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Getex discuss procedures for dust removal in asbestos cement roofs

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article image Removal of asbestos cement roofs

Asbestos Cement (AC) materials typically bind approximately 10 to15% of asbestos by weight in a cement matrix. This is considered to be a low concentration and being bound in a stable cement matrix is less likely to generate dangerous levels of airborne fibres, than when compared with sprayed coatings and insulation.

It is the responsibility of the controller of premises to identify the ACM, assess the risks posed by the ACM identified and implement the control measures to eliminate the risks arising from the ACM and prevent exposure to airborne asbestos fibres [NOHSC: 2018(2005)].

As per the NSW OHS Regulation 2001 a competent person is required to prepare Asbestos/Hazardous Materials Surveys, Asbestos/Hazardous Substances Management Plans, Asbestos Air Monitoring and Asbestos Clearance Inspections.

A competent person preparing the above documents should have:

  • Demonstrated years of experience in asbestos related issues
  • Appropriate Qualifications
  • Appropriate levels of Professional Indemnity Insurance, specifically mentioning asbestos
  • A solid understanding of Asbestos Removal options and techniques of asbestos removal
  • Specialised knowledge of Asbestos Air Sampling testing and interpretation of results- In general, consultants who are considered for major projects must hold NATA accreditation for both asbestos fibre counting and air volume measurement for asbestos air monitoring
  • A solid understanding of Asbestos Clearance criteria and the epidemiology of asbestos related diseases
An Asbestos Consultant is a competent person suitable for the preparation of an asbestos site audit or asbestos/hazardous materials survey and Hazardous Substances Management Plan (HSMP). Asbestos Consultants may also be considered as Occupational Hygienists in their chosen field or specialised branch.
An Occupational Hygienist can recognise occupational factors that cause illness or inefficiency and understand their effect on human beings; evaluate the magnitude of these factors and of the response of an exposed population to them; and prescribe methods to eliminate, control or reduce the influence of the adverse factors.

If a consultant so chooses, he or she, may decide to make a submission to the Australian Institute of Occupational Hygiene and become registered as a consultant in occupational hygiene. Further study and experience may enable them to be considered for higher grades of membership.

Persons acting as Occupational Hygienists, often have all the necessary requirements, experience and qualifications to do so. However, they may not possess the specific skills necessary to advise on asbestos related issues. It is better to visit the AIOH website and select Asbestos consultant from the Consultant search area and ask the hygienist for evidence of their experience.

Structural Engineering consultants provide engineering reports such as Structural Adequacy Reports assessing such things as cracks in roofing and walls. It is Structural engineers who concern themselves with the inspection, monitoring, maintenance, rehabilitation and demolition of structures and structural systems and their components.

Structural engineers carry out strength, serviceability (displacement), and fatigue calculations.
Involving a structural engineer as well as an asbestos consultant/ occupational hygienist is a good practice and a highly recommended component of managing asbestos containing materials which are in the form of potentially brittle roofing materials.

Dust which has accumulated on surfaces found underneath an asbestos cement roof may be a potential problem. And this may depend more upon other factors such as the intended use of the building, the likelihood of any disturbance of the dust and the likelihood of personnel coming into contact with the dust, rather than simply its asbestos content.

Although the possibility that the dust may contain materials such as asbestos or lead should be considered, it may be determined that it may or may not be an issue for a particular site and personnel.

WorkCover NSW says that “if you use a contractor to assist you and the area of bonded asbestos sheeting (fibro) is over 10 square metres, then you need to have it removed by a licensed asbestos removal contractor. If under this amount, then a license is not required”. 

The definition of Licensed Work is found within Chapter 10 of the Occupational Health and Safety Regulation 2001. Licensed work includes:

  • Demolition work
  • Restricted demolition work
  • Friable asbestos removal work 
  • Bonded asbestos removal work (other than work done in relation to bonded asbestos material having a total less than 200 square metres)

The Occupational Health and Safety Regulation 2001 defines “friable asbestos material” as any material that contains asbestos and is in the form of a powder or can be crumbled, pulverised or reduced to powder by hand pressure when dry.

Dust which has resulted from the natural weathering of asbestos cement sheeting and/or the removal of asbestos cement sheeting is a powder. Years of degradation resulting from the effects of weather and industrial processes, such as chemical off-gassing, often results in thick accumulation of dust and debris on top of the internal structures of warehouse type buildings, for example the top of bearers, joists, door frames, machinery and trusses.

If a warehouse with an asbestos roof has been converted to include levels of offices or a warehouse has small enclosed offices on the warehouse factory floor area, then it is likely that the surfaces within the ceiling space above the ceiling (and the ceiling surface) of the office/s will contain dust and/or debris which contains asbestos. The dust is friable asbestos material. Only a contractor who is licensed for friable asbestos work should remove friable asbestos materials (i.e. a contractor with an AS1 friable license). The majority of asbestos roofing contractors have licenses which permit them to remove bonded asbestos containing materials only.

Questions to consider asking the contractor include:

  • How do they intend to approach the dust issue - Have they considered its possible implications?
  • What advice do they give in relation to the “historical” dust which has accumulated within the building?
  • Have they provided a price to remove this dust?
  • Can they do this themselves or will they subcontract another asbestos contractor with an AS1 license to clean the surfaces?
  • When will they do this? Before or after the roof removal?
  • What reassurance do they provide in relation to the dust/debris that they themselves will create when they remove the roof?
  • Will they provide plastic drop sheets within the warehouse, above the offices, exterior to the building?
  • Are they insured against creating further issues of contamination?
  • Are they available to talk to the staff of the client?
The controller of premises may experience problems in the future when a contractor or employee discovers dust/debris in the ceiling space above their office or in or adjacent to their machinery or work space. Offices may be vacated or a factory may cease production until the areas are assessed and an asbestos removal plan is formulised and the area decontaminated. The cost of dust removal at a later time may be higher and occur at an inconvenient time in relation to finances and production.

Consider engaging the services and advice of

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