NYC-WTC_000196874

NYC 9/11 Public Portal Document

LEAD-IN-DUST SAMPLING

Lead-in-dust threshold levels The New York City Health Code, part 173.14 and the Federal Departments of Housing and Urban Development (HUD) and Environmental Protection Agency (EPA) have established acceptable lead-in-dust levels for re-occupancy after a lead abatement has occurred (commonly referred to as “final clearance” levels). As stated in the Code, final clearance after abatement has taken place is achieved when dust wipe samples indicate lead levels below those listed below:

For Window sills: 250 pg'fV For Floors: 40 pg/ft^ For Exterior Concrete or Rough Surfaces: 800 pg/ft^

Although the lead-in-dust samples collected at P.S. 89M were not collected in response to lead abatement, the same thresholds are used since no other regulations or standards are applicable to this project.

Sampling Methodology ATC provided all laboratory analytical services in support of this limited inspection. ATC is certified by the New York State Department of Health’s Environmental Laboratory Accreditation Program to perform lead and related analyses of environmental samples (Laboratory ID Number: 10879). The laboratory utilizes the United States Environmental Protection Agency analysis method number SW846-7420 and the National Institute of Occupational Safety and Health method number 7082M.

The lead-in-dust samples were obtained by gently wiping a pre-measured surface area with non-alcohol moistened towelettes. ATC’s representative wore disposable gloves; a new glove was worn with each new sampling procedure, and care was taken to avoid contamination of the towelette and collection vial, Towelettes were then placed into 50ml plastic vials and immediately sealed. The chain of custody form was completed and documents the measurement of the area sampled.

Results of Dust Wipe Sampling Forty (40) dust wipe samples were collected from areas indicated to ATC. Laboratory analysis indicate that all dust wipe samples collected from the indicated areas contain lead on floor, window sill and exterior concrete or rough surfaces below the guideline level of 40 pg/ft^ 250 pg/ft^and 800 pg/ft^ respectively. See laboratory report and chain of custody for more details.

PS 89M <S«rc « •IOCI•! (t INC November 11, 2002

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NYC-WTC_000196876