NYC-WTC_000199569

NYC 9/11 Public Portal Document

NYC DEP BANHazmat UhC~l«^-ZWV31 14.30 Exec nc(n.c.»> Fax:7185953744 ■ u-ii .nw... . Dec 13 '01 11:06 P.Ol

7A Ambient Air Sampling

To: Related Management Company SyfejoeS: Summary o? Ambient Air Sampling to Dat® Rq: Trlbeca Tower From: Fred Burkhardt Date: December 11,2001 J ........ ..

The following Is a brief summary of the observations. naal»time monitoring, and ambient air sampling performed al Trlbeca Tower to date. Apartment Visual inspection ATC visually inspected 409 units for accumulated dust and/or debris consistent with material that from ATC's experience emanated from the collapse of the World Trade Center Buildings. Thirty-four units were inaccessible or ths occupants refused access and were not inspected. Of the 406 units inspected, ATC did not ohserva any dust and/or debris accumulations that In ATC's opinion was consistent with widespread deposition of material that emanated from the collapse of the World Trade Center Buildings. However, ATC observed adjacent to open windows In four units, limited dust accumulations (no debris) although inconsistent with material that emanated from the collapse of the World Trade Center Buildings present nonetheless.

Ak Snmoiing vlo TEM ATC collscted a total of 60 common area and 149 residential unit samples to ascertain the presence or absence of airborne asbestos. All samples were collected and analyzed in accordance with th© AHERA Transmission Electron Microscopy (TEM) method as set forth at 40 CFR Part 763. Subpart E. Appendix A which provides resolution down to O.Sp. structure size. Of th© total 209 samples collected, a single asbestos structure was detectable on only two samplss. In the absence of a specific ambient air standard, ATC has selected as a criteria for acceptable ambient air sample sets, the AHERA re-oceupancy requirement following an asbestos abatement action of an average of less than 70 asbestos structures per square millimeter (<70 s/mm’) per sample set. This criteria has been selected because the AHERA requirement is the most stringent raoecupancy requirement available, and has been designed to be protective of children following an asbestos abatement project. Based upon analytical sample results for sll samples recording levels well below the AHERA clearance requirement, it is ATC's opinion that th© ambient air samples collected throughout the building are representative of the ambient conditions at the time of testing and that the areas tested meet en eceeptablo criterion for re-occupancy

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