A final asbestos remediation plan for Libby and Troy calls for the cleanup of several hundred remaining properties over the next two to three years, the U.S. Environmental Protection Agency said Monday.

The final plan — officially called a record of decision — will continue the cleanup work the EPA has been conducting for 15 years in Libby and Troy in the wake of widespread asbestos contamination from the former W.R. Grace & Co. vermiculite mine near Libby.

The federal agency will continue to replace contaminated soil with clean soil and remove and dispose of accessible contaminated building materials at remaining properties.

Since 2002, when the Libby area was deemed a Superfund site and placed on EPA’s National Priorities List, the EPA has investigated more than 7,100 properties and has cleaned 2,275, at a cost of just over $500 million.

The total cost includes not only the cleanup but also the investigation, scientific studies, “the whole works,” EPA Remedial Project Manager Mike Cirian said.

The federal agency and state Department of Environmental Quality will work with community members to put in place “a robust plan for institutional controls to make sure the remedy remains protective,” the EPA advised in a press release.

A long-term plan to manage any asbestos that might be encountered following cleanup is part of the final remedial plan.

As part of Grace’s $250 million settlement approved in 2008 for Libby asbestos cleanup, $11 million was put into a state-controlled operation and maintenance fund that can’t be tapped until 2017.

“That was a guarantee for any unforeseen site conditions for homes that have already been cleaned,” Cirian said.

Examples of such unforeseen contamination would include excavation that turns up asbestos-laden soil or if a building collapses and sealed-off asbestos is exposed.

Cirian said the agency has about 300 sites left to clean in the Libby area.

“We’ll try to get 150 done this year, and we plan to start earlier, around April 1,” he said. “We’ll try to make it a long season.”

One of the remaining challenges is getting access to roughly 700 properties for which property owners have either declined or deferred the federal government’s offer to clean their homes.

LeRoy Thom, a member of the Libby Technical Assistance Group that has been watchdogging the cleanup, said any uncleaned properties pose a problem after the EPA has wrapped up its work.

“It’s a real Catch 22,” Thom said. “The EPA has tried to tell people to get [the cleanup] done, but if they don’t and that land [or building] becomes available for sale, then someone else has to incur that cost.

“In the very beginning there was an understanding they [the EPA] would do the cleanup, whatever needed to be done,” Thom said. “Gov. Martz made the EPA promise to a complete cleanup ... now they’re leaving several hundred not cleaned.”

Nick Raines, manager of Lincoln County’s Asbestos Resource Program, said he hopes the record of decision, combined with information provided in recent studies, will encourage some of the property owners who previously have declined access to their home to reconsider.

“Many wanted to wait until the final decision to see what was necessary,” Raines said. “We’ve encouraged the EPA to be very clear about the drawbacks of not participating and what liabilities they face if they opt not to participate.”

Raines said there’s still some concern among community residents about what Libby’s future will look like without the EPA there, “what institutional controls look like and what support will be left in place.

“Overall we’re pretty excited to see the record of decision finalized and signed,” Raines said. “It’s a milestone, a huge step forward in having an answer in what the final cleanup will be.”

EPA officials have been working toward a final record of decision for some time. Among the crucial components needed to complete the process were a long-awaited toxicity report and health risk assessment that essentially determined it is possible to live and work in Libby and Troy without excessive exposure to asbestos.

The risk assessment, released in November 2015, confirmed that cleanup to date has been protective, and that the EPA doesn’t need to return to properties that have been cleaned.

A record of decision is still pending for the vermiculite mine site.

Features editor Lynnette Hintze may be reached at 758-4421 or by email at lhintze@dailyinterlake.com.