Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-62 - General occupational health standards › Part I-1 - ASBESTOS, TREMOLITE, ANTHOPHYLLITE, AND ACTINOLITE › Section 296-62-07751 - Appendix I - Work practices and engineering controls for Class I asbestos operations - Nonmandatory

Current through Register Vol. 24-14, July 15, 2024
This is a nonmandatory appendix to the asbestos standards for
				  construction and for shipyards. It describes criteria and procedures for
				  erecting and using negative pressure enclosures for Class I Asbestos Work, when
				  NPEs are used as an allowable control method to comply with WAC
				  296-62-07712(7)(a).
				  Many small and variable details are involved in the erection of a negative
				  pressure enclosure. OSHA and most participants in the rulemaking agreed that
				  only the major, more performance oriented criteria should be made mandatory.
				  These criteria are set out in WAC
				  296-62-07712. In addition, this
				  appendix includes these mandatory specifications and procedures in its
				  guidelines in order to make this appendix coherent and helpful. The mandatory
				  nature of the criteria which appear in the regulatory text is not changed
				  because they are included in this "nonmandatory" appendix. Similarly, the
				  additional criteria and procedures included as guidelines in the appendix, do
				  not become mandatory because mandatory criteria are also included in these
				  comprehensive guidelines.
In addition, none of the criteria, both mandatory and
				  recommended, are meant to specify or imply the need for use of patented or
				  licensed methods or equipment. Recommended specifications included in this
				  attachment should not discourage the use of creative alternatives which can be
				  shown to reliably achieve the objectives of negative-pressure
				  enclosures.
Requirements included in this appendix, cover general
				  provisions to be followed in all asbestos jobs, provisions which must be
				  followed for all Class I asbestos jobs, and provisions governing the
				  construction and testing of negative pressure enclosures. The first category
				  includes the requirement for use of wet methods, HEPA vacuums, and immediate
				  bagging of waste; Class I work must conform to the following provisions:
-
Oversight by competent person
-
Use of critical barriers over all openings to work
								area
-
Isolation of HVAC systems
-
Use of impermeable dropcloths and coverage of all
								objects within regulated areas
In addition, more specific requirements for NPEs
				  include:
-
Maintenance of -0.02 inches water gauge within
								enclosure
-
Manometric measurements
-
Air movement away from employees performing removal
								work
-
Smoke testing or equivalent for detection of leaks
								and air direction
-
Deactivation of electrical circuits, if not
								provided with ground-fault circuit interrupters.
Planning the Project
The standard requires that an exposure assessment be
				  conducted before the asbestos job is begun WAC
				  296-62-07709(3).
				  Information needed for that assessment, includes data relating to prior similar
				  jobs, as applied to the specific variables of the current job. The information
				  needed to conduct the assessment will be useful in planning the project, and in
				  complying with any reporting requirements under this standard, when significant
				  changes are being made to a control system listed in the standard, (see WAC
				  296-62-07719 ), as well as those
				  of USEPA (40 C.F.R. Part 61, subpart M). Thus, although the standard does not
				  explicitly require the preparation of a written asbestos removal plan, the
				  usual constituents of such a plan, i.e., a description of the enclosure, the
				  equipment, and the procedures to be used throughout the project, must be
				  determined before the enclosure can be erected. The following information
				  should be included in the planning of the system:
A physical description of the work area;
A description of the approximate amount of material to be
				  removed;
A schedule for turning off and sealing existing ventilation
				  systems;
Personnel hygiene procedures;
A description of personal protective equipment and clothing
				  to be worn by employees;
A description of the local exhaust ventilation systems to be
				  used and how they are to be tested;
A description of work practices to be observed by
				  employees;
An air monitoring plan;
A description of the method to be used to transport waste
				  material; and
The location of the dump site.
Materials and Equipment Necessary for Asbestos Removal
Although individual asbestos removal projects vary in terms
				  of the equipment required to accomplish the removal of the materials, some
				  equipment and materials are common to most asbestos removal operations.
Plastic sheeting used to protect horizontal surfaces, seal
				  HVAC openings or to seal vertical openings and ceilings should have a minimum
				  thickness of 6 mils. Tape or other adhesive used to attach plastic sheeting
				  should be of sufficient adhesive strength to support the weight of the material
				  plus all stresses encountered during the entire duration of the project without
				  becoming detached from the surface.
Other equipment and materials which should be available at
				  the beginning of each project are:
-
HEPA Filtered Vacuum is essential for cleaning the
								work area after the asbestos has been removed. It should have a long hose
								capable of reaching out-of-the-way places, such as areas above ceiling tiles,
								behind pipes, etc.
-
Portable air ventilation systems installed to
								provide the negative air pressure and air removal from the enclosure must be
								equipped with a HEPA filter. The number and capacity of units required to
								ventilate an enclosure depend on the size of the area to be ventilated. The
								filters for these systems should be designed in such a manner that they can be
								replaced when the air flow volume is reduced by the build-up of dust in the
								filtration material. Pressure monitoring devices with alarms and strip chart
								recorders attached to each system to indicate the pressure differential and the
								loss due to dust buildup on the filter are recommended.
-
Water sprayers should be used to keep the asbestos
								material as saturated as possible during removal; the sprayers will provide a
								fine mist that minimizes the impact of the spray on the material.
-
Water used to saturate the asbestos containing
								material can be amended by adding at least 15 milliliters ( ¬ ounce) of
								wetting agent in 1 liter (1 pint) of water. An example of a wetting agent is a
								50/50 mixture of polyoxyethylene ether and polyoxyethylene polyglycol
								ester.
-
Backup power supplies are recommended, especially
								for ventilation systems.
-
Shower and bath water should be with mixed hot and
								cold water faucets. Water that has been used to clean personnel or equipment
								should either be filtered or be collected and discarded as asbestos waste. Soap
								and shampoo should be provided to aid in removing dust from the workers' skin
								and hair.
-
See WAC
								296-62-07715 and
								296-62-07717 for appropriate
								respiratory protection and protective clothing.
-
See WAC
								296-62-07721 for required signs
								and labels.
Preparing the Work Area
Disabling HVAC Systems: The power to the heating,
				  ventilation, and air conditioning systems that service the restricted area must
				  be deactivated and locked off. All ducts, grills, access ports, windows and
				  vents must be sealed off with two layers of plastic to prevent entrainment of
				  contaminated air.
Operating HVAC Systems in the Restricted Area: If components
				  of a HVAC system located in the restricted area are connected to a system that
				  will service another zone during the project, the portion of the duct in the
				  restricted area must be sealed and pressurized. Necessary precautions include
				  caulking the duct joints, covering all cracks and openings with two layers of
				  sheeting, and pressurizing the duct throughout the duration of the project by
				  restricting the return air flow. The power to the fan supplying the positive
				  pressure should be locked "on" to prevent pressure loss.
Sealing Elevators: If an elevator shaft is located in the
				  restricted area, it should be either shut down or isolated by sealing with two
				  layers of plastic sheeting. The sheeting should provide enough slack to
				  accommodate the pressure changes in the shaft without breaking the air-tight
				  seal.
Removing Mobile Objects: All movable objects should be
				  cleaned and removed from the work area before an enclosure is constructed
				  unless moving the objects creates a hazard. Mobile objects will be assumed to
				  be contaminated and should be either cleaned with amended water and a HEPA
				  vacuum and then removed from the area or wrapped and then disposed of as
				  hazardous waste.
Cleaning and Sealing Surfaces: After cleaning with water and
				  a HEPA vacuum, surfaces of stationary objects should be covered with two layers
				  of plastic sheeting. The sheeting should be secured with duct tape or an
				  equivalent method to provide a tight seal around the object.
Bagging Waste: In addition to the requirement for immediate
				  bagging of waste for disposal, it is further recommended that the waste
				  material be double-bagged and sealed in plastic bags designed for asbestos
				  disposal. The bags should be stored in a waste storage area that can be
				  controlled by the workers conducting the removal. Filters removed from air
				  handling units and rubbish removed from the area are to be bagged and handled
				  as hazardous waste.
Constructing the Enclosure
The enclosure should be constructed to provide an air-tight
				  seal around ducts and openings into existing ventilation systems and around
				  penetrations for electrical conduits, telephone wires, water lines, drain
				  pipes, etc. Enclosures should be both airtight and watertight except for those
				  openings designed to provide entry and/or air flow control.
Size: An enclosure should be the minimum volume to encompass
				  all of the working surfaces yet allow unencumbered movement by the worker(s),
				  provide unrestricted air flow past the worker(s), and ensure walking surfaces
				  can be kept free of tripping hazards.
Shape: The enclosure may be any shape that optimizes the flow
				  of ventilation air past the worker(s).
Structural Integrity: The walls, ceilings and floors must be
				  supported in such a manner that portions of the enclosure will not fall down
				  during normal use.
Openings: It is not necessary that the structure be airtight;
				  openings may be designed to direct air flow. Such openings should be located at
				  a distance from active removal operations. They should be designed to draw air
				  into the enclosure under all anticipated circumstances. In the event that
				  negative pressure is lost, they should be fitted with either HEPA filters to
				  trap dust or automatic trap doors that prevent dust from escaping the
				  enclosure. Openings for exits should be controlled by an airlock or a
				  vestibule.
Barrier Supports: Frames should be constructed to support all
				  unsupported spans of sheeting.
Sheeting: Walls, barriers, ceilings, and floors should be
				  lined with two layers of plastic sheeting having a thickness of at least 6
				  mil.
Seams: Seams in the sheeting material should be minimized to
				  reduce the possibilities of accidental rips and tears in the adhesive or
				  connections. All seams in the sheeting should overlap, be staggered and not be
				  located at corners or wall-to-floor joints.
Areas Within an Enclosure: Each enclosure consists of a work
				  area, a decontamination area, and waste storage area. The work area where the
				  asbestos removal operations occur should be separated from both the waste
				  storage area and the contamination control area by physical curtains, doors,
				  and/or airflow patterns that force any airborne contamination back into the
				  work area.
See WAC
				  296-62-07719 for requirements for
				  hygiene facilities.
During egress from the work area, each worker should step
				  into the equipment room, clean tools and equipment, and remove gross
				  contamination from clothing by wet cleaning and HEPA vacuuming. Before entering
				  the shower area, foot coverings, head coverings, hand coverings, and coveralls
				  are removed and placed in impervious bags for disposal or cleaning. Airline
				  connections from airline respirators with HEPA disconnects and power cables
				  from powered air-purifying respirators (PAPRs) will be disconnected just prior
				  to entering the shower room.
Establishing Negative Pressure Within the Enclosure
Negative Pressure: Air is to be drawn into the enclosure
				  under all anticipated conditions and exhausted through a HEPA filter for 24
				  hours a day during the entire duration of the project.
Air Flow Tests: Air flow patterns will be checked before
				  removal operations begin, at least once per operating shift and any time there
				  is a question regarding the integrity of the enclosure. The primary test for
				  air flow is to trace air currents with smoke tubes or other visual methods.
				  Flow checks are made at each opening and at each doorway to demonstrate that
				  air is being drawn into the enclosure and at each worker's position to show
				  that air is being drawn away from the breathing zone.
Monitoring Pressure Within the Enclosure: After the initial
				  air flow patterns have been checked, the static pressure must be monitored
				  within the enclosure. Monitoring may be made using manometers, pressure gauges,
				  or combinations of these devices. It is recommended that they be attached to
				  alarms and strip chart recorders at points identified by the design
				  engineer.
Corrective Actions: If the manometers or pressure gauges
				  demonstrate a reduction in pressure differential below the required level, work
				  should cease and the reason for the change investigated and appropriate changes
				  made. The air flow patterns should be retested before work begins again.
Pressure Differential: The design parameters for static
				  pressure differentials between the inside and outside of enclosures typically
				  range from 0.02 to 0.10 inches of water gauge, depending on conditions. All
				  zones inside the enclosure must have less pressure than the ambient pressure
				  outside of the enclosure (-0.02 inches water gauge differential). Design
				  specifications for the differential vary according to the size, configuration,
				  and shape of the enclosure as well as ambient and mechanical air pressure
				  conditions around the enclosure.
Air Flow Patterns: The flow of air past each worker shall be
				  enhanced by positioning the intakes and exhaust ports to remove contaminated
				  air from the worker's breathing zone, by positioning HEPA vacuum cleaners to
				  draw air from the worker's breathing zone, by forcing relatively uncontaminated
				  air past the worker toward an exhaust port, or by using a combination of
				  methods to reduce the worker's exposure.
Air Handling Unit Exhaust: The exhaust plume from air
				  handling units should be located away from adjacent personnel and intakes for
				  HVAC systems.
Air Flow Volume: The air flow volume (cubic meters per
				  minute) exhausted (removed) from the workplace must exceed the amount of makeup
				  air supplied to the enclosure. The rate of air exhausted from the enclosure
				  should be designed to maintain a negative pressure in the enclosure and air
				  movement past each worker. The volume of air flow removed from the enclosure
				  should replace the volume of the container at every five to fifteen minutes.
				  Air flow volume will need to be relatively high for large enclosures,
				  enclosures with awkward shapes, enclosures with multiple openings, and
				  operations employing several workers in the enclosure.
Air Flow Velocity: At each opening, the air flow velocity
				  must visibly "drag" air into the enclosure. The velocity of air flow within the
				  enclosure must be adequate to remove airborne contamination from each worker's
				  breathing zone without disturbing the asbestos-containing material on
				  surfaces.
Airlocks: Airlocks are mechanisms on doors and curtains that
				  control the air flow patterns in the doorways. If air flow occurs, the patterns
				  through doorways must be such that the air flows toward the inside of the
				  enclosure. Sometimes vestibules, double doors, or double curtains are used to
				  prevent air movement through the doorways. To use a vestibule, a worker enters
				  a chamber by opening the door or curtain and then closing the entry before
				  opening the exit door or curtain.
Airlocks should be located between the equipment room and
				  shower room, between the shower room and the clean room, and between the waste
				  storage area and the outside of the enclosure. The air flow between adjacent
				  rooms must be checked using smoke tubes or other visual tests to ensure the
				  flow patterns draw air toward the work area without producing eddies.
Monitoring for Airborne Concentrations
In addition to the breathing zone samples taken as outlined
				  in WAC 296-62-07709, samples of air
				  should be taken to demonstrate the integrity of the enclosure, the cleanliness
				  of the clean room and shower area, and the effectiveness of the HEPA filter. If
				  the clean room is shown to be contaminated, the room must be relocated to an
				  uncontaminated area.
Samples taken near the exhaust of portable ventilation
				  systems must be done with care.
General Work Practices
Preventing dust dispersion is the primary means of
				  controlling the spread of asbestos within the enclosure. Whenever practical,
				  the point of removal should be isolated, enclosed, covered, or shielded from
				  the workers in the area. Waste asbestos containing materials must be bagged
				  during or immediately after removal; the material must remain saturated until
				  the waste container is sealed.
Waste material with sharp points or corners must be placed in
				  hard air-tight containers rather than bags.
Whenever possible, large components should be sealed in
				  plastic sheeting and removed intact.
Bags or containers of waste will be moved to the waste
				  holding area, washed, and wrapped in a bag with the appropriate labels.
Cleaning the Work Area
Surfaces within the work area should be kept free of visible
				  dust and debris to the extent feasible. Whenever visible dust appears on
				  surfaces, the surfaces within the enclosure must be cleaned by wiping with a
				  wet sponge, brush, or cloth and then vacuumed with a HEPA vacuum.
All surfaces within the enclosure should be cleaned before
				  the exhaust ventilation system is deactivated and the enclosure is
				  disassembled. An approved encapsulant may be sprayed onto areas after the
				  visible dust has been removed.
Statutory Authority:
					 RCW
					 49.17.040, [49.17.]050 and[49.17.]060 .
					 97-01-079, § 296-62-07751, filed 12/17/96, effective 3/1/97. Statutory
					 Authority: Chapter 49.17 RCW. 94-15-096 (Order 94-07), § 296-62-07751,
					 filed 7/20/94, effective 9/20/94; 87-24-051 (Order 87-24), § 296-62-07751,
					 filed 11/30/87.