Assure 360

When to visual in the four-stage clearance

Written by Nick Garland on 10/02/2022

One of the main objectives of the new analysts’ guide is to reduce analyst exposure, by clarifying what is licensed work, and what falls under the analyst’s remit. But the HSG 248 document is now massive, running to 238 pages. In cases where it hasn’t been fully read and understood there’s the potential for misunderstanding.

I’ve been thinking about this after a recent project, in which a difference in understanding created the risk of costs spiralling out of control. The project in question related to a wall that had sporadic asbestos insulation spatters underneath an imperfect layer of paint. The job was to scrape the wall back and then encapsulate the residues – so far so normal.

However, in this case the analyst was unwilling to enter the enclosure prior to encapsulation. This created the potential situation that, if the analyst wasn’t happy with their visual after encapsulation, the licensed asbestos removal contractor (LARC) would have to strip all the paint off and start again. The analyst’s view was that the project was not yet finished, the enclosure was therefore live, and that in line with HSG 248, ‘they do not do live enclosure entry’. For the LARC it represented a very expensive project risk.

So what does the guidance suggest? On the surface of it, HSG 248 is fairly ‘clear’:

The nature and extent of exposure will depend on several factors including the activity, the type and condition of the ACM and the effectiveness of any controls. For example, all entry into asbestos enclosures carries a risk of exposure to airborne fibres. Analysts should avoid as far as possible entering ‘live’ enclosures while removal or remediation work is still being carried out. If entry into a ‘live’ enclosure does occur there will be potential exposure to asbestos fibre concentrations above the control limit or short-term exposure limit.

Para 1.6, Pg 11 HSG248

However, if we look deeper (and when I say deeper, I mean we have to read to page 193) there’s more guidance under the section “Clearance for specific situations” – the bold is mine, for emphasis:

Inaccessible or impossible to remove asbestos

Spray-applied asbestos is often found in crevices or holes through walls where pipe work or girders run. These may leave asbestos residues that are impossible to remove. In these cases, the analyst may permit the use of non-flammable sealant such as foams or plaster to fill the hole and seal the asbestos within it. Before the sealant is applied the analyst must be satisfied that as far as reasonably practicable the asbestos has been removed.

Para A5.78, Pg 193 HSG248

Use of encapsulant or sealant

Where asbestos has been sprayed on to porous surfaces (e.g. breeze blocks, bricks, plaster and concrete), it is almost impossible to obtain an asbestos-free surface. The analyst should satisfy themselves that further removal is not reasonably practicable, and should advise the contractor and/or building client to seal the residual asbestos with a permanent proprietary sealant. The visual inspection can restart once the sealant has been applied and dried. In these circumstances encapsulation of asbestos should not take place before the analyst has seen the residual asbestos. A note should be made on the CfR and recorded in the asbestos register and management plan for the premises.

Para A5.80 Pg 194 HSG248

This second paragraph matches my example situation perfectly, but in fact both paragraphs make clear that the analysts must complete a visual before the LARC encapsulates any remaining asbestos to make sure (essentially) they are not hiding anything. While the general guidance in paragraph 1.6 says that analysts should avoid live enclosures ‘as far as possible’, this subsequent guidance takes us to the heart of the issue – a live enclosure is one where removal work is ongoing. In these situations, the enclosures are not ‘live’ as all possible removal has been finished.

Going further

In fact, my personal preference is to go a step further. I believe all such projects should be broken down like this:

  1. LARC cleans the enclosure
  2. Supervisor is satisfied that the surface is completely clean and no more dust or debris can be removed
  3. Analyst does visual and agrees or rejects the supervisor visual
  4. Reclean or not as appropriate
  5. Stage 3 air test:
    1. If it passes – optional encapsulation in half-masks after the enclosure comes down as an extra reassurance to the client
    2. If it fails – reclean. Encapsulate and repeat the air test

With either option after the stage three air test, the client gets valuable extra information that they wouldn’t get with the traditional approach. Based on what happens, they know to what degree they need to be cautious about the wall.

This is my personal preference, and I’d be interested to hear opposing views on it, so let me explain my reasoning. First, read this rather long paragraph from the Analysts’ Guide:

There may be occasions when some asbestos is to remain in situ in the enclosure. It may be that only damaged asbestos lagging is being removed from pipe work, and that undamaged material is to remain; or it could be that only a proportion of asbestos ceiling tiles is being removed. The analyst should have been made aware of this in the discussion on the scope of work as part of stage 1. The contractor should have checked the condition of the remaining ACMs as materials in poor condition could lead to a failure in the four-stage clearance when the analyst checks. If the analyst does find asbestos materials in poor condition these will need to be dealt with (eg repaired, encapsulated or removed, all of which actions are likely to need agreement of the building client and the involvement of a licensed contractor. The four-stage clearance should stop at this point and the contractor/building client should be informed. The four-stage clearance should not restart until the matters have been rectified. Any remaining ACMs in good condition should be recorded in the CfR so that the building client can update the asbestos register and management plan accordingly.

Para A5.76 Pg 192 HSG248

My logic is that if we are working on a wall that only ever had occasional splashes of debris – the risk starts at low. If:

  • the project is actually to remove all exposed asbestos, and leave any that is concealed by a stable paint layer;
  • the walls have been rigorously scraped and cleaned (possibly several times over the years);
  • the thorough visual inspection(s) cannot locate any asbestos / dust / debris / loose paint (or it would fail and a re-clean would be demanded), all that remains is the possibility of asbestos under some remaining stable paint.

The selection of the scrape and vac technique is therefore intentionally leaving some asbestos in by design, and paragraph A5.76 is the reference that we should be looking to. This allows the analyst to make a judgement that all loose paint has been removed, and the asbestos left in by design would be noted on the four-stage clearance (4SC) certificate.

While we haven’t 100% removed the asbestos-containing material (some is being left in by design), stage two has passed, and there is no absolute need for encapsulation. But if the air test subsequently identifies a problem then we must encapsulate. On the other hand, if the whole 4SC passes, and we still want to encapsulate, well, that’s an ultra risk-averse decision that can be completed as a non-licensed activity.

I appreciate this is possibly a left field opinion, but I believe it addresses what we are trying to do which is understand and mitigate risk, rather than blindly follow what we’ve done before.


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