The site is underlain by a thin veneer of soil over highly fractured siltstone and shale of the Passaic Formation. Borehole logging and coring indicated bedding plane fractures and near-vertical fractures with variable strike orientations. Average fracture aperature and spacing are approximately 180 microns and 36 cm., respectively. Bedrock matrix porosity and organic carbon content averaged 0.056 and 0.00074, respectively. The water table is approximately 30 ft. below grade, within the bedrock. The saturated open intervals at the injection and extraction wells are approximately 30 to 68 ft and 44 to 69 ft below grade, respectively.

• Fractured Bedrock

• Trichloroethene (20,000 µg/L)

• Tracer (dye) Test

Comments:
Tracer Test Implementation

Injection and extraction were performed at 1.0 gpm for a continuous 7-day period in March 2003. A solutionof 20,000 mg/L (2%) KMnO4 and 10,000 mg/L (1%) NaBr was injected during the first 24 hours of the test.KMnO4 and NaBr served as reactive and conservative tracers, respectively. Clean potable water was injected during days 2 through 7 to "chase" the tracer slug and maintain a consistent flow-field. Due to the close proximity of the injection and extraction wells and the low storativity of the bedrock, steady-state flow conditions were achieved within approximately one hour after the begining of the pumping. Water samples were collected before, during, and after the extraction period. Thirty ground water samples were obtained from the extraction well and analyzxed. Pumping rates and water levels were also monitored closely to evaluate any changes in bedrock permeability during the test associated with manganese dioxide (MnO2) precipitate.

Tracer Test Results
Initial detection of KMnO4 and Br occurred within 4 hours after the start of the injection. The KMnO4 concentration at the extraction well peaked at 374 mg/L after 78 hours, and was still 144 mg/L at the end of the 7 day extraction period. Seventeen days later, the KMnO4 concentration was 31 mg/L at the extraction well. During the test, the TCE concentration at the extraction well decreased from 21.4 mg/L (pre injection) to a minimum of 2.7 mg/L at 88 hours, but later rebounded to the pre-test concentration. The mass of Br removed was evaluated by integration, and this established the fraction of the injected tracer slug removed during the test. The difference between the extracted mass of KMnO4 and Br, normalized verses injected mass, indicated the relative mass of permanganate consumed and it's consumption rate during the test period. The decrease in TCE and increase in Cl during the test were used to calculate the mass of TCE destryed by reaction with KMnO4.

This was a pilot test

The pilot test results are being used to develop a plan for long-term reduction of TCE concentrations in monitored ground water.