Zonolite Company/W.R. Grace, 12340 Conway Road, Beltsville (Muirkirk), Maryland
Table of Contents || Return to Map || Return to State Listing

EPA
Region		 Location of facility Type of facility Amount
of ore
received
(in tons)		 Did
EPA
visit
the
site?		 Were
samples
taken?		 Results of
evaluation
3 12340 Conway Road, Beltsville (Muirkirk), Maryland Former exfoliation facility 93,100.2 Yes-March 31, 2000 Yes According to an EPA database compiled from W.R. Grace shipping invoices, 93,100.2 tons of Libby ore were shipped to this site between January 1966 and November 1988. The W.R. Grace records identified this facility alternately as being located in the cities of Baltimore and Muirkirk, Maryland. This facility was listed as a vermiculite exfoliation plant in reports issued by the U.S. Geological Survey in 1970, 1975, 1980, 1985, and 1990. It was determined that Zonolite Company/W.R. Grace operated an exfoliation facility at this site from approximately 1966 through the early 1990s. W.R. Grace continued manufacturing gypsum and cement at the site until 1998. In addition to receiving vermiculite ore from the Libby mine, this facility also received ore from a W.R. Grace mine located in Enoree, South Carolina (the Enoree mine is listed separately in this database). The Baltimore site was located within an industrial park, encompassed approximately 1.74 acres, and included an L-shaped corrugated metal building where exfoliation processes had occurred. The nearest residences were located approximately 1/2 mile south and southwest of the site. The furnaces, equipment, and silos from the exfoliation processes were removed by W.R. Grace before it vacated the property. No documentation was found indicating that the site was cleaned at that time although, according to W.R. Grace, such facilities would have been cleaned up before they were resold or before the lease was terminated. Cleanup activities could have included power washing, sweeping, and HEPA vacuuming. Usually, air samples were collected after a facility was cleaned to verify the absence of airborne asbestos fibers. Vermiculite was delivered to the site via rail, and then fed into six silos by a belt conveyer for storage. A belt conveyer would then feed the vermiculite into furnaces located within the building. The furnaces heated the ore until it expanded or "exfoliated." Exfoliated vermiculite from this facility was used for attic insulation, lightweight aggregates, agriculture products, and Monokote--a fireproofing material. At the time of EPA's visit, the site was being leased by a bus maintenance and storage company. The majority of the property was covered by gravel or asphalt parking lots. EPA collected samples on two separate occasions. In September 2000, four bulk samples were collected, two from inside the former exfoliation building and two from soils outside the building. The two samples from inside the building contained less than 1-percent asbestos and the two outdoor samples did not contain detectable levels of asbestos. These samples were analyzed using polarized light microscopy (PLM). In May 2002, EPA collected eight bulk, dust, or soil samples. One sample was collected from inside the former exfoliation building and seven were collected outdoors from various locations at the site. One of the samples contained less than 1-percent asbestos, as analyzed using PLM. The other seven samples did not contain any detectable levels of asbestos. Asbestos structures were found in two samples that were analyzed using transmission electron microscopy (TEM). In addition, an air sample was collected from inside the building and this sample did not contain detectable levels of asbestos. This sample was analyzed using TEM. On the basis of this information and the results of a health investigation by the Agency for Toxic Substances and Disease Registry (ATSDR), EPA decided no further action was necessary. The ATSDR health report for this site found, overall, that conditions at the site did not pose a threat to current workers at the site. This report pointed out that although an isolated area inside the former exfoliation building contained trace levels (less than 1-percent) of asbestos, that area was used to store extra materials and was isolated by two walls; therefore, it posed no apparent health hazard. However, this report stated that future disturbances to this area could result in asbestos exposures to workers. ATSDR's health consultation report for this site can be found at ATSDR.

GAO-09-6R