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Asbestos blasting techniques – is the end nigh?

Written by Nick Garland on 27/06/2016
 

The draft guidance that was doing the rounds last year on blasting techniques (whether that is Quill, Torbo or ice) has now been released as ALG meeting minutes, rather than a full ALG Memo. I am not too sure on where that places it in the regulatory framework, but it is clearly guidance that shouldn’t be ignored. There a few changes to the February 2015 draft that prompted my original summary.

The following piece is an update on the main points to be aware of.

The memo starts with the recognition that blasting may be required in a few rare occasions, but also declares that the process should only be considered as a last resort and not a go-to silver bullet. It also insists that the use of the process (above other more traditional approaches) must be fully justified by the licensed contractor, with evidence in support. What this translates to is that the method must not merely address and mitigate the significant additional hazards, but that the reasons for introducing them in the first place are declared and justified:

  • Noise (>85dB(A)).
  • Vibration
  • Manual handling (holding the lance, but also moving the ‘garnet’ around)
  • High fibre release (HSE results suggest typically 4-10f/ml, but can be up to 20f/ml).
  • Difficult to conduct mandatory personal monitoring because of the dust
  • Risk of enclosure breach
  • Increased risk of blocked NPU filters due to dust and moisture (leading to inadequate ventilation)
  • High levels of carbon dioxide produced by dry ice blasting systems (an asphyxiant and source of positive pressure).

Clients are normally the main driver as to why blasting is being considered (“I want an asbestos free building”). It would therefore be wise to involve them in the decision process, explore whether the reasons for that desire outweigh the added hazards and ultimately justify why it is required. The guidance states that robust processes should be in place to ‘prevent misuse’. Or put another way – review of the justification and sign off by senior management. The technique must also be declared on the ASB5.

The guidance suggests the following controls:

  • Careful phasing so when blasting is taking place, no other task is being conducted
  • Limit the enclosure team to only those directly involved in the blasting process
  • Wet blasting processes (fibre suppressant included in the ‘garnet’)
  • Task sharing – spread out to limit the manual handling / vibration exposure
  • Regular clean up (obviously) but use of a wet-vac**
  • Increased personal monitoring and SEM analysis rather than the traditional microscope on site approach – this will add significant cost and organisational headache
  • Water vapour protection filters for the NPUs
  • Individual careful assessment of what blasting media to use and the pressure levels / moisture content. In other words – specify in your method what the pressure levels and moisture content will be.
  • Reduce the noise levels to as low as possible
  • Hourly monitoring of NPU performance
  • Double sheeting for additional enclosure protection.
  • Hearing protection.
  • Air-fed RPE with dust filter
  • If a dry ice system is being used the process will introduce POSITIVE pressure to the enclosure, therefore the NPUs should be rated appropriately to cope with the carbon dioxide.

** Wet Vacs may be problematic guidance as they do not typically have HEPA filters but the moisture in the ‘garnet’ will damage a standard vac.

These controls will considerably increase time, plant and materials and with them costs. It is difficult to imagine a client stomaching the substantial increase.

I can almost hear the echo of ‘It’s only guidance’, which it is, but the imperative is to implement something equivalent or better and the suggested controls are quite specific and difficult to argue against. As it must be declared on the ASB5, the likely increased chance of an enforcement visit will mean that Ignoring the document will be a high risk card game with your license as the stake.

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