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Drilling asbestos-containing material (ACM)

Drilling of ACM for any purpose is not encouraged by VWA. The preference is to remove the material without any drilling and replace it with a non-ACM. However, the Regulations do not prohibit drilling into ACM (as long as the task is controlled in accordance with the Regulations).

The drilling of asbestos cement sheeting can release asbestos fibres into the atmosphere so precautions must be taken to protect the drill operator and other persons from exposure to these fibres. A hand drill is preferred to a battery-powered drill because the quantity of fibres that can become airborne is significantly reduced if a hand drill is used.

Equipment

In addition to any equipment required to complete the particular task, the following equipment may be required on site before the work begins:

  • a non-powered hand drill or a low-speed battery-powered drill or drilling equipment. Battery-powered drills need to be fitted with a local exhaust ventilation (LEV) dust control hood wherever possible. If a LEV dust control hood cannot be attached and other dust control methods (such as pastes and gels) are unsuitable, then shadow vacuuming techniques needs to be used
  • disposable cleaning rags
  • bucket of water and/or a misting spray bottle
  • duct tape
  • sealant
  • spare PPE
  • a thickened substance, such as wallpaper paste, shaving cream or hair gel
  • a suitable asbestos waste container (eg 200 micron plastic bags or a drum, bin or skip lined with 200 micron plastic sheeting)
  • 200 micron plastic sheeting
  • warning signs and/or barrier tape
  • an asbestos vacuum cleaner fitted with a HEPA filter
  • a sturdy paper, foam or thin metal cup or similar (for work on overhead surfaces only).

Personal protective equipment (PPE)

Preparing the asbestos work area

  • If the work is to be carried out at height, appropriate precautions must be taken to prevent the risk of falls.
  • Ensure appropriately labelled asbestos waste disposal bags are available.
  • Carry out the work with as few people present as possible.
  • Segregate the asbestos work area to ensure unauthorised personnel are restricted from entry (eg close doors and/or use warning signs and/or barrier tape at all entry points). The distance for segregation needs to be determined by a risk assessment taking into account the area, the nature of the work and the type of asbestos etc. If drilling a roof from outside, segregate the area below.
  • If access is available at the rear of the asbestos cement, segregate this area as well.
  • If possible, use plastic sheeting secured with duct tape to cover any surface within the asbestos work area that could become contaminated.
  • Ensure there is adequate lighting.
  • Avoid working in windy environments where asbestos fibres can become airborne.
  • If using a bucket of water do not re-soak used rags in the bucket as this will contaminate the water. Instead either fold the rag so a clean surface is exposed or dispose as asbestos waste and use another rag.

Drilling vertical surfaces

  • Tape both the point to be drilled and the exit point (if accessible) with a strong adhesive tape (such as duct tape) to prevent the edges crumbling.
  • Cover the drill entry and exit points (if accessible) on the ACM with a generous amount of thickened substance.
  • Drill through the paste.
  • Withdraw the drill and use damp rags to clean off the paste from it and any debris from the wall.
  • Dispose of the rags as asbestos waste as they will contain asbestos dust and fibres.
  • Seal the cut edges with sealant.
  • If a cable is to be passed through insert a sleeve to protect the inner edge of the hole.

Drilling overhead horizontal surfaces

  • Mark the point to be drilled.
  • Drill a hole through the bottom of the cup.
  • Fill or line the inside of the cup with shaving cream, gel or a similar thickened substance.
  • Put the drill bit through the hole in the cup so that the cup encloses the drill bit and make sure the drill bit extends beyond the lip of the cup.
  • Align the drill bit with the marked point.
  • Ensure the cup is firmly held against the surface to be drilled.
  • Drill through the surface.
  • Remove the drill bit from the cup, ensuring that the cup remains firmly against the surface.
  • Remove the cup from the surface.
  • Use damp rags to clean off the paste and debris from the drill bit and the wall.
  • Dispose of the rags as asbestos waste as they will contain asbestos dust and fibres.
  • Seal the cut edges with sealant.
  • If a cable is to be passed through, insert a sleeve to protect the inner edge of the hole.

Decontaminating the asbestos-related activity area and equipment

  • Use damp rags to clean the equipment including the drill.
  • If required, use damp rags or an asbestos vacuum cleaner to collect any loose debris on any plastic sheeting used to cover any surface within the asbestos work area.
  • Carefully roll or fold any plastic sheeting used to cover any surface within the asbestos work area so as not to spill any dust or debris that has been collected.
  • Use damp rags and/or an asbestos vacuum cleaner to clean any remaining visibly contaminated sections of the asbestos work area.
  • Place debris, used rags, plastic sheeting and other waste in the labelled asbestos waste bags/container.
  • Wet-wipe the external surfaces of the asbestos waste bags/container to remove any dust before they are removed from the asbestos work area.
  • Disposal of equipment, such as drills and drill bits, as asbestos-contaminated waste is always an alternative to decontamination or bagging it.

Personal decontamination

Carry out the following personal decontamination procedure in a designated area:

  • If disposable coveralls are worn for the activity, clean the coveralls and respirator while still wearing them. Coveralls can be cleaned using a HEPA vacuum, damp rag or fine-water spray and the respirator can be cleaned with a wet rag or cloth.
  • While still wearing the respirator remove coveralls, turning them inside-out to entrap any remaining contamination and then place them into a labelled asbestos waste bag.
  • Remove the respirator. If a non-disposable respirator was used, inspect it to ensure it is free from contamination, clean it with a wet rag and store in a clean container. Disposable respirators do not require cleaning. They need to be placed into a labelled asbestos waste bag or waste container dedicated for asbestos waste.

Clearance procedure

  • Visually inspect the asbestos work area to make sure it has been properly cleaned.
  • Consider seeking a competent independent person’s visual assessment to confirm there is no visible asbestos residue.
  • Clearance air sampling is not normally required for this task.
  • Dispose of all waste as asbestos waste.