Twin Cities suburbs file lawsuit alleging coal tar sealcoat contaminated stormwater ponds

A lawsuit filed by seven Minnesota suburbs alleges seven manufacturers knowingly contributed to the contamination of hundreds, if not thousands, of state stormwater ponds by way of coal tar. 

Coal tar, a common pavement sealant, contains high levels of chemicals called polycyclic aromatic hydrocarbons (PAHs). 

“The biggest concern about the PAHs is that they are a known cancer-causing chemical,” said Burnsville Director of Public Works Ryan Peterson.

Peterson says the majority of driveways have been sealed with coal tar. He says in Burnsville, one of the suing cities, there are 16,000 properties. Almost all have a driveway.

“When you have that many driveways you have that much more potential for increasing our liability,” he said.

Peterson says rain can wash sealcoat flakes off driveways, which then contaminates the stormwater with PAHs. The water finally settles in stormwater ponds, creating an environmental concern for plants and wildlife. It is important to note this issue does not impact cities’ drinking water.

Officials say the PAHs in stormwater ponds are not considered an immediate public health concern. However, PAHs can be harmful to people depending on how long they are exposed to contaminated vapors or sediments, according to the Minnesota Pollution Control Agency. 

Cleanup of contaminated stormwater ponds can be costly. Peterson says in 2015, it cost $115,000 to clear the Walden Pond of PAHs. 

Attorney Dan Shulman represents the suburbs filing suit. Joining Burnsville in this lawsuit are Eden Prairie, Minnetonka, Bloomington, Golden Valley, Maple Grove and White Bear Lake.

“They want to protect their people in these communities and they don’t want them to pay for something they shouldn’t have to pay for,” said Shulman.

He says clearing Minnesota ponds of PAHs, he says, will cost millions.

“This may be a beacon not just around this state, but elsewhere that this is a serious situation,” he said.

FOX 9 reached out to all seven accused companies. Only one got back to us and wrote:

“[We do] not believe there is merit to these claims and [intend] to vigorously defend these matters.”