Worldwide, the very mention of asbestos sparks fears of deadly consequences to those exposed – and rightly so. A group of minerals made up of many small fibres, asbestos is a known carcinogen linked with a range of diseases including lung cancer, asbestosis and mesothelioma.

Since the 1990s, our understanding of asbestos and the potential health risks it can cause has greatly improved. We now know that if left buried and undisturbed, asbestos doesn’t pose a health risk. But what if your project requires asbestos to be disturbed, exposed or removed?

When asbestos fibres become airborne, the potential health risks change significantly. Stringent rules and legislation are abundant, and dealing with asbestos can be a costly exercise causing unwanted attention if not managed appropriately.

But what is the best way to manage this? In many contaminated land cases, the level of asbestos in soils is low – yet our immediate reaction is to treat it as a high-risk waste.

Asbestos was commonly used in New Zealand from 1940-1980 in various building materials. As a result, there are now increasing examples of asbestos contaminated sites being discovered. Growing population in cities like Auckland have resulted in a flurry of new building construction and infrastructure improvement – often where asbestos buildings have been inappropriately demolished or where asbestos waste was previously dumped.

Many places in the world, including New Zealand, currently treat asbestos in soil differently than all other contaminants, but why?

Asbestos-related diseases are linked to exposure to free asbestos fibres, generally at high concentrations over the long-term. But long lag times between exposure and becoming sick, growing fears fanned by media reports and an ever increasing New Zealand asbestos register is influencing the way we deal with it. Perhaps more than necessary.

With no New Zealand guidance for assessing, remediating or managing asbestos-contaminated sites, any asbestos found in soil is managed in accordance with the Health and Safety in Employment (Asbestos) Regulations 1998, developed to manage asbestos in buildings – quite a different situation to asbestos in soils.

Owners in both the management of the soil during earthworks and off-site disposal of excess spoil are under pressure to over deliver when it comes to handling this material, for fear of a mis-step under the public eye. 

Up until now, low-level asbestos contaminated soil has been disposed of at a Class A landfill. These facilities use systems designed to provide a degree of redundancy for leachate containment, and collect landfill leachate and gas. Many of these measures aren’t applicable to the safe disposal of low level asbestos contaminated soil – and prove to be a costly solution for owners. Because of this, Coffey is taking a new approach that allows owners to effectively manage the risk of low level asbestos in soil, rather than disposal sites traditionally designed to deal with much higher risk contaminants.

Sometimes the simpler option is the most effective one

Safety is always at the core of what we do – which is why mitigating risks to both our people and others exposed to asbestos is our key concern.

But we also believe that with such serious consequences at stake, decisions for dealing with asbestos must be information driven – not emotive. 

Instead of disposing of all low-level asbestos contaminated soils at Class A landfills, we should consider the degree of risk that actually exists. At the end of the day, our actions should be dictated by one simple question: how can we effectively manage the risk of asbestos becoming airborne?

Minimal disturbance and encapsulation are key to disposal cost savings

We know asbestos is a risk to human health when fibres become airborne, which is why we believe that often the most effective way to deal with this contaminant is to disturb it as little as possible and manage it in situ.

We’ve assisted several developers in managing risks during earthworks for redevelopment of asbestos contaminated sites using cap designs and on-going land use controls to protect future site users. A key element of these solutions has been our experts working with council to gain appropriate consent approvals.

In situ asbestos management is often feasible at a development where land use controls can more easily be enforced. But residential and commercial developments often call for soil to be removed from site. And until now, the only option has been for removed soil to be taken to a Class A landfill.

But managed fill sites are now a genuine alternative. These sights are cheaper to access and provide a simpler, more cost effective solution for the project owner. In our experience, capping and land use controls associated with many managed fill sites (disposal sites requiring resource consent to accept well-defined types of non-municipal waste, for example low-level contaminated soils) are more than enough for minimising risks of asbestos in soil – effectively cutting your disposal costs by two thirds or more.

Worksafe NZ recently endorsed the Western Australian guidelines for asbestos investigation and management. These guidelines advocate a weight of evidence approach to assessing risks associated with asbestos in soil. This takes into account laboratory data as well as other lines of evidence, like frequency and occurrence of positive asbestos results.

This method allows for more informed decision making on asbestos disposal options, and is an approach we’ve adopted successfully within New Zealand  gaining regional council approval for our client to dispose of low-level asbestos contaminated soil at a managed fill site. 

By avoiding the need to use a Class A landfill for disposal, we’ve been able to save our client significant disposal fees.

How can Coffey help?

By using our expertise and ingenuity, and collaborating with our clients and regulators, we’ve delivered real cost savings on management of soil contaminated with asbestos in New Zealand.

These strategies have been reviewed and approved by the local and regional councils – with very little risk to our client.

Asbestos is an emotive contaminant that should be treated in a risk-based nature – the same as every other contaminant we are exposed to.

Our specialists have the technical expertise and track record when it comes to dealing with asbestos contaminated soils.