The Vermiculte Northwest site was home to a vermiculite exfoliation plant from 1951 to 1973. The facility was operated by Vermiculite Northwest, Inc. and later by W.R. Grace and Company. Vermiculite ore from Libby, Montana was received at the Site via rail car. The vermiculite product manufactured at the Site was sold under the trade name Zonolite. Both vermiculite ore from Libby and the manufactured product Zonolite are known to contain a significant quantity of amphibole asbestos. Records show that up to 10,317 tons of vermiculite ore were processed at the Site from January 1967 to October 1970. According to a former employee, the vermiculite off-loading and manufacturing processes created significant dust at the Site. Also, asbestos contaminated by-products were created in the process (including unexpanded ore referred to as “stoner rock”). Stoner rock was piled at the Site for disposal at unknown locations.
After 1973, the Site was occupied by the Wilbert Vault Company, which manufactured concrete products. Spokane County acquired the Site property in January, 2000 and has since used it as an equipment storage and maintenance yard.
In 2000 and 2001, the EPA START contractor conducted two Site visits that included sampling and analysis. The initial visit in 2000 was to determine if asbestos existed in soils or on surfaces at the Site. Eight bulk soil and wipe samples were collected. All samples contained from trace amounts to 2% total asbestos fibers. In 2001 the START contractor was tasked to conduct a removal site evaluation at the facility. The START collected 27 soil samples, which included 14 samples taken from residential locations. Analytical results showed asbestos levels in 9 samples from the Spokane County-owned Site, including two samples with concentrations of 2% and 3% asbestos. Four of the residential area samples showed trace levels of asbestos.
In 2002, the EPA Region 10 Office of Environmental Assessment (OEA), conducted a study to determine whether asbestos present in soils at the Site could become airborne when the soil is disturbed, posing a potential exposure risk to people at the Site. The OEA study consisted of three phases: collection and analysis of bulk soil samples; air monitoring in a laboratory enclosure while soils samples from the Site were agitated, and; air monitoring on Site while activities were performed that simulated likely property maintenance or soil excavation activities. That study revealed that asbestos in soil at the Site can become airborne if the soil is disturbed.
In September 2004, Spokane County applied for and was accepted into Washington Department of Ecology’s (Ecology’s) Voluntary Cleanup Program, to conduct remediation activities at the Site. Spokane County had previously, in 2002, demolished, removed and disposed of three buildings at the Site that were formerly used as vermiculite warehouse and processing buildings. In 2006, Spokane County conducted a study (through a contractor) to identify the vertical extent of asbestos contamination is soils in the former vermiculite processing area (the southwest quadrant of the Site). The study found asbestos present in significant concentrations at depths greater than four feet. As a result of this study, Spokane County and Ecology concluded that encapsulation of asbestos contaminated soils in place, at least in the fairly level southwest quadrant of the Site where asbestos contaminated soils were deep, was a more feasible alternative than removal and disposal. In 2007, Spokane County developed a design and completed work on an asphalt and soil cap and cover over the southwest quadrant of the Site, where the former vermiculite processing and handling buildings were previously located, where the highest concentration of asbestos was found in soils, and where asbestos was found to occur at depth.
During 2009, EPA is conducting additional site investigation at both the Spokane County-owned site and the surrounding residential neighborhood to evaluate the extent and level of residual asbestos contamination in soils and whether asbestos in soils, even at low concentrations, can readily become airborne and present an inhalation hazard.
