Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

Maintain the cleaning zone under negative pressure using a HEPA filtered air filtration device whenever possible.

11.3 Site-specific Cleaning Procedures

11.3.1 Lemon Grass Restaurant

This is a 2,351 sq ft space with variable ceiling height. One air handling unit is located above the ceiling toward the south end of the floor. This is a recirculating air unit with no outdoor air supply. Return air enters the unit through a grille located in the side of the unit. The air handling unit is accessible and is provided with access doors. The air handling unit distributes supply air through a main supply air duct and several branch ducts. Supply air diffuser openings are located on the underside of the supply duct (most of the diffusers have been removed). The supply diffuser openings extend in a line to the north of the air handling units and are spaced approximately 15’ apart. There are approximately four 18” supply diffuser openings located to the north of the air handling unit. There is a separate ducted make-up air system that delivers outdoor air to the cooking stations. The make-up air system consists of a single duct with diffuser openings on the underside of the duct, and a blower assembly that is located in-line with the duct. Outdoor air is provided to the make-up air system through a ducted outdoor air intake located in an exterior wall of the building approximately 10’ above ground level.

VENTILATION SYSTEM COMPONENTS TO BE CLEANED

The following system components will be cleaned in the Lemon Grass Restaurant:

a. Air handling unit and components b. Reheat Coil c. Supply air ducts and terminal difiusers d. Makeup Air System e. Dissembled Duct Sections on Floor

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.

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NYC-WTC_000145216