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New Zealand Guidelines for the Management and Removal of Asbestos 3rd Edition

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SECTION 7: SAFE REMOVAL OF FRIABLE ASBESTOS

Figure 11: Fire-damaged asbestos-contaminated sheeting material – now friable

View large image and description of Figure 11.

This section applies to the removal of, or work on:

7.1 Planning and Programming Considerations

As the removal of friable asbestos by an asbestos removalist is done under contract or tender, the precise nature of the work to be done should be understood by both the contractor and client.

7.2 Information to be supplied by the Property Owner, Occupier or Agents (Client), including Principals and Persons in Control of a Place of Work

It is the responsibility of the owner to ensure an asbestos removalist carries out the removal of ACM.

The owner should nominate one or more persons to liaise with the asbestos removalist.

If a Certificate of Competence for restricted work is required and the asbestos removalist does not initially provide this, the owner or their agent should request this information.

If in doubt, the owner or their agent should contact their nearest Department of Labour office to determine any licensing requirements before any ACM removal.

The owner or their agent should supply the asbestos removalist with precise details of the scope of the work to be done prior to commencement of any work. However, it is recognised that in some cases the full extent of Asbestos-contaminated materials present will not be known until after the removal is underway.

In the preparation of the job specification, the following considerations should be addressed:

Location

  1. indoors;
  2. outdoors but protected;
  3. outdoors exposed to weather;
  4. enclosed in ducts or trenches below ground level;
  5. difficult or unusual site conditions, which will influence the selection or application of removal methods, particularly in regard to transport, scaffolding or weather protection;
  6. technical description of the material to be removed with details of the type of asbestos present and any special or unusual materials or circumstances; and
  7. any issues that may affect the safety of workers or the public.

The extent of the removal work should be adequately detailed on drawings, preferably coloured, to indicate areas for removal. Otherwise, information of the following nature should be provided:

  1. surface dimensions of flat or large curved areas, thickness of insulation, external diameters of pipes, length of each size pipe, and number and type of pipe fittings - e.g. flanged joints, valves, tees, expansion bends. Particular detail is to be provided if asbestos is to be removed from any part of the building's air-conditioning system;
  2. details of any pipe-work sections that are steam or electrically heated and the arrangement of its insulation;
  3. details of any section or materials to be left in place;
  4. confirmation and details of residual heat that will remain in pipe-work, boilers, turbines or refinery equipment;
  5. any unusual or specific hazards associated with the removal job;
  6. temperature considerations - normal working temperature at the removal area;
  7. conditions of substrate surfaces - special requirements, such as the removal (or otherwise) of protective paint or lacquer from pipe-work or for the application of paint or other protective coatings to the substrate from which the asbestos-contaminated materials have been removed;
  8. types of fittings and supports and whether or not these may be removed or disposed of with the waste;
  9. type of finish required or specification for re-insulation;
  10. special service requirements - e.g. where there is any potential hazard from contact with live electrical equipment in use in the removal area, attention should be drawn to this fact;
  11. site occupancy restrictions and conditions;
  12. cleaning of adjacent areas (adjacent areas that are to be cleaned or are to be protected from airborne dust and are to be cleaned on completion);
  13. safety practices to be followed under relevant legislation;
  14. location of any relevant electrical cables; and
  15. location of any relevant in-ground services.

Where electrical switch gear or panels are to be sealed, consideration should be given to the provision of supplementary ventilation to dispose of potential heat build-up and consequent fire risk.

7.3 Information to be supplied by the Asbestos Removalist

Restricted work involving asbestos must be notified to the Department of Labour. Please see Appendix F for the notification of Particular Hazardous Work form.

In all cases of restricted work, the asbestos removalist must provide their Certificate of Competency details to their clients.

7.3.1 Asbestos Removal Control Plan

The asbestos removalist should develop a site-specific control plan before commencing any asbestos removal work.

The purpose of each asbestos removal control plan is to help ensure the removal is well planned and carried out in a safe manner.

The asbestos removal control plan should include specifications and/or drawings addressing at least all of the items in Appendix A which are relevant to the particular removal job.

Additional information should be included for each individual removal job as necessary.

The control plan should be finalised in consultation with the client.

Consideration should be given to the removal of all asbestos from a building at the one time. Piecemeal removal often leads to the contamination of other work areas thus placing other persons at risk.

As the removal of asbestos may be dependent upon progress of other contractors at the site, details of planning schedules that will control the work and allow for effective removal without other personnel being present in the removal areas should be agreed upon.

Conversely, the work of other contractors should be scheduled to preclude them working near to, or accidentally breaking into the asbestos removal area.

7.4 Planning for Emergencies

NOTE: It is important to remember that ambulance services will not enter into any area where their staff may be put at risk, including an asbestos-contaminated workplace. Therefore, in the event that a worker may need to be stretchered out of the workplace, other procedures may need to be developed and practiced.

A site-specific emergency plan reflecting the risks involved should be developed before any ACM removal work commences.

Workers involved in ACM removal should be trained for emergency situations, particularly if they involve confined spaces or friable asbestos removal, where specialist skills may be required.

Emergency planning should include provisions for emergency and fire evacuation, including exit arrangements and emergency communications such as audible alarms. The alarms should be used for emergencies only.

Emergency exit arrangements need to be adequate for the risks involved. Barriers and signs or other warning devices can be used to communicate emergency arrangements.

A first aid kit and first aid officer should be readily available at all times and sufficient suitable fire extinguishers and hoses should be available at strategic locations. The locations of fire extinguishers and hoses should be displayed in written and/or graphic format.

7.5 General Training Requirements

Persons carrying out asbestos removal work should be trained so they can carry out this work safely and without risk to their own health and others. This training must reflect the specific type of asbestos work to be undertaken.

This training must include information in the site-specific asbestos removal plan (refer to Appendix A), specifically:

Asbestos removalists must also provide the following information to all of their asbestos removal workers and to all applicants for employment as an asbestos removal worker:

Asbestos removalists should keep a written record of all training provided to each of their asbestos removal workers and ensure that these records are readily accessible.

The asbestos removalist must ensure that the removal is continually supervised and that the operation is carried out in a safe and proper manner, in accordance with the precautions listed in these guidelines.

7.6 Supervisory Personnel

The asbestos removalist must ensure that persons supervising the removal of asbestos-contaminated materials defined as "restricted" must carry a Certificate of Competency in such work from the Department.

The asbestos removalist must ensure that supervisory personnel have a detailed knowledge of the precautions and procedures outlined in these guidelines. With this knowledge and at least two years' practical experience, they should assume the following responsibilities:

7.7 Non-Removal Persons Entering the Removal Enclosure

In some cases, non-removal persons may be required to enter the removal enclosure - for example, to undertake inspections or monitoring.

In these instances, the asbestos removalist must ensure that these persons receive the appropriate training, supervision and PPE required ensuring their safety and health while in the removal area.

The information provided should be site-specific and include:

If they provide and wish to use their own PPE, such as respirators, the asbestos removalist should check these to ensure that they are free from defects and suitable for the types of asbestos being encountered.

7.8 Site Preparation for the Removal of Friable Asbestos from Buildings and other Structures

There are two "asbestos removal boundaries" for asbestos removal work: the boundary of the asbestos work area and the boundary of the asbestos removal site.

The asbestos work area is the immediate site in which removal work of ACM is taking place.

The asbestos removal site is the region surrounding and adjacent to the asbestos work area.

The asbestos work area and the asbestos removal site should be clearly defined. The boundaries of the two should be determined by a competent person and should be based on a risk assessment.

All interested parties must agree on the asbestos removal boundaries before any asbestos removal work may commence.

If a workplace and the type of asbestos removal work involved are both similar to those at a previously determined site, the same boundaries can be applied after a reassessment for each site.

In determining the asbestos removal boundaries, consideration needs to be given to the:

In all cases, the procedures adopted for the removal of friable asbestos must be designed to contain the asbestos and minimise airborne exposure. The steps required to be taken will vary from job to job but in all cases:

The steps to be taken will be determined by the likelihood of asbestos fibre release and the size of the job in terms of time taken to complete it and the area involved. In the following sections, the site preparation that is considered appropriate for three commonly performed removal tasks are discussed:

7.9 Electrical and Lighting Installations

The risk of electrical injury, particularly when water is involved, must be addressed prior to removal of any asbestos-contaminated materials.

The best control is de-energisation (turning the power off) and removal of electrical installations from the asbestos work area.

If electrical installations cannot be disconnected and removed, they must at the very least be de-energised.

The de-energised installation must be tagged and locked out so it cannot be inadvertently re-energised. Any electrical cabling or equipment remaining in the asbestos removal area must be labelled and protected from mechanical damage or the ingress of water, and in accordance with AS/NZS 3000 (wiring rules).

A licensed electrician must perform the safe removal and reinstallation of electrical cables and electrical equipment and ensure that any electrical cabling or equipment is safe prior to re-energisation.

If there are smoke, thermal or fire detectors in the asbestos work area, a competent person should remove the heads and isolate the circuits as required prior to the removal works commencing.

Upon completion of the asbestos removal work, a competent person should replace the heads, reactivate and test the system and prepare a certificate stating that the heads are operational and forward this to the person in control.

All portable electrical tools and equipment, including flexible leads, and any electrical installations utilised by workers during the asbestos removal must comply with AS/NZS 3012:2003 Electrical Installations - Construction and Demolition Sites.

7.10 In-Ground Services

Care must be taken to identify and locate all in-ground services (such as water, gas or sewer pipes) in the asbestos work area or the asbestos removal site.

If necessary, appropriate action must be taken to ensure that these services do not present a hazard to asbestos removal workers. Conversely, it must also be established that asbestos fibres do not contaminate any such services, possibly by disconnecting those services for the duration of the removal work.

7.11 Preparation of a Site for a Major Removal Programme

Wherever practicable, enclosed "negative pressure" asbestos work areas should be established for any large-scale removal of friable asbestos-contaminated materials.

Similar large enclosures can also be used for the removal of non-friable asbestos-contaminated materials if a risk assessment concludes that enclosure is an effective control for the risks involved.

The design and installation of the enclosure should take account of:

Work methods may also need to be adapted for the work environment within the enclosure.

Heavy duty plastic sheeting - minimum 200µm (microns) - should be used for the enclosure. Recycled plastic must not be used.

Every location where the asbestos work area connects to the outside environment or the rest of the building (such as windows, ducts, wall cavities, conduits and lift entrances) should be enclosed so that an airtight seal is maintained for the duration of the asbestos work.

Vertical shafts should be properly sealed off to prevent the thermosyphon effect spreading asbestos fibre throughout the building.

Existing floor coverings should be removed where practicable. A double layer of plastic sheeting (suitably fixed by double-sided tape or adhesive to prevent movement between layers) should be used on the floor of the containment area and a turn-up should be used where the floor joins the side walls.

The plastic sheeting should enclose all the walls, windows and doors. Wooden cleats may be used to anchor the plastic sheeting to the walls.

7.11.1 Airlocks

Airlocks should be provided at the entry points to the changing area. These airlocks should be constructed using double sets of overlapping plastic with suitable provisions for ensuring a seal.

7.11.2 Viewing Panels

Viewing panels are installed in enclosures to allow for inspection of removal operations and should be placed in appropriate locations.

7.11.3 Lighting Requirements

Adequate lighting needs to be provided within the enclosure, either naturally, using clear plastic or Perspex panels in the enclosure walls, or artificially, preferably from outside the enclosure and again using clear plastic or Perspex panels. Lights within an enclosure can increase the temperature within the enclosure.

7.11.4 Lift Shafts

Where asbestos is removed from an entire floor of a multi-story building, all passenger lifts should be prevented from stopping at the floor from which asbestos is being removed. Removal workers may gain access to the floor via the fire stairs or from a lift dedicated for this purpose. Where a lift is used for access, all exit doors to other floors should be sealed. It is important that emergency escape exits are available when blocking off such areas.

7.11.5 Furniture and Fixtures

All movable furniture, plant and fittings (such as curtains, desks, mats and false ceiling tiles) must be removed from the asbestos removal area. The immovable items should be fully wrapped and sealed in suitable plastic sheeting so that they are effectively isolated from the removal area. In regions of heavy traffic or high wear, additional masking or barricading may necessary.

7.11.6 Masking and Preparation of Enclosure and Other Equipment

Where masking operations may liberate asbestos fibres, all persons in the removal area must wear respiratory protective devices approved for asbestos. This precaution is particularly applicable when removing existing barriers or partitions such as false ceiling tiles, or the erection of scaffolding.

7.11.7 Ceiling Spaces

Where asbestos materials may have fallen onto a false ceiling, the ceiling should be removed only under full removal conditions. Any utility or service line which penetrates into the ceiling space must be sealed.

Ceiling spaces may be sealed by constructing a plastic-lined frame within the ceiling space. This frame should be removed only after the completion of the final clearance inspection.

Aside from specific asbestos extraction units, all ventilation and air-conditioning networks servicing the removal area should be closed down for the duration of the removal job.

All vents should be thoroughly masked to prevent the ingress of asbestos fibre into the duct network. Upon completion and after final cleaning of the removal area, all mechanical ventilation filters for re-circulated air should be replaced.

Additional care must be taken to ensure that asbestos fibres cannot escape at points where pipes and conduits pass out of the removal area. Greater attention to masking and compliance testing should be given in these regions, particularly if service riser-shafts pass through the removal area.

If the asbestos work area is adjacent to areas occupied by unprotected persons, priority should be given to performing the removal work during periods when these areas are unoccupied or to a greater isolation of the removal area. In addition, hoarding should be constructed to form a barrier between the asbestos work area and the adjoining occupied areas. A plastic-lined barrier should be erected within this hoarding. A buffer area should be reserved between the hoarding and occupied areas.

Any platforms and/or fixed scaffolding required for the safe removal of the asbestos-contaminated material should be erected during the early stages of the work. Where it is necessary to construct platforms and fixed scaffolding within the enclosed area, decontamination and visual inspection of these structures will be necessary at the end of the removal work.

7.11.8 Air Inlets

Air inlets are needed to help maintain a suitable volume of negative air pressure.

If the Negative Air Units (NAUs) are turned off, air inlets should be filtered to prevent the escape of dirty air out of the inlets into the environment.

NOTE: Air inlets into the enclosure will be required to balance the air flow because too much negative air pressure can cause the enclosure to implode or seals to fail.

7.11.9 Extraction Units (Negative Air Units or NAUs)

To prevent the escape of airborne asbestos fibres from the removal area enclosure, an exhaust extraction fan should be installed in a position to create a negative air pressure of approximately 12 Pascals (water gauge) within the removal area.

While accepting that the measurement of this pressure is not always possible, a good guide to the effectiveness of the system can be gauged from the inwards effect on the plastic tenting. If there is a visible bellowing inwards, there is good negative pressure. In this arrangement, the major and usually only route of air into the removal area would be through the decontamination unit. Where plastic tenting has not been used, the correct flow of air should be verified by using smoke testing.

The extraction units must be run continuously (i.e. 24 hours a day) until all asbestos removal and decontamination tasks have been completed and clearance given.

Below is a basic formula for calculating the number of air handling units required based on the volume of the space to achieve a pre-determined number of air changes per hour:

Volume of air space (V) = (Width x Length x Height)

CFM Rating (cubic feet/minute) (R) = found on the air handling size unit

In this example the predetermined number of air changes = 4 and is over a 60 minute period:

V x 4 = 4V
R x 60 = 60R
4V / 60R = Number of Units Required

The calculated amount should be rounded to the nearest full number.

7.11.10 Extraction Unit Filtration

The air extracted by this system should pass through an appropriate High Efficiency Particulate Air (HEPA) filter to ensure removal of any asbestos fibres.

Ideally, air extraction units should be situated so that access to the filters can be gained from the removal area.

This expedites the otherwise difficult decontamination of these units and allows another unit to be brought into service in the event of a breakdown.

Where it is not possible to change the filter within the removal area, a temporary enclosure should be constructed around the unit during the filter replacement.

Every employer must take all practicable steps to ensure that dust control equipment used in the course of the asbestos work is inspected for defects at least once every seven days by a person who has:

  1. the relevant knowledge, experience, and skill to inspect dust control equipment for defects; and
  2. either:
    1. a relevant qualification; or
    2. a certificate issued by his employer as evidence that he is in possession of the required knowledge, experience, and skill.

The HEPA filter should comply with the minimum 99.97% efficiency requirement detailed in AS 1324.1:2001 Air filters for use in general ventilation and air-conditioning - Application, performance and construction. The HEPA filter must also comply with AS 4260:1997 High efficiency particulate air (HEPA) filters - classification, construction and performance. A coarse pre-filter should be installed on the air intake side of the negative air unit to prolong the useful life of the high efficiency filter.

Where practicable, the discharge point for this extraction unit should be to the outside air, distant from other working areas, air-conditioning inlets or breathing air compressors. Where this is not possible, testing of the exhaust air is to be carried out.

Procedures should be established for changing these HEPA filters so that areas outside the enclosure are not contaminated. The most satisfactory method for assessing the integrity of the HEPA filter and seal fittings is regular inspection in conjunction with a static pressure alarm to indicate any failure in the system.

When installing the asbestos removal area containment, extra consideration should be given to the alteration of the fire rating of the building and to the provision of the fire-fighting facilities, emergency exits and emergency lighting.

7.11.11 Signage

This diagram shows an example of asbestos warning awareness signage

View description.

The asbestos removal site should be clearly defined to ensure that non-essential persons do not enter and to clearly delineate the removal site and warn persons that asbestos removal work is being carried out.

Warning notices stating "ABESTOS HAZARD AREA - KEEP OUT" must be placed at entrances to the removal area. These signs, with lettering of 100mm in height, are to be placed so they are clearly visible. Other more general signs may be used elsewhere in the buildings to indicate that construction work is in progress.

Examples of warning labels and signs are provided in Section 11 of these guidelines.

All signs and barriers should remain in place until a clearance to re-occupy has been granted.

7.12 Compliance Testing of Removal Area Prior to Commencement of Work

When the asbestos removalist is satisfied that the enclosure is complete, and before any asbestos removal begins in an enclosure, a competent person should carry out a visual inspection to check the integrity of the structure. Smoke testing may also be used to detect leaks.

Negative air exhaust units should not be used while the smoke test is being conducted. Only smoke-generating devices incorporating non oil-based, non-toxic smoke fluid should be used. Flares should not be used.

Attention should be given to the billowing inward of the plastic sheeting. At the beginning of each working period the inspection should be repeated and any defects rectified immediately.

If any leaks or other deficiencies in the enclosure are found during the testing, work should not proceed until these have been rectified.

If air monitoring or visual examinations of the enclosure and items of equipment indicate that asbestos dust might be escaping from the enclosure, asbestos removal work should be stopped until any defects have been rectified.

Following any such incident and before work commences it is essential to:

A supply of expandable foam sealant, polyester insulation or equivalent should be maintained on the site to assist with sealing leaks.

7.13 Decontamination Facilities

The decontamination unit should be situated immediately adjacent to, and joined to, the enclosed asbestos removal area. Where it is not physically possible to locate the decontamination unit in this way, alternative procedures to minimise asbestos contamination should be implemented. See Section 7.14 (Remote Decontamination Units.)

The decontamination unit should be divided into three distinct areas:

  1. a dirty decontamination area;
  2. a clean decontamination area; and
  3. a clean changing area.

These areas should be separated by suitable airlocks or buffer zones. Normally these airlocks have spring-loaded doors or two or more overlapping sheets of plastic sheeting positioned to define the boundary between each segment of the decontamination unit, while allowing personnel access and an air-flow towards the asbestos work area.

To ensure there is sufficient airflow through the decontamination unit if doors are used, they should have large openings with a hinged flap operating as a one-way valve.

A typical layout is shown in Figure 12.

Figure 12: Typical layout of a decontamination facility for heavy contamination

View large image and description of Figure 12.

The dirty decontamination area should provide for:

The clean decontaminated area should provide for:

The clean changing area should provide for:

All water from the decontamination facility should pass through a high efficiency particulate filter or other trap before it passes into sewer mains.

The filter or trap must be capable of capturing particulates down to 5µm - refer to Section 7.22 (Waste Water Management) of these guidelines.

Workers must not smoke, eat or drink in any part of the decontamination unit.

7.14 Remote Decontamination Units

Remote decontamination units are not located next to the asbestos work area.

They should only be used if a decontamination unit cannot be located immediately adjacent to the asbestos work area.

When a remote decontamination unit is to be used, the asbestos removalist may need to implement additional procedures to minimise asbestos contamination including, for example, methods for the connection and disconnection of airline respirators.

The route of access from the asbestos work area to the decontamination unit should be suitably signposted and barricaded to restrict public access.

An isolated changing area should be attached to the asbestos work area. Before workers enter this changing area, all obvious signs of asbestos dust should be removed from their protective clothing using an asbestos vacuum cleaner.

The isolated changing area is used to discard outer garments including coveralls and overshoes and to dress in fresh outer/protective clothing for the journey to the decontamination unit.

Control monitoring must be conducted in the immediate vicinity of the access route and at other suitable locations outside the asbestos area to ensure that no contamination is being spread outside of the isolated changing area and asbestos work area.

Respiratory protection should continue to be worn until the appropriate phase of the decontamination procedure within the remote decontamination unit.

7.15 Procedure for Entering the Asbestos Work Area

The procedure for persons entering the asbestos work area should be as follows:

7.15.1 Clean Change Area

7.15.2 Clean Decontamination Area

7.15.3 Dirty Decontamination Area

7.16 Procedure for Leaving the Asbestos Work Area

The decontamination procedure for persons leaving the asbestos work area should be as follows:

7.16.1 Asbestos Work Area

7.16.2 Dirty Decontamination Area

7.16.3 Clean Decontamination Area

7.16.4 Clean Change Area

7.17 Person Outside the Enclosure

The asbestos removalist should ensure a worker is stationed outside the asbestos work area for the duration of the asbestos work to:

Records of these activities should be kept on a daily basis.

7.18 Sealing the Enclosure and Decontamination Unit upon the Completion of the Asbestos Removal Work

After the removal work has been completed, all plant and equipment within the asbestos work area and the decontamination unit, including any remaining non-removable items, should be vacuumed and/or wet wiped to remove any residual dust.

When decontamination is not possible, the items should be wrapped in plastic and sealed and only opened in another removal area.

When emptying the asbestos vacuum cleaner, any asbestos contained should be disposed of as asbestos waste, including the containment bag and filters.

Once the asbestos supervisor is satisfied that the asbestos work area and decontamination unit are clean, all of the clean surfaces should be sprayed with PVA using airless spray equipment.

Items of equipment that may be damaged by the application of the PVA can be screened with plastic sheeting.

Any layer of plastic forming the inner surface of the enclosed work area or decontamination unit should also be sprayed with PVA.

The final layer of any plastic enclosing the asbestos work area and decontamination unit should not be taken down until a visual inspection has found no visible asbestos residue and clearance monitoring indicates airborne asbestos fibre levels are below 0.01/mL.

Settled dust sampling may also be considered as an indicator of cleanliness.

Plastic sheeting and any similar materials used for the enclosure must be treated as asbestos waste. This need not apply to scaffolding or other equipment used to add strength to the enclosure, but any such equipment should be vacuumed, damp-wiped and sprayed with PVA as part of the clean-up process.

Ropes, warning signs and protective plastic isolating areas should not be removed until the asbestos work area and decontamination unit have had a satisfactory clearance inspection.

7.19 Mini-Enclosures for Small-Scale Asbestos Removal Work

Mini-enclosures are suitable for asbestos removal work in areas with restricted access, such as ceiling spaces, and for emergency asbestos removals.

The mini-enclosure has to be large enough to allow movement inside the enclosure and contain all the equipment needed for the asbestos removal work.

The frame of a mini-enclosure can be made from a variety of materials, but has to be strong enough to support the plastic sheeting that forms the enclosure.

Machinery that consumes oxygen or emits exhaust fumes must not be placed in a mini-enclosure.

Heavy duty plastic sheeting, 200µm minimum thickness, should be used to make the enclosure. Recycled plastic must not be used.

The tape used to connect the plastic to the frame must be strong enough to securely hold the plastic to the frame.

A smoke tube should be used to check the sealing of the plastic sheeting.

A slit will have to be made in the plastic sheeting to allow entry. The slit can then be taped from inside the enclosure.

A typical layout is show in Figure 13:

Figure 13: Layout of a mini-enclosure for small-scale asbestos removal

Figure 13: Layout of a mini-enclosure for small-scale asbestos removal

View large image and description of Figure 13.

The hazards and work procedures that need to be considered for large enclosures also need to be taken into account for all mini-enclosures.

Workers leaving the mini-enclosure must follow the personal decontamination procedures.

7.20 Dry Decontamination – Suitable for Small-Scale Non-Friable Asbestos Removal Work – Service and Maintenance

Personal decontamination must be undertaken each time removal workers leave the asbestos work area and on completion of asbestos service and maintenance work.

Personal decontamination should be done within the asbestos work area where recontamination cannot occur.

Asbestos-contaminated PPE should not be transported outside the asbestos work area except for disposal purposes.

The procedure for dry decontamination is:

This form of personal decontamination may also be appropriate after the service and maintenance or removal of:

However, some of these forms of asbestos-contaminated materials could be friable making more extensive decontaminated procedures necessary. The measures adopted should always address the risks of each individual asbestos removal job.

7.21 Vehicular/Machinery Decontamination

Vehicular decontamination units are required when asbestos removal works require the use of heavy machinery and/or trucking in the asbestos removal area - for example, large-scale removal of contaminated soil or of internal building asbestos-contaminated materials.

A risk assessment should be undertaken by the asbestos removalist to determine the extent or necessity of vehicular decontamination procedures.

The vehicular decontamination unit should be located away from the personal decontamination unit and should be adjacent to the asbestos removal work area.

The decontamination unit may be purpose-built with suitable heavy duty timbers and plywood. The decontamination unit must be lined internally and externally with heavy duty plastic sheeting of 200µm thickness. The sheeting must be checked regularly for damage and leaks and, if any are identified, it must be removed and replaced before usage continues.

The unit must be watertight to prevent excess water run-off during wash-down procedures.

Spring-loaded doors on either side of the unit should be used to ensure that an airlock is maintained as the vehicle/machine is passing through the unit.

During entry and exit procedures, only one set of doors should be open at one time, to prevent airborne fibres from escaping the enclosure.

All materials used in the construction of the decontamination unit must be disposed of as asbestos waste once the unit is dismantled upon completion of removal works.

Extraction fans should be installed to force the air back into the asbestos work area.

After each vehicle/machine has been thoroughly washed, the unit must be liberally doused with water to arrest any fibres remaining in the decontamination unit.

7.21.1 Procedures for Decontamination of Machinery

At all times when in the asbestos work area and the vehicular decontamination unit, the machine operator must:

Once the machine has been thoroughly washed and the decontamination unit has been washed down, another operator similarly kitted in clean PPE and RPE is to enter the decontamination unit from the clean side to extract the machine from the decontamination unit to the clean area.

NOTE: No operator can exit from the asbestos working area through the vehicular decontamination unit.

7.21.2 Procedures for Decontamination of Vehicles

At all times when in the asbestos work area and the vehicular decontamination unit, the vehicle operator must:

7.22 Waste Water Management

The vehicular decontamination unit must be suitably constructed so that no water escapes its confines, except to where it is to be collected for filtration or disposal.

The water from the decontamination process is to be collected in a "sump" and regularly disposed of as contaminated waste.

Alternatively, a trap should be constructed with a HEPA filtration unit to extract and collect asbestos fibres from the water before it is collected as normal contaminated water from the vehicles or machinery.

No unfiltered water is to be dumped in council catchments.

7.23 Decontamination of Waste Removed from Asbestos Work Area

Waste bags and wrapped items need to be decontaminated before leaving the enclosure.

Asbestos-labelled bags need to be wetted down and not overfilled, to reduce the risk of splitting and tearing.

Refer to Section 11 of these guidelines for further information on the removal of asbestos waste from the removal area.

7.24 Glove Bag Removal Method

Glove bags are single-use bags constructed from transparent, heavy duty plastic with built- in arms and access ports.

Generally these glove bags are approximately one metre wide and 1.5 metres deep.

Glove bags are designed to isolate small removal jobs from the general working environment. They provide a flexible, easily installed and quickly dismantled temporary enclosure for small asbestos removal jobs.

The glove bag removal method is especially suited for the removal of asbestos lagging from individual valves, joints, piping etc.

A major advantage of all glove bags is that they contain all waste and contamination within the bag, eliminating the need for extensive PPE and decontamination.

The only significant limitation on the use of glove bags is the volume of waste material they are able to contain. Care needs to be exercised to prevent overfilling of the bag with water or waste.

See Figure 14:

Figure 14: Use of glove bags

Figure 14: Use of glove bags

View large image and description of Figure 14.

  1. Cutting and removal tools that will be used in the removal should be placed into the glove bag at the start of the job. When the removal is complete, tools should be either disposed of as asbestos waste or sealed for re-use in future removal jobs.
  2. The glove bag should completely cover the pipe or object on which the asbestos removal work is to be performed. The lagging on either side of the bag must be sound enough to support the weight of the bag and its wet contents.
  3. Cut the sides of the glove bag to fit the size of the object from which asbestos is to be removed. Attach the sides of the glove bag to the object by folding in the open edges together and securely sealing them with duct tape. Seal all openings in the glove bag with duct tape or an equivalent. The bottom and side seams of the glove bag should also be sealed with duct tape or an equivalent to prevent any leakage if there is a defect in a seam.
  4. Thoroughly saturate the asbestos-contaminated materials with a wetting agent and then remove it from the pipe, beam or other surface. The wetting agent should be applied with an airless sprayer through a pre-cut port as provided in most glove bags, or through a small hole cut in the bag. Asbestos-contaminated materials that have fallen into the bag should be thoroughly saturated. Any canvas should be cut and peeled away from the asbestos-contaminated materials. If the asbestos-contaminated materials are dry, it should be re-sprayed with the wetting agent before it is removed.
  5. Thoroughly clean the pipe or surface from which the asbestos has been removed with a wire brush and wet wipe it until no traces of the asbestos-contaminated materials can be seen. Wash down the upper section of the bag to remove any adhering asbestos-contaminated materials.
  6. Seal any edges of the asbestos-contaminated materials that have been exposed by the removal or by any maintenance activity to ensure these edges do not release any airborne asbestos fibres after the glove bag is removed.
  7. Once the asbestos-contaminated materials have been removed and sealed, insert a vacuum hose from an asbestos vacuum cleaner into the glove bag through the access port to remove any air in the bag that might contain airborne asbestos fibres. Once the bag has been evacuated, squeeze it tightly as close to the top as possible, twist it and seal it with tape, keeping the asbestos-contaminated materials safely in the bottom of the bag.
  8. Remove the vacuum line from the bag and then remove the glove bag from the work place for proper disposal as asbestos waste.

7.25 Wrap and Cut Removal Method

This method of removal produces the lowest levels of airborne asbestos fibres and is most appropriate for redundant plant and equipment.

The plant or equipment to be removed should be double wrapped with minimum 200µm thick plastic and taped so that the ACM is totally sealed within the plastic.

The wrapped plant and equipment can then be cut from the rest of the plant and equipment using mechanical shear or oxy-cutting tools. Only exposed metal should be cut and care should be taken to ensure the plastic wrapping is not punctured and/or melted.

If lagging has to be removed to allow pipe to be cut, the glove bag removal method should be used to expose the metal at the point to be cut and for a sufficient length on either side.

The insulation should be thoroughly wetted, bagged and disposed of as asbestos waste. The pipe should then be cut at the centre of the exposed section.

7.25.1 Removal of Decorative Coatings (Textured Ceilings)

Because of the relatively low asbestos content (range of 3-10%) and the nature of the product, it may not be necessary to adopt all the procedures set out in Sections 7.12 to 7.20 for major removal programmes. This is especially so if complete saturation with water is possible as this greatly reduces the release of asbestos fibres.

However, where contamination of the asbestos-contaminated materials covers a large area (typically greater than a standard three-bedroom residential dwelling) and where work exposure exceeds a maximum of 8 hours total work duration, then procedures as described in Sections 7.3 to 7.12 of these guidelines must be followed.

7.25.2 Procedures for Small-Scale Removal Work - Domestic Dwellings

The minimum procedures that must be followed in instances of domestic dwellings are that the room(s) must be isolated from adjoining areas. This can be done by sealing doors and other openings with tape. It may not be necessary to totally enclose the removal area with polythene sheeting, provided the surfaces can be vacuumed with an asbestos vacuum cleaner and wet-wiped clean. The floor must be covered.

All furniture, fittings and curtains must be removed. Negative air pressure should be maintained within the work area.

Procedures must be adopted to ensure that the asbestos-contaminated materials do not contaminate other areas. Work methods must be methodical and orderly, thereby reducing the release of airborne fibres and the spread of asbestos. Protective clothing should remain in the removal area and be disposed of as asbestos waste at the completion of the job.

7.26 Decontamination of Soil

Figure 15: Farmland contaminated with material including asbestos

Figure 15: Farmland contaminated with material including asbestos

View large image and description of Figure 15.

NOTE: In the Health and Safety in Employment (Asbestos) Regulations 1998, decontamination of soils is considered restricted work and must only be undertaken by a person who holds a current Certificate of Competency in this type of work.

7.26.1 General

Asbestos fibres or dust can be released from materials present on the site, including materials buried at insufficient depth, by weathering, erosion or disturbance by, for instance, vehicles or during construction activities.

The tendency for asbestos fibres to be released is increased if the contaminated material consists of friable asbestos, such as pipe lagging, asbestos blankets, rope or millboard.

If the site is well drained and dry then the tendency for asbestos fibres to release is also increased.

7.26.2 Excavation and Removal Offsite

This process is suitable for all types of asbestos contamination.

The site should be appropriately secured or boarded off to prevent the unintentional entry by members of the public or other non-essential personnel.

Appropriate warning signage should be erected at all entry points and are not to be removed until the work is completed.

The methods used for this decontamination should be based on a risk assessment. The use of professional site remediation advice and/or services should be considered as they can develop an RAP (remediation action plan) for the asbestos removalist to work to.

The minimum suitable respiratory protection is a P2 half face-piece respirator with particulate filter. The type of decontamination facilities should be determined by a risk assessment by the asbestos removalist.

During soil decontamination the topsoil should be dampened down to minimise the generation of dust and all visible pieces of asbestos-contaminated materials should be picked up individually so that the risk of asbestos fibre inhalation is effectively eliminated.

The method of dampening should be such so as not to cause pooling or run-off of contaminated water.

If this is not practicable, the contaminated topsoil should be removed to a depth that has no visible contamination or asbestos debris.

The contaminated soil must be disposed of as asbestos waste at a registered tip-site. The trailer used for removing the asbestos-contaminated materials from site to the registered tip-site must be lined in accordance with Section 11 of these guidelines.

All documentation should be maintained by the asbestos removalist and provided to the client.

In addition, there should be:

Figure 16 – Fire-damaged asbestos-contaminated sheeting

Figure 15: Farmland contaminated with material including asbestos

View large image and description of Figure 16.

7.27 Site Remediation for Fire-Damaged Asbestos-Contaminated Materials

The remediation and clean up of fire-damaged asbestos containing products, including cement bonded products such as cladding material, is a restricted activity that requires the direct supervision and management by a person holding a Certificate of Competence for restricted work.

The asbestos removalist must complete a site investigation to assess:

Generally, fire damaged asbestos-contaminated materials attracts a lot of attention due to the high public health concern. The asbestos removalist may be required to deal with a variety of agencies including fire investigation, police, public health, regional councils and the Department.

Fire damaged asbestos-contaminated materials need to be kept wetted down, but not to the point of causing pooling. Any water used for the wetting down of fire damaged asbestos-contaminated materials will be contaminated and must be captured and treated as such.

The site should be appropriately secured or boarded off to prevent the unintentional entry by members of the public or other non-essential personnel.

Appropriate warning signage should be erected at all entry points and not to be removed until the work is completed.

The removal method adopted by the asbestos removalist should be one that minimises the risk of further contamination.

In addition, there should be:

7.28 Removal Techniques for Buildings and Structures

The removal of asbestos-contaminated materials from buildings and other structures should be carried out by methods that will minimise the release of asbestos fibre into the atmosphere during and after the removal operation. The choice of method is determined by the nature of the asbestos materials, the quantity of insulant and its location.

Breaking through the finishing compound and cutting the reinforcing wire in lagging can liberate considerable quantities of dust. Care should be taken in the selection of tools and in keeping the insulation wet. Tools should allow cutting of the insulation into small sections while keeping asbestos fibre levels in the removal area to a minimum.

NOTE: Power, telephone and fire alarms may lie beneath asbestos insulation. These cables must be clearly identified prior to the commencement of any cutting as severe damage and / or hazard to the worker could result.

As the techniques used for the removal of sprayed thermal insulation from buildings are not dissimilar from those used for removal from steam pipes and boilers, the following removal methods may be adapted to the removal of asbestos from industrial plant and machinery.

7.28.1 Removal by Soaking or Total Saturation

The quantity of asbestos-containing insulation to be removed from pipes or ducts is often so extreme, or the material so thick, that the spray method (see following technique) will not suppress fibre release sufficiently. An alternative is to soak the insulation by the introduction of water through appropriate applicators.

The following steps are recommended for the soaking procedure:

The asbestos-contaminated materials should be properly soaked and small sections that dislodge should be properly disposed of.

7.28.2 Spray Method

Water is very effective in preventing release of asbestos fibre. This method should be used only where small quantities of asbestos-contaminated materials are to be removed and where the following conditions apply to the material:

The spray should be applied in such a manner as to ensure that the entire surface of ACM is wet but minimal run-off occurs.

In many instances adding a wetting agent to the water will facilitate more rapid wetting of the insulation material.

It is desirable for the asbestos-contaminated materials to be wetted through its full depth and maintained in a wet condition. A manually controlled, consistent low-pressure coarse spray, such as from an adjustable pistol grip garden hose, should be used for this purpose.

The design of the spraying equipment will be dependent on availability of water supply and access to the area to be sprayed.

It is important that the spray should be copious, but not such that the water droplets generate dust from impact with the surface of the insulation. When using cutting equipment to remove asbestos, the water spray should be directed at the site of the cut and the wetted material removed as the cut progresses.

The wetted asbestos-contaminated materials should be removed in sections and immediately placed in suitably labelled containers and properly sealed. Any small sections that dislodge should be collected and properly disposed of.

Asbestos fibre release is significantly depressed although not entirely eliminated by this technique, so appropriate respiratory protection should be used.

7.28.3 Dry Removal

This method is considered the least desirable removal technique and must only be used where spray and soaking methods cannot be used - for example where there are live electrical conductors or where major electrical equipment could be permanently damaged or made dangerous by contact with water.

Notwithstanding the general guidance given earlier in these guidelines, the greater potential for the generation of the airborne asbestos dust in dry removal techniques demands that particular attention be given to work methods.

7.29 Protective Clothing and Equipment

When the use of respiratory devices and protective clothing is required, adequate rest breaks should be provided to take into account the physical strain caused by the use of such equipment.

Care should be taken in the selection of all tools and equipment for asbestos removal tasks. In addition to suitability for these tasks, all tools should prevent or minimise the generation and dispersion of airborne asbestos fibres as much as possible.

The use of power tools in asbestos removal work should be avoided because of the possibility of internal contamination which commonly occurs with such devices. In general, manually operated hand tools are preferred.

At the end of removal work, all tools should be:

CAUTION

In general circumstances high speed abrasive power tools or pneumatic tools such as angle grinders, sanders, saws and high speed drills should not be used for asbestos removal - for example, when removing asbestos fibrolite sheeting.

7.29.1 Spray Equipment

A constant low pressure water supply is required for wetting down asbestos. This can be achieved with a mains-supplied garden hose fitted with a pistol grip. If no water supply is readily available, a portable pressurised vessel such as a pump up garden sprayer may be used.

7.29.2 Asbestos Vacuum Cleaners

Asbestos vacuum cleaners should comply with the requirements of AS/NZS 60335.2.69:2003 Household and Similar Electrical Appliances - Safety - Particular requirements for wet and dry vacuum cleaners, including power brush, for industrial and commercial use and AS 4260:1997 High Efficiency Particulate Air Filters (HEPA) - Classification, construction and performance.

Asbestos vacuum cleaners should only be used for collecting small pieces of asbestos dust and debris. Larger pieces should never be broken into smaller sizes so they can be vacuumed. Vacuum cleaners used on asbestos work should not be used for any other purpose and must be labelled "For Asbestos Use Only".

Asbestos vacuum cleaners should not be used for vacuuming wet materials because this can damage the HEPA filter.

Use the correct attachment to the asbestos vacuum cleaner for the type of surface you are cleaning.

Procedures should be established for the general maintenance of asbestos vacuum cleaners in a controlled environment. They should be cleaned externally with a wet cloth after each task, the hose and attachments stored in a labelled container or impervious bag and a cap should be placed over the opening to the asbestos vacuum cleaner when the attachments are removed.

PPE should be worn whenever an asbestos vacuum cleaner is opened to change the bag or filter or to perform other maintenance or decontamination.

Emptying asbestos vacuum cleaners can be hazardous if the correct procedures are not followed. Asbestos vacuum cleaners should only be emptied by a competent person with the correct PPE in a controlled environment and in compliance with the manufacturer's instructions.

Whenever possible, asbestos vacuum cleaners should not be hired as they can be difficult to fully decontaminate. If hiring is necessary, they should only be hired from organisations that provide vacuum cleaners specifically for work with asbestos.

When the work is complete the asbestos vacuum cleaner should be decontaminated with the bag and filter being removed in accordance with the manufacturer's instructions and disposed of as asbestos waste. The inside and outside of the vacuum should be wet-wiped and the asbestos vacuum cleaner should be re-sealed in the storage container provided.

7.29.2 Inspection of Equipment

All equipment used for the removal of asbestos-contaminated materials should be inspected before the commencement of the removal work, after any repairs and at least once every seven days when it is being used continually.

A register should be maintained with details of these inspections, the state of the equipment and any repairs.

7.30 Dismantling of Asbestos Removal Area

The asbestos removal job should only be considered to have been completed when the asbestos removalist has complied fully with the clearance criteria - refer to Section 9 of these guidelines.

7.30.1 Clearance and Visual Inspection Procedures

On completion of the asbestos removal job, all tools and equipment not used for cleaning should be removed from the removal area so that efficient vacuuming of the inside of the removal area enclosure can be undertaken. When taking these tools and equipment from the removal area, appropriate decontamination procedures should be observed.

After clearance has been given, any sealing plastic used should then be dismantled, folded inwards and placed in appropriate disposal bags and sealed. The sealing plastic should not be re-used, but must be treated as asbestos waste. Safety barricades and warning signs must not be removed until the complete removal area has been thoroughly cleaned.

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