Vents installed on Tecumseh Products property release gases from groundwater barrier

By DEANE ERTSThe permeable reactive barrier (PRB) that was constructed at the western boundary of the Tecumseh Products factory along South Maumee Street has been equipped with ventilation stacks recently.The vents were installed to facilitate the natural process that is going on beneath the ground where the PRB is doing what it was installed to do - clean the contaminants from the groundwater under the factory that were deposited there over the course of the company’s decades of manufacturing on the site.The contaminants were discovered two years ago when the property was being assessed by the Consolidated Biscuit Company as a possible site to locate a baking facility in Tecumseh. The Ohio-based biscuit company eventually dropped plans to purchase the property.Last summer, Tecumseh Products constructed, in compliance with an EPA consent order, what amounts to a 730-foot-long filter (the PRB) to clean the groundwater flowing slowly from the property’s soil toward the east.The trench that was dug to install the barrier was four feet wide and, in places, 18 feet deep. The soil that was removed was replaced with finely powdered iron, which is not harmful to either the surrounding soil or the the groundwater that slowly filters through it.Jason Smith, Tecumseh Products environmental director, explained that as the water filters through the PRB, a chemical reaction occurs that produces gases, principally methane, as the contaminants are breaking down.“The gases produced are basically the same as you might get from a pile of rotting leaves or a compost heap. It’s a completely natural process that is going on down there,” said Smith. “The ventilation stacks were installed to allow the gases to escape, even when there is a snow pack on the ground. Heavy snow or ice could impede the process and the stacks will allow process to continue at its natural pace.”The flow of most groundwater under Tecumseh is in an easterly direction because of the slope of the watershed that feeds the River Raisin. All of the city wells that supply drinking water for the residents are located in areas unaffected by the contamination.A number of residents in the area affected by the contamination attempted to file a class action suit against Tecumseh Products but the suit was denied by Lenawee Circuit Court Judge Margaret Noe, who ruled that the litigants must file separate suits.At this date, a handful of cases are slated to go to trial next year.Tecumseh Products has drilled a number of monitoring wells to track the success of the PRB and reports of sample tests from the wells will be made known when enough data have been compiled to show a trend.