Stormwater ponds were built to perform flood control and water quality functions.
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Cities must test for PAHs before they dredge their ponds, and there are thousands of ponds. Also, starting in around 2023, cities will be required to perform work to restore the water quality function of their ponds. Again, the cost of complying with these regulations will be higher because of the presence of PAHs in the sediment from coal tar sealant runoff.
Coking facilities produce raw coal tar, which they sell to steel and aluminum refiners. Refiners use about 95 percent of the raw coal tar in their production processes. Coal tar is the waste byproduct of these coking facilities.
It is a thin black coating applied to paved surfaces (typically driveways, parking lots, playgrounds, etc). It is not commonly used to pave roads. Sealant manufacturers claim their product protects the paved surfaces below from oil damage and weathering.
Within several years of applying coal tar sealant, the combination of friction from vehicles driving on the surface and environmental/weather exposure wears the sealant off into fine particles that wash from the driveway, down roads, and into stormwater ponds.
Yes, the product manufacturer recommends reapplying the sealant every few years because they know the products break down over time.
Yes, coal tar contains high concentrations of PAHs (polycyclic aromatic hyrdocarbons). PAHs make up more than 50 percent of the raw coal tar. The EPA has designated 16 PAHs as priority pollutants and seven of those as probable human carcinogens. Nearly all seven of these PAHs are in raw coal tar. While in sediment, coal tar is not a public health concern. Once it is dredged, coal tar could pose a health risk if the dredged soils are not properly disposed of in an authorized landfill designed to ensure the waste cannot migrate into the environment.
Yes, asphalt is, and has always been, an alternative to coal tar sealant. And while asphalt also contains PAHs, coal tar sealants have 1,000 times more PAHs than asphalt sealants.
No, the City is not suing users of the coal tar sealant. Residents are not responsible for the damages the City alleges because they were not warned of the dangers of using the sealant. To the contrary, residents were led to believe it was a safe product to use because it was sold as an option for surfacing and re-surfacing driveways.
It is very costly to remediate stormwater ponds contaminated with coal tar and no end in sight. Even though there is now a ban, coal tar sealants were used for years and remain on many properties. Litigation is appropriate because polluters should pay for remediation of the damage they cause. Without a lawsuit, remediation costs would be shouldered by innocent taxpayers.
Minnesota cities are the first to systematically address the problem and to incur disposal costs. Part of this is due to the statewide ban, which also evidences the state’s concern for human and ecosystem health. While in the ponds, sediment coal tar waste does not create a public health concern. But it could if the sediment, once dredged, was not properly disposed of in contained landfills. That is why the cost of disposal is so high. Moreover, statewide thousands of ponds still need to be dredged; it is important to address the issue now before tens of millions of dollars in costs are incurred.
The cities are seeking compensatory damages for past and future costs of testing waste/sediment and removing and disposing of that waste from the stormwater ponds.