Cities Sue Companies over Sealant Pollution in Minnesota Ponds

Seven Minnesota cities are suing a group of companies that refine coal-tar sealants to help pay for cleanup after the product’s harmful chemicals ended up in stormwater ponds across the state.

The cities filed separate federal lawsuits last month to try to hold the companies accountable for products used by Minnesota residents to seal driveways and parking lots for years, Minnesota Public Radio reported. The removal of contaminated material from stormwater ponds is a costly process, and the cities are looking for help to cover the expenses.

“They have this problem, it’s not going away, and it’s going to cost money,” said attorney Robin Greenwald, who represents the seven cities. “They either have to have the taxpayers burdened with that cost, or the polluter.”

Pittsburgh-based Koppers, one of the companies named in the suits, said the cities’ claims don’t have merit. The company plans to fight the lawsuits.

The state banned sealants made from refined coal tar in 2014 as concern grew over the presence of polycyclic aromatic hydrocarbons (PAHs) in the environment.

Some of the chemicals are known to cause cancer in humans. Coal-tar sealants contain significantly higher levels of PAHs, which means the chemicals could pose a human health risk.

Minnesota has roughly 30,000 stormwater ponds designed to catch water that runs off roads, roofs and lawns. Stormwater carries pollutants into the retention ponds, including sediment and phosphorus and nitrogen from leaves and lawn fertilizer.

Cities then remove sediment from their stormwater ponds roughly every 20 years and use the extra dirt in areas where the nutrients can be beneficial. But this process isn’t possible because sediment containing high PAH levels is considered hazardous waste that needs to be taken to a landfill, said Raymond Hozalski, an environmental engineering professor at the University of Minnesota.

“Now, all of a sudden, your costs go up by roughly a factor of two to three,” Hozalski said.

Burnsville, one of the cities that filed suit, has hundreds of stormwater ponds, so the cleanup could cost millions of extra dollars over time.

Burnsville is joined by Bloomington, Golden Valley, Maple Grove, Eden Prairie, White Bear Lake and Minnetonka in filing lawsuits.