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Dover AFB
Dover AFB, DE
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Client:
USEPA Robert
S. Kerr Environmental Research Center
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| Wells
and Control Panel Layout at
Dover AFB National Test Site |
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The surfactant flood
was one of the innovative technologies to be evaluated at the national
test site located at Dover Air Force Base, Delaware. At the Test Cell
#1 (a closed system), a known, but undisclosed, amount of PCE was injected
at a depth of 29 to 41 feet. The estimated PCE in the test cell was
79 liters based on the pre-partitioning tracer test conducted by the
University of Florida researchers. The goal of the SESR demonstration
was to remove as much of the PCE as possible from the test cell. The
selected surfactant included a mixture of sodium dihexylsulfosuccinate
(AMA), isopropyl alcohol, and CaCl2.
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TASKS
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- Conducted
in situ surfactant flushing to demonstrate surfactant
recovery from the subsurface and enhanced DNAPL (tetrachloroethylene,
PCE) removal
- Conducted
demonstration (two months actual flushing) of above ground
treatment processes to accomplish surfactant-contaminant
separation and surfactant concentration for reuse.
- In
order to maximize contact and mixing between surfactant
and DNAPL in the formation, a predominantly vertical flow
pattern was initially used to inject surfactant solution.
Eight of the 12 pre-existing wells in the test cell were
configured as vertical circulation wells to improve the
sweep efficiency.
- Based
on the PCE concentration in the effluent, the recovered
PCE during the surfactant flood was close to 58 liters.
Nine liters of the PCE was recovered during the tracer
test.
- The
observed PCE groundwater concentrations indicated that
70% - 95% reduction in groundwater concentrations were
achieved during the surfactant flood at eight wells.
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It is believed that the remaining PCE mass may be trapped
in clays beneath the treated area (> 41 feet bgs)
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