NYC-WTC_000188121

NYC 9/11 Public Portal Document 10/01/01 MON 10:10 FAX 212 695 5984 Bechtel URS Greiner JV lg|UU7

• Filter Cassettes — Filter cassettes should be mailed in a cardboard box and packed with paper. Avoid using packaging peanuts or other static producing material because the static charge will draw material away and off the filter surface. This is especially true for asbestos fiber samples. Filter cassettes shall be taped over the top and bottom to keep the plugs on the end of the cassette and to prevent sample tampering prior to analysis. • Charcoal Tubes - Charcoal tubes should be mailed in a cardboard box and adequately packaged to prevent breakage during shipment. Bulk solutions must never be shipped in the same package as charcoal tubes. • Bulk Samples - Bulk samples shall be packaged in labeled containers compatible with the sample and tightly sealed to prevent leaks and spills. Keep in mind that some bulk samples may be considered as hazardous materials by the Department of Transportation and have special requirSul3nts for packaging, labeling, and method of shipment.

Data Review The Contractor will assess and interpret monitoring data and results based on standard industry practices and professional judgment. All calculations performed on raw data (e.g. time- weighted-average calculations) shall be documented and reviewed by a Certified Industrial Hygienist.

Additional Site Monitoring Requirements

Monitoring Frequency Monitoring or sampling frequency will be influenced by a number of factors including the following: • frequency of contaminant release (i.e., continuously, intermittently, one time release) • frequency of operation • number of samples required * number of different work groups requiring assessment *. number of woric shifts requiring monitorings.. 7; >

Each of these factors should be considered to determine the monitoring frequency.

When monitoring a worker’s exposure for comparison to a published exposure limit value such as the OSHA PEL’S or ACGIH TLV’s, monitoring may need to be conducted over a lull eight hour (or longer) work shift or a 10 to IS minute period of time. For extended work shifts, samples should be for the shift duration and adjusted to reflect extended work duration. For asbestos, samples will be collected for maximum 8 hours during the highest expected fiber exposure, for a period of time in order to avoid overloading filters.

In some cases, monitoring may need to be continuous if there is the potential for build-up of a dangerous atmosphere. Monitoring duration can also be affected by the duration of the operation being monitored (i.e., it may only operate one hour a day) or by the length of time a worker performs an operation. Duration can also be affected by the contaminant concentration in air. Often times, higher concentrations of air contaminants will require the collection of shorter-term samples so as to avoid overloading the sample collection device being used.

CITY_21MC100_007083337

NYC-WTC_000188126