In this part of the State, retreating late Pleistocene glaciers deposited a layer of till (unconsolidated deposits of clay, with intermixed sand, gravel, and silt) ranging up to 40 feet thick. These glacial deposits overlie sedimentary bedrock consisting of layered sequences of Paleozoic shale and
limestone. Bedrock beneath areas south of the Site includes units of the Wills Creek Formation, consisting of thin, interbedded calcareous silty shale and siltstone or argillaceous (shaly) limestone and dolostone. Bedrock to the north of the Site consists of the Tonoloway Formation, a dark gray,
laminated limestone. A transition zone between these two formations, characterized by extensive
interfingering is mapped beneath the northern part of the Site, making identification of the Tonoloway
Wills Creek contact difficult. The bedrock layers in the vicinity of the Site strike approximately N80E and dip to the northwest at an angle of about 25 degrees. Bedrock underlying the Site is moderately fractured, with fracture frequency diminishing with depth. These fractures are generally oriented parallel to bedding planes and dip to the northwest.

Groundwater at the Site is present in the glacial overburden and the bedrock. In the overburden, groundwater occurs within discontinuous gravel lenses within the till and a distinct layer of
weathered bedrock at the base of the overburden, however this predominantly clay unit is generally not very permeable. Groundwater in the overburden at the Site is typically encountered at a depth of about 7 to 8 feet below grade. Groundwater in the bedrock is present primarily in fractures or bedding planes. Most of these water-bearing fractures are in the shallow bedrock (upper 30 to 40 feet
below grade). Ground water at the Site generally flows from west to east, towards Mauses Creek.

• Dense Non-aqueous Phase Liquids (DNAPLs)
• Fractured Bedrock
• Light Non-aqueous Phase Liquids (LNAPLs)

The shallow bedrock plume is approximately 450 feet wide and 860 feet long. Contamination is in the overburden, shallow, intermediate and deep bedrock aquifers.

• Tetrachloroethene (27,800 µg/L)
• Trichloroethene (20,400 µg/L)
• 1,2-Dichloroethene (17,400 µg/L)
• Vinyl chloride (23,400 µg/L)
• 1,1,2-Trichloroethane (241 µg/L)

• Pumping Tests

• Pump and Treat

MCls were set as cleanup goals.

Since startup the trends of VOC concentrations detected in wells screened at all depth intervals have generally decreased or remained approximately at their 2004 levels, with few exceptions.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0301428