The soil beneath the Site generally consists of varying thicknesses of weathered bedrock or saprolite, which is composed of predominantly silty clays to clayey silts. Fractured bedrock is located beneath the soil. The fractured bedrock consists primarily of white to gray, fine to coarse-grained, massive to foliated, granites, grano-diorites, quartz
diorites, and quartz monzonites on the west side of the facility. The intermediate intrusive rocks on the east side of the facility consist of dark, greenish-gray to black, medium-to-coarse grained, massive, well-jointed
metamorphosed bodies, probably dioritic in composition.
Groundwater in the general vicinity of the Site exists within two zones. The first or uppermost, water-bearing
zone is within the silty clay residual saprolite soils overlying the bedrock. Groundwater in the lower water-bearing zone in bedrock is typically under semi-confined or confined conditions with flow direction being controlled by the presence and orientation of secondary openings. Groundwater movement generally occurs from areas of higher hydraulic head (higher elevations) toward areas of lower
hydraulic head (lower elevations or stream valleys). Groundwater yields from the bedrock are typically higher
than the upper zone above bedrock with yields high enough to sustain private water supplies. Private water wells tapping the bedrock aquifer and the shallower saprolite zone are present in the general vicinity of the Site.
Targeted Environmental Media:
 Dense Non-aqueous Phase Liquids (DNAPLs) - Fractured Bedrock
The TCE bedrock plume is about 3,300 feet long.
Major Contaminants and Maximum Concentrations:
- Tetrachloroethene (870 µg/L)
- Trichloroethene (30,000 µg/L)
- 1,1,1-Trichloroethane (28,000 µg/L)
- 1,2-Dichloroethene (19,000 µg/L)
- 1,1-Dichloroethene (7,200 µg/L)
- Methylene chloride (1,000 µg/L)
- Toluene (2,800 µg/L)
- Manganese (10,600 µg/L)
- Zinc (29,500 µg/L)
- 1,1-Dichloroethane (420 µg/L)
No technologies selected.
- Pump and Treat
Comments:
There is a groundwater divide at the site. Five bedrock wells were set at the north and three at the south. The system became operational in 2006.
The cleanup goals were set at MCLs or state standards whichever were lower.
ppb
1,1,1 -trichloroethane 200
1,1,2,2-tetrachloroethane 0.17
1,1,2-trichloroethane 5
1,1-dichloroethane 70
1,1-dichloroethene 7
1,2-dichloroethane 0.38
1,2-dichloroethene (total) 700
1,2-dichloropropane 0.56
1,3-dichloropropene 81
aluminum 15,000
antimony 6
arsenic 10
benzene 1
beta-BHC 7.3
bromodichloromethane 0.60
bromomethane 55
cadmium 5
chloroform 0.19
chromium 50
dibromochloromethane 0.41
dieldrin 0.0042
iron 4,500
manganese 858
mercury 1.1
methylene chloride 5
naphthalene 21
nickel 100
tetrachloroethene 0.7
thallium 2
toluene 1,000
trichloroethene 2.8
vanadium 250
vinyl chloride 0.015
zinc 2,100
The pump and treat system continues operation. Down gradient wells generally show a decreasing concentration trend.
http://www.epa.gov/region4/waste/npl/nplnc/duraclnc.htm
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