Site geology consists of the Middle Member of the Triassic Stockton Formation, which is overlain by approximately 3.6 meters of unconsolidated sandy silt and silty clay. Bedrock was encountered at a depth of 154 meters below ground surface (bgs) and is comprised of interbedded arkosic sandstone, siltstone, and shale. The ground water table varies depending on pumping water supply, but is generally more than 18 meters bgs.
Targeted Environmental Media:
 Fractured Bedrock
The vertical and lateral extent of the plume were not identified.
Major Contaminants and Maximum Concentrations:
- Trichloroethene (0 µg/L)
- Borehole Geophysics
- Natural Gamma
- Caliper
- Other (Sonic Borehole Imaging)
- Fluid Loggings
- Temperature
- Conductivity/Resistivity
- Chemical Oxidation (In Situ)
- Other (In-Situ Chemical Oxidation (ISCO))
Comments:
Mobile activated carbon wellhead treatment units were used in correlation with permanganate solution. ISCO treatment proceeded downward and outward from the perched zone beneath the former source area and along the fracture zones that extend to the water table.
The objective of this study was to use permanganate to treat TCE within a fractured, interbedded sandstone, siltstone, and shale water supply aquifer and reduce the concentration of TCE to below drinking water standards.
The status of this study was not identified in the reference cited.
The use of ISCO raises the concern of permanganates impact on the water supply. Mobile activated carbon wellhead treatment units serve an important role in assuring that the permanganate ISCO solutions do not affect the water supply.
References: John Roberts, Richard Brown, Marc Carver, and Shari Walsh. Characterization and Treatment of a Trichloroethene Plume in the Fractured Stockton Formation. The Fifth International Conference on Remediation of Chlorinated and Recalcitrant Compounds. May 22-25, 2006. Monterey, California.
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