Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

11.2 General Cleaning Procedures

11.2.1 Hand wet-wiping: Wiping may be performed in cases where dry cleaning methods such as HEPA vacuuming or mechanical brushing, cannot successfully remove contaminants of concern. Damp wiping should be performed with disposable towels or rags properly wetted with Simple Green or a similarly environmentally friendly degreasing agent. If disinfection is required, a Foster Products 40-80 HVAC and Wall Disinfectant or equivalent quarternary ammonium compound cleaning solution may be used.

It is not necessary to establish negative pressure in locations where wet wiping is the only cleaning performed. If possible, the components to be cleaned should be removed, placed in a 6-mil polyethylene bag, and cleaned outside of the occupant space. If removal of the components is not possible, use of a disposable drop cloth in the work area is recommended.

11.2.2 Manual HEPA vacuum with soft bristle brush attachment: Manually vacuum internal HVAC surfaces from top to bottom to remove all visible debris. Maintain the cleaning zone under negative pressure (minimum -0.02 inches water gauge) using a HEPA filtered air filtration device during manual vacuuming

11.2.3 Power driven mechanical or pneumatic brush system for duct runs: This type of equipment may only be used in ducts where negative pressure has been established using a HEPA filtered vacuum collection device (minimum of 3000 fpm air velocity in cleaning zone of the duct). Always work in the direction of the air flow. Apply the mechanical brushing equipment to dislodge debris from the interior surfaces of the duct. Following mechanical brushing, all surfaces of the cleaning zone shall be air washed with a pressurized air source to transport all dislodged debris to the vacuum collection device. Note that air washing alone is not a sufficient cleaning method and will not be considered acceptable for proper duct cleaning.

11.2.4 Chemical wet cleaning of evaporator or chilled water coils: Wet cleaning of the coils and drip pan shall be performed using commercially available coil cleaner, subject to approval of Environmental Professional. Saturate the coils with a pump sprayer and thoroughly rinse with clean water. Cleaning solution and rinse water will collect in the condensate drain pan; if significant lead or asbestos contamination has been identified in the dust on the coils and/or in the drain pan, the water must be collected and tested for proper disposal.

Maintain the cleaning zone under negative pressure using a HEPA filtered air filtration device. If odors are present and it is not possible to exhaust the HEPA filtered air filtration device outside the building, it may be necessary to use an activated carbon bed in air filtration device to eliminate odors.

11.2.5 Electric Heating and Reheat coils: Clean electric heating and reheat coils using only dry methods. No water or encapsulant may come into contact with electric heating or re-heat coils. Dry clean using one or more of the following methods:

11.2.6 Manual HEPA vacuum 11.2.7 Pressurized air cleaning (only if cleaning zone is maintained under negative pressure) 11.2.8 Manual brushing using manual HEPA vacuum to collect dust

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