Fractured Bedrock
Targeted Environmental Media:
 Dense Non-aqueous Phase Liquids (DNAPLs) - Fractured Bedrock
Major Contaminants and Maximum Concentrations:
- Total petroleum hydrocarbons (25,320 µg/L)
- Other (Pneumatic Fracturing)
- Bioremediation (In Situ)
- Reductive Dechlorination (In Situ Bioremediation)
Comments:
Reductive Dechlorination (In Situ Bioremediation) Treatment was conducted at the site from 1996 to 2004, with final performance sampling completed in September 2005. The system was initially turned on in 1996 and was in operation until 2001; the system was turned back on in 2003 and remained in operation until 2004. Between 2001 and 2003, quarterly ground water monitoring was conducted. BEM Systems, Inc., enhanced the remediation system by pneumatic fracturing of the bedrock to increase the permeability of the rock and provide a pathway to the dense nonaqueous phase liquid (DNAPL) in the fractured bedrock. BEM also introduced a hydrogen releasing compound to promote biological remediation by reductive dechlorination of the chlorinated contaminants. The system was further enhanced by bioaugmentation after reducing conditions were achieved.
The goal was to evaluate a treatment train approach to reduce chlorinated contaminants at a fractured bedrock site.
Through ground water extraction and addition of a hydrogen release compound, the initial contaminant concentration of 25,320 µg/L in 1993 was reduced to 227 µg/L by June 2004, a reduction of nearly 95 percent.
The length of operation of a remedial system at a site may be reduced by use of a treatment train approach.
References: Kirchenbauer, Michael, and Sandra Gaurin. Pneumatic Fracturing and Bioremediation, Final Remedial Approach in Fractured Bedrock. The Ninth International In Situ and On-Site Bioremediation Symposium. May 7 - 10, 2007. Baltimore, Maryland.
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