Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

Reheat Coils

1. Note that if reheat coils are present, by dry vacuuming or air washing. No liquids may come into contact with the electric reheat coil.

Supply Air Ducts and Terminal Diffusers

1. Remove all terminal diffusers into 6-mil polyethylene bags and proceed to the enclosure constructed for cleaning of the air handling unit. Terminal diffusers shall be wet-cleaned. The diffusers should be sprayed with Simple Green or a similar environmentally safe degreaser and hand washed as needed to remove adhered materials. 2. Seal the diffuser openings using 6-mil polyethylene sheeting to be secured with duct tape. 3. Install a vacuum collection device at the terminal end of the duct section to be cleaned. If the entire duct is not cleaned as one unit, then isolate the section of the duct to be cleaned using a zoning device. 4. The supply 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 air handler 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.) The vacuum collection equipment shall be configured to maintain a minimum of 3000 feet per minute air velocity in the cleaning zone. (See Requirements Section for use of this equipment.)

11.3.3 Combustion Make-up Air Riser

The combustion make-up air riser extends from the ceiling of a second floor mechanical closet to the roof of the building.

VENTILATION SYSTEM COMPONENTS TO BE CLEANED

The following system components will be cleaned:

a. Combustion riser b. Associated vents c. Roof cap

CLEANING PROCEDURES

Note that the HEPA-filtered vacuum collection devices shall be exhausted to the outdoors.

Combustion riser, associated vents and roof cap

1. Remove all vents into 6-mil polyethylene bags and proceed to work area appropriate for cleaning the vents. The vents shall be wet-cleaned. The vents should be sprayed with Simple Green or a similar environmentally safe degreaser and hand washed as needed to remove adhered materials. 2. Seal the vent openings using 6-mil polyethylene sheeting to be secured with duct tape. 3. Install a vacuum collection device at the bottom of the riser on the second floor.

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NYC-WTC_000145220