A Houston dry cleaners site reduced chlorinated solvent concentrations in groundwater by 98 to 99 percent in less than 90 days after implementing CL-Out bioremediation, according to a case study.
Control Technologies, the project consulting and engineering firm, says the switch saved the dry cleaners hundreds of thousands of dollars.
After discovering perchloroethylene (PCE), a possible human carcinogen, in the soil and groundwater at the site, the dry cleaners implemented a dual-phase extraction system for nine years. While the system removed 1.2 million gallons of water and reduced the total chlorinated volatile organic compounds (CVOCs) from 115,000 µg/L to 36,000 µg/L, the removal rate had reached an asymptote with PCE concentrations higher than 4,000 µg/L.
To treat the residual contamination in an area of about 20,000 square feet, the dry cleaners and Control Technologies selected CL Solutions’ CL-Out bioaugmentation. CL-Out microbes were injected into the ground water on three occasions between July 2005 and February 2006. The total injection volume of CL-Out was less than .1 percent of the pore volume of the treated aquifer.
California’s Airborne Toxic Control Measure bans dry cleaning machines that use PCE by Jan. 1, 2023. The California Air Resources Board identified PCE as a toxic air contaminant in 1991.