WTC monitoring scope update, July 2002

NYC 9/11 Public Portal Document

fax or alternative format agreed upon and within two days ofrequest. Final air sampling shall be performed with 24 hours of final visual inspection.

14. Post Clean-up Air Sampling Procedures a. Sampling shall not begin until a visual inspection confirms the absence ofvisible dust and debris. Post cleaning air sampling shall be performed upon successful visual inspection and completed within 24 hours Within 24 hours ofwhat?. A successful visual inspection shall be an inspection that verifies the absence of dust and debris. b. All surfaces must be completely dry prior to the start of sampling. c. Window air conditioning units where applicable shall be run/operated at least 15 minutes prior to the start ofsampling. The air conditioning units shall operate continuously throughout the sampling. Why is the air conditioning unit operated after glean up when it w:asn’ t operated during samplingnriortoclean un? It should be operated during sampling priorto glean up as well, d. Upon completion ofthe cleaning, either aggressive or modified aggressive air sampling procedures will be conducted to verify attainment ofthe clean-up criteria. Aggressive or modified aggicssivc air sampling will be used for Scope A. clean-ups, based on consultation wit}iresident. Inaggressivearr monitormgs3mplmg sy tionSj before tlle sitart ofsampliugj a 1 horsepower clcctiic Icafblower will be usedto dirccit exhaust air against wall.5^ ceilings. floorS 31id other surfHCCs* directin^ the exhaust, CHXition shnll he tHken to iiiimniize disturbance und potential dsxiidge to fhniishings suid persons! belongings. The procedure described below for modified ag^r^s^sivosampling techniques will also be employed e. In modified aggressive sampling, one 20-inch fen shall be installed per 10,000 cubic feet of room space and run at low speed. The fan shall operate continuously throughout sampling and shall not be turned offuntil sampling is completed. When should this fen be turned on? f. For studio apartments 3 air samples shall be collected. For 1-bedroom apartments and above 5 air samples shall be collected. Sampling equipment shall be placed in living areas and away from obstructions. The sampling cassette must be placed on a tripod and not taped to existing surfaces. g- Common spaces will be sampled without the use of forced air devices (fans, leafblowers etch For small spaces, less than 160 square feet, 3 air samples will be collected. For large spaces greater than 160 square feet and less than 25,000 square feet 5 air samples will be collected. For spaces greater than 25,000 square feet, 1 afr sample will be collected for each 5,000 square feet. Sampling equipment shall be placed away from obstructions. The sampling cassette must be placed on a tripod directed downward at a 45 degree angle and not taped to existing surfaces. h. Air samples shall be collected in accordance with the procedures specified in NIOSH 7400 Method for PCM and 7402 for TEM. Air sampling cassettes need to be monitored to ensure pumps are not clogging by monitoring flow rates. The minimum sampling volume required is 3600 liters. i. 24-hour tum-around-time shall be specified for the analysis ofall post-cleaning air samples for Scope B cleanups. j- The contractor shall document all the necessaiy information regarding sampling activities, fill

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