Document v1kXrEmOjwZBMberpN6Je10Mq

GRACE RECEIVED BY DEC 24 legal department CAMBRIDGE, MA Construction Products Division W..R. Grace & Co. 62 Whiltemore Avenue Cambridge, Mass. 02140 (617) 876-1400 December 19, 1985 John S. Sheahan Oakland Scavenger Company 2601 Peralta Company Oakland, CA 94607 Dear Mr. Sheahan: This is in response to your August 21, 1985 letter written to F. W. Eaton, in which you requested additional information covering asbestoscontaining dust generated at W. R. Grace's Newark Plant. Specifically, you expressed interest in the test method and results referenced in a previous correspondence (F. W. Eaton to J. S. Sheahan, 11/26/84). Between 1979-1984, W. R. Grace conducted air monitoring tests at six different locations during the transportation and disposal of waste fines and rock. At each site, the waste transporter and/or landfill compact operator was monitored for exposure to respirable fiber. The methodology that was followed is the standard test presently being used for the determination of Asbestos Fibers In Air as outlined by the National Institute for Occupational Safety and Health (NIOSH #P & CAM239)* ' Basically, the sample is collected by drawing a measured amount of air through a membrane filter by means of a personal sampling pump. A portion of the filter is placed on a glass slide and transformed from an opaque solid membrane to a transparent gel. Fibers are sized and counted, using a phase contrast microscope at 400x magnification. Exposure for each sampling period is calculated, results are averaged, and a time weighted average is determined based on hours of exposure vs. total hours worked. Individual sarnie times for the waste transporter ranged from 43-126 minutes. Exposure levels were between 0.002-0.42 fibers/cm3. Sample times for the landfill compactor operator were between 24-32 minutes and the exposure levels ranged from 0.06-0.26f/cm3. Please note, these are not time weighted averages (TWA), but the instantaneous exposures used to calculate the TWA exposures reported to you in F. W. Eaton's letter, dated 11/12/85. You will recall that the TWA exposures were calculated to be less than 0.05 fibers/cc. 15197341