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: June 27, 2007

Point of Contact:
Sam Williams
3990 Old Town Avenue, Suite B-101
San Diego CA 92110 
Tel: 619-297-1530 
Fax: 619-297-1532
Email: swilliams@
geosyntec.com

Inactive landfill
Unknown, CA


Hydrogeology:

The site consists of two fracture patterns. One aligns with a major drainage channel adjacent to the site; the other corresponds to the canyon where the landfill was built. Fractured bedrock and a weathered bedrock transition zone were observed at this site.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

A lateral and vertical extent were not identified.

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

Site Characterization Technologies:

  • - Borehole Geophysics
    • Caliper
    • Acoustic Televiewer
    • Other (Electrical, Borehole image processing system (BIPS))
  • - Tracer (dye) Test
  • - Other (Very low frequency (VLF) survey; STING resistivity method)

Comments:
The STING system uses 64 electrodes instead of 4 and it is computer controlled. Any combination of four electrodes can be selected at a time and then measurements can be made with it.


Remedial Technologies:

No technologies selected.

Comments:
Injection wells and piezometers were installed at three separate depth intervals. The results of the tracer test indicated that the majority of the transportation of contaminants occurs in the transition zone. The electron donor was tagged with a sodium bromide solution and injected into the test area. KB-1 was injected after the electron donor reached the appropriate redox conditions. Specific information relating to the redox conditions was not identified in the reference cited.
Remediation Goals:

The objective of the pilot study was to stimulate naturally occurring biologic degradation to increase degradation rates so that the contaminant concentrations of the chlorinated VOCs are reduced before they migrate off site.


Status:

The pilot study is ongoing. Results were not provided in the reference cited.


Lessons Learned:

The delivery of an electron donor and microbes is a vital element to any successful in situ bioremediation project. A thorough understanding of hydrogeologic conditions is required to achieve delivery. A multi-faceted investigation was performed to characterize the fractured bedrock at the site.

References: Sam Williams and Brian Hitchens. Characterization of Fractured Bedrock in Preparation for an In-Situ Bioaugmentation Pilot Study. The 2006 North American Environmental Field Conference & Exposition. January 10-12, 2006. Tampa, Florida.

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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