Repaving Those Parking Lots
Austin targets coal-tar sealants as polluters
Officials in Austin, Texas, are coping with water pollution they attribute to an unexpected source: parking lot sealants.
Over the past few years, tests have revealed that many of Austin's streams and ponds register high concentrations of polycyclic aromatic hydrocarbons (PAHs). A joint study conducted by Austin officials and the U.S. Geological Survey fingered runoff from coal-tar-based parking lot sealants as the primary culprit, a finding researchers say is the first of its kind. "This simply wasn't on anybody's radar screen," says Nancy McClintock, assistant director of Austin's Watershed Protection and Development Review Department.
Although some PAHs are suspected to be carcinogens, state and federal officials have determined that the levels of pollution in Austin's streams and ponds are insufficient to harm people. Instead, the PAHs primarily raise concerns for the health of aquatic life. Lab and field research shows the pollution could be adversely affecting species diversity and sensitive species.
The findings have prompted Austin officials to call for businesses and residents to voluntarily stop selling and using coal-tar sealants, while they consider regulatory action. Officials are contemplating an outright ban on coal-tar sealants, which are designed to improve the appearance of parking lots and increase the longevity of the underlying surface. "Our data to date justifies banning the coal-tar- based products, but we have more work to do in terms of data verification and looking at legal ramifications," McClintock says.
According to Barbara Mahler, the report's lead author and a research hydrologist with the U.S. Geological Survey, coal-tar sealants are widely available and are especially common in the Midwest. "It's certainly an issue that should be a concern for any community," she says.
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