How to prevent, manage & remove asbestos in soil

What is asbestos in soil?

Asbestos is highly hazardous and is a common contaminant of land earmarked for development and construction across Australia. If asbestos fibres become airborne and are inhaled, they present a serious risk to health. In December 2003, asbestos was banned in Australia making it illegal to import, store, supply, sell, install, use or re-use asbestos materials. However, prior to this, Australia was the highest per capita user of asbestos products in the world. Therefore, asbestos is a common contaminant in soil on sites through industrial use, waste disposal or demolition of previous constructions.

Asbestos in soil can take a range of forms, each of which is likely to present asbestos contamination to varying degrees of concentration, degrees of deterioration and size of materials.  The types of asbestos most likely to be found in contaminated soil are:

• Asbestos-Containing Material (ACM);

• Fibrous Asbestos (FA); and

• Asbestos Fines (AF).

Contamination is often identified during a change of land or property use and has significant implications for landowners, developers, purchasers, councils, communities and other stakeholders.

What causes asbestos in soil?

Asbestos is a naturally occurring, fibrous, silicate mineral that was used extensively within building products throughout Australia (typically between the 1950s and the 1970s) due to its reinforcing and insulating properties. Asbestos is present in as many as one in three homes in Australia built prior to 1990. This historical use of asbestos in building materials, coupled with poor demolition and disposal practices, has resulted in widespread asbestos contamination in soils throughout Sydney and Australia, such as: 

• Poor demolition and removals;

• Illegal dumping; 

• Uncontrolled fill; 

• Onsite building waste; 

• Roof runoff to soil; 

• Use of contaminated recycled materials; 

• Damage to properties (i.e. from fire / severe weather event); 

• Underground infrastructure (telecoms pits and pipework); 

• Asbestos disposal sites; and 

• Naturally occurring asbestos.

Given the complexities associated with the soil environment, asbestos in soil contamination must be managed with careful consideration of the potential for it to impact on human health during preparation, development and construction activities on the land. The long-term risk to people using the land and future developments must also be considered. 

The risk of asbestos in soil is dependent on the previous uses of the site, the quantity and nature of the asbestos material used in previous construction activities and the way that previous buildings were demolished or renovated.  

How to prevent asbestos in soil

There has been significant development in our understanding of the risks and hazards that asbestos presents to human health during the last 30 years. Since 2003, when Asbestos was banned in Australia, substantial legislation and codes of practice have been developed to ensure that those involved in demolition, waste disposal and land management are managing and preventing the contamination of soil and land with asbestos and other contaminants. However, a historical lack of understanding and absence of legislation, along with continued examples of non-compliance and poor management, means that there remain many pieces of land and property where soil contamination by a range of contaminants – including asbestos – is present.

In these instances, it is essential that Contaminated Land and Hazardous Materials specialists are engaged in the assessment, analysis and remediation of contamination in soils and plans for the development and use of contaminated land.

Identification of Asbestos Contamination in Soil

Identification of Asbestos contamination must be completed by a suitably qualified and experienced assessor/ competent person. The competent person must be able to identify, investigate and assess asbestos contamination as part of wider environmental site assessments. 

This should include: 

• A site history review;

• Review of records (asbestos register, aerial photos showing structures); 

• Anecdotal information; 

• Review of development plans; and

• A site visit and walkthrough.

Visual observation can be used initially utilising a grid based systematic walkthrough of areas of concern that have been identified during preliminary site investigations. During visual observation, comments should be made on the presence, or absence, condition (bonded or friable) and distribution of asbestos materials. Any dumped material, uncontrolled fill and structural footprints should be identified and suspected of containing asbestos materials. Additionally, any existing asbestos containing structures should be noted. 

Field sampling may be undertaken for confirmation of assumptions, such as rough impact delineation or to confirm asbestos presence within suspected material. 

The concentration of asbestos in soil does not necessarily mean that airborne fibres will be released. For an accurate picture of the risks and hazards associated with Asbestos in soils, a Tier 2 exposure assessment involving air monitoring should be undertaken to quantify the potential risk associated with disturbing asbestos.