In addition, Class I asbestos work shall be performed using one or more of the following control methods pursuant to the limitations stated below:
Negative Pressure Enclosure (NPE) systems: NPE systems may be used where the configuration of the work area does not make the erection of the enclosure infeasible, with the following specifications and work practices.
The negative pressure enclosure (NPE) may be of any configuration,
At least 4 air changes per hour shall be maintained in the NPE,
A minimum of -0.02 column inches of water pressure differential, relative to outside pressure, shall be maintained within the NPE as evidenced by manometric measurements,
The NPE shall be kept under negative pressure throughout the period of its use, and
Air movement shall be directed away from employees performing asbestos work within the enclosure, and toward a HEPA filtration or a collection device.
Before beginning work within the enclosure and at the beginning of each shift, the NPE shall be inspected for breaches and smoke-tested for leaks, and any leaks sealed.
Electrical circuits in the enclosure shall be deactivated, unless equipped with ground-fault circuit interrupters.
Negative pressure glove bag systems may be used to remove ACM or PACM from piping.
In addition to specifications for glove bag systems above, negative pressure glove bag systems shall attach HEPA vacuum systems or other devices to bag to prevent collapse during removal.
The employer shall comply with the work practices for glove bag systems in paragraph (g)(5)(ii)(B)(4) of this section.
The HEPA vacuum cleaner or other device used to prevent collapse of bag during removal shall run continually during the operation until it is completed at which time the bag shall be collapsed prior to removal of the bag from the pipe.
Where a separate waste bag is used along with a collection bag and discarded after one use, the collection bag may be reused if rinsed clean with amended water before reuse.
Negative pressure glove boxes may be used to remove ACM or PACM from pipe runs with the following specifications and work practices.
Glove boxes shall be constructed with rigid sides and made from metal or other material which can withstand the weight of the ACM and PACM and water used during removal:
A negative pressure generator shall be used to create negative pressure in the system:
An air filtration unit shall be attached to the box:
The box shall be fitted with gloved apertures:
An aperture at the base of the box shall serve as a bagging outlet for waste ACM and water:
A back-up generator shall be present on site:
Waste bags shall consist of 6 mil thick plastic double-bagged before they are filled or plastic thicker than 6 mil.
At least two persons shall perform the removal:
The box shall be smoke-tested for leaks and any leaks sealed prior to each use:
Loose or damaged ACM adjacent to the box shall be wrapped and sealed in two layers of 6 mil plastic prior to the job, or otherwise made intact prior to the job.
A HEPA filtration system shall be used to maintain pressure barrier in box.
A water spray process system may be used for removal of ACM and PACM from cold line piping if, employees carrying out such process have completed a 40-hour separate training course in its use, in addition to training required for employees performing Class I work. The system shall meet the following specifications and shall be performed by employees using the following work practices.
Piping shall be surrounded on 3 sides by rigid framing,
A 360 degree water spray, delivered through nozzles supplied by a high pressure separate water line, shall be formed around the piping.
The spray shall collide to form a fine aerosol which provides a liquid barrier between workers and the ACM and PACM.
The system shall be run for at least 10 minutes before removal begins.
All removal shall take place within the water barrier.
The system shall be operated by at least three persons, one of whom shall not perform removal, but shall check equipment, and ensure proper operation of the system.
After removal, the ACM and PACM shall be bagged while still inside the water barrier.
A small walk-in enclosure which accommodates no more than two persons (mini-enclosure) may be used if the disturbance or removal can be completely contained by the enclosure with the following specifications and work practices.
The fabricated or job-made enclosure shall be constructed of 6 mil plastic or equivalent:
The enclosure shall be placed under negative pressure by means of a HEPA filtered vacuum or similar ventilation unit:
Before use, the mini-enclosure shall be inspected for leaks and smoke-tested to detect breaches, and breaches sealed.
Before reuse, the interior shall be completely washed with amended water and HEPA-vacuumed.
During use, air movement shall be directed away from the employee's breathing zone within the mini-enclosure.
Glove bag systems may be used to remove PACM and/or ACM from straight runs of piping and elbows and other connections with the following specifications and work practices:
Glovebags shall be made of 6 mil thick plastic and shall be seamless at the bottom.
Glovebags used on elbows and other connections must be designed for that purpose and used without modifications.
Each glovebag shall be installed so that it completely covers the circumference of pipe or other structure where the work is to be done.
Glovebags shall be smoke-tested for leaks and any leaks sealed prior to use.
Glovebags may be used only once and may not be moved.
Glovebags shall not be used on surfaces whose temperature exceeds 150 deg. F.
Prior to disposal, glovebags shall be collapsed by removing air within them using a HEPA vacuum.
Before beginning the operation, loose and friable material adjacent to the glovebag/box operation shall be wrapped and sealed in two layers of six mil plastic or otherwise rendered intact,
Where system uses attached waste bag, such bag shall be connected to collection bag using hose or other material which shall withstand pressure of ACM waste and water without losing its integrity:
Sliding valve or other device shall separate waste bag from hose to ensure no exposure when waste bag is disconnected:
At least two persons shall perform Class I glovebag removal operations.