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: December 15, 2004

Point of Contact:
Thomas Maguire
113 John Robert Thomas Drive
Exton PA 19341 
Tel: 610-594-3940 
Email: forensic@
chesco.com

Petroleum source site
Central Area, MA


Hydrogeology:

Geology:
-Thin veneer of glacially derived overburden.
-Metamorphic bedrock (Schist/Gneiss).
-Horizontal foliations.
-Fracture fabric (horizontally and vertically anisotropic)

Hydrogeology:
-Discontinuous saturated overburden deposits
-Variable vertical gradients
-Contrasting bedrock/overburden flow vectors
-Extremely limited intrinsic permeability in shallow bedrock

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

Major Contaminants and Maximum Concentrations:
  • - Benzene-toluene-ethylbenzene-xylene (BTEX) (var)
  • - Methyl tert butyl ether (var)

Site Characterization Technologies:

No technologies selected.


Remedial Technologies:

  • - Fracturing
  • - Pump and Treat
  • - Soil Vapor Extraction
    • With Air Stripping
  • - Multi Phase Extraction
  • - Other (enhanced biodegradationa and natural attenuations)
Comments:
Remediation technologies were evaluated through a series of pilot tests and interim response actions.

The inability to transmit fluids (ground water and vapors) through the shallow bedrock regime where the source mass resided was the principal limitation of remediation.
Remediation Goals:

-Hydraulic control of source areas
-LNAPL recovery
-Source mass removal
-Reduction on Aqueous-phase plume


Lessons Learned:

Mass removal technologies are most effectively applied in source areas. Attempts to recover mass in conjunction with hydraulic control, at distal portions of a plume or at depth, prove to be inherently inefficient and possibly detrimental.

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