Field staff (inspectors, investigators, biologists, etc.) for the Watershed Protection Department watch for sealant applications in progress and freshly sealed parking lots as they drive throughout the city on their other job duties. Whenever new sealant is found, it is screened for the presence of coal tar. Enforcement action is taken when coal tar-based pavement sealant is found applied after the ban was initiated. That enforcement action through municipal court typically involves remediation of the applied sealant.  The requirement for remediation is full removal of the coal tar sealant. Besides remediation, legal action can include fines and jail time.

The city produces and disseminates educational materials to producers, applicators, buyers, and to the general public through various means. City staff also periodically checks distributors to monitor product on their shelves.

Citizens may call in suspected coal tar application to the City’s 24-Hour Pollution Hotline at 512-974-2550.

Coal tar based sealants should not be disposed of as regular garbage. Austin and Travis County residents may dispose of Household quantities of coal tar based products at the City of Austin’s Household Hazardous Waste Facility. The facility is located at 2514 Business Center Drive and is open on Tuesdays and Wednesdays from noon to 7 p.m. Businesses requiring information regarding the disposal of coal tar based products may call 512-974-3443.

If you have specific questions concerning the regulations governing the disposal of coal tar containing wastes, please contact the Municipal Solid Waste Permits Section of the Texas Commission on Environmental Quality at (512) 239-2334.

Are there PAH concentrations of concern in asphalt-based pavement sealants?

Coal tar and asphalt have different molecular structures stemming from their origins: coal tar is a byproduct of the production of coke from coal and asphalt is derived from the refining of crude petroleum. Product analyses by the City of Austin indicates that coal tar sealcoat products have median concentrations of total PAHs about 70 times higher than concentrations in asphalt-based sealcoat products.

• Coal tar - Coal tar is a byproduct of the coking of coal when coal is carbonized to make coke. It is a brown or black liquid of extremely high viscosity which smells of naphthalene and aromatic hydrocarbons. Coal tars are complex and variable mixtures of phenols, polycyclic aromatic hydrocarbons (PAHs) and heterocyclic compounds.
• Coal tar pavement sealant - Coal tar sealants are surface finishes for parking lots, driveways, and airports used both commercially and by homeowners across the country. They are usually not applied to public streets. They contain varying concentrations of coal tar depending on product and formulation. They are the black, shiny emulsion painted or sprayed on asphalt pavement in an effort to protect and beautify the asphalt. Coal tar pavement sealant is marketed as a way to extend the life of asphalt, while also restoring a rich dark color. It is also marketed as having better resistance to gasoline, motor oil, and kerosene is allegedly more durable and absorbs less water while retaining its color longer.
• Polycyclic Aromatic Hydrocarbons (PAH’s) - PAH’s are a group of chemicals formed during the incomplete burning of coal, gasoline, wood, garbage or other organic substances such as tobacco, charcoal broiled meat, and incense. As a pollutant, they are of concern because some compounds have been identified as cancer-causing. For example, one PAH compound, benzo[a]pyrene, is notable for being one of the first chemical carcinogens discovered; one of many found in cigarette smoke. PAHs are lipophilic (mix more easily with oil than water). The larger compounds are less water-soluble and less volatile (less prone to evaporate). Therefore, PAHs in the environment are found primarily in soil, sediment and oil substances, as opposed to water or air. However, they can be found in particulate matter suspended in air.

By removing this potent source of PAHs to our environment, we are reducing PAHs in our streams. A United States Geological Survey (USGS) study conducted in 2014 showed a 58% reduction in PAH’s in lake sediment from Lady Bird Lake.

Besides urban runoff as a pathway, PAH can originate from atmospheric fallout of particulates from naturally occurring combustion sources like forest fires or from fossil fuel combustion - incomplete burning of carbon-containing materials like oil, wood, garbage, and coal. Automobile exhaust and industrial emissions are additional sources. They contain high levels of PAHs. More PAHs form when materials burn at low temperatures such as in wood fires and cigarettes than in high-temperature furnaces.

Many useful products such as mothballs, blacktop, and creosote wood preservatives contain PAHs. They are also found at low concentrations in some special purpose skin creams and anti-dandruff shampoos that contain coal tars.

Considering Seal Coating your Parking Lot?

The following recommendations will assist you in getting a better job that lasts longer while protecting the environment

Choose the Right Applicator

• Learn about the company and their track record. Ask the applicator for references and contact the Better Business Bureau or Chamber of Commerce to see if complaints have been lodged against the contractor. Take a few hours and visit some properties that the sealant company has done. Be sure and include a site that is more than a year old.
• Always ask the applicator what warranty is offered with the product and the workmanship. Often products are given a manufacturer’s warranty that may convey to the property owner when applied correctly. Get the warranty in writing before the start of work.
• Sealants come in a variety of packages and product names. Several producers require applicators be trained to apply their product, take a few minutes and inquire as to the applicators expertise.
• Get a written contract or agreement for the work.

Choose the Right Product

• Research the sealant to be used, how long it is likely to last and how it is made. Remember that coal tar containing sealants are banned in Austin and its ETJ. Check the Material Safety Data Sheet (MSDS) for information on the sealant ingredients. The company sealing your lot should have the MSDS available
• If you have old coal tar sealant present, consider having it removed prior to re-sealing. Equipment is available in Texas which can remove sealant with a shot blasting process. It can be done if dust is controlled and the removed sealant is disposed of in the trash. This eliminates the possibility of future coal tar pollution from old degrading sealant.
• Consider using a lighter colored sealant. Lighter colored sealant will often reduce the surface temperature of the parking lot. The payoff would be cooler cars for customers and staff parked all day, as well as a reduction in the heat island effect.

Ensure a Good Application

• Be certain that the sealant is applied at a proper dilution. Sealants are produced and designed to work best when the material is properly blended with water and fortifiers. Sealants are offered in concentrated forms as well as pre-diluted. Mixing must be done as recommended for the specific product to avoid premature failure of the application.
• Ask the applicator how long sealing a parking lot and re-striping will take. Some of the alternative sealants take longer to dry than the conventional coal tar based sealants. Often freshly applied asphalt based sealants are abraded quickly by traffic if not fully cured.
• Be certain to turn off the sprinklers, postpone trash/dumpster collection service and deliveries until the sealant has cured. Dried sealant and cured sealant look the same, but they are a world apart when a car drives over it.
• The contractor should not apply sealant when rain is in the forecast. The wash-off of freshly applied sealant is the most potent form of pollution discharge from a parking lot. Report any incidents of sealant wash-off to the 24-Hour Pollution Hotline at 512-974-2550

For additional information of the recommendations provided, please call 512-974-2550.