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Jan 22, 2014

 

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Jeni Garcin-Flatow
Remediation
406-841-5016

 

DEQ Approves the Enhanced Bioremediation Plan for the Bozeman Solvent Site Cleanup

 

Helena -- The Montana Department of Environmental Quality (DEQ) recently approved the Enhanced Bioremediation 100% Design Report for the Bozeman Solvent Site in Bozeman, Mont. The city of Bozeman and CVS Pharmacy will begin implementing this phase of the cleanup next month.

Enhanced bioremediation was one of the cleanup methods selected in the August 2011 Record of Decision (ROD). It will address the tetrachloroethene (PCE) contamination at the Hastings Shopping Center.

Enhanced bioremediation works by injecting an organic compound into the groundwater, which then stimulates the growth of microorganisms. These microorganisms break down the contamination in the soils and groundwaters until DEQ's site-specific cleanup levels are met.

"Since the Record of Decision was implemented, DEQ, CVS Pharmacy and the city of Bozeman have worked closely and have made great progress," said DEQ Director Tracy Stone-Manning. "This part of the cleanup is huge in protecting human health and the environment and we are excited to begin this phase."

Several monitoring wells are in place to measure the reduction of PCE in the groundwater. DEQ expects that groundwater cleanup levels of five parts per billion (ppb) will be met within five years of using this cleanup method.

Several parts of the ROD have already been implemented. In 2012, the city of Bozeman put a permit system in place that requires an air ventilation system in trenches and excavations at the Hastings Shopping Center that protects workers in those trenches and excavations from inhaling PCE contaminated vapors. The city of Bozeman also developed a procedure for providing clean drinking water to residents and businesses that have groundwater drinking wells impacted with PCE concentrations greater than five ppb. In 2013, land use restrictions were put in place for portions of the Hastings Shopping Center to prohibit residential development and construction of structures that could interfere with cleanup. The Controlled Groundwater Area Order limits the installation of new groundwater wells, and remains in place to limit the movement of contamination.

The city of Bozeman and CVS Pharmacy will continue to monitor the groundwater to make sure that the cleanup actions are working.

For more information regarding the Bozeman Solvent Site, please contact Kate Fry at 406-841-5066 or at kfry@mt.gov or visit the webpage at http://deq.mt.gov/statesuperfund/bozeman_solvent.mcpx.

Background
An enhanced bioremediation pilot test was conducted in 2008. The results of the pilot test demonstrated that PCE concentrations at the Hastings Shopping Center were reduced. Pilot test monitoring also showed that methane and vinyl chloride were generated in soil vapor and vinyl chloride in the groundwater. Methane and vinyl chloride are common byproducts of enhanced bioremediation and can be used to demonstrate that the organic compound is working. The enhanced bioremediation design includes a soil vapor monitoring network and installation of a soil vapor extraction system to capture and treat methane and vinyl chloride soil vapors. The treated vapors will be discharged to the atmosphere.

The city of Bozeman and CVS Pharmacy are currently working on the design documents for the sub-slab vapor extraction system that will be installed beneath a portion of the Hastings Shopping Center building. The system is to remove and treat sub-slab vapors from the building before PCE contaminated vapors can move into indoor air. This system is expected to be put into place by the summer of 2014.

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