A thin sequence of silts and clays overlie shallow bedrock. The bedrock is made up of fractured siltstone and shale. The depth to water is approximately 10 feet below ground surface.
Targeted Environmental Media:
 Fractured Bedrock
The targeted treatment zone is 15 to 45 feet below ground surface.
Major Contaminants and Maximum Concentrations:
- Trichloroethene (40,000 µg/L)
No technologies selected.
- Bioremediation (In Situ)
- Reductive Dechlorination (In Situ Bioremediation)
Comments:
Injection wells were set up in four lines that spanned the breadth and length of the plume. The full-scale program was initiated in April 2004. During the first four months, injections took place every month in order to establish an anaerobic reactive zone. After that, quarterly injection took place through April 2006, when active injection outside the source area ceased. Initially, between 200 and 400 gallons of injection volume was provide via each well; injections were increased for some wells to between 800 and 1,500 gallons in order to optimize the effort.
No remediation goals were identified within the references abstract.
In October 2005, TCE concentrations outside of the source area were reduced to less than 10 ug/L and approximately 50% of the plume was reduced to less than 1 ug/L. After active injection was stopped, rebound was observed in only one monitoring well (a maximum of 15 ug/L of TCE and 140 ug/L cis-DCE). TCE and cis-DCE continued to decline and optimization of the source area injection activities have shown near complete depletion of TCE. Since treatment, ethene has been measured at 1,300 ug/L, which has been the highest concentration of any of the chlorinated compounds. Complete dechlorination of TCE to ethene is continued with only two injection events per year. As of May 2008, the plume measured less than 10 ug/L TCE and 70% of the plume measures less than 1 ug/L.
References:
Martin, Jennifer P., Purvee Shah, Frank Lenzo, and Mike Bedard. Complete Treatment of a TCE Plume in Fractured Bedrock in Two Years with Enhanced Bioremediation. Presented at the Tenth International In Situ and On-Site Bioremediation Symposium. Baltimore, MD. May 5-8, 2009.
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