NYC-WTC_000207915

NYC 9/11 Public Portal Document

104 East 25lh St., 10th Floor New York, New York 10010 www.atc-enviro.com 212.353.8280 Fax 212.353.8306 ASSOCIATES INC.

January 28, 2003

Mr. Bernard P. Orlan Director, Environmental Health & Safety New York City Board of Education 28-11 Queens Plaza North Long Island City, NY 11101 -4008

Re: Wipe Sample.s for Dioxins P. S. 150M ATC Project No. 15-19125-0289

Dear Mr. Orlan:

ATC Associates Inc. (ATC) is pleased to provide this report of the results of the wipe-samples for polychlorinated dibenzo-p-dioxins (PCDDs)and dibenzofurans (PCDFs) collected on December 24, 2002, at the referenced location. The New York City Department of Education (DOE) requested these samples to evaluate possible contamination in the school building..

Scope of Work

The samples were collected using gauze pads and hexane as a solvent. The pads and solvent were provided and samples were analyzed by Pace Analytical Services, Inc. (Pace) of Minneapolis, MN, a laboratory experienced in dioxin analysis. The analysis was performed by modified EPA Method 8290 using combined capillary column gas chromatography/high resolution mass spectrometry.

Tenzin Namgyal, Industrial Hygienist of ATC’s New York City office, collected the samples. consistent with generally accepted industrial hygiene practices. There were inherent limitations created by constraints of time, operational and work practice variability, variations in contaminant concentrations, and sampling and analytical accuracy. The results of the sampling represent conditions found on the date the samples were collected.

Results

ATC submitted one wipe sample (plus one blank) for PCDDs/PCDFs to Pace for analysis. The sample area was one square meter (1 m2). The location sampled was the Main Entrance - Lobby.

The sample was analyzed for sixteen (16) PCDD/PCDF isomers. The results for each isomer were then converted to 2, 3, 7, 8 -tetrachloro-dibenzo-p-dioxin (2, 3, 7, 8-TCDD) equivalents by multiplying by an established equivalency factor. This provides a single value (in nanograms) for the analytical results for each sample. A copy of the laboratory analysis report is attached.

CITY_21MC100_003017170

NYC-WTC_000207915