(CN) – The U.S. Environmental Protection Agency is considering adding subsurface intrusion to the method it uses to identify hazardous waste sites eligible for federally funded long-term cleanup.
The EPA published its proposed rule on Feb. 22 in the Federal Register.
Subsurface intrusion – most commonly vapor intrusion – is the migration of hazardous substances, pollutants or contaminants from contaminated groundwater or soil into an overlying building, similar to the way radon gas seeps into homes.
According to the EPA: “Dry cleaning solvents and industrial de-greasers are products that contain hazardous substances that, when released to the environment, can migrate into the soil and subsurface environment, enter buildings by seeping through cracks in easements, foundations, sewer lines and other openings and ultimately result in human exposure.”
Exposure can raise the lifetime risk of cancer or chronic disease.
Tetrachloroethylene or perchloroethylene, commonly used in dry cleaning, has been classified as a likely carcinogen by the National Academy of Sciences. Numerous lawsuits have been filed due to water contamination from dry cleaners.
“Vapor intrusion is a particular concern because concentrations of vapors can rise to a point where the health of residents or workers in those buildings could be at risk. Intrusion of contaminants in a non-vapor state may also be a pathway of concern because of the potential for human exposure to the liquids, the resulting precipitates, or associated vapors,” the EPA said.
To ensure that such contamination is consistently evaluated, the EPA wants to add a subsurface intrusion component to the Superfund Hazard Ranking System.
Sites that receive scores above a specific threshold will be eligible for addition to the National Priorities List. The EPA targets sites on this list for investigation and remediation through the Superfund program; only on the list are eligible for federal funding for long-term permanent cleanup.
Such listing is required for the EPA to spend more than $2 million on remediation. By adding subsurface intrusion, hundreds of sites that would not have previously ranked high enough to qualify for a spot on the list now may qualify.
The 60-day public comment period began on Feb. 23.