NYC-WTC_000197422

NYC 9/11 Public Portal Document

600 West Cummings Park, Suite 6500 Woburn, Massachusetts 01801-6350 www.atc-enviro.com 781.932.9400 Fax 781.932.6211 ASSOCIATES INC.

July 1,2002

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 Samples for Dioxin High School of Economics and Finance (M833) ATC Project No. 15-19125-0291

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 dibenzofrirans (PCDFs) collected on May 25, 2002, at the referenced location. The New York City Board of Education (BOE) requested these samples to evaluate possible contamination in the school building.

SCOPE OF WORK

Wagdi Abdelshahid, Industrial Hygienist of ATC’s New York City office, collected the samples 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.

The sampling was performed 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 dates the samples were collected.

WIPE SAMPLING^ESIJIJ^S

ATC submitted three (3) wipe samples for PCDDs/PCDFs to Pace for analysis. A copy of the laboratory report is provided in the Attachment. Samples were taken from surfaces throughout the building. The area of each sample was one square meter (1 m2).

Each 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. The sample locations and concentrations are shown in the table.

CITY_21MC100_003029250

NYC-WTC_000197422