The bedrock at the Site is predominantly micaceous schist with thin beds of amphibolite and pegmatite intrusions. The designation shallow bedrock generally refers to the upper 10 to 20 feet. The ranges of values for the shallow and
intermediate bedrock hydraulic conductivities were 0.001 to 43 ft/day.

• Fractured Bedrock

The overburden plume in 2003 was stable and approximately 840 feet wide and 1,560 feet long. By 2008 it had shrunk to approximately 360 feet by 480.

The shallow bedrock plume in 2003 was stable and approximately 1,380 feet wide by 2,000 feet long. By 2008 it was 720 feet wide by 1,000 feet long.

The vertical extent of the plume is generally between 10 and 50 feet below the ground surface. Lesser concentrations of contaminants occur in wells in the deep bedrock aquifer, at depths of about 200 feet. ````````````````````````````````````````````````````````

• Acetone (18,000 µg/L)
• Benzene (17 µg/L)
• 2-Butanone (MEK) (37,000 µg/L)
• 4-Methyl-2-pentanone (MIBK) (2,200 µg/L)
• Toluene (23,000 µg/L)
• Trichloroethene (43 µg/L)
• Vinyl chloride (19 µg/L)
• 2,4-Dimethylphenol (2,200 µg/L)
• 4-Methylphenol (p-cresol) (51,000 µg/L)
• Chromium (222 µg/L)

• Other (Monitored Natural Attenuation)

Cleanup levels were set at background which for the organics is generally less than 1 ug/L.

Since completion of the cap in 1998, the contaminants for which groundwater cleanup levels were established have decreased in concentration. Many contaminants are below the MCL and some are at or approaching the respective cleanup goal of background concentrations in recent sampling events.