MIDDLEVILLE, MI -- Groundwater contaminated with known carcinogenic chemicals is discharging into the Thornapple River and the responsible company is asking state regulators to let dilution solve the problem.

Bradford White Corporation, a water-heater manufacturer in Middleville, wants the Michigan Department of Environmental Quality to consider a pollution exemption that would allow continued discharge of groundwater plumes contaminated with chlorinated solvents into the Thornapple River.

Presently, the contaminant discharges are above the state's Part 201 environmental cleanup criteria, but Bradford White is asking the DEQ to allow a "mixing zone" in the river that would dilute the contamination.

Under a mixing zone designation, discharges would be acceptable so long as concentrations of chlorinated solvents in the river don't exceed acceptable state surface water thresholds, said David Wierzbicki with the DEQ remediation division in Grand Rapids.

The volatile organic compounds entering the river are vinyl chloride, trichlorethylene (TCE) and ethylene dichloride. The Environmental Protection Agency considers vinyl chloride and trichlorethylene to be carcinogens, and ethylene dichloride a probable carcinogen.

Local officials and river watershed groups weren't aware of the dilution request until contacted by MLive.

Walter Bujak, a member of the Thornapple River Watershed Council, said in an email it is "totally unacceptable" that the discharge of any amount of carcinogens into the river is being considered.

"The solution they are trying to sell to us is the old 'dilution is the solution to pollution' pitch from the industrial era," Bujak said. "I can't believe this is happening in America today right in our own backyard."

Jon Bylsma, an attorney with Varnum Law representing Bradford White, refuted the notion that the company is solely relying on dilution to rid groundwater of chlorinated solvents.

"We've taken significant steps using the latest technology as that technology has been developed and that has significantly remediated this issue on-site," Bylsma said. "The idea that Bradford White is just using the river to wash this all away is the opposite of what the data shows and the reality is."

The Thornapple River is a tributary of the Grand River that enters upstream of Grand Rapids. Wierzbicki said it's possible but not likely that the solvents would accumulate in higher concentrations downstream.

Erv Gambee, president of the watershed council, said he plans to alert residents downstream and municipal officials of the proposal.

"In the future we'll be asking ourselves, 'Why did we do that?'" Gambee said.

Village Manager Duane Weeks said he was unaware that Bradford White wanted to continue discharging contaminated water into the Thornapple River but knew the company was talking with state regulators about lowering levels of chlorinated solvents in the groundwater.

The company's request was publicly disclosed in the DEQ Environmental Calendar, a bi-weekly clearinghouse for permitting decisions, new administrative rules and other official notices that is not widely read by the general public.

The public can comment on Bradford White's request until Sept. 28.

The contamination plumes are from degreasers previously used at Bradford White to clean metal parts prior to painting, according to the company's mixing zone determination request. Although they were stored in concrete pits, the substances seeped into the groundwater beneath the plant.

The resulting groundwater plume underneath the plant eventually spread west toward the river and south to residential areas of Middleville.

A map of eastern Middleville detailing monitoring and extraction well locations as well as portions of the groundwater plumes.

The plumes have not affected the village water supply, Wierzbicki said.

Though there are community wells north of the Bradford White plant plume and southeast of the residential area plume, modeling shows the plumes aren't headed toward either, he said, adding that the projection is confirmed by monitoring wells.

Middleville water has not been tested for chlorinated solvents.

Beyond water concerns, chlorinated solvents pose a threat to residential homes through vapor intrusion. Compounds like vinyl chloride in soil can vaporize and enter poorly-sealed homes, causing illnesses when regularly inhaled.

Wierzbicki said that groundwater sampling hasn't indicated vinyl chloride is migrating upward toward the surface. However, no Middleville homes have been tested for vapor intrusion, he said.

Bradford White has tried to remediate the plumes by pumping and treating contaminated water and using bacteria, Wierzbicki said. Pockets of contaminated groundwater remain that are above acceptable levels.

The DEQ gave Bradford White the choice of either cleaning up those areas or requesting a mixing zone.

Bylsma said it wasn't a choice. He called the dilution request a "necessary" and "common" action.

"Bradford White does not see this as a choice between remediation efforts and a mixing zone determination," Bylsma said. "The remediation efforts, which have been going on for decades and have been very successful, will continue as best as we can do that. The mixing zone determination is a necessary and very common step any time there's an impact zone that is near a water way."

The application states the discharge of contaminated water into the river wouldn't degrade the river because it's already happening.

According to the company application, the "majority" of polluted groundwater is already being captured by a trench and treated by an air stripper system. Cleanup began in 2004. The last time the chemicals were used was in the mid-1980s.

At the area where groundwater enters the river, vinyl chloride was detected this year at 62 parts per billion (ppb). Ethylene dichloride was detected at 1,510-ppb and TCE was detected at 830-ppb. Those concentrations are above the state's criteria for contamination at the groundwater-surface water interface (GSI).

Wierzbicki said levels of chlorinated solvents in the groundwater have and will continue to decrease with existing cleanup efforts.

"They're doing everything they can to keep it out of the river," Wierzbicki said. "They're cleaning up the groundwater as best they can, as efficiently they can ... It's just difficult to intercept (everything)."

Written comments can be mailed to David Wierzbicki, DEQ Remediation and Redevelopment Division, 350 Ottawa Ave. NW, Unit 10, Grand Rapids, MI 49503.

Comments can also be emailed to Wierzbicki at wierzbickid@michigan.gov.