Document J35VMDp0G944681VQk4jeR2OO

J>-'cv tuDftc: Asbestos Survey CSP Telephone Co. Manholes (Alexandria, VA) Case: 48106-3 Reference: ~1752 Befl Laboratories date August 30, 1983 trorr. P. A. Huggins MH 78691 IF-110 X7927 MEMORANDUM FOR RECORD Introduction On July 27, 1983, a survey was conducted at two CSP Telephone Company manholes located in Alexandria, Virginia. The survey was requested by Mr. Calvin Deemer (Staff Manager-Safety, CSP Telephone Company) in response to employee questions regarding asbestos exposure during work in manholes situated near busy traffic intersections. Qnployees were concerned chat asbestos released from vehicle brake linings would result in significant asbestos exposure in manholes. Conclusions - No asbestos was detected in the dust samples collected at two manhole locations. - All fiber concentrations measured during this survey are below applicable Occupational Safety and Health Administration (OSHA exposure standards. - Employees should be informed of the results of this survey. Materials and Methods Air sampling and filter analysis were conducted in accordance with National Institute for Occupatioanl Safety and Health (NIOSH) methodology (NX06H P&CAM 239), "Asbestos Fibers in Air". Sampling was performed using Dupont Model P2000, Bendix Model HD 55, and MSA Model G personal sampling pumps, and 0.8 um mixed cellulose ester filters (Millipore Corporation). Pumps were operated at a flow rate of approximately 2.0 liters per minute (LPM) and calibrated before and after sampling using a Gilmont precision rotameter (No. B9165). Filter analyses was conducted by sizing and counting fibers using a phase contrast micro scope. All fibers which have a physical dimension longer than 5 micrometers (um) and a length to diameter ratio of 3 to 1 or greater, were counted. Bulk samples were collected in glass vials and analyzed by polarized light microscopy using dispersion staining techniques. Prior to analysis, bulk samples were washed with distilled water and acetone to remove soluble dirt and debris. comomvAL 2 Results Bulk samples were collected at three sites in each manhole visited. These samples included bulk dirt and dust from the manhole collars, from the surface of cable splice covers and from the bottom floor of the manhole. Analyses of these individual bulk samples by polarized light microscopy indicated there was no asbestos present. The limit of detection for this method is on the order of It. Air samples were collected at each mnahole at above ground locations as well as inside the manholes during routine ventilation procedures. Results are listed in Table 1. Discussion Airborne fiber concentrations (Table 1) measured at all sampling locations ranged from 0.006 fibers/cm3 to 0.103 fibers/cir.'. During this survey, C&P Telephone Company employees at the manhole site were instructed to test and ventilate the manhole in accordance with Bell System Practices (BSP-620-140-301) . The hightest fiber concen tration occured during the initial purging of the manhole with the blower (0.103 fibers/cm3 and 0.93 fibers/ar.3) . However, no employees occupy the manhole during this period. Air samples were collected at each manhole at above ground locations as well as inside the manholes during routine ventilation procedures. Results are listed in Table 1. Above ground fiber concentrations listed in Table 1 are as follows: 0.013 fibers/cm3, 0.018 fibers/cm3, and 0.006 fibers/cm3. These values are lower than t-hose observed in the manhole during continuous ventila tion (i.e., 0.012 fibers/cm3 to 0.062 fibers/cm3). This is an expected outcome since dust in the manhole is disturbed by the forced air blower. Since no asbestos was detected in the bulk samples, it may not be appropriate to compare airborne fiber concentrations to the OSHA exposure limits for asbestos. (Permissible exposures limit-PED 2 fibers/cm3 and action level-AL 0.1 fibers/cm3.) However, even if these standards are utilized, the fiber concentrations measured during periods in which the manhole would be occupied, are below the most stnnoent OSHA exposure limit for airborne fibers, the OSHA action level for asbestos (0.1 fibers/cm3). MH-78691-PAH-mpb Attachment As Above Copy to (see attached) Patricia Huggins 003881 2 Results Bulk samples were collected at three sites in each manhole visited. These samples included bulk dirt and dust from the manhole collars, from the surface of cable splice covers and from the bottom floor of the manhole. Analyses of these individual bulk samples by polarized light microscopy indicated there was no asbestos present. The limit of detection for this method is on the order of It. Air samples were collected at each mnahole at above ground locations as well as inside the manholes during routine ventilation procedures. Results are listed in Table 1. Discussion Airborne fiber concentrations (Table 1) measured at all sampling locations ranged from 0.006 fibers/cm3 to 0.103 fibers/cm3. During this survey, C&P Telephone Company employees at the manhole site were instructed to test and ventilate the manhole in accordance with Bell System Practices (BSP-620-140-301). The hightest fiber concen tration occured during the initial purging of the manhole with the blower (0.103 fibers/cm3 and 0.93 fibers/cm3). However, no employees occupy the manhole during this period. Air samples were collected at each manhole at above ground locations as well as inside the manholes during routine ventilation procedures. Results are listed in Table 1. Above ground fiber concentrations listed in Table 1 are as follows: 0.013 fibers/cm3, 0.018 fibers/cm3, and 0.006 fibers/cm3. These values are lower than those observed in the manhole during continuous ventila tion (i.e., 0.012 fibers/cm3 to 0.062 fibers/cm3). This is an expected outcome since dust in the manhole is disturbed by the forced air blower. Since no asbestos was detected in the bulk samples, it may not be appropriate to compare airborne fiber concentrations to the OSHA exposure limits for asbestos. (Permissible exposures limit-PEL 2 fibers/cm3 and action level-AL 0.1 fibers/cm3.) However, even if these standards are utilized, the fiber concentrations measured during periods in which the manhole would be occupied, are below the most stringent OSHA exposure limit for airborne fibers, the OSHA action level for asbestos (0.1 fibers/cm3). MH-78691-PAH-mpb Attachment As Above Copy to (see attached) 7* 1 f*\ ^ ^ t; c a '* Patricia Huggins 003882 3 Copy to C. Deemer P- M. Rich A. G. Bickelman, K. jen W. Stone, M.D. W. J. Schreibeis G. M. 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