The Stockton Formation is a complex and heterogeneous leaky bedrock multi-aquifer system that includes sandstones, siltstones and shales. Lithologic and hydraulic properties
change over short horizontal and vertical distances. The Stockton Formation, is the oldest unit in the Triassic-aged Newark Group. It dips to the northwest at approximately 12 1/4 degrees and is divided into three members; the middle Arkose Member, which underlies the property, constitutes the major aquifer in the area.
This system within the source area is overlain by approximately 2.5 to 16 feet of overburden, including urban fill. The urban fill ranges in thickness from 2 to 6 feet and includes clay, silt, sand, gravel, and cobbles. The weathered part of the shallow bedrock groundwater system ranges from a half-foot to 12 feet thickness within the source area.
Targeted Environmental Media:
 Dense Non-aqueous Phase Liquids (DNAPLs) - Fractured Bedrock
- Light Non-aqueous Phase Liquids (LNAPLs)
The lateral and vertical extent of the plume is not known. The shallow, intermediate, and deep bedrock systems are contaminated. The original estimate of lateral extent was approximately 1,200 feet wide at widest and 1,800 feet long at the longest point.
Major Contaminants and Maximum Concentrations:
- Tetrachloroethene (26,000 µg/L)
- Trichloroethene (87,000 µg/L)
- 1,2-Dichloroethene (5,100 µg/L)
- Vinyl chloride (2,700 µg/L)
No technologies selected.
- Pump and Treat
Comments:
The facility production wells were fitted with air strippers in 1986 and have been treating groundwater ever since. One well is in the shallow bedrock, one well is in the shallow and intermediate zones, and the third is finished in shallow, intermediate, and deep zones. All three wells are open hole. The minimum pumping rate for the three combined is 75 gpm.
In addition to the on-site wells, a municipal well also was being used to capture offsite migration. It was closed in 2004.
Note the Dichloroethene and vinyl chloride concentrations above are 2005 numbers.
Cleanup goals for TCE and PCE are 4.5 ug/L and 3.5 ug/L respectively.
Concentrations in the monitoring wells have been falling but are still well above the cleanup goals. An investigation into the extent of contamination was expected to be complete in 2010.
http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0300585
|
