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 31, 2010

Point of Contact:
Byron Mah
USEPA 5 Post Office Square, Suite 100
Mail Code: OSRR07-1
Boston MA 02109-3912 
Tel: 617-918-1249 
Email: mah.byron@

Davis Liquid Waste
Smithfield, RI


A permeable shallow overburden aquifer overlies a fractured rock system. Both are sources of drinking water. The hydrogeology of the regional groundwater flow system at the site is complicated by the existence of a bedrock dike which is thought to effect groundwater flow in the overburden and bedrock. In effect this impediment to flow in the over burden aquifer may cause contaminants in the overburden aquifer to pool along the western edge of the dike, and enable the heavier compounds to move vertically downward into the bedrock. This effect is exhibited by the increase of contaminants in the bedrock wells above those levels in the overburden wells.

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


Groundwater contamination is characterized by high levels of volatile organics, low levels of extractable organics, and wide spread inorganics. The boundary of the 1-1,000 parts per billion (ppb) range of total volatile organic contamination in the bedrock groundwater extends approximately 890 feet from the site towards the bedrock dike and is approximately 400 feet wide. Data indicates higher levels of contamination in the bedrock aquifer along the western edge of the bedrock dike than in the overburden (shallower aquifer). The bedrock aquifer therefore poses a long-term potential source of groundwater contamination.

Major Contaminants and Maximum Concentrations:
  • - Arsenic (128 µg/L)
  • - Benzene (190 µg/L)
  • - Chloroform (2,000 µg/L)
  • - 1,1-Dichloroethene (74 µg/L)
  • - Lead (175 µg/L)
  • - Tetrachloroethene (39,000 µg/L)
  • - Trichloroethene (6,600 µg/L)
  • - Xylenes (14,000 µg/L)

Site Characterization Technologies:

No technologies selected.

Remedial Technologies:

  • - Pump and Treat
The level of PCE contamination is high enough to suspect the presence of a DNAPL.
Remediation Goals:

MCLs were selected as cleanup goals when available.


As of 2009 the pump and treat system has not been built. The ROD proposed treating the overburden first and then the bedrock aquifer.

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