Soil Bioremediation at Dry Cleaners

Permanently remove vapor intrusion risk

Soil bioremediation is a more effective strategy for managing the vapor intrusion risk at dry cleaners where solvents have contaminated soil or shallow ground water.  Soil bioremediation quickly eliminates the problem, while long-term vapor mitigation ties up resources in on-going operation, maintenance and monitoring costs.  Soil bioremediation eliminates the source of  vapors entering the cleaners and adjoining properties.  The source removal restores the full property value without disrupting operations.

CL-Out microbes have been used at many sites in the US and Canada to remove PCE contamination from soil at dry cleaners and other industries where solvents are used. CL-Out is a consortium of microbes selected for their ability to cometabolize chlorinated solvents under aerobic conditions.  The microbes are pumped into the soil through small boreholes in the building or surrounding area.  Once in the soil, the microbes produce metabolic enzymes that convert the PCE into carbon dioxide and water without generating harmful by products.

The following case studies are examples of how quickly and cost effectively CL-Out bioremediation removes the soil contamination:

Chicago, Illinois

CL-Out bioremediation reduced concentrations of dry cleaning solvents in soil to allow for the redevelopment of a property into luxury condos.  After the old building was removed, the contractor mixed CL-Out microbes into the PCE-contaminated soil.  After 90 days the soil was tested to verify success.

The 90-day sampling showed that the remediation met the site cleanup standards.  PCE was reduced by more than 95% from a maximum of 3,100 mg/kg to less than 120 mg/kg.  A “No Further Action” letter was submitted to IEPA.  The CL-Out cost for the project was $13,000.

Orange County, California

At a site in southern California, the soil and ground water contamination was removed at at operating dry cleaners without interrupting the business operations.  CL-Out microbes were injected into the soil and ground water through small-diameter borings.  Inside the building, hand-dug borings less than 3-inches in diameter were used for the treat the soil. Two drums of CL-Out microbial solution were injected into 80 cubic yards of contaminated soil.

After 30 days soil sampling showed the PCE concentration was reduced by 85% from 775 ug/Kg to 115 ug/Kg.  No daughter product were generated during the bioremediation.

The ground water was treated simultaneously and the contaminant concentrations were reduced by more than 90%.

The cost for CL-Out to treat both soil and ground water was $9,500.

Click here to view the full case study.

Call CL Solutions to discuss removing the vapor intrusion risk at your property.


New Chlorinated Solvent Results

CL-Out bioremediation continued to show outstanding results in bioremediation of PCE, TCE and other chlorinated solvents at three recent applications. Results show more than 90% PCE removal with a single application of CL-Out for in situ ground water treatment. The PCE remediation did not cause an increase in vinyl chloride showing that the breakdown pathway was by dioxygenase cometabolism and not by reductive dechlorination.

A site in Massachusetts showed the following ground water results:
PCE 1,100 ug/L reduced to 30 ug/L, 97% removed
TCE 39 ug/L reduced to 5.6 ug/L, 85% removed
No other daughter products were detected.

Ground water remediation in Florida showed these results:
PCE 182 ug/L reduced to 16.1 ug/L, 91% removed
TCE 9.82 ug/L reduced to 2.77 ug/L, 71% removed
cis 1,2 DCE 3.26 ug/L reduced to 0.282 ug/L, 91% removed
vinyl chloride was not detected before or after bioremediation.

Ground Water contamination at a site in New Jersey followed the same trend:
PCE 690 ug/L reduced to less than 5 ug/L, 99% removed
TCE 7,980 ug/L reduced to less than 810 ug/L, 89% removed
No breakdown products were detected.

These sites join the hundreds of sites remediated by CL-Out aerobic cometabolism.

Aerobic PCE Bioremediation

One of the easiest ways to remove a large mass of residual PCE from ground water is to treat the ground water following source soil excavation. Because CL-Out microbes cometabolize PCE under aerobic conditions,  the microbes can be applied to the ground water in the base of the excavation to treat residual contamination in the soil and ground water.  The excavation can serve as an easy access route into a large area of ground water in lieu of multiple injection points.

This method has been used at many dry cleaner locations with a variety of soil types and geologic settings.  Recently this method has been used at a former dry cleaners near Dayton, Ohio.  At this site the PCE concentrations were reduced from 570 ug/L to 43 ug/L with one application into the source soil excavation cavity.



Overcoming TCE Cometabolism Rate Limits

Aerobic cometabolism of TCE may be limited by the potential microbial toxicity of by products or by product metabolic repression.  An independent comparison of induced cometabolism using soluble methane and CL-Out bioaugmentation showed that CL-Out bioaugmentation removed more TCE.  The TCE removal rate by CL-Out when supplemented with an oxygen source was a steady rate that continued past apparent limits of induced cometabolism.  The significant difference may be in that the population of beneficial microbes that can be added is much higher than the population level that may be achieved through biostimulation.  For a brief summary of the study follow this link Overcoming TCE Metabolic Limits.

Remove The Tea Bag Without Removing The Building

When a source of ground water contamination or contaminant vapors is present under a building, efforts to mitigate the spread of contamination may continue indefinitely with mounting costs.  Bioremediation may be used to remove the source of vapors or ground water contamination without damage to the building or interrupting operations.

There are many examples of this approach in the case studies on this site.  You can call us to find whether this approach is applicable to your site and the potential cost savings.

Bioremediation Using Petrox EC Under a Factory Floor

Bioremediation Using Petrox EC Under a Factory Floor