A combination of the Meddybemps granite with a gabbro-diorite intrusion.
Targeted Environmental Media:
 Dense Non-aqueous Phase Liquids (DNAPLs) - Fractured Bedrock
No separate-phase has been detected; though the concentrations, up to 10,000 ug/l in the last sampling round, and the quick rebound of contaminant levels following permanganate injection are suggestive that DNAPL is present in the bedrock.
Major Contaminants and Maximum Concentrations:
- Tetrachloroethene (10,000 µg/L)
No technologies selected.
- Chemical Oxidation (In Situ)
- Pump and Treat
Comments:
A pump and treat system is containing the plume. Implementation of the oxidation system began in 2001. Two temporary systems were installes in 2002 to add the reagent continually. About 146,000 gallons of water with 100 mg/L of the reagent have been injected in the northern plume area and 195,000 gallons of water with 90 mg/L into the southern plume.
None provided
Recirculation for over 144 days - 900,000 gallons average rate of 4.3 gpm - 385 gallons 40%NaMnO4
Significant declines in dissolved phase PCE
After NaMnO4 amendments stopped, rebound of dissolved-phase PCE
As of 1/1/04, the EPA project managers are exploring blasting options within a limited area of the site to increase the distribution of the permanganate in the bedrock. The contractor is to submit a work plan/cost estimate by late January and the goal is to have the blasting take place prior to spring (in eastern Maine that could be May).
Insufficent oxidant mass was delivered to the source zone relative to the PCE mass andor the source zone was not effectively swept by NaMnO4-amended ground water
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