U.S. Army Corps Study Targets Merrimac Groundwater

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A new technical review by the U.S. Army Corps of Engineers has found that concentrations of the explosive DNT may be increasing in groundwater in the rural town of Merrimac.  Residential areas that may be in the path of contamination originating from Badger Army Ammunition Plant are the Inspiration Drive Area and the Weigand’s Bay Area, the January 2009 report says.  So far, the Army has not found unsafe levels of DNT in private wells that it has tested.

“Residential areas near the Wisconsin River may potentially be affected by DNT migration from the Deterrent Burning Ground in the future,” the report says.  “Results indicate concentrations of some DNT isomers have shown slight increases in the last several years.  The Wisconsin Enforcement Standard and Preventive Action Limit have been exceeded for 2,4-DNT and 2,6-DNT.”

Authors of the report, who included an environmental engineer, several chemists, and a geologist, said that environmental safeguards should be improved.  “Groundwater monitoring is insufficient to delineate groundwater vertical and horizontal contamination pathways in the aquifer,” they said.  “Sentry wells should be installed in areas where the public may be impacted by contaminants.”

The Deterrent Burning Ground is a closed hazardous waste disposal site located in the northeast corner of Badger.  It was used as a demolition landfill and for open burning of deterrent, asphalt shingles, building timbers, and office wastes.  Deterrent is an organic liquid containing dibutyl phthalate and DNT that is used to modify the burning characteristics of nitrocellulose-based propellants.  The EPA has classified DNT as a probable human carcinogen.

The Army Corps study was conducted in part to fulfill a Wisconsin Department of Natural Resources (WDNR) requirement for a Five Year Review to determine if the cleanup remedy is protective of human health and the environment.  In 2002, the WDNR approved the installation of an Enhanced Biodegradation System (EBS) and a 7-acre landfill cap.  The cap system was installed to prevent infiltration of rain and melting snow which could carry contaminants to groundwater.  The EBS was designed to promote the degradation of residual DNT left in subsurface soils.

“Monitoring of the EBS needs to be improved to verify effectiveness and protectiveness of the groundwater,” the report says.  “There is no current method to determine if operation of the EBS is potentially affecting groundwater contamination and migration.”  If the current EBS is found not to be effective, the report lists a number of alternative cleanup methods.

In response to growing concerns about groundwater quality at the northeast corner of Badger, Citizens for Safe Water Around Badger (CSWAB) requested a meeting with WDNR, EPA and local Army officials but the WDNR project manager turned the group down, saying such a meeting was “premature.”  The group wants the WDNR, as the lead regulatory agency on cleanup, to set an enforceable timeline for implementation of the report’s recommendations and to expand required testing of nearby private wells while pending investigations are underway.

“The report reinforces everything that the community has been saying for a very long time,” said Laura Olah, Executive Director of CSWAB and resident of the Weigand’s Bay neighborhood. “I only hope that it’s not too late.”

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