Chain of custody form for DEP environmental samples, 2001

NYC 9/11 Public Portal Document

analyzed for asbestos only, and horizontal surfaces which were also analyzed for total dust. Generally, pre-cleaning air sampling was not conducted because of concerns that given the presence of significant levels of dust, using the aggressive technique might make overloading the filters more likely.

Pre-cleaning sampling also included the collection of micro vacuum samples from up to six porous surface areas (e.g., carpets, furniture fabric) in twelve of the thirteen residential units, and both commercial units included in the study (Mattress Store, Chiropractor’s Office). The samples were collected from a 10 cm x 10 cm area using dedicated, disposable templates which were left in place. Each unit contained a different number of porous surface sample areas, except Unit 4B which did not have any porous surfaces from which to collect a sample. The micro vacuum samples were analyzed for lead and for asbestos (TEM).

3.3 Sampling During Cleaning

All sampling conducted during cleaning activities was undertaken for the purpose of documenting potent!^ worker exposure to asbestos, lead and alpha-quartz. Samples were collected from the breathing zone (5-6 ft.) in the center of the room being cleaned. The pumps were run the entire length of the work day (no less than 8 hours) and were not stopped during breaks. As reflected in Attachment A, Personal Monitoring Data, on only one occasion during the study was the permissible exposure level exceeded for alpha-quartz.

3.4 Post-Cleanup Sampling

Post-cleaning sampling conducted was designed to determine if the cleaning methods attained the health-based benchmarks established in EPA's COPC/Benchmarks Report’^. Following cleanup activities in the thirteen residential and two commercial units, post-cleanup wipe and micro vacuum samples were collected in the same manner as the pre-cleanup samples.

The post-cleanup samples were collected from locations adjacent to the pre-cleanup sampling locations whenever possible. In situations where the pre-cleanup sampling location was now inaccessible, a new sample was collected as close to the initial location as possible. Post-cleanup air samples were collected in each of the thirteen residential units and in each of the two commercial units included in the study. The analyses for these samples included MMVF, alpha- quartz, lead, and asbestos. The building's four hallways, two stairwells, basement and elevator shaft were also included in this sampling event; however, the elevator shaft did not include alpha­ quartz analysis.

All of the aforementioned post-cleanup area air samples were collected following a minimum settling period of sixteen (16) hours and included the implementation of aggressive and/or modified-aggressive air sampling techniques. Aggressive sampling employs the use of a leaf blower followed by circulating fans, whereas the modified-aggressive sampling employs the circulating fans without the initial use of a leaf blower. Aggressive sampling was utilized because

U.S. Environmental Protection Agency. (September, 2002). World Trade Center Indoor Air Assessment: Selecting Contaminants of Concern and Setting Health-Based Benchmarks.

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