Seven communities in the area are suing several chemical manufacturers for compensation for the environmental costs of their products.

Eden Prairie, Minnetonka and five other cities have filed lawsuits against seven refiners of coal tar for allegedly contaminating numerous storm water ponds with pollutant and potentially carcinogenic chemicals.

In court records released Jan. 2, the cities alleged the companies knew of the environmental risks of their products and continued to market them as “safe and effective components” of pavement sealants. The cities are now seeking compensation for the cost of cleaning up the harmful runoff.

Eden Prairie, Minnetonka, Bloomington, Burnsville, Golden Valley, White Bear Lake and Maple Grove have all filed identical suits against the companies they claim should pay for the costly cleanup of the polycyclic aromatic hydrocarbons that have polluted numerous storm water ponds and waterways in the southwestern suburbs.

PAHs were found in high concentrations in coal tar pavement sealants used across the region until Minnesota banned the sealants in 2014 due to health and environmental risks, according to the Minnesota Pollution Control Agency.

The cities claim seven companies — Koppers Inc., Ruetgers Canada Inc., Rain Carbon Holdings, Rain Carbon LLC, Stella-Jones Corp., Coppers Creek Chemical Corporation and Lone Star Specialty Products LLC — knew their pavement-sealant products would significantly contaminate their environments and continued to sell them as safe products.

The wear and tear of cars, snow and sunlight on coal tar sealants, which contain 15 to 30 percent PAHs by volume, grinds the material into particles that are then washed away into whatever drainage systems are nearby, the suit says.

For Eden Prairie, Minnetonka and the other cities, that means PAHs “inevitably” end up in waterways and storm ponds, where they accumulate and pollute the water, the lawsuits add.

Storm ponds are designed to collect storm water runoff as it drains from roadways and surrounding areas. The ponds filter the water before it reaches lakes and streams, but chemicals like PAH stick around when deposited in high volumes. Even five years after the state ban on coal tar pavement sealant, runoff from older applications of the sealant continues to pollute waterways, the suits say.

Minnetonka and Eden Prairie, like many other cities, maintain their storm water ponds by dredging them periodically. The hazardous PAH accumulation in the cities’ storm water ponds requires special handling that changes the dredging and disposal protocol. The result is a steep increase in the cities’ costs for managing their storm water infrastructure — anywhere from two to 10 times as expensive, said lead attorney Robin Greenwald.

Greenwald is the head of law firm Weitz & Luxenberg’s Environmental and Consumer Protection Unit and said the issue of PAH pollution has been a long time coming.

“USGS (U.S. Geological Survey) has looked at this for many years,” Greenwald said. “These are the first cities that I’m aware of that are going to address the increased costs of removing coal tar.”

“The cities don’t have anywhere else to go for money,” she added, with the result that either residents or the polluters pay the “extraordinarily high” costs.

Because other sealants exist asphalt-based alternatives contain much lower levels of PAH and function similarly — and because, according to MPCA and U.S. Geological Survey studies, the vast majority of storm water pond PAH pollution comes from coal tar pavement sealant runoff, the cities are arguing that the companies knew, or should have known, about the dangers of their products.

The suits target the cost of disposing of this waste, which is necessary to protect public health from exposure to PAHs during dredging operations, the complaints say, arguing that “the polluter should pay for the increased costs of these additional disposal requirements, not the taxpayers.” A statement released along with the complaints estimates the cost of cleanup will run into the hundreds of millions of dollars at minimum.

The seven cities are seeking compensation for damages, “including all costs to investigate, monitor, abate, contain, prevent, treat, remove, and dispose of PAHs from the city’s property and waters, and to ensure that the responsible parties bear such expense, rather than the city or its citizens or taxpayers,” reads the lawsuits.

In a statement, Koppers Inc. refuted the claims, saying, “Koppers does not believe there is merit to these claims and intends to vigorously defend these matters.”

The other defendants did not respond to a request for comment before press time.