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Driveway Sealcoats

Sealcoating Your Asphalt Driveway?

Whether you plan to seal your own driveway or hire a professional contractor, be aware that a new law was passed to protect our environment from harmful chemicals in coal tar-based driveway sealcoats.

Statewide ban now in effect in Minnesota

Effective January 1, 2014, the sales and use of coal tar-based sealcoats are banned in Minnesota. The ban will minimize the unnecessary release of harmful and persistent chemicals into our environment. The coal tar-based sealcoat ban is expected to reduce 67% of the PAHs going into the environment, but vehicle emissions and residential wood-burning account for the other 30% and are less feasible to address.

What's all the Coal Tar fuss about?

Among the chemicals in coal tar-based sealcoat, coal tar pitch is known to cause cancer in humans and polycyclic aromatic hydrocarbons (PAHs) are probable human carcinogens. The more persistent PAHs can harm the aquatic food chain. Studies around the U.S. have shown that PAHs are released from coal tar-based sealcoats into the air and homes, workplaces, and shopping centers, and also into ponds, lakes and streams. In addition to the potential health risk of PAHs, there can be substantial costs for cities and private property owners to manage sediment in stormwater ponds that is contaminated with PAHs from coal tar-based sealants. Coal-tar-based sealcoats have been on the market since the early 1960s, but only recently have the adverse health risks become widely known, still very little has been published to date about the potential for adverse human-health outcomes.

For more information visit the MPCA web page linked below:

What are other sources of PAHs?

PAHs are a group of organic compounds formed when burning anything carbon based, either naturally or from human activity, be it wood, gasoline or even just grilling your steak. Some PAHs are known carcinogens and are persistent in the environment, while others decompose easily and are of little health risk. Some skin and hair care products also contain PAHs. Coal tar based sealants contain 1000 times more PAHs than do similarly performing asphalt based sealants. The City continues to use an asphalt based emulsified sealer during the rock/chip sealcoating maintenance of our streets, which contains minimal PAHs.

What should I do?

Before you buy materials or hire somebody, ask to ensure that the sealcoat is either a diluted asphalt emulsion , an asphalt/polymer blend, or other alternative that does not contain coal tar pitch. Do not select products if their container labels, or product information show the words "coal tar," "refined coal tar," "refined tar," "refined coal tar pitch," "coal tar pitch volatiles," "RT-12," "tar" or similar terms.

Driveway Care Basics

  • Monitor your pavement's condition and invest in treatments before significant deterioration occurs.
  • Good Habits can prevent damage.
    • Place blocks under motorcycle and bicycle kickstands, trailer tongue jacks and other point loads to prevent surface indentations.
    • Avoid turns while your vehicle is stationary to reduce surface scuffing.
    • Clean up spilled gas, oil or other petroleum products with absorbent pads or oil-dry to minimize permanent damage to the asphalt pavement.
  • When maintenance is needed, talk to two or more sealcoat contractors, sealcoat providers or pavement engineering consultants with experience using safer alternatives to coal tar like petroleum asphalt-based products. Consider sealing cracks before serious deterioration occurs; cracking is fairly common in our cold climate.
  • Work only with providers who can show you complete product data sheets so you can avoid coal tar content and make sure you are choosing safer alternatives.
  • Be aware of best application practices and make sure they are used.

Sources: MPCA and Minnesota Asphalt Pavement Association

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