U.S. EPA Contaminated Site Cleanup Information (CLU-IN)


U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Fractured Bedrock Project Profiles

Last Updated: March 22, 2010

Point of Contact:
Nanjun V. Shetty
7041 Old Wake Forest Rd
Raleigh NC 27616 
Tel: 919-872-6600 
Email: nshetty@
ensr.com

Unknown manufacturing facility
Western, NC


Hydrogeology:

The site consists of silty-clay, saprolitic soils overlying a partially weathered rock zone. Fractured bedrock lies within the partially weathered rock zone. Groundwater velocities are low.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

Major Contaminants and Maximum Concentrations:
  • - 1,1,2,2-Tetrachloroethane (0 µg/L)
  • - Trichloroethene (0 µg/L)
  • - Chloroform (0 µg/L)

Site Characterization Technologies:

  • - Other

Comments:
No site characterization technologies were identified within the references abstract.


Remedial Technologies:

  • - Fracturing
  • - Bioremediation (In Situ)
    • Reductive Dechlorination (In Situ Bioremediation)
  • - Other (Zero valent iron)
Comments:
Hydraulic fracturing was conducted in order to inject a remediation product developed by Adventus Americas (EHC-LB). EHC-LB was mixed with sand and guar prior to injection into the saprolite and partially weathered rock zone. Approximately 3,000 and 3,500 pounds of EHC were injected into the saprolite and partially weathered rock zones respectively. The area of EHC influence extended approximately 10 to 15 feet from the injection point.
Remediation Goals:

None provided


Status:

The injected EHC created anaerobic zones that were suitable for chlorinated aliphatic hydrocarbon reduction. This conclusion was based on high concentrations of total organic carbon and metabolic acids and negative oxidation-reduction potential within nearby monitoring wells. Within the partially weathered rock zone, concentrations of TeCA, TCE, and chloroform after 11 weeks were reduced by 86%, 98%, and 66% respectively. These values were reduced by 98% in measurements taken approximately 26 months after injection. Also detected were potential degradation products of the chlorinated aliphatic hydrocarbons. Within the saprolite zone, concentrations of TeCA, TCE, and chloroform initially increased despite the presence of dechlorinating bacteria. After approximately 26 months, the saprolite zone indicated an overall 95% decrease of the key chlorinated aliphatic hydrocarbons.


Lessons Learned:

Enhanced reductive dechlorination is still taking place despite the reductions in chlorinated aliphatic hydrocarbons.

References:
Shetty, Nanjun V., Matt Zenker, Jay Bennett, Joseph McKeon, Mark Torgerson, and Joanna Moreno. Reductive Dechlorination of Chlorinated Ethenes, Ethanes, and Methanes in Saprolite Soils, Poster Session D7. Presented at the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Monterey, CA. May 19-22, 2008.

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