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:
Ian Osgerby
Army Corps of Engineers
696 Virginia Road
Concord ME 01742 
Tel: 978-318-8631 
Fax: 978-318-8614
Email: Ian.t.osgerby@
usace.army.mil

Former PR-58 Nike Missile Battery Site
Davisville, RI


Hydrogeology:

The site is classified into three hydrogeological zones. Zone 1 contains an upper shallow overburden sand; Zone 2 contains a deep overburden ground water zone with sandy silty gravel to sandy gravelly silt and a weathered bedrock zone. Zone 3 is identified as containing a competent bedrock zone of ground water with the upper 60 feet made of competent bedrock.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

Chlorinated volatile organic compounds (CVOCs) were identified in monitoring well (MW) 03-14D and 80 feet west at MW EA-102; no contaminants were detected farther west, southwest, and north.

Major Contaminants and Maximum Concentrations:
  • - Carbon tetrachloride (20,911 µg/L)
  • - 1,1,1,2-Tetrachloroethane (20,911 µg/L)
  • - Tetrachloroethene (20,911 µg/L)
  • - Trichloroethene (20,911 µg/L)
  • - 1,1,2-Trichloroethane (20,911 µg/L)

Site Characterization Technologies:

No technologies selected.


Remedial Technologies:

  • - Thermal Treatment (In Situ)
    • Steam Enhanced Extraction
  • - Other (Dual-phase vacuum extraction system)
Comments:
Approximately 1,550 pounds per hour of steam was injected in four wells along with a central extraction point and six surrounding, pneumatic control triple well clusters screened across the three hydrogeologic zones. The injection system operated over a period of 8 weeks. Subsurface temperatures were monitored throughout the pilot test.
Remediation Goals:

Steam-enhanced remediation was used to evaluate whether the CVOCs could be remediated by steam injection and air using a dual-phase vacuum extraction system.


Status:

Several hundred pounds of CVOCs were extracted despite difficulties in introducing steam into the series of microfractures in the weathered and competent bedrock.


Lessons Learned:

Pneumatic control triple well clusters screened across the three hydrogeologic zone aided in the successful introduction of steam into the fractured bedrock subsurface.

References: Osgerby, Ian T., Jim Shulz, Greg Crisp, and Ken Manchester. Chlorinated Soils Remediation Using Steam Injection Into Fractured Bedrock. Proceedings of the 22nd Annual International Conference on Soils, Sediments, and Water (Massachusetts). October 16-19, 2006.

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