Preliminary scope of work document for cleaning 114 Liberty Street,

NYC 9/11 Public Portal Document

December 17, 2002 114 LIBERTY STREET REMOVAL OF DUST. DEBRIS, AND CONTAMINATED MATERIALS feet of floor space over 25,000 square feet, plus appropriate blanks, shall be collected both inside and outside each work area and analyzed for Asbestos.

2. Clearance air sampling shall be performed utilizing aggressive methods as described below:

a. Before starting the pumps, the exhaust of forced-air equipment shall be directed against all walls, ceilings, floors, ledges and other surfaces in the work area. This pre-sampling agitation shall continue for at least five minutes per 1,000 square feet of floor space.

b. At least one 20-inch (minimum sized) fan shall be placed in the work space and operated at slow speed while pointing towards the ceiling. A minimum of one fan per 10,000 cubic feet of room space shall be used.

3. Clearance wipe sampling shall not commence until at least one hour after the completion of the air sampling and the removal of the fans from the work area.

C. Post-abatement clearance wipe sampling shall include the following number of samples:

1. At least one wipe sample for every 10,000 square feet of floor space, with a minimum of three (3) samples, plus appropriate blanks, shall be collected in each work area and be analyzed for both Dioxins/Furans and for the previously listed metals.

D. Monitoring requirements and procedures are as follows:

1. The sampling zone for indoor air samples shall be representative of the building occupants' breathing zone.

2. If possible, outdoor ambient and baseline samplers should be placed about 6 feet above the ground surface in reasonable proximity to the building and away from obstructions and drafts that may unduly affect airflow.

3. Air sampling equipment shall not be placed in comers of rooms or near obstructions such as furniture.

4. Samples shall have a chain of custody record.

E. Work Area Clearance

1. Acceptance Air Clearance Criteria: Decontamination of the work site meets the requirements of this test when the following airborne concentrations are achieved:

Parameter Clearance Level Note Asbestos - 70 s/mm^ As set forth in the AHERA standard

2. Acceptable Surface Clearance Criteria: Decontamination of the work site meets the requirements of this test when the following surface concentrations are achieved:

24 © AMBIENT GROUP, INC.-2002 AIR AND WIPE SAMPLING

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