Section 855.470  Clearance Air Monitoring and Analysis

a)         Following the completion of Section 855.465, cleanup procedures, the contractor shall notify the project manager that contained areas are ready for clearance air monitoring.

b)         The project manager shall conduct a visual inspection of the contained area.  The project manager shall document the findings of the inspection.  If the project manager finds the contained area to be clean, he or she shall then arrange for the air sampling professional to sample the air in the work area and adjacent areas for airborne fiber concentrations.  The air sampling professional shall conduct clearance air monitoring as explained in this Section.

c)         Sampling shall not begin until at least 12 hours after wet cleaning has been completed.  Air sampling may not be conducted unless all surfaces in the contained area are dry.

d)         The HEPA filtered negative air pressure equipment shall be in operation in the contained area during clearance air monitoring.

e)         The air sampling procedures and analysis shall be conducted in accordance with Asbestos Hazard Emergency Response Act (AHERA) (40 CFR 763) and Section 855.170(b)(1) requirements.

f)         Air sampling equipment shall be placed randomly in the work areas, but shall not be placed in corners of rooms or near obstructions.

g)         The following aggressive sampling techniques shall be used during all clearance air monitoring:

1)         Before sampling begins, the exhaust from forced air equipment (such as a one horsepower leaf blower) shall be directed against all walls, ceilings, floors, ledges and other surfaces in the room.  This procedure requires at least five minutes per 1,000 sq. ft. of floor.

2)         20-inch fans shall be used for air circulation during the sampling procedure.  The fan exhaust shall be directed toward the ceiling.  The fans shall be operated on the lowest speed setting.  Fans shall be operated in the center of each room where sampling will take place.  At least one fan per 10,000 cubic feet of room space shall be used.

h)         The air sampling professional shall report the clearance air monitoring results in writing to the project manager.

i)          If the air sampling results indicate a concentration of airborne asbestos fibers in excess of AHERA clearance criteria (70 structures per millimeter squared), the contractor shall re-clean the contained area.  The contractor shall not be released until the contained area meets AHERA clearance criteria.