facility had created a perched groundwater mound, nearly 1 mile in diameter, which leaked downward into the regional aquifer. Attempts to eliminate the perched mound through pump-and-treat methods had not been effective. Hydro Geo Chem was retained to develop a more effective approach for protecting regional water quality and determine whether existing systems were effective or even necessary.
Hydro Geo Chem's Approach
Through a thoughtful analysis of site conditions supported by numerical modeling, Hydro Geo Chem identified the following important characteristics at the site:
Seepage from the perched mound could not be stopped by conventional pump-and-treat methods
The unsaturated zone contained a microbial population sufficient to biodegrade benzene and other VOCs in perched mound seepage.
Vapor extraction and aerobic bioremediation beneath the perched mound would remove these contaminants before seepage reached the regional aquifer.
Based on these insights, we designed a vapor extraction/enhanced bioremediation system to operate between the perched mound and the regional aquifer. We also explained to the state regulatory agency why pump-and-treat remediation of the perched mound was ineffective and could be eliminated. The client saved an estimated $4 million by eliminating this system. Our analysis and designs were incorporated into a Corrective Action Plan for the site which was accepted by the State.
HYDRO GEO CHEM, INC.