TOWN OF MERRIMAC — Recent groundwater samples from several wells in and around a defunct weapons plant have shown spikes in contamination levels, drawing the attention of government officials.
Those charged with ensuring safe drinking water near the former Badger Army Ammunition Plant presented the findings and announced plans for increased monitoring during a public meeting Wednesday night in Prairie du Sac.
In addition to more testing, the U.S. Army also has contracted with a separate federal agency to analyze four known groundwater contaminant plumes that are slowly moving from inside the plant’s boundaries toward the Wisconsin River.
Earlier this month, the Army found that water sampled from a homeowner’s private well southeast of Badger contained dinitrotoluene, a chemical used to produce explosives, at 62 parts per trillion.
Wisconsin’s safety enforcement standard for the chemical, known as DNT, is 50 parts per trillion. Exposure has been linked to increased cancer risk and other illnesses.
The private well is in the Water’s Edge subdivision, located along the Wisconsin River in the town of Merrimac.
The Army also recently reported DNT spikes exceeding enforcement standards at two monitoring wells along the northeastern edge of the plant. Those wells are at the front end of a plume traveling southeast toward Weigand’s Bay.
The findings prompted concern from Wisconsin Department of Natural Resources officials, who have asked the Army to increase testing frequency.
“Hopefully that’s just something that’s temporary,” DNR hydrogeologist Jason Lowery told those who attended Wednesday's meeting at the River Arts Center. “But I think the additional monitoring that the Army’s going to be doing will flesh that out.”
Lowery said variations in data are not unusual, and typically are temporary. However, he said the best approach is for officials to increase monitoring until they know for sure.
The Army has offered bottled water to the homeowner whose private well was affected, and is working with the DNR to determine the next steps.
The government’s cleanup at the plant, which was operational from World War II to the Vietnam War, has included placing protective caps over portions of contaminated soil. Recent contaminant level increases observed in one plume, Lowery said, may have been the result of elevated water tables flushing chemicals from the capped soil.
Laura Olah, executive director of the nonprofit group Citizens for Safe Water Around Badger, questioned whether increased testing is sufficient. She suggested officials also examine whether cleanup remedies at known contamination sites have been effective.
“To me, what we’re kind of talking around is: What about the source area?” Olah said.
New analysis to begin
As the Army moves forward with more sampling, it also has contracted with a separate federal agency to analyze four plumes that include seven contaminants officials have been tracking. The U.S. Geological Survey will conduct that review, and may have results available by the end of the year.
USGS specialists will use 17 years of sampling data to remap the plumes and determine whether they have changed over time. They also will conduct a statistical analysis to see if there are untested areas that need sampling, and whether increased testing frequency at existing wells makes sense.
“This was prompted by questions about whether the monitoring network is adequate for future objectives,” USGS hydrologist Matthew Pajerowski said about the Army’s request.
He said the analysis won’t be able to predict the future path of the plumes, but should show which areas may be vulnerable.