West St. Paul is next to join a list of about 15 metro cities in banning coal-tar-based driveway sealants.
A first reading of a new ordinance forbidding the common sealants is on the City Council's agenda for Monday.
Studies have shown that when such sealants are used, chemicals called polycyclic aromatic hydrocarbons (PAHes) can end up in nearby surface waters, where they can build up to potentially harmful levels, a city briefing paper said.
If they build up in storm-water runoff ponds, the city's cost for dredging and disposing of the pond sediments can increase dramatically.
The ordinance will prohibit residents from applying coal-tar sealants to driveways and parking lots or hiring someone to do it. And it prohibits contractors from directing employees to use the sealants in the city.
Other south-metro cities that have outlawed the sealants include Inver Grove Heights, Rosemount and Prior Lake.
Many retailers and manufacturers are already phasing out coal-tar sealants.