Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

Study

Common Areas Vestibule, Elevator, Stairwells, Hallways, Utility Rooms, Trash Chute Accesses and Laundry Room.

Cleaning Method: Test 4A, 4B - Surface cleaning using industrial filtered vacuums. Air filtration utilizing an air filtration device (AFD). Soap and water wet wipe of all horizontal and vertical surfaces. Equipment Used: Nilfisk™ Vacuum (CFM 127), AFD. Filtration Status: HEPA Unit Size: Four Levels Total: 2,556 sq. ft.; 30,492 cu. ft. Hallways (per level) 639 sq. ft.; 7,623 cu. ft. Vestibule 150 sq. ft.; 1,500 cu. ft. Elevator Compartment 48 sq. ft.; 384 cu. ft. Laundry Room (Included as hallway) Utility Rooms (Included as hallway)

AFD Status: Required AFD Specifications: 400/600 cfm Unit Air Exchange Rate: 19.5 min at 400 cfin (hallway) Minimum Air Exchange Required: Every 30 minutes

Description: The vestibule is located on Cedar Street and provides access to the building’s only elevator and one stairwell. A second stairwell is accessed from Liberty Street. Four hallways connect the two stairwells and elevator access point on each floor (2"** floor to 5* floor). Each hallway contains a utility room with a trash chute access. The laundry room is located off of the 2*^ floor hallway. The common areas contain no porous building material. All walls and ceilings in the stairwells are painted. Carpeting is not present in any of the common areas. Minimal dust was observed in the common areas.

Difficult Areas Encountered: • The common areas were used daily by all individuals working in the building. These areas were frequently damp mopped to control the migration of dust. • Dust accumulations were heavy at the base of the walls where the baseboard trims were removed. • Hallway walls were vacuumed, but not wet wiped as a result of wallpaper paste residue left when the wallpaper was removed prior to the pilot study.

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NYC-WTC_000145190