An industrial metal fabrication facility in southeast Massachusetts,
groundwater contaminated with perchloroethylene (PCE),
trichloroethane (TCE), and other industrial solvents.
- Groundwater at this
facility was contaminated by a surface release of used degreasers. Both
overburden and bedrock aquifers were impacted. Assessment of the
site indicated that the two are in hydraulic community.
- Eight years and over
5 million gallons of traditional pump and treatment remediation
had not reduced site contaminant concentrations to the state
drinking water standards.
- Contaminant
- Perchloroethylene (PCE),
trichloroethane (TCE), and other industrial solvents.
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Photo of an inoculation point |
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- Contaminant
- Perchloroethylene (PCE),
trichloroethane (TCE), and other industrial solvents.
- Treatment Method
- in-Situ
- Thirty-two (32) inoculation
points were driven to the bedrock surface and set with 1/2 inch PVC well
screen. The points were arranged in a grid pattern from upgradients of
the known extent of contamination to the property boundaries. The
microbial products were mixed with nutrients, biocatalyst, and injected
into the points and the impacted monitoring wells
Groundwater samples were
collected prior to injection of the microbes and at 3 month intervals. The
goal of the program is to achieve PCE levels of 5 ug/L throughout the
site.
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Results |
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Concentrations of PCE have been declining at an average rate of 50%
each quarter. In the most contaminated area, concentrations have
been reduced from 120 to 28 ug/L in six months. In a less
contaminated area, concentrations have declined from 77 to 11ug/L.
Site closure is anticipated within 12 to 18 months from the time of
initial inoculation. |
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