environment magazine

Asbestos In Soil – Current Issues

By Hazel Davidson, Technical Marketing Manager, ALcontrol Laboratories

For several years, many site operatives/consultants/developers have considered asbestos in soil to only be of major concern if high quantities are present and categorised as hazardous waste (> 0.1%).  Another common misconception is that asbestos is not such an issue as long as the soil is wet.  However, over the last 12 months or so, current thinking on asbestos in soil is changing as a result of a number of initiatives by various industry bodies, some of which are described in this article.

Currently, environmental laboratories offering asbestos in soil analysis can provide a variety of methods:

1.  Gross visual screen for Asbestos Containing Material (ACM) 2.  Detailed screen using a x10 – x 40 standard optical microscope (ACM and fibres) 3. Identification of asbestos type by Phase Contrast Optical Microscopy (POCM) or Polarised Light Microscopy (PLM) 4.  Quantification by gravimetric measurement (only ACM) to 0.1% 5.  Quantification by sedimentation and fibre measurement using POCM or PLM (free fibres) to 0.001%

ALcontrol is accredited for methods 2, 3 and 5 to provide a comprehensive asbestos service to clients.

UKAS (the accreditation body for laboratories) will not now accredit any new laboratories using methods 1 and 4, as these are not considered either robust or fit for purpose, and over the next year or so, laboratories currently accredited for these methods will have their accreditation withdrawn, unless they have submitted methods 2 and 5.   In addition, all asbestos analysis must be accredited, and laboratories will not be able to offer unaccredited methods.   However, if the gravimetric stage (as part of an accredited quantification method) gives a result of > 0.1%, then the material is classified as hazardous waste and this will be an accredited result.  If the result from this stage is < 0.1%, this cannot be quoted as an accredited result, and the sample must proceed to the sedimentation method (Method 5), in case free fibres constitute > 0.1%.

Unfortunately, UKAS is only implementing these changes during annual surveillance audits.  Therefore, the current situation allows some laboratories to offer accredited asbestos methods which UKAS no longer consider to be suitable.

It is critical that, as the risk to human health is from respirable fibres, and not the bound ACM, screening and quantitative methods must include the fibres.

These accredited methods are much more labour intensive and time consuming - an analyst can only perform 3 – 4 samples per day by the sedimentation method, in comparison with 30 – 40 per day for the gravimetric method.  In addition, only a small proportion of the sample is actually analysed for Method 5, so the mixing and homogenisation of the initial soil is critical, and therefore takes longer.   These factors are likely to impact significantly on costs for site investigation work.

Another problem is that asbestos testing is currently only requested for approximately 30% of soils sent to laboratories.  ALcontrol provides a brief description of all received soils, and if prep staff suspect any samples, these are scheduled for an asbestos screen and ID (Methods 2 and 3), even if the client has not requested it.  Approximately 20% of these samples are confirmed as containing asbestos.  The worrying issue is the 70% of samples which are not tested at all.

In lieu of an asbestos SGV (soil guideline value), the value of 0.001% is often taken as indicative of human health risk, based on studies of respirable fibres generated from soil dust, performed by the Institute of Occupational Medicine (IOM) in 1988. The value of 0.1% as indicative of hazardous waste, is taken from the Interdepartmental Committee for the Redevelopment of Contaminated Land ( ICRCL) guideline document, published in 1990, Guidance Note 64/85 ‘Asbestos on Contaminated Sites’.

Industry action in the UK

Due to increasing levels of concern within the industry, there are a number of initiatives aiming to improve the current situation:

• The Environmental Industries Commission (EIC) has set up a working subgroup of their Laboratories Working Group to review the current situation and to raise awareness. They are organising a technical conference on 1st November 2011 at the Manchester conference centre, with experts from most concerned organisations (the EA, Defra, the HSE etc.). CLAIRE are organising this, and information can be obtained from the Events Calendar at www.claire.co.uk

• The Health & Safety Laboratory is re-writing HSG 248 ‘The Analyst’s Guide’, to reflect the current changes in analysis, and this should be available for consultation by the middle of 2012.

• The EIC has also conducted a survey, using Survey Monkey, on the current state of awareness within the industry, and over 200 participants completed this. The data is currently being analysed, and will be available to EIC members.

• CIRIA have funding for a project to develop guidelines for site management and how to comply with current legislation and ‘Duty of Care’, and the Steering Group will have been appointed by the end of September.

• The Association of Geotechnical Specialists (AGS) has also set up a subgroup to discuss asbestos issues and liaise with the other industry groups.

• The Society of Brownfield Risk Assessement (SOBRA) is also discussing the issues and possible ways forward.

• CLAIRE are producing training modules for site staff

• The EA and Defra are aware of the concerns and are actively working with  industry groups, although there are no immediate plans to publish an SGV for  asbestos.

• There is an all party working group also looking at the problems, with a subgroup specifically considering the issue of low level asbestos in soil in primary schools

In summary

The levels of asbestos in the many thousands of soil samples that are arriving at ALcontrol's laboratories clearly indicate that asbestos is a very common contaminant and greater awareness is urgently required.

It is apparent from recent court cases that even the probability of limited exposure to asbestos by site workers or any staff can result in an award of damages, and asbestos related claims cost the insurance industry more than any other category.

Considering the widespread use of asbestos in construction, the number of buildings demolished on sites for redevelopment, and the movement of soil around these sites, it is highly probably that soil dust will be airborne and therefore present a risk.

There is a desperate need for guidance within the industry, and although it is recognised that costs for sampling and analysis will increase, the costs of future litigation over unreported asbestos would be significantly greater.