E-mails 2003 M. Gilsenan

NYC 9/11 Public Portal Document

24" from the spray discharge tip to the surface being treated. Encapsulant coatings may not be fogged into the system. A continuous film thickness should be achieved in treated areas, as per manufacturer's instructions. Encapsulants shall be water-based, with low VOC (volatile organic compound) emissions, and meet NFPA smoke development and flame spread requirements for ventilation system products. Encapsulant coatings shall be applied in accordance with applicable federal, state, or local regulations regarding the use of such products and MSDS copies for any encapsulant products used in the AC/ventilation system shall be available on-site.

Areas of damaged interior AC/ventilation system fan unit or duct insulation that is abraded or delaminated such that application of an encapsulant coating would be inappropriate as determined by the NADCA-certified ASCS should be removed in consultation with building management. Replacement of such insulation with an appropriate material shall be the responsibility of building management.

Procedures

1. Identify the system to be cleaned including outside air intake, fan unit, supply ducts and return ducts if appropriate.

2. Determine how the system will be segregated for cleaning; typically the fan unit will be cleaned separately from the ductwork unless the ductwork consists of very short runs on the same floor. Cleaning should start from the furthest point in the system and proceed towards the collection device.

3. Lock out and tag out the fan unit. Building management will be responsible for identify and disabling in-duct smoke detectors if present.

4. Attach a local capture, HEPA filtered. Air Filtration Device (AFD) or vacuum collection system to place the system under negative pressure. Sufficient negative pressure shall be maintained to prevent the dispersion of dust outside of the duct. Isolation/zone pillows shall be used as necessary to isolate sections of the system, so that sufficient negative pressure is maintained in each work zone.

5. Exhaust the AFD or vacuum collection system to the outdoors. If no window is available, a stairwell may be appropriate. Alternately, two AFD’s or vacuum collection systems may be connected in series so that a second unit filters the exhaust air from the first. Alternately, the cleaning contractor can have the collection equipment leak tested in-place by an independent third party to ensure that contaminants do not leak through the air cleaning device.

6. Cover all open supply air grilles, supply diffusers, and return air grilles located in the affected ductwork using fire-retardant polyethylene sheeting or bags and duct tape or preservation tape.

7. Place the air handling units and their components under containment prior to beginning work. A temporary Zip-wall containment of 6-miI, fire retardant polyethylene sheeting extending from the floor to the ceiling deck, with a flapped entrance, and maintained under negative pressure using a HEPA-filtered air filtration device is sufficient. The footprint of the containment should be large enough to accommodate a ladder or scaffolding if needed.

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