A removal site evaluation has been conducted at the Site by EPA in response to an agency wide initiative to investigate vermiculite facilities that received vermiculite ore from the W.R. Grace vermiculite mine in Libby, Montana. The Site, also referenced as the “GAO 144 site” was the former location of a vermiculite expansion (or, exfoliation) plant. The expansion plant operated from 1950 until 1970 and between 499 and 1,225 tons of vermiculite concentrate from the W.R. Grace vermiculite mine in Libby, Montana was believed to have been shipped to the GAO 144 site.
Historical aerial photographs indicate that demolition of most the facility buildings was conducted in phases beginning sometime between 1960 and 1968 and ending sometime between 1988 and 1993. While some of the Site is paved, much of the remaining portion of the Site is either sparsely vegetated or heavily wooded.
During the Spring of 2010 (March 24, 25, and 30; and April 15) EPA and EPA’s contractor conducted activity-based air sampling (ABS) and bulk material sampling at the Site. The objective of the field effort was to evaluate potential human exposure risk from disturbance of materials potentially contaminated with asbestos.
Of the four ABS events, three rounds did not yield detectable concentrations of asbestos in the air samples collected. The only detection of asbestos in any ABS air sample – at the detection limit of the analytical technique – was for an air sample associated with ABS Round 1, collected in the area that appeared somewhat elevated above the surrounding terrain (the “plateau” area).
The preliminary analytical results for all bulk samples indicated either non-detect or trace (present but below levels that can be quantified) quantities of asbestos, except for two samples that reported low percentage levels of Libby amphibole asbestos (0.5 percent and 0.75 percent). These samples were also collected in the plateau area.
A Site visit was conducted on October 20, 2010 with members of EPA’s national Asbestos Technical Review Workgroup in attendance. The group included members from EPA Region 8 familiar with Libby, MT vermiculite, members of the Environmental Response Team (ERT) familiar with sampling efforts at sites that received vermiculite from Libby, and On-Scene Coordinators (OSCs) from other Regions that are familiar with the investigation of the Libby “sister sites.” The draft data, historical information, and known current Site uses were presented to the team. Included in the input provided by the visiting group was a recommendation to conduct visual confirmation of the presence/absence of vermiculite below land surface in the soil plateau and surrounding areas.
On November 12, 2010, EPA OSC Stilman, EPA Toxicologist Fredericks and START conducted a Site visit to further investigate the plateau area within what is believed to be the former location of the vermiculite expansion buildings and processing and storage facilities; uneven mounds and concrete debris are also located in this area. The purpose of the Site visit was to excavate small test pits into the plateau and other areas on the Site to visually confirm the presence/absence of vermiculite beneath the ground surface. Test holes were excavated in several areas of the plateau and selected other areas of the Site. In the plateau area test holes, EPA visually identified vermiculite at depths ranging from less than 6 inches below ground surface (bgs) to somewhat deeper than 12 inches bgs. EPA did not observe vermiculite in any of the test excavations on other areas of the site. Based on these findings, EPA determined that vermiculite appears to be present below the elevated land surface in the plateau area. The area where vermiculite is present is roughly estimated to occur in a zone about 175 feet wide by 250 feet long. The height of the plateau appears to area range from between about 0 feet to 6 feet above natural grade.
In a follow-up sampling investigation, EPA and W. R. Grace collected additional samples of the plateau on December 6, 2010. The results of the sampling confirmed Libby amphibole asbestos within the plateau. Soil samples collected in the subsurface of the plateau were found to have concentrations ranging from "no asbestos found to 2% tremolite. Asbestos was identified in each of the bulk samples of vermiculite from <1% to 2% tremolite.
In March 2011, EPA completed a removal site evaluation determining the Site meets the criteria for removal eligibility.
In April 2011, EPA signed an action memorandum establishing the site presents a health risk.
In May 2011, the US Bankruptcy Court approved an agreement between EPA and W.R. Grace for conduct of a removal action at the Site.
In October 2011 all work plans were approved. On October 31, 2011, contractors mobilized on site and began removal operations.
By April 27, 2012 all Site clean-up activities were completed, including submittal of a final report.
No further action is anticipated by EPA.
