Case Study: Dry Cleaners Site, Southern California
CL-Out® fast dry cleaner bioremediation cost-effectively removed solvents from soil and ground water at a site in Soutern California. After one application of CL-Out® bioremediation, the total chlorinated solvents concentration in ground water decreased by 90%. At the same time, the contaminant concentrations in soil decreased by an average of 85%. The remediation provided immediate risk reduction including avoiding vapor intrusion by vinyl chloride
Project Design and Implementation
Investigation found dry cleaning solvents in soil and groundwater around a dry cleaning machine. The solvent entered the soil below the building and percolated through the soil to a perched ground water. The soil and sediments are interbedded alluvial and marine sediments with a high permeability. The impacted soil volume covered approximately 80 cubic yards. The area of ground water impact and treatment covered approximately 2,000 square feet.
Based on the volumes of impacted soil and ground water, the remediation plan included five drums of hydrated CL-Out®. Two drums treated the soil and perched ground water beneath the dry cleaning machine. Three drums treated the deeper ground water in the diffused area of the plume. The total injection volume was less than .1% of the pore volume of the treated soil and ground water.
CL-Out® bioremediation destroys chlorinated solvents by aerobic cometabolism. Dextrose provided the carbon source to support microbial growth. EHC-O by Adventus maintained the aerobic conditions to support cometabolism and prevent potential production of vinyl chloride.
Fast Dry Cleaner Bioremediation Results
Post–treatment soil and ground water sampling was approximately 30 days after the injection. The post-treatment soil samples came from locations adjacent to pretreatment sampling locations. The shallow soil samples all showed a decrease in solvent concentrations and no generation of vinyl chloride. Post-treatment ground water samples came from existing monitoring wells. The perched ground water showed a decrease in PCE concentrations but a slight increase in TCE and DCE concentrations. The deeper ground water showed a decrease in all concentrations. Vinyl chloride was not detected in either the perched or deep ground water. The following table shows the fast dry cleaner bioremediation results.
The 30-sampling results show that the site progressing toward fast closure. Additional ground water treatment is unlikely to be necessary to achieve site closure after sufficient post-treatment monitoring.