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Golden UST
Golden, OK
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Client:
Swift/Whitfield,
Golden, OK
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| Surfactant
Mixing Tanks and Injection
Manifolds at Golden UST Site |
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The Golden UST site is located
in the town of Golden, in southeastern Oklahoma. The main contaminant
is gasoline fuel as a result of the leakage of USTs from two former
corner gas stations. Depth to the contaminated zone was 5 to 25-foot.
Most free phase NAPLs were trapped in the shallow zone (5 to 15 ft)
containing sandy silt, silty clay, and predominantly silt. The treated
area covered approximately 25,000 ft2. The primary goal of the project
was to remove all free phase gasoline. The secondary goal was to demonstrate
significant decrease in soil and groundwater concentrations (one to
two orders of magnitude). The tertiary goal was to see how low the final
contaminant concentration in groundwater could be achieved.
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TASKS
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- Conducted
in situ surfactant flushing to recover free phase LNAPL
(gasoline) using low concentration surfactant approach.
- One
pore volume of 1% surfactant (190,000 gallons) were injected
to the contaminated shallow zone (source area, mostly
silty material) over two month period to mobilize the
trapped NAPL.
- Initial
values of free phase gasoline thickness on water table
were between 2.7 to 3.3 feet. No visible or instrument
evidence of free phase gasoline was detected during the
post surfactant sampling event.
- The
observed benzene concentration indicated that 50% - 95%
reduction in groundwater concentrations were achieved
during the freshwater injection phase of the surfactant
flush.
- The
remaining trace of residual and dissolved NAPL will be
removed by the final polishing steps using either biological
treatment or abiotic chemical oxidation.
- Sampling
events for post-oxidation and bioremediation are underway.
Soil coring samples will be collected to assess the effectiveness
of the surfactant flushing.
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