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@
pa.gov

West Kingston Town Dump/Uri Disposal Area
South Kingstown, RI


Hydrogeology:

The Site is located in the Chipuxet River Basin. This basin is considered a major groundwater aquifer and consists of glacial outwash deposits. These outwash deposits are discontinuous
layers of silt, sand, gravel, and cobbles with a thickness of as much as 150 feet. Bedrock in the area is mapped as the Ten Rod Granite Gneiss. Regional groundwater flow is generally toward the south, although, as explained below, Site groundwater flow is toward the west. Hydraulic conductivity in the glacial outwash aquifer decreases with depth. Groundwater flow in bedrock is believed to be confined to bedrock fractures.

Overburden at the Site consists of approximately 5 feet of fine sand and silt lying on top of a gravel and cobble layer; below that is interbedded gravel and sand beds grading into fine to coarse sand. As with the overburden thickness, the depth to bedrock also varies sharply across he Site. The bedrock is exposed just northeast of the Site, and ranges from 20 feet below ground surface (bgs) in the vicinity of the Former Drum Storage Area, to 30 feet bgs at the center of the Site near URI pond, before dipping sharply in the direction of Hundred Acre Pond.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

The PCE/TCE plume is approximately 2,500 feet long.

Major Contaminants and Maximum Concentrations:
  • - Trichloroethene (311 µg/L)
  • - Tetrachloroethene (542 µg/L)

Site Characterization Technologies:

  • - Surface Seismic Surveys
  • - Vertical Chemical Profiling
    • Packer Isolation
  • - Pumping Tests

Remedial Technologies:

  • - Chemical Oxidation (In Situ)
    • Permanganate
  • - Other (Monitored Natural Attenuation)
Comments:
The first two permanganate injections into source areas occurred in September 2009 and March 2010. The injections are expected to last 6-12 years. Estimated cleanup time is 80 to 325 years.

The downgradient plume will be subject to monitored natural attenuation.
Remediation Goals:

The selected remedy is for the Former Drum Storage Area only and the cleanup goals for groundwater are MCLs. The Town Dump and the URI Disposal Area
have each been capped with a RCRA impermeable cover system as part of a landfill closure administered by the state.

The MCL for the two chemicals of concern (PCE and TCE) is 5 ug/L.


Status:

Long term monitoring continues.

Permangante injections are scheduled at 6-month intervals. PCE/TCE levels appear to be trending down for the most part.

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