Asbestos removal evaluation lab report, schools

NYC 9/11 Public Portal Document i ERDPUEES wnalyst zed NYC-WTC_000144622 APPENDIX 4 NOSTR = Number of asbestos structures counted in the analysis EFA = Effective filter arca of the final sampling Alter in square milll- meters GO = Number of grid openings analyzed GOA = Average area of one TEM grid opening in square millimeters SPL = Amount of carpet area sampied (in square feet or square centi- meters) 143 V = Volume of sample filter DATA ON PRECISION AND PERCENT RECOVERY Seodics on the precision and level of asbestos of the bulk-carpet piece ultrasonic shaking (sonication) technique and the nique were perfonned as part of the 1988 EPA snudy. Six samples were collected using cach method from carpei anificlally contaminated with oy | ution (1 x 1) asbestos structures per square fot (s/f or 1.08 x 10° ste’cm? The artificial contamination was sccomplished by Spraying a known area of a carpet with a water solution of known asbestos concentration. Because there was no independent way t measure the concentration of asbestos on the carpet, no accuracy determination could be made. However, the relative efficiency of recover of one method to the other could be assessed. The mean asbestos recovery re micro: vacuuming technique was 2.3 x 10’ s/ft* (2.5 x 10° sém®). jinis was approximately see which wae 19 0 Ie ht Be nea extraction technique which was 7.9 x 10° 85 x 10° sf ie a The calculated coefficient of variation (CV) for the microvacuum technique was 166%. The CV for the bulk-carpet sonication procedure was 43%. It should be noted that the values given in reference 2 for structures per square foot are the correct vatues.!! There was an English/metric conversion error in the article which provided Incorrect values for structures per square meter throughout the paper. A similar set of tests using “real world” carpeting that had been contami- nated over a 15-year period of normal use has been performed by the authors® laboratories. The carpet sampics were collected from a cafeteria in the Social Security Administration in Balilmore, Maryland. The cafeteria had an acoustical plaster celling containing 1 to $% chrysoille. All furnish-