Compatible Technologies to Improve In-Situ Remediation of Chlorinated Solvents: A Case Study

A chlorinated solvent plume (perchloroethylene or PCE) was discovered
in the shallow ground water as a result of historical operating practices surrounding a
Houston area dry cleaning facility. Permeable shallow soil at the site allowed rapid
vertical migration at the source and lateral migration in the shallow ground water. This
migration resulted in an off-site migration of the plume beneath an apartment complex
causing concern for potential vapor intrusion hazards; as well as, a decrease in property
value. A ground-water extraction and treatment system was installed to address the
dissolved phase concentrations. The system reduced the total volatile organic compound
(VOC) concentration in the source area from 115,400 to 36,500 µg/l. However, over
time, operating maintenance and cost escalations were exceeding the ongoing remedial
benefit. The system was shut down after nine years of operation. A review of available
remedial technologies that could be implemented within the physical constraints of the
site was conducted. In-situ enhanced aerobic bioremediation was selected to address the
remaining ground-water concentrations because of the permeability of the formation, the
relatively aerobic conditions, and the benefit of reducing the risk of VC accumulation.

Click here for a link to the full report from the 2007 Battelle Conference on Bioremediation