Chain of custody for environmental assessment, Nov 2001

NYC 9/11 Public Portal Document

apartment we collected a bulk sample and sent it to the If any dust and/or debris was found in the laboratory for analysis. material present at the time we were in the If no sample could be taken due to insufficient apartment, the inspector documented this on the log.

4.2 Air Sampling Procedures Methodology. The technician ALC's licensed technicians collected air samples using TEM The samples were taken in three (3) apartments and at collected five (5) air samples on each floor. on each floor. The technician identified the locations that two separate areas in the hallways appeared to contain the most visible dust and debris to perform sampling.

pumps. Once the pumps were in The air samples were collected using high volume air sampling date. sample numbers, pump number, place the air sampling technician recorded the location, time, • flow rate, start and stop times and his initials. to prevent the vibrations of the motor The air cassette was independent of the pump motor. This is or tripod was used to hold the cassette in from affecting the fibers in the cassette. A separate stand horizontal stand. This is to insure place. The cassette was angled 45 degrees downward from the that no asbestos will drop into the cassette while sampling. required fl ow rate, noting this rate on the Using a rotameter, we calibrated each pump to the sample record. After calibrating the pumps. the end cap from the cassette was removed: the pump was turned on and run for the required amount of time.

ensure they were still operating, the cassettes The sampling pumps were checked periodically to equipment. If at any time the area being sampled were still in place, and no one has disturbed the inside the cassettes were examined for was suspected of having high fiber counts, the filter filter. "overloading", or an excessive amount of fibers and/or debris on the technician then calibrated the When the pre -determined volume of air has been collected, the the current flow rate. This rate will often be different from the sampling pump again to determine period. That difference is usually due to the • flow rate measured at the beginning of the sampling of air. clogging of the filter, thereby adding increased resistance to the flow time was recorded as well as on the Once the pre -determined volume of air has been reached, the cassette was angled upward and the cap replaced cassette. Before the pump was turned off, the placed in sealed containers, labeled with an identifying code and the end plug. The cassettes were samples were then submitted to the laboratory to be analyzed for and a sample log was kept. The custody record was prepared and accompanied the samples to the asbestos content. A chain of laboratory.

4.3. Asbestos Analysis and Methodology internal code to ensure proper, Each air sample is cross-referenced by field designation and lab consistent handling through a chain of custody. Sample preparation takes place within a HEPA any possible contamination. Air sampling was conducted at a level Filter clean bench to avoid during normal approximating the breathing zone of persons anticipated to be present in the area concentration of the area. operations. Samples collected represent the typical airborne fiber

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