The U.S. Environmental Protection Agency is giving owners of residential and commercial property in Libby and Troy a final opportunity to participate in the investigation and cleanup of Libby asbestos linked to exposure from the former W.R. Grace vermiculite mine near Libby.

The federal agency expects that less than 10 percent of remaining properties to be investigated are likely to need a cleanup.

Property owners who have not yet participated in an investigation and/or cleanup need to sign access agreements by March 31. Access agreements have been mailed to property owners and are also available at EPA’s Information Center in Libby, 108 E. Ninth St.; or call 406-293-6194.

The EPA is providing this final opportunity to ensure the protection of future residents from possible exposures, the agency said in a press release Tuesday. Property owners who do not participate could become financially responsible for future cleanup. The agency may file a notice of environmental conditions with the Lincoln County Clerk and Recorder’s Office for properties within the Superfund site that have not participated in EPA’s program. This property notice would be recorded and maintained by Lincoln County and the state of Montana to inform future owners, lenders and renters that investigation and potentially necessary cleanup work at the property has not been completed.

If necessary, outdoor property cleanups consist of removing contaminated soil and backfilling the area with clean soil. The agency works closely with property owners to help them minimize disturbance as much as possible and to return properties to pre-cleanup conditions.

Indoor cleanups involve removing vermiculite-containing insulation from accessible areas inside homes and buildings. Contaminated materials are disposed of at a county landfill. EPA installs new insulation at locations where it is removed.

EPA’s risk assessment shows that cleanups have been effective in reducing cancer and non-cancer risks in Libby and Troy. Since 1999, EPA has completed an investigation and/or cleanup at 7,500 of 8,100 private properties identified within the Superfund site. Cleanups took place at 2,447 properties. Air asbestos concentrations today are about 100,000 times lower than when the mine and processing facilities were operating. The mine closed in 1990.

It is now possible to live and work in Libby and Troy without excessive exposure to asbestos, the agency said.

For more information on the Libby site visit www.epa.gov/superfund/libby-asbestos.