Chemical plume won’t ‘get bigger or spread’
MICHIGAN CITY — As officials continue studying and devising a plan of action to deal with a plume of polluted groundwater from a former dry cleaners on Michigan Boulevard, they are confident it will not get any larger or spread any farther.
The plume, contaminated with chemicals from the former Concord Custom Cleaners location at 11th Street and Michigan Boulevard, has spread north-northwest from that site, under several residential blocks toward Trail Creek.
“That entire area is on municipal water, so there will be no drinking water exposure,” hydrologist Jim Berndt of August Mack Environmental told residents at a meeting on the contamination on Sept. 6.
The most likely source of exposure would be through vapors seeping up from the groundwater and entering homes, but the city has so far tested seven homes and “absolutely zero” contamination, he said.
A resident asked about kids getting dirt in their mouths, but Berndt said that would not be a problem as the vapors dissipate quickly once the they get near the surface, and only become a problem when trapped inside a space like a basement or crawlspace.
Another resident asked about the safety of food grown in gardens over the plume, but again, Berndt said it was not a problem.
“That water is at least 35 feet deep,” he said, so plants won’t absorb it and the vapors would dissipate first.
Lisa Bradley, a toxicologist with Haley & Aldrich, said there is a natural degradation of the chemical as it heads toward the surface.
“If there is no exposure, there are no risks. These are carcinogens, but you can have PCE in the groundwater under your home and not be at risk,” she said.
“If the levels are below the target, there are no risks,” she added, and so far we have “found nothing.”
Michael Kuss, general manager of the Michigan City Sanitary District, said the chemicals tend to sink in water, so “there are some significantly high levels under the groundwater, but really really low levels in the subsoil.”
The plume is several decades old, he said, so it is unlikely to get any larger or stronger than it is now.
“Since no more chemicals are being added, and since the plume is effectively stopped by Trail Creek, it should not grow, just dissipate. I don’t expect it to go anywhere,” he said, though adding that PCE and related chemicals degrade very slowly, so dissipation will be a long-term proposition.
Asked about possible pollution in Trail Creek, he said that should not be an issue either.
“So far we have seen no impacts on Trail Creek. If any chemicals do enter the creek, the dissolution effect would be so great that nothing would show up in testing.”
The plume starts at the former dry cleaning site, but exactly how the chemicals got into the groundwater is uncertain, Kuss said.
“It could have been improper disposal or it could have just been leaky pipes,” he said, though because the chemicals were stored above ground, he said a leak likely would have been noticed.
“That’s why we are suing Begley” – the company which owned Concord Custom Cleaners. “They put it there and they should clean it up.”
Mayor Ron Meer echoed that sentiment.
“The city didn’t cause this so we are going to go after those who did. We want Begley to pay for the whole thing.”
There are several potential ways of cleaning the plume, according to Steve Stanford, operations manager of the Sanitary District.
Those include cleaning and treating the groundwater, though he said that “could take 100 years.”
The more preferable alternative would be treating it with other chemicals “to break down the chemicals in the groundwater,” he said.
Other costlier methods are possible, but first the complete size and scope of the plume must be mapped out, and all the homes tested for vapors, Kuss said.
“We’re not worried about the plume getting bigger, and it will keep going in the same general direction.”
Berndt said monitoring wells in the area will continue to be sampled even after the cleanup has begun. “We will continue testing until we’re sure it’s all gone.”
How long that takes and how much it will cost are two of the questions still to be answered.