- Associated Press - Monday, December 15, 2014

BOZEMAN, Mont. (AP) - State environmental regulators want the city of Bozeman to drill more monitoring wells and provide more information on the city’s plan for cleaning up contamination seeping out of an old landfill.

The Montana Department of Environmental Quality wrote a letter to the city this past week stating that two additional wells will be helpful in verifying that landfill gas is the primary source of pollution detected south and west of the landfill and help gauge how far a plume of volatile organic chemicals has traveled.

The DEQ also wants the city to back up its hope that the pollution can be addressed by flushing the contaminated ground with clean air pumped from treatment wells by citing examples of comparable cleanups that have used similar approaches.

“These examples will provide support for the degree of certainty that the proposed chosen remedy will prove effective,” state scientists write in a Dec. 8 letter signed by environmental science specialist John Collins.

The state also specifies that the city should identify a “backup plan” in the event its first choice for cleaning up the contamination at the Story Mill landfill doesn’t work as well as hoped, the Bozeman Daily Chronicle reported (https://bit.ly/1stBALg).



The city’s preferred cleanup alternative involves a combination of new remediation techniques in addition to expanding the landfill’s existing system for extracting the gasses produced by decomposition.

Essentially, the approach would try to address contamination near the old landfill by blowing clean air into groundwater and contaminated gasses in gaps between soil particles, then sucking out air saturated with volatile contaminants for above-ground treatment. Pollutants present in groundwater, it is hoped, would gradually be carried off as they dissolve into air pumped through the soil.

The DEQ must approve the city’s remediation plan

The landfill accepted household wastes from 1969 to 2008 and disposed of waste in an unlined cell until 1995. The city has monitored water quality at the site since 1981.

City staff said they hadn’t yet reviewed the DEQ letter and were unable to immediately respond.

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