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: January 2, 2011

Point of Contact:
David Lederer
USEPA 5 Post Office Sq., Suite 100
Mail Code OSRR07-4
Boston MA 02109-1367 
Tel: 617-918-1325 
Email: lederer.dave@
epa.gov

Sullivan's Ledge
New Bedford, MA


Hydrogeology:

The shallow bedrock is highly fractured and the fracture planes vary both in frequency and orientation. This means that the shallow bedrock exhibits the properties of a porous medium, with groundwater flowing in the direction of the hydraulic gradient. Contaminant migration in the shallow bedrock groundwater would be expected to follow the shallow groundwater flow paths and form contaminant plumes.

The deep bedrock contains fewer fractures than the shallow bedrock; these discrete fracture planes follow a regional north/northwest lineament trend. Contaminant migration in these deeper fractures is controlled by the orientation of these fractures. The potential exists for contamination to migrate relatively long distances along these specific fractures. However,
given the significant depths (greater than 200 feet) and unpredictability of the fracture orientations, the exact locations of all deep bedrock fractures are technically infeasible to determine. Furthermore, the possibility of locating all pockets of contamination within these fractures is highly unlikely.

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

Contaminants:

The bottom of the quarries is 150 feet bgs. VOCs have been identified to 200 feet bgs.

Major Contaminants and Maximum Concentrations:
  • - Benzene (1,000 µg/L)
  • - 1,2-Dichloroethene (51,000 µg/L)
  • - Trichloroethene (4,000 µg/L)
  • - Vinyl chloride (6,900 µg/L)
  • - Polychlorinated biphenyls (PCBs) (sludge)

Site Characterization Technologies:

  • - Vertical Chemical Profiling
    • Multi-sampling port

Remedial Technologies:

  • - Pump and Treat
Comments:
There are three bedrock recovery wells at the site. Two pump from a depth of 150 feet (2008).

During 2005 a bedrock pump was lowered to 150 feet bgs where it began to pump a tar-like sludge with elevated levels of PCBs.
Remediation Goals:

This site was given a technical impracticability ruling and cleanup goals are the significant reduction of contaminant mass in the aquifer and the protection of local surface water bodies.


Status:

For the most part, concentrations of total VOCs have decreased significantly since treatment plant startup conditions in 1999; although there have been some upward trends for certain monitoring wells.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0100744

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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