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:
John E. Vidumsky
Barley Mill Plaza 27/2267
P.O.Box 80027
Wilmington DE 19880-0027 
Tel: 302-892-1378 
Fax: 302-892-7641
Email: john.e.vidumsky@
usa.dupont.com

Trichloroethylene-contaminated site in Tennessee
Unknown, TN


Hydrogeology:

Saturated overburden and karst bedrock.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

Major Contaminants and Maximum Concentrations:
  • - Tetrachloroethene (0 µg/L)

Site Characterization Technologies:

  • - Fracture Trace Analysis

Comments:
Water bearing zones were identified by a surface geophysical survey. Emulsified oil was used as a visual tracer to assess the hydraulic connections along fractures within the karst bedrock.


Remedial Technologies:

  • - Pump and Treat
  • - Bioremediation (In Situ)
    • Reductive Dechlorination (In Situ Bioremediation)
Comments:
Pump and treat was used for 12 years for source removal and plume control. A bioremediation pilot test took place within the source zone during 2005 and 2006 using emulsified oil along with bioaugmentation with KB-1". Based on the results of the pilot test, a 76-meter long biobarrier was installed in 2007 to treat the residual plume downgradient of the source area.

Eleven wells were used to place the biobarrier (three existing and eight new). During barrier placement, bioaugmentation took place when amended groundwater distributed the KB-1" culture into the formation. Wells spanned the breadth of the plume, screened the top five to ten feet of bedrock, and were positioned to intercept water bearing zones. In order to capture the entire plume thickness and water bearing fractures, specific screen intervals were selected. Treatment zones transecting the plume were created by circulating groundwater amended with emulsified oil between wells.
Remediation Goals:

None provided


Status:

The pilot test demonstrated the effectiveness of biotreatment within the source zone and this treatment approach was continued at the site. Thus far, the concentration of chlorinated volatile organic contaminants in the source area has decreased from an average of 9 mg/L to 0.004 mg/L.


Lessons Learned:

Groundwater amended with emulsified oil moved more quickly between injection and extraction wells than was anticipated and traveled further downgradient than was originally expected. The pilot and subsequent biobarrier showed that emulsified oil followed by bioaugmentation with KB-1" can limit plume migration and also be used as a cost-effective method for fracture characterization.

References:
Vidumsky, John E., Bradley Nave, Carl R. Elder, and Douglas G. Larson. Use of Emulsified Oil as a Tracer and Biobarrier to Treat TCE in Fractured Bedrock, Platform Abstract Session E3 . Presented at the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Monterey, CA. May 19-22, 2008.

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For more information on Fractured Bedrock, please contact:

Ed Gilbert
Technology Assessment Branch

PH: (703) 603-8883 | Email: gilbert.edward@epa.gov