Full Scale Bioaugmentation of a Low Permeability TCE Site Using KB-1®


Courtesy of SIREM

Problem Definition
Widespread trichloroethene (TCE) contamination at Spill Site 7 has resulted from historical solvent spills at a former liquid oxygen facility that operated from 1960 to 1966. Site geology consists of low permeability and highly heterogeneous materials. The source area was located upgradient of a zero valent iron permeable reactive barrier (PRB). The project objectives included ensuring the remedy would not negatively impact this PRB.

Results from a bench-scale treatability study demonstrated that both biostimulation and KB-1® bioaugmentation were required to promote complete reductive dechlorination of TCE to ethene in a reasonable time frame. A pilot test was performed that included hydraulic fracturing to deliver electron donor amendments into the low permeability geologic materials. Pneumatic injections were then used to deliver KB-1® into the fractured zones in the injection wells. Following successful completion of the pilot test, full-scale injection of 310 liters of KB-1® was conducted in 39 shallow injection locations accessing 165 fractures.

Notable Results
Analytical data from the pilot test indicated accelerated degradation of TCE to ethene after KB-1® bioaugmentation. TCE and cis-1,2-dichloroethene (cDCE) concentrations have dropped from 670 and 1,300 micrograms per liter (μg/L), respectively, to concentrations approaching site clean up standards (5 and 70 μg/L). cDCE and vinyl chloride concentrations were both observed to increase initially and subsequently decrease to concentrations approaching site clean up standards, followed by corresponding increases in ethene concentrations. Seven months after full-scale
bioaugmentation no negative impact on the PRB was observed and Dehalococcoides (Dhc) were detected at concentrations up to 108 Dhc per liter.

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