Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

vacuum collection equipment shall be configured to maintain a ntiinimum of 3000 feet per minute air velocity in the cleaning zone.

Make -Up Air System

1. All non-porous surfaces of the outdoor air intake located on the exterior of the building shall be cleaned using manual wet-wiping and HEPA vacuuming methods as needed to remove adhered materials. Note that the air intake for the condenser compartment of the air handling unit is located adjacent to the outdoor air intake for the makeup air system and should be cleaned concurrently. 2. The section of the duct from the outdoor air intake through the blower unit shall be cleaned using HEPA vacuum methods. It may be necessary to install a service opening in order to perform this cleaning. 3. Clean blower assembly and blower housing in place by a combination of hand vacuuming, damp wiping and air washing. As required in this document, air washing shall only be performed after a vacuum collection device has been installed. 4. Seal the diffuser openings using 6-mil ethylene sheeting to be secured with duct tape. 5. The makeup air duct shall be cleaned using a pressurized air mechanical brush system in combination with a vacuum collection device. The direction of cleaning shall be from the blower assembly toward the terminal end of the duct. (It is permissible to use a mechanical brush followed by application of pressurized air in lieu of combination style equipment.) It may be necessary to install a service opening in order to perform the duct cleaning. The vacuum collection equipment shall be configured to maintain a minimum of 3000 feet per minute air velocity in the cleaning zone.

Dissembled Duct Sections on Floor

1. Transport dissembled duct sections to the enclosure constructed for cleaning of the air handling unit for wet cleaning. The dissembled duct sections should be sprayed with Simple Green or a similar environmentally safe degreaser and hand washed as needed to remove adhered materials.

11.3.2 Food Exchange Restaurant

This is a 2,324 sq ft space with 10’ high suspended acoustical ceiling on the south side and a solid gypsum drywall suspended ceiling on the north side. An older tin ceiling is present on the deck of the south side and an additional layer of gypsum is attached to the deck on the north side. Prior to the start of work, the suspended acoustical ceiling on the south side will be removed by WRS Infrastructure and Environment, Inc.

Two nearly side-by-side air handling units are located above the ceiling. These are recirculating air units with no outdoor air supply. Return air enters the ceiling plenum through passive return grilles located in the false ceiling below each unit. The air handling units draw return air fi-om the ceiling plenum through grilles in the sides of the units. The air handling units distribute supply air to supply air ducts that extend to the north and to the south of the units. The ducts are approximately 50’ long (north-south dimension). Supply air is distributed to the occupant space through supply diffusers off of the supply duct; the diffusers are flush with the false ceiling. There are supply grilles off the supply air duct that extend in a line to the north and to the south

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NYC-WTC_000145218