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:
Anna Krasko
USEPA 5 Post Office Square, Suite 100
Mail Code OSRR07-1
Boston MA 02109-3912 
Tel: 617-918-1232 
Email: krasko.anna@
epa.gov

Picillo Farm
Coventry, MA


Hydrogeology:

The Site is underlain by unconsolidated overburden materials which include glacial outwash deposits ranging from 20 to 80 feet in thickness. The deposits consist primarily of fine to coarse sand and gravel with scattered boulders in upland areas and organic-rich swamp deposits in some lowland areas. Lenses of silty sand and clay have been observed at some locations but are not common.
Compact boulder-rich till consisting of a poorly sorted mixture of sand, gravel, silt and boulders underlies much of the Picillo study area. The till unit varies in thickness from 5 to 40 feet and is laterally discontinuous. A thick unit of boulders present in till often obscures the true bedrock
surface. Silt-rich till rather than boulder-rich till was observed in portions of the disposal area, ranging from less than a few feet thick to more than 20 feet thick.

The glacial deposits are underlain by a generally highly fractured and weathered bedrock. From bedrock core observations it appears that ground water flows through fractures as well as through the weathered rock matrix. The RI determined that approximately 10 to 40 feet of weathered bedrock overlies competent bedrock in most locations. The degree of weathering and fracturing in bedrock varies considerably throughout the site.

Several significant features of the bedrock surface beneath the Site are: (1) a bedrock trough which extends from the northeast portion of the disposal area in a northeast direction and forms a bedrock low under a small pond on the Picillo Farm property; (2) fractures extending in a north-northwest direction from the pond up to Perry Hill Road; (3) a local bedrock topographic high under the disposal area from which the bedrock slopes toward the west, north and east; and; (4) a northeast-southwest treading fracture system underneath the Unnamed Swamp drainage. The highest bedrock elevations occur in the western portion of the disposal area and to the south of the disposal area. Bedrock lows coincide for the most part with surface water bodies in the area.

Depth to groundwater ranges from 0 to 30 feet bgs.

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

Contaminants:

The 1998 1 ppm total volatile organics (TVO)plume in the shallow bedrock was approximately 1,200 feet long and 780 feet at its widest.

Major Contaminants and Maximum Concentrations:
  • - 1,1,2-Trichloro-1,2,2-Trifluoroethane (19,000 µg/L)
  • - Chloroform (42,000 µg/L)
  • - 1,1,1-Trichloroethane (18,000 µg/L)
  • - Trichloroethene (9,300 µg/L)
  • - Toluene (38,000 µg/L)
  • - Acetone (27,000 µg/L)
  • - 2-Butanone (MEK) (8,500 µg/L)
  • - 1,2-Dichloroethane (2,700 µg/L)
  • - Chlorobenzene (1,300 µg/L)
  • - Carbon tetrachloride (500 µg/L)

Site Characterization Technologies:

  • - Surface Seismic Surveys
    • Refraction
  • - Pumping Tests
  • - Fracture Trace Analysis
  • - Coring
  • - Other (very low frequency (VLF) surveys)

Remedial Technologies:

  • - Pump and Treat
  • - Soil Vapor Extraction
    • In Unconsolidated Overburden
Comments:
The pump and treat system for the bedrock came online in 2001. In 2003 contaminant concentrations had fallen sufficiently to close down the UV/oxidation and peroxide destruction units and replace them with carbon.
Remediation Goals:

Remediation goals were MCLs.


Status:

The pump and treat system continues to operate and the 1 ppm TVO plume has shrunk to approximately 210 feet wide and 390 feet long.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0101284

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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