Keyhole source treatment to reduce pce ground water plume Case Study
CL-Out bioremediation was used in a keyhole treatment to reduce the mass of contamination near the source and down gradient concentrations in the plume. At a former manufacturing facility in Ohio the concentration of PCE near the source was over 100,000 ug/L. Down gradient of the source the PCE concentrations were less than 10% of the source concentration. Aggressive treatment in the source area reduced the source concentration and in the down gradient plume.
After one treatment with CL-Out bioremediation, the concentrations decreased as follows:
PCE was reduced from 120,000 to 12 ug/L.
TCE was reduced from 2,000 to 12 ug/L
Cis 1,2-DCE was reduced from 9,500 to 8,100 ug/L.
Vinyl chloride, however, increased from 1,200 to 22,000 ug/L.
The vinyl chloride increased as the aggressive cometabolic treatment stimulated some incomplete reductive dechlorination.
Down gradient from the source, the concentrations decreased with slight to no increase in daughter products. The following results were measured in the down gradient plume:
PCE reduced from 5,000 to 1,600 ug/L.
TCE reduced from 43 ug/L to BDL.
Cis 1,2-DCE was reduced from 140 to 23 ug/L.
Vinyl chloride was not detected before or after treatment.
Keyhole treatment was a cost effective approach to reducing the mass of contamination in a ground water plume by focusing aggressive treatment on the source area. Concentrations in the rest of the plume decreased as the microbes and treated water dispersed through the plume.