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: August 3, 2011

Point of Contact:
Julie Konzuk
130 Research Lane
Suite 2
Guelph ON N1G 5G3 
Tel: 519-822-2230 
Fax: 519-822-3151
Email: jkonzuk@
geosyntec.com

Former chemical manufacturing facility
Unknown, SC


Hydrogeology:

The site consists of saprolite from 0 to 40 feet below ground surface (bgs) and discretely-fractured metagabbro bedrock from 40 feet to more than 200 feet bgs.

Targeted Environmental Media:
  • - Dense Non-aqueous Phase Liquids (DNAPLs)
  • - Fractured Bedrock

Contaminants:

Not identified in the references cited.

Major Contaminants and Maximum Concentrations:
  • - Tetrachloroethene (150 µg/L)

Site Characterization Technologies:

No technologies selected.


Remedial Technologies:

  • - Chemical Oxidation (In Situ)
    • Permanganate
Comments:
In situ chemical oxidation (ISCO) treatments targeted primary fracture migration pathways, focusing on a suspected dense nonaqueous phase liquid (DNAPL) source zone for mass treatment. Groundwater was recirculated with the permanganate amendment to prevent off-site migration of permanganate, while distributing the permanganate throughout treatment area. Permanganate waste and consumption was minimized through the use of pulsed injection followed by rebound monitoring in targeted rebound areas.
Remediation Goals:

Not identified in the references cited.


Status:

Permanganate was effectively distributed over a wide area. Small increases of chloride were observed; however, tracer testing results indicate that dilution is significant. Within the DNAPL mass, PCE concentration rebounded within weeks of treatment termination; however, PCE concentrations were reduced downgradient of the site boundary and were sustained with slow rebound. Chloride ion concentrations decreased by 62 mg/L, which is equivalent to the destruction of between 74,000 and 370,000 ug/L of PCE. Selection of pump and treat as the selected remedy would only have treated and reduced PCE concentrations by 400 ug/L. ISCO treatment increased the mass removal rate by 185 times compared to pump and treat.


Lessons Learned:

ıIt is important to understand contaminant migration pathways.
ıTreatment is labor intensive.
ıActual mass of permanganate required was greater than what was estimated.
ıPhased injections allow for: (1) assessment of rebound potential; (2) detection of DNAPL areas through the use of parent to daughter dechlorination ratios; (3) more focused treatment, lowering groundwater issues and costs through concentrated permanganate usage.
ıAnticipate contaminant rebound therefore many injections will be required.
ıIt is unlikely that this process will allow cleanup to maximum contaminant levels (MCL).

References:
Konzuk, Julie; Suzanne OıHara; Karen Berry-Spark; Mark Watling; and Evan Cox. 2010. Lessons Learned from Full-Scale Implementation of In Situ Chemical Oxidation in Fractured Bedrock. From Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May 2010, Monterey, CA.

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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