Asbestos removal evaluation lab report, schools

NYC 9/11 Public Portal Document - eee wee eee en em me "442 SETTLED ASBESTOS DUST SAMPLING AND ANALYSIS The Asbestos Hazard Emergency Response Act (AHERA) requires that all Carpet in areas of schoo! buildings in which ACM is present be cleaned with cither a high-efficiency particulate air (HEPA) filtered vacuum cleaner or a hot water cxiraction cleaner (steam cleaner). The potential for airborne asbestos fiber reentrainment during carpet cleaning activities was shown In studies in which aisbore asbestos concentrations were found to be between two and four times greater during cleaning than before the carpet cleaning activities? There are currently two methods used by the authors’ laboratories for collecting and indirectly preparing samples to evaluate the amount of asbes- tos in of on a carpet. Direct collection and direct preparation procedures such as tape lift sampling have been investigated and cannot be used effec- tively with carpeting. There are currently no standard EPA methods for assessing asbestos in carpeting. One of the methods which is used is an ultrasonic extraction procedure in which a square piece cut from a carpet is mildly sonicated in water with the surfactant to release asbestos fibers both on the surface and embedded in the carpet. This method is similar to one that has been published about how to measure asbestos fibers in clothing and fabric materials.4 The other method is a vacuuming procedure which uses a modified ais sampling cassette to vacuum a sampic of dust primarily from the surface of the carpet. The microvacuuming technique is non-destructive to the carpet. Both methods use the particic dispersion techniques developed over the years for the analysis of asbestos in drinking water”~ THE ULTRASONIC PREPARATION PROCEDURE Samples of carpet arc collected by cutting a piece (usually 10 centimeters by 10 centimeters) from the carpet with a razor blade or utility knife and placing it in a wide-mouth polyethylene jar or Ziploc” bag. In the labora- tory, Give (5) centimeter by five (5) centimeter squares of carpet are cut and placed carpet-side down in a 1,000 milliliter beaker containing 100 milll- liters of 0.1% solution of the surfactant aerosol OT or a 0.002% solution of the surfactant methyl cellulose in pasticle-free water. The beaker is placed in an ultrasonic bath for 30 minutes. The carpet piece is removed and rinsed into the beaker with 100 milliliters of particle-free water. The entire suspen- sion (200 milliliters) is dien shaken vigorously by hand to disperse the particles and then allowed to sit for two minutes to allow the denser panicles to sink and the light particles to float to the top. At this time, three mea- sured aliquots of differcnt volumes (usually one (1), ten (10) and fifty ($0) millititers) are extracted with disposable graduated pipettes 1/4 to 1/2 inch below the water surface in the beaker. The aliquot is mixed with particic- a en free wi NYC-WTC_000144619