Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

of the air handling units; these are spaced approximately 15’ apart. There are 5 supply grilles each located to the north and south of the air handling units.. The air handling unit is not provided with access doors and is diflBcult to access.

VENTILATION SYSTEM COMPONENTS TO BE CLEANED

The following system components in the Food Exchange Restaurant will be cleaned:

a. Air handling units and components b. Supply air ducts and terminal difiusers

CLEANING PROCEDURES

General; Any interior surfaces of the air handling unit or ventilation system that are porous shall be cleaned using manual HEPA vacuuming methods. After successful completion of visual inspection and verification sampling, a lockdown encapsulant shall be applied to the porous surfaces using a hand-operated sprayer or brush, using care not to coat electrical or mechanical components.

Note that if any dissembly of the air handling units is required to complete the work, the air handling unit shall be reassembled by a qualified HVAC professional after all parts are dry and are verified clean.

Note that all HEPA air filtration devices and HEPA-filtered vacuum collection devices shall be exhausted to the outdoors.

Air Handling Units

1. Ensure that the air handling unit motors are locked out and is electrically isolated, and place the air handling units and their components under containment prior to beginning work. A temporary Zip-wall containment of 6-mil, fire retardant polyethylene sheeting extending from the floor to the ceiling deck, 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. Note that WRS Infrastructure and Environment, Inc. may construct the containment prior to the start of ventilation system cleaning. 2. Clean the filter racks at the return air sides of the units by damp wiping. 3. Prior to cleaning, place polyethylene sheeting underneath the coils. Wet clean the upstream and downstream sides of cooling coils. Apply manufacturer-approved cleaning solution to the coils using low pressure methods (i.e., airless sprayer, hand operated pump). 4. Clean the blower assembly and blower housing in place. The blower assembly and blower housing shall be cleaned 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. 5. HEPA vacuum remaining interior surfaces and components to remove all visible debris. No encapsulant materials may be used inside the condenser compartment.

15

NYC-WTC_000145219