Four significant stratigraphic units underlie the site: glacial till, saprolite, the Preakness Basalt and the Feltville Formation (sedimentary rock) With few exceptions, these units do not yield significant quantities of water and the till and saprolite are dense and the bedrock competent.
The hydraulic conductivity of the Preakness Basalt in the source zone area, as derived from a 12-hour constant rate pumping test, ranges from 5x10-4 to 7x10-4 ft/day.
Near vertically plunging faults that transect the site play a role in the migration pattern of the TCE plume. The faults appear to limit the horizontal migration of the plume in the Preakness Basalt and likely exacerbate vertical migration of contaminants to the Feltville Formation.
Targeted Environmental Media:
 Dense Non-aqueous Phase Liquids (DNAPLs) - Fractured Bedrock
This was a source zone pilot test and the plume was nolt delineated.
Major Contaminants and Maximum Concentrations:
- Trichloroethene (500,000 µg/L)
- Borehole Geophysics
- Single Point Resistance
- Caliper
- Video Camera Televiewer
- Flow
- Pumping Tests
- Coring
- Tracer (dye) Test
- Chemical Oxidation (In Situ)
- Fracturing
Comments:
The pilot test was performed between October 21, 2003 and December 24,2003. A 5% solution of KMnO4 was injected into wells under pressure. To preclude plume displacement, the total injection volume was less than 10% of the estimated bedrock fracture volume.
The pilot test was successful in reducing average TCE concentrations from all wells that are located in the DNAPL source zone by 55%. This represents the difference pre-test sampling on Oct 2003 and post test sampling on April 2004. Concentration rebound was observed at the last sampling event.
This was a pilot test.
Unknown on December 2004.
Latest data was presented at 2004 U.S. EPA/NGWA Fractured Rock Conferenc, September 13-15, 2004, Portland, ME
1. Use of hydrofracturing versus a greater injection well density.
2. A paced injection schedule, over an approximately two year period, to incorporate the potential for TCE rebound.
3. Use of passive diffusion bag samplers .
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