EPA defines study area for mine site

As the Environmental Protection Agency prepares for the final phase of cleanup for most of the Libby Asbestos Superfund Site, plans are also starting to move forward with the last remaining area. Operable Unit 3, as the former W.R. Grace and Company vermiculite mine site is now known, is the last area to undergo a feasibility study and plans are in place to begin that study this summer.

The first step of the feasibility study was taken last month, when the agency sent a letter to Grace representatives outlining the boundaries of the OU3 study area. The proposed area includes a wider boundary around the mine site, included forested area thought to be contaminated due to previous mine-related activities.

“The OU3 feasibility study area delineated by the EPA, based on the multiple lines of evidence discussed above, is shown as the blue line in Figure 5,” project manager Christina Progess wrote in a letter to Grace representatives dated April 29, 2016. “This study area for the FS ecompasses areas that are impacted by LA due to mine-related activities and for which remedial actions may be needed to address these impacts. This area also includes a wildfire mitigation zone based on modeling and other information from the United States Forest Service. The wildfire mitigation zone consists of an approximate one-mile management area, based on topography and other ground features, around the forest duff area of potential concern. Mitigation measures, such as fuels management, vegetation treatments and fire suppression measures may be necessary to ensure a wildfire in OU3 could be extinguished before reaching the areas within OU3 with the highest contamination levels. The fire mitigation zone will be further refined through additional vegetation data collection, modeling and on-the-ground assessment of fire-related conditions.”

In addition to the potential contamination risk scenarios created by wildfire, the study also seeks to refine the data and risks associated with other activities in the area. Those activities include rock hounding in the disturbed area of the mine site, hiking along Rainy Creek, commercial logging in various areas in and around the mine site, firefighting operations, forest worker activities and emptying ash from wood stoves where burned firewood was derived from areas around the mine.

The goal, Progess said, is for the agency to understand as much about the various activities that take place in and around the mine site, so that proper mitigation measures can be taken to address potential exposure scenarios. In order to accomplish the goal, the agency will be gathering significant bark and duff samples from the mine site and the surrounding forested areas and creeks.

“There are a lot of uncertainties around these areas,” said OU3 project manager Christina Progess. “Which is why we need to take additional bark and duff samples this summer.”

Progess said the agency’s refined boundaries will now include some residential properties, but the changes will not impact those property owners. Even though residential properties might by physically included inside the boundaries, they will continue to be listed with the primary area, Operable Unit 4, and the inspection and remedial action protocols for those properties will not change as a result of the boundary refinement.