SAFE WORK PROCEDURE:

CUTTING ASBESTOSCEMENT (AC)

PIPE WITH K-12 SAW

INTRODUCTION

Asbestos-Cement (AC) pipe has been used extensively in British Columbia water systems.

The accepted safe practice for cutting AC pipe includes wetting the pipe and cutting with hand tools or hand crimpers only, in order to reduce worker exposure to asbestos fibres. There are two problems with this procedure: over time, AC pipe becomes saturated, and cutting with hand saws or snap cutters becomes more difficult and less efficient. The second problem is the length of time it takes a worker to follow this procedure.

In May, 2011, the BC Municipal Safety Association, the Corporation of Delta and WorkSafeBC participated in an exercise of cutting AC Pipe with a K-12 saw and water attachment, while monitoring for asbestos and carbon monoxide exposure. Sampling was conducted by AMEC Earth & Environmental.

In the trial, the workers’ asbestos exposure exceeded the Occupational Health and Safety Regulation exposure limit of 0.1 f/cc, which means the process may not be used without additional personal protective equipment and safe work procedures. Specifically, work must follow the moderate risk work procedures outlined in WorkSafeBC’s “Safe Handling of Asbestos, A Manual of Standard Practices”, revised in 2006.

In addition, during the trial, the carbon monoxide monitor registered a peak exposure of 41 ppm. The trench used for the trial was only 3’ deep, so it can be expected that in deeper excavations, without sufficient ventilation, the exposure to carbon monoxide will get to a level that cannot be tolerated. Therefore, continuous ventilation of the excavation as well as continuous monitoring for carbon monoxide must be conducted when the K12 saw is in operation, with the monitor set to alarm at the Short Term Exposure Limit (STEL) of 100 ppm.

As data has only been collected from this one trial, additional worker exposure monitoring for asbestos and carbon monoxide must be done whenever this process is used. Any municipality using this procedure is asked to forward the results of worker exposure sampling to the BC Municipal Safety Association, with the aim of eventually being able to use this procedure without further sampling.

PURPOSE OF SAFE WORK PROCEDURE

During regular asbestos cement (AC) pipe maintenance activities in municipalities, asbestos may be disturbed when cutting the pipe, potentially releasing airborne asbestos fibres. The intention of this safe work procedure is to provide a guideline for performing the work in a manner which will protect workers from airborne asbestos fibres.

Potential Hazards

  • Exposure to asbestos fibres*
  • Exposure to carbon monoxide*
  • Excavation failure
  • Noise exposure
  • Strains/sprains (back, shoulder)
  • Traffic hazards in work area
  • Cuts from saw

Items marked with an asterisk are addressed in this safe work procedure. Each municipality will need to establish safe work practices/procedures for the remaining hazards, and train staff in those practices and procedures. Each municipality must also ensure there is an Exposure Control Plan completed for both Asbestos and Carbon Monoxide.

Equipment

  1. K12 saw with spray hose attachment, fitted with either a diamond blade saw or masonry carbide blade saw.
  2. Hose to attach to K12 saw
  3. Generator with Ground Fault Circuit Interrupter (GFCI)
  1. Ventilation blower system (generator, blower, hose)
  1. Barrier tape marked with “Authorized Personnel Only” warning
  1. Stakes or pylons for holding barrier tape
  2. Continuous water source
  3. Labeled asbestos disposal bags (at least 3)
  4. Duct tape (for sealing PPE and disposal bags)
  5. Carbon Monoxide monitor
  6. Running water in the trench, or two five gallon buckets full of water, (one inside the work zone and one immediately outside) to facilitate clean up
  7. Cloth for cleaning tools after cutting AC Pipe
  8. Cloth for wiping face after leaving the workzone

Personal Protective Equipment

The following PPE is required during AC pipe cutting with a K12 saw and water

  1. Full face, dual cartridge respirator (at a minimum)
  2. P100 cartridges
  3. Disposable, impermeable protective coveralls, complete with hood, booties and elastic gathers at wrists
  4. Work gloves
  5. Rubber boots with steel toes
  6. Hard hat
  7. Hearing protection

Work Area Preparation Procedures

  1. Conduct pre-excavation preparation.
  2. Establish appropriate work zone set up/traffic control in the area of the excavation.
  3. Excavate the necessary area. Follow appropriate excavation safe practices.
  4. Establish safe area around the excavation, mark off with stakes/pilons and barrier tape. There must be several feet of clear space outside the excavation, so the worker can exit the

trench but still stay inside the asbestos

containment area.

  1. Post signs which state:
  1. Workers intending to be inside the barricade must have (at a minimum) a full face dual-cartridge respirator with P100 cartridges. Workers must have been fit-tested and trained in the use, limitations and maintenance of the respirator, in accordance with CSA Standards and WorkSafe Regulation. Workers shall inspect and clean their respirators prior to each use and complete a positive and negative fit test.
  2. Labeled asbestos waste bags must be available and placed in the work area for disposal of protective coveralls, contaminated waste and waste AC pipe.
  3. Set the upper limit of the carbon monoxide gas detector to 100ppm. Calibrate and bump test the gas detector in accordance with manufacturers’ instructions prior to use.
  4. Set up the blower assembly and position hose in trench, to provide maximum fresh air for the worker while blowing away any CO fumes.

Cutting Procedure

  1. Before entering the taped-off area, worker must don personal protective clothing:
  2. Disposable coveralls. Ensure coveralls fit snugly to the contours of the wearer and will not be subjected to tearing when the worker bends or turns.
  3. Respirator; perform positive and negative fit check.
  4. Put on work gloves
  5. Tape wrists of coveralls to gloves
  6. Tape ankles of coveralls to work boots.
  7. Pull up protective hood of coveralls. Note: If the worker’s head will be exposed to falling, flying or thrown objects, or other harmful contact, a hard hat must be worn over the hood of the coveralls.
  8. Attach Carbon Monoxide monitor to the worker
  1. Any electrically-powered tools used in a wet environment must be attached to a GFCI.
  2. The area of AC pipe to be cut must be sufficiently wetted prior to the cut to remove any dirt, sand or gravel from the pipe.
  3. Attach the water supply hose to the K12 saw, turn on water.
  4. Operate K12 saw in accordance with manufacturer’s instructions, making sure that water is continually applied to minimize or eliminate dust.
  5. If the gas detector alarms, the worker must shut down the K12 saw and exit the excavation immediately, and not re-enter the excavation until the exhaust has visibly left the space.

Clean-up and Decontamination

Waste AC pipe, tools, materials and PPE must be cleaned or disposed of in the following manner, while the worker is still wearing the respirator:

  1. Hose down all pipe and tools in the trench.
  2. Break up wet pieces of AC pipe to be disposed of, place in disposal bag.
  3. Gently squeeze the bag to expel the air. Twist the top portion of the bag into a tail and seal with duct tape. Place into a second bag. Set bag aside.
  4. Rinse reusable tools with running water, or in a bucket of water.
  5. Wipe off any tools which can’t be hosed or submerged, with a damp cloth. Tools and materials must be thoroughly washed and inspected to ensure there is no visible asbestos contamination before being removed from the authorized work zone.
  6. While still wearing the respirator, the worker must hose off or wipe down rubber boots and gloves and inspect to ensure no visible asbestos contamination.
  7. The worker shall remove the disposable coveralls, and place in another asbestos waste bag. Place this bag into the first disposal bag. Gently squeeze the bag to expel the air. Twist the top portion of the bag into a tail and seal with duct tape. Ensure bag is clearly labeled “Asbestos Waste”
  8. The worker will leave the work area boundary while still wearing the respirator, and thoroughly wash hands, remove the respirator and then clean the respirator and face with a clean cloth from the designated clean water bucket. This procedure is known as “personal decontamination”. The worker will seal the Respirator filters with duct tape (if they will be reused) and place the respirator and filters into a sealable bag for storage. If the filters will not be reused, they must be disposed of as asbestos waste.
  9. Asbestos waste contained in the disposal bags must be transported and disposed of in accordance with local, Provincial and Federal regulations.

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AC Pipe SWP Revised 111124Page 1 of 5