Perchlorate Remediation Receives Greener Cleanup Leadership Award

The Massachusetts Department of Environmental Protection awarded Irwin Engineering of Natick, Massachusetts the 2016 Greener Cleanup Leadership Award for the innovative in situ bioremediation of perchorate contamination of soil and ground water at the Concord Road Site in Billerica, Massachusetts. The award honors LSPs and their clients for promoting greener cleanup principles and practices to reduce the overall net environmental footprint of hazardous waste site cleanup response actions under the Massachusetts Contingency Plan.

In addition to implementing best practices, Irwin Engineers was able to close the site at least 5 years sooner and saving their client over $5 million. The site cleanup achieved residential soil standards without site use limitations and achieved ground water levels protective of drinking water.

Land Farming Application Reduces TPH by 90% to 99%

Petrox microbes were added to excavated petroleum-contaminated soil to accelerate the degradation of DRO and ERO total petroleum hydrocarbons. Petrox was added by spraying the surface of the soil with a hydrated Petrox solution.  The microbes were mixed into the soil using a tractor-mounted disc tiller.  photo-2              photo-1

After approximately 60 days, soil samples were taken for testing.  The soils showed 90% to 99% petroleum removal.  The following chart shows the range of DRO and ERO concentrations before and after Petrox treatment.

land-farming-results

Bioremediation of Naphthalene and Methylnaphthalene Isomers

Petrox bioremediation accelerates the removal of naphthalene and isomers of methylnaphthalene.  These petroleum compounds are often slow to remediate due to their low volatility and strong affinity for absorption onto soil particles.  The remediation rate of these compounds is slower than BTEX compounds.  They often also rebound as the absorbed phase solubilizes following removal of the compound from ground water to reestablish phase equilibrium.  Petrox bioremediation accelerates the remediation of these compounds by a combination of metabolizing the dissolved phase and a biosurfactant effect that strips the compound from soil to make it available for metabolism.

For example, Petrox achieved more than 90% removal of these compound in less than 9 months at a site of a former underground storage tank (UST) in Florida.  After the UST and surrounding contaminated soil were removed, the residual BTEX compounds were treated by chemical oxidation.  The chemical oxidation, however, did not remove the naphthalene and methylnaphthalene isomers. Petrox was applied to the ground water in and around the former UST cavity.

Nine months after the Petrox application the following reductions in concentrations were achieved.  The concentrations are the average of four ground water sampling locations.

Naphthalene –  367 ug/L reduced to 18 ug/L,  95% removal.

1 Methylnaphthalene – 255 ug/L reduced to 33 ug/L, 87% removal.

2 Methylnaphthalene – 400 ug/L reduced to 30 ug/L, 93% removal.

The Petrox was injected into the ground through a continuous low-volume injection system.  This application method did not impact the use of the property or require major construction. The application was also far less costly than alternatives.

The greatest benefit was the relatively rapid removal of difficult contaminants.

 

 

 

 

 

 

Soil Mixing to Improve Distribution of Microbial Solution

Bioaugmentation results can be accelerated and amplified by soil mixing to improve distribution and contact.  The equipment shown in this example was used to blend Petrox with contaminated soil to a depth of 10 feet.

Soil Mixing Equipment to Improve Microbial Solution Distribution

Soil Mixing Equipment to Improve Microbial Solution Distribution

Click here to view a short video of soil mixing.

Cometabolism of 1,1,1-TCE in a Mixed Solvent Plume

One of the benefits of CL-Out cometabolism is that the enzymes produced by the Pseudomonas sp. organisms convert a wide range of organic chemicals into organic acids that can be metabolized.  The aggressive application of CL-Out organisms to soil and ground water at a chemical mixing company removed the source of ground water contamination by chloroethanes and chloroethenes,  including PCE and 1,1,1-TCA.  The aerobic cometabolism of these compounds simultaneously achieved MCLs in less than 6 months.  Click here to view the case study Mixed Solvent Plume Cometabolism by CL-Out