Dane County's Coal Tar Ban and What Goes on a Madison Driveway

Every driveway sealed in Dane County since July 1, 2007 has been sealed under a county rule with no statewide equivalent. Chapter 80 of the Dane County Code bars applying, selling or displaying coal tar sealers anywhere in the county, and its current wording also catches any pavement sealer above 0.1 percent PAHs by weight, whatever it is made from. A statewide version, 2021 Assembly Bill 131, would have prohibited coal tar and high-PAH sealants across Wisconsin, but it failed to pass in March 2022, so the county rule is the one that governs a Madison job.

This guide reads the ordinance the way a property owner needs it: what it prohibits and whom it binds, why a lake commission wrote it, what happens to PAHs once they leave a driveway, which sealers remain legal, and the questions that confirm a crew's product before the first coat. It quotes the county code and federal and state research rather than product marketing, and it has nothing to sell.

What Chapter 80 prohibits, and whom it binds

Section 80.08 carries three prohibitions. No person may apply a coal tar sealant product or high PAH sealant product within Dane County. No person may allow one to be applied upon property in the county under that person's ownership or control. And no person may sell, offer to sell or display one for sale within the county. Sellers must post a notice stating that application of these products in Dane County is prohibited by section 80.08.

The definitions in section 80.04 are broad on purpose. A coal tar sealant product is any material containing coal tar, coal tar pitch, coal tar pitch volatiles or any variation, made for use on an asphalt or concrete surface. A high PAH sealant product is any pavement sealant carrying over 0.1 percent polycyclic aromatic hydrocarbons, measured by weight, which works out to 1,000 milligrams per kilogram. The ordinance itself notes that many PAHs are known human carcinogens and toxic to aquatic life.

Enforcement belongs to the Environmental Health Division of Public Health Madison and Dane County, and the county's corporation counsel can seek an injunction. The forfeiture schedule is steep for professionals: a commercial applicator's first-violation forfeiture is twenty times what a homeowner faces for sealing their own property, and it doubles for a second violation and again for a third within 12 months. Section 80.11 adds that each day an illegally applied product remains on the property is a separate offense.

Section 80.09 allows two narrow exceptions. A seller may still sell a restricted product to a buyer who signs a form stating it will not be applied within Dane County, and the seller must keep that form for at least three years. The department, after consulting the director of the Land and Water Resources Department, may also exempt bona fide research. Neither exception lets anyone put the product on a driveway in the county.

A lake ordinance that grew a sealcoat clause

Chapter 80 began as a lawn fertilizer rule. It was first published in April 2004 to limit phosphorus in lawn fertilizer, and the coal tar section arrived three years later through an ordinance amendment published April 19, 2007 and effective July 1, 2007. Amendments followed in 2011 and 2018, and the 2018 amendment is the source of the current definitions, prohibitions and exemptions. The chapter's title now reads as a pairing: regulations for lawn fertilizer and coal tar sealcoat products.

The pairing is deliberate. The Dane County Lakes and Watershed Commission recommended the chapter, and the County Board adopted it under section 33.455 of the Wisconsin Statutes. Its findings say that regulating nutrients and contaminants entering the lakes, including phosphorus in fertilizer and PAHs in coal tar sealcoat, will improve and maintain lake water quality. The ordinance treats a driveway as part of the watershed of Mendota, Monona, Wingra, Waubesa and Kegonsa, which is exactly what it is.

It also reaches past municipal lines. The chapter states that it applies in all areas of Dane County, and cities and villages wholly or partly in the county may take over administration only if they adopt standards at least as restrictive. For a property owner in Madison, Middleton, Fitchburg, Sun Prairie or Verona, the practical result is one rule everywhere in the county, with no weaker version inside any city limit.

From a sealed driveway to Lake Monona

Sealer does not stay on the pavement forever. Tires, shovels and weather wear the top of a coat into fine particles that wash off in the next rain. The U.S. Geological Survey measured coal tar sealcoat at 35,000 to 200,000 mg/kg of PAHs, roughly 1,000 times the level in asphalt-based sealers, and in the lake and stream sediment studies it summarizes, coal tar sealcoat accounted for 70 to 80 percent of the PAHs. Dane County's 1,000 mg/kg limit sits far below every coal tar product in that range.

The local plumbing makes the path short. The city's stormwater utility runs over 500 miles of pipe, more than 26,000 inlets and about 300 ponds, and the city's street sweeping program exists because debris in the gutter, from salt and sand to oil and leaves, would otherwise wash into storm sewers and out to the lakes and streams. A coal tar coat on a driveway that drains to the street would feed that system with every storm, the same route road salt takes, as the post on salt and lake chloride explains.

The evidence that bans work comes from other places but applies here. USGS reports that runoff from coal tar sealed pavement collected 111 days after application still killed all of the test organisms in both species studied, and that after Austin, Texas banned coal tar sealcoat in 2006, sediment cores from Lady Bird Lake showed a 58 percent drop in PAH concentrations from the pre-ban peak. USGS also found PAH levels 25 times higher in the house dust of apartments whose parking lots had been coated with coal tar, so the rule protects kitchens as well as lakes.

What a legal sealer on a Madison driveway is made of

Two product families clear the 0.1 percent line. Asphalt emulsion sealers carry asphalt in water, and as the water evaporates the asphalt forms the black film. Acrylic and other polymer sealers use synthetic binders instead. The Minnesota Pollution Control Agency notes that acrylic sealers contain no PAHs, while asphalt-based sealers contain some at far lower levels than coal tar. Either is legal in Dane County as long as the product stays under the PAH limit.

Performance depends more on application than on chemistry. The makers' instructions come down to four conditions: at least 50 degrees and climbing for a day, a dry forecast for a day, two coats with clean silica sand, and a day with no traffic afterward. At the Dane County Regional Airport station, normal lows sit above 50 degrees only from June through September, so even the right product has to go down in the right weeks. The driveway sealcoating page covers preparation and timing in detail.

Cost gives no reason to cut corners on the product. In Angi's material figures, coal tar and asphalt emulsion cost nearly the same per square foot, and acrylic costs more than either. The ban removed a product, not a price tier, so a crew has no financial reason to reach for a restricted drum, and a bid that is unusually low should be explained by its scope, not its ingredients.

Questions to settle before the drums open

Most homeowners will never see a coal tar product for sale in Dane County, because stores inside the county cannot display one. The risk comes from product bought outside the county or left over from earlier years, so the useful checks are simple and happen before the crew starts spreading anything.

None of this requires suspicion of a particular crew. It turns the county rule into a paperwork step, the same way a written quote turns square footage and coats into numbers that can be compared. Cracks and soft spots still have to be dealt with before any legal sealer goes down, and the crack filling page covers that first step.

• Ask for the product name and its safety data sheet, and read the composition section for coal tar, coal tar pitch or pitch volatiles, the terms the ordinance uses.
• Ask the crew to confirm in writing that the product contains no coal tar and stays under the county's 0.1 percent PAH limit.
• Ask where the product was bought; a purchase outside the county does not make applying it inside the county legal.
• Notice the smell: the Minnesota Pollution Control Agency describes coal tar products as having a strong mothball-like odor that asphalt and acrylic sealers lack.
• For an old coating of unknown origin, the same agency describes a jar test: scrape a little into mineral spirits, and dark coffee-colored liquid suggests asphalt while amber, tea-colored liquid suggests coal tar. A lab test settles it.
• On a managed lot, put the product requirement in the contract, since the ordinance reaches anyone who allows application on property they control.