This site contains areas of glacial deposition overlying basalt flows. The fractured basalt zone has an average hydraulic conductivity of 0.1 inches/second and is located below a sand and gravel aquifer at 100-125 feet above mean sea level. The main water bearing unit is composed of sand and gravel located at 25 feet below the ground surface. However, a water table can be found between 5 and 15 feet above a clayey layer located at 160 feet above mean sea level.
Targeted Environmental Media:
 Dense Non-aqueous Phase Liquids (DNAPLs) - Fractured Bedrock
The TCE plume extends 4,000 feet off-site and is approximately 2,000 feet wide and 470 feet deep. Studies indicate that the rate of natural attenuation occuring at this site is approximately 3,000 kg/year.
Monitoring wells and surface waters have been sampled at least monthly for volatiles and metals. To date, 95% degradation of the TCE to concentrations of approximately 400 ppb have been achieved. TCE groundwater concentrations, affected by variable groundwater flow velocities and desorption of TCE from the site soils, are expected to reach pseudo steady-state conditions in 1999.
Major Contaminants and Maximum Concentrations:
- Trichloroethene (8,000 µg/L)
- 1,1,1-Trichloroethane (Not given)
- Chloroform (48,000 µg/L)
- Pumping Tests
- Other (Bromide tracer)
Comments:
No characterization technologies are described by the report.
- Pump and Treat
- Bioremediation (In Situ)
- Reductive Dechlorination (In Situ Bioremediation)
- Other (Zero Valent Iron)
Comments:
A zero valent iron PRB was installed, down gradient, across the fractured basalt and the overlying sand and gravel. The iron was injected into the bedrock fractures as a guar/iron slurry, simply by pumping the slurry down boreholes. The wall reduced contamination concentrations but not to acceptable levels. A larger groundwater stripper and vapor phase carbon units were installed to provide the added capacity required for the treatment of the contaminated ground water emanating from the seep.
In 2001 a pilot bioremediation treatment was begun for treatment of the source area of DNAPL in fractured rock. New nutrient injection and ground water monitoring wells were installed in an area known to contain high levels of TCE in the ground water. Hydraulic pulse interference tests were conducted on all wells to quantify the hydraulic connection between wells. Bromide tracer tests simulating the proposed nutrient injection, quantified the travel times between the injection and monitoring wells in both the unconsolidated sediments and fractured bedrock. Field data highlighting the heterogeneous nature of the natural VOC degradation processes active, with virtually complete conversion of TCE to cis-1,2-DCE observed in the unconsolidated sediments but with apparently no degradation observed in the fractured bedrock wells. Bioremediation amendments continue to be periodically added
In December 2008 a four well pump and treat system became operational.
The site has a finding of technical impracticability for groundwater
A full-scale PRB was intalled at the Caldwell Trucking Superfund site in northern New Jersey in April 1998. The total installation costs for the initial PRB system is approximately $1,120,000 which includes $670,000 for hydrofracturing and $450,000 for PRB construction.
A field pilot test of in-situ enhanced bioremediation in the source area was initiated in 2001. The layout included six nutrient injection wells and seven downgradient monitoring wells (wells screened in glacial deposits and fractured bedrock). Injection wells were bioaugmented witha culture of naturally occuring microoranisms (KB-1culture of dehalococcoides ethenogenes) in March 2001. In over sixteen months of operation, the system was optimized by adjustment of the amendment composition and the injection frequency. The initial equimolar mixture of methanol, acetate, and lactate was modified in Feb. 2002 to eliminate acetate and increase the lactate concentration. The injection frequency was also increased from monthly to weekly to daily in order to achieve more consistent biodegradation.
The pilot test demonstrated the complete degradation of TCE to ethene and 1,1,1-trichloroethene to ethane in areas that had previously shown little if any biodegradation. Approximately 50%reduction of 1,1,1-TCA and 70% - 100% reduction of TCE was achieved.
The pump and treat system continues operation.
http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0200340
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