Rosemount will add its name to a list of about 15 cities that ban a common type of driveway sealant to stop chemicals from running off into storm-water ponds and creating expensive and hazardous pollution problems.

A new ordinance that goes into effect this week prohibits the use of coal-tar sealants for blacktop driveways, parking lots and other surfaces.

Rosemount residents will be expected to use -- and hire contractors who use -- safer, asphalt-based sealers. A violation would be punishable as a misdemeanor.

The Minnesota Pollution Control Agency has found that coal-tar sealants are a key contributor to PAHes (polycyclic aromatic hydrocarbons) that are showing up in storm-water holding ponds in Minnesota. The PAHes make the silt that builds up in storm-water ponds both hazardous and expensive to dispose of.

Bans by cities on coal tar sealants help reduce this pollutant, said Don Berger, MPCA program administrator of storm-water policy. "The longer that coal-tar sealants are put down on hard surfaces, the more it extends the problem."

Other cities that have banned coal-tar sealants include Inver Grove Heights, Prior Lake, Edina, Falcon Heights, Golden Valley, Little Canada, Maplewood, New Hope, Roseville, Vadnais Heights and White Bear Lake. 

The MPCA counted it a major victory in March when Jet Black International, a large national franchiser of pavement seal-coating based in Eagan, announced that it would voluntarily phase out coal-tar-based sealants for all 25 Minnesota franchises this year and change to a safer asphalt emulsion by 2013.

"Coal-tar residues that can contaminate storm-water ponds may become a thing of the past thanks to a voluntary phase-out by ... Jet-Black International," the MPCA said on its website in March.

"When an industry leader embraces science-based recommendations like this, it really helps," MPCA Commissioner Paul Aasen said.

An extensive survey by the MPCA found that the only retailers still selling coal tar-based driveway sealers are Sears and Hardware Hank, Rosemount Public Works Director Andrew Brotzler reported to the City Council April 3.

Rosemount staff found no retailers selling the coal tar products in Rosemount.

The MPCA still has no idea how many of the 20,000 storm ponds in the metro area contain pollutants, Berger said. "We don't have an answer to how many are contaminated to the point where their sediment needs to go to a municipal solid waste landfill."

Cities are in the midst of taking a survey of their ponds to report their number and condition to the state. Once that information comes in, the size of the storm pond pollution problem will be clear, but what to do about it has not been addressed, Berger said.

Laurie Blake • 952-746-3287