Environmental assessment report, 100 Church Street, April 2002

NYC 9/11 Public Portal Document

NYCLD Space TRC performed asbestos surface dust sampling on floors 2 through 6 and 20 following cleaning activities conducted by ZAR’s cleaning contractors. Surface dust samples were collected on many surfaces within the space. Results, which are presented in Appendix A, are organized as follows: Table la Carpel Table lb - Top of Perimeter Induction Units Table Ic - Hard Surfaces Table Id - Soft Goods Table le - Computer/Copier Equipment Table If-Boxed Items Table Ig -Field Blanks A total of one hundred and nineteen (119) samples were collected and analyzed for asbestos in surface dust via ASTM 5755 microvacumn method. A post cleaning target concentration of less than 10,000 structures per square centimeter (str/cm^) for all samples and a geometric mean concentration of less than 1,000 str/cm^ for each data set was established. In calculating the geometric mean, one-half of the sample detection limit was used in the calculation for samples found to be below the analytical detection limit.

Carpet results indicated that three (3) of the ten (10) samples collected were in excess of the post cleaning target concentrations. The carpet has since been removed and replaced with new carpeting.

Results of sampling the tops of the perimeter induction units indicated that one (1) of the seven (7) samples was in excess of the post cleaning target and the geometric mean was slightly higher than the 1,000 target geometric mean. These areas have since been re-cleaned and all induction units have been painted.

TRC sampled hard surfaced items such as desks, bookshelves, file cabinets, floors. None of the twelve (12) surface samples exceeded the post cleaning target concentration. Nine (9) of the twelve (12) samples were less than the analytical detection limit. Although results indicated no action was required, all furniture was re-cleaned twice, once according to a defined wet-wipe

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