Asbestos bulk sampling results letter, 19 Park Place, Mar 2002

NYC 9/11 Public Portal Document

Page 2.

Bulk Sample Collection and Asbestos Analysis Procedures; Representative bulk samples were collected by penetrating the total depth of the material with a sample container providing a core of all materials present. Representative sampling is based upon the material's physical character and distribution throughout the survey area. The sample is first determined in the laboratory to be either friable or non-friable, organically-bound (NOB), and either homogenous or heterogeneous. Sample analyses of both friable and NOB materials are performed in accordance with procedures described in the New York State Department of Health Environmental Laboratory Approval Program (NYSDOH ELAP) Certification Manual as "Polarized- Light Microscope Methods for Identifying and Quantitating Asbestos in Bulk Samples," Item No. 198.1, dated 03/01/97. If the analysis of a friable material reveals the presence of asbestos, the asbestos is quantified by type and the asbestos concentration is expressed as a percentage of the total matrix. The total amount of asbestos in the sample is also reported. If the analysis of a friable material indicates the presence of asbestos but at a concentration less than 1% of the total matrix, the result is reported as a trace for each type of asbestos found. If the analysis of a friable material does not indicate the presence of asbestos, the result is reported as no asbestos detected ("NAD"). All NOB materials are gravimetrieally reduced by ashing and acid digestion prior to .analysis. If the weight of the residue after ashing and acid digestion is less than 1% of the starting weight, then the results are reported as non-asbestos containing (i.e., less than 1% asbestos by weight). If the analysis of an NOD residue which weighs 1% or more of the starting weight reveals the presence of asbestos, the asbestos is quantified by type and the asbestos concentration is expressed as a percentage of the total matrix. The total amount of asbestos in the sample is also reported. If the analysis of an NOB material does not reveal the presence of asbestos, the results are reported as inconclusive by polarized light microscopy (neither negative nor positive for asbestos). Polarized-light microscopy is not consistently reliable in detecting asbestos in floor coverings and similar NOB materials. Before this material can be considered or treated as non-asbestos containing, confirmation must be made by quantitative transmission electron microscopy (TEM). Sample analysis of NOB materials by transmission electron microscopy is performed in accordance with procedures described in the NYSDOH ELA? Certification Manual as "Transmission Electron Microscope Method for Identifying and Quantitating Asbestos in Non-Friable Organically Bound Bulk Samples," Item No. 198.4, dated 03/01/97.

NYC-WTC 000098083