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.

• Fractured Bedrock

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

• Trichloroethene (311 µg/L)
• Tetrachloroethene (542 µg/L)

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

• Chemical Oxidation (In Situ)
  • Permanganate
• Other (Monitored Natural Attenuation)

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.

Long term monitoring continues.

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

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0101322