114 LIBERTY 2 OF 2

NYC 9/11 Public Portal Document

December 17, 2002 114 LIBERTY STREET REMOVAL OF DUST, DEBRIS, AND CONTAMINATED MATERIALS

"RAM AIR 2M" as manufactured by Aramsco of Thorofare, NJ, or "Environmental Ltd., 300" as manufactured by Torchcross Agency Environmental, Hagerstown, MD or approved equal.

PART 3- EXECUTION

3.01 PRESSURE DIFFERENTIAL ISOLATION:

A. The Contractor shall coordinate this item with the Building Owner at the commencement of work.

B. In all areas, an alternate ventilation system must be installed. Portable Air Filtration Devices, capable of moving large quantities of air through a HEPA (High Efficiency Particulate Air filter capable of 99.97% efficiency at 0.3 microns) are to be installed. Each unit shall be serviced by a dedicated minimum 115V-20A circuit with ground fault circuit interrupter(GFCI)supplied from temporary power supply installed under requirements of Section 06, Temporary Facilities. Do not use existing branch circuits to power fan units.

C. Provide brand new AFDs, or provide on-site certificate of the HEPA filters. Certify that the AFDs have been tested via the DOP smoke challenge procedure and shall conform to GSA's Federal Standard 209B; ANSI N101.1; and MIL-F 51068E, as published by the US Army.

D. The Contractor shall size each zone area, provide the number of AFDs to guarantee no less than four (4) complete air changes per hour during contaminated dust and debris removal and clean-up.

1. Portable AFD use and positioning shall conform to ANSI Z9.2 and is to be coordinated with Ambient Group, Inc.

2. The Contractor shall provide a minimum of one (1) additional AFD unit for each Work Area as a back-up.

E. Locate fan unit(s) so that makeup air enters the Work Area primarily through decontamination facilities and traverses the Work Area as much as possible. This may be accomplished by position the HEPA filtered fan unit(s) at a maximum distance from the worker access opening or other makeup air sources.

F. Vent HEPA filtered fan units to outside of building so that:

1. At no time shall the negative pressure ventilation units exhaust within 40 feet of a receptor, or adversely affect the air intake ports, louvers, or entrances for the building or adjacent buildings.

2. Heavy duty ducting or equivalent, or larger, shape and dimension as that of the negative pressure ventilation exhaust port shall be used to exhaust to the outside of the structure.

3. All ducting shall be sealed and braced or supported to maintain airtight joints.

G. Should it not be feasible for the Contractor to exhaust to the building exterior, the following alternative is possible:

1. Vent each HEPA filtered fan unit to inlet of second unit, compatible with the primary 36 © AMBIENT GROUP, INC. -2002 PRESSURE DIFFERENTIAL & AIR FILTRATION SYSTEM

NYC-WTC 000155688