NATURALLY OCCURRING ASBESTOS
The term ‘naturally occurring Asbestos’ refers to fine fibrous minerals of the serpentine and amphibole groups that occur in rocks or soil. ‘Asbestos’ was mined and then made into products due to its ability to withstand heat, erosion and decay and, as a bonus, also had fire and water-resistant properties.
All Asbestos comes from Nature
Asbestos is a commercial term, however all Asbestos comes from nature.
Naturally occurring Asbestos may be disturbed by weathering or human activities such as ground-disturbing activities such as road building, agriculture, forestry, mining, quarrying and urban development which causes the fine fibres to disburse into the air where they could be breathed in.
The geological occurrence of Asbestos
Although Asbestos and asbestiform minerals may form in a wide range of rock types, large accumulations are usually associated with ultramafic rocks which are typically dark rocks rich in magnesium and iron with relatively low silica and potassium and composed mostly of minerals such as olivine and pyroxene.
Naturally occurring Asbestos in NSW
Major deposits in NSW include slip fibre and cross-fibre accumulations at Woodsreef and Baryulgil Chrysotile Asbestos deposits. Tremolite is known to be associated with Ordovician Byng Volcanics, with the Ordovician to Early Silurian Rockley Volcanics, the Fifield Alaskan ultramafic complexes west of Dubbo and is also associated with amphibolites in the Curnamona Geological region around Broken Hill.
Naturally occurring Asbestos in Central West NSW
In the Central West of NSW there are Fibrous Temolite sites around Sofala, Cow Flat and Blayney, Serpentinite belts around Dog Rocks (Oberon) and Lucknow and Geological Units with high Asbestos potential stretching from North Orange, east of the city and down to Newbridge. See map below (scroll for more after this image).
Based on the assessment where known locations of Asbestos has been identified and probable sites where Asbestos indicator minerals and/or textures have been identified, 6 694 479 626 km2 or about 0.83% of NSW is affected by rocks with significant potential to host naturally occurring Asbestos.
The main naturally occurring Asbestos areas with potential impacts from disturbing activities are:
- The major serpentinite belts including the Great Serpentinite Belt in the New England region along with the Coolac Serpentinite in southwest NSW and serpentinites associated with the Gilmore Suture in south central NSW.
- Ordovician to Early Silurian rocks east of Orange.
- Ultramafic complexes in central west NSW including areas near Fifield southwest of Dubbo.
The only certain way to identify whether Naturally Occurring Asbestos is present on your property is to have on-site testing conducted. Testing can be performed by independent service providers with test laboratories should be accredited by the National Association of Testing Authorities (NATA) – such as Regional Enviroscience.
One indication of areas with NOA is that they may have flora lacking in numbers or variety, with the plant species present showing inhibited or stunted growth – Agricultural crops and grazing pastures may be similarly affected. Soils that form from the rock-types typically associated with NOA tend to have low fertility and a mineral composition that can harm plant growth.
The recommended action is to minimise disturbance of NOA material. In most circumstances leaving the material in place and covering with soil or other material that is known to be free of NOA is an effective control.
Persons conducting businesses or undertakings (PCBUs) in NOA areas will have requirements for an Asbestos management plan under the Work Health and Safety Act 2011. People who are not conducting a business or undertaking who propose to disturb NOA on their property should consider developing an Asbestos management plan.