Groundwater contamination from Badger discharges to the wetlands at Weigland’s Bay North on Lake Wisconsin just off Highway 78 west of Merrimac. The Army maintains the annual discoloration following the spring thaw is unrelated to the contamination.

The Wisconsin Department of Natural Resources has issued a formal letter to the U.S. Army cautioning the military that it must fully comply with state environmental regulations in pending cleanup decisions at the former Badger Army Ammunition Plant (Badger) located in rural Sauk County, west of Merrimac.

In its response to the Amry’s March 2020 PFAS investigation at Badger, the DNR emphasized that Superfund law (CERCLA) “does not give the federal government sovereign immunity from adhering to state regulations.”

The DNR also stated that the Army is still responsible for cleaning up all contaminants, including toxic chemicals like PFAS, that do not yet have numerical standards. Testing by the U.S. Army detected low concentrations of PFAS chemicals at former fire-training areas at Badger.

“The lack of promulgated numerical cleanup standards for a hazardous substance does not prevent an entity in Wisconsin from responding to a discharge of PFAS in Wisconsin,” the DNR said in a May 15 letter.

The groundwater contamination at Badger has a long history. It was 30 years ago that the U.S. Army first revealed groundwater contamination from Badger was an imminent threat to nearby drinking water wells. Today, four distinct groundwater contaminant plumes still plague the community, migrating past the plant boundary and discharging explosives and solvents to surface water and wetlands of the Wisconsin Riverway.

In a separate letter to the Army, the DNR commented on potential solutions for site-wide groundwater contamination, particularly the Deterrent Burning Grounds (DBG) plume in the town of Merrimac. The contaminant source area is a former hazardous waste disposal site inside the old munitions plant boundary.

Active remediation (as opposed to relying solely on monitored natural attenuation) may be necessary in the down-gradient portion of the DBG plume due to the rising contaminant concentrations, the DNR said.

The DNR noted that groundwater sampling suggests that groundwater contaminant plumes located in the Town of Merrimac area are expanding and recommended that an enhanced monitoring network be developed and installed, adding that “long-term use of residential wells as the primary means of plume delineation is unacceptable.”

The Army recently announced that it is investigating the occurrence of the industrial solvent trichloroethylene (TCE) in residential wells located on Weigland’s Bay North. TCE was detected above the groundwater enforcement standard in three residential wells. Another three homes had low levels of TCE below the health-based standard.

Army contractors plan to conduct soil borings up-gradient of the residential wells and install a push drilling machine to test groundwater.

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