Asbestos is found in a wide array of materials categorised as Asbestos-Containing Materials (ACM), identified in today’s asbestos registers and widely spoken about in today’s workplace health and safety climate. But less commonly discussed is asbestos in soil. This certainly isn’t due to a lack of asbestos-contaminated soil but perhaps to the difficulty in identifying asbestos in soil.
It’s consequential to note that your asbestos register will unlikely identify asbestos-contaminated soil. This is because it is generally outside the scope of an asbestos survey that aims to identify asbestos risks in structures above ground. In addition, most asbestos products today are generally permanently attached to a fixed position and easy to see, unlike asbestos in soil which can move freely horizontally and vertically, making an accurate assessment impossible without mechanical and analytical intervention.
There are two main ways that asbestos can contaminate soil. Firstly, from the ground itself, as this is where all-natural minerals are formed. Secondly, is the result of asbestos-containing materials ending up on/ in the environment, leading to the material’s (asbestos binding matrix) decomposition, releasing asbestos fibres from their bonds and allowing the fibres to move freely with the soil. The latter is most common and usually results from:
- inadequate asbestos removal work or demolition
- degradation of a building or structure on site
- legacy or illegal dumping
- waste burial
- past use of contaminated fill/topsoil.
What should you do if asbestos in soil is thought to be present?
Asbestos in soil can pose a significant risk to human exposure. If this is the case, control measures such as barricading and dust mitigation should be implemented immediately. However, engaging effective control measures without knowing the extent of the affected area can often be challenging. Therefore, until a Licenced Asbestos Assessor can quantify the scope of asbestos-contaminated soil, the worst-case sicario should always be used to establish control measures.
Contact a hygienist company such as Global Asbestos Audits with Licenced Asbestos Assessors to conduct a Preliminary Site Investigation (PSI) and establish adequate interim control measures to help prevent exposure and cross-contamination of asbestos in soil.
Preliminary Site Investigation
The Preliminary Site Investigation (PSI) usually involves establishing a site history to identify the characteristics of the site (such as the location and layout, building construction, geological setting, current and past activities, current and past uses, and heritage considerations), to aid the full site inspection.
Using the findings from the site history as a reference, the LAA will conduct a site assessment, expanding the investigation. Initial samples of bulk material (potential ACM) and soil from likely hot spots help clarify the asbestos in soil hypothesis and aid in developing a sampling program for the Detailed Site Investigation (DSI).
Detailed Site Investigation
The full site investigation is based on a predetermined Sampling Analysis Program (SAP) formulated from the PSI, using methods aligning with NEPM guidelines and Australian standards. The SAP generally involves taking soil samples at different determined depths in a grid-like fashion to determine the extent of the asbestos soil contamination horizontally and vertically. Then, the soil samples are sent to a NATA-accredited laboratory for testing asbestos in the soil.
The DSI report is formulated from the analytical finding, outlining the extent of the asbestos soil contamination in the sampling area and the type of contamination, being friable or bonded. Using these findings, the DSI will outline the possible methods to remediate the site and make it safe for human occupation, as well as outline the appropriate control measures for the duration of the event.
Rectification methods for asbestos in soil
There are three main courses of action for eliminating or reducing exposure risks to asbestos in soil. Selecting the appropriate action plan will vary on several situational factors outlined in the DSI report. Factors such as the location, type of soil, intended use of the site, historical or arachnological significance, and type of asbestos in soil contamination (friable or bonded) will affect the outcome.
Remediation of asbestos in soil
The remediation process involves combing the contaminated soil and removing the pieces of bonded asbestos. This method is typically implemented for surface contamination where no friable asbestos fibres are in the soil. Often a rake with specified lengths is used to ensure all the surface contamination has been effectively removed.
New machinery has recently been approved for use in Australia to remediate bonded asbestos in soil. The process involves transporting the contaminated soil in EPA-approved transport to the facility. However, this can be more economical depending on the location and quantity of contaminated soil.
Removal of asbestos in soil
Removing asbestos in soil is congenial for bonded and friable asbestos soil contamination; however, in most situations, this is performed under an A-class licenced asbestos removalist. Soil is removed from a predetermined buffer zone, both horizontally and vertically of the contamination zone, before being transported in EPA-approved vehicles to a registered asbestos soil waste facility. The soil is continuously watered down while excavating using hand tools or machinery with enclosed HEAPA-filtered cabins. Asbestos air monitoring is conducted on various persons and locations during the process.
Encapsulation of asbestos in soil
Encapsulating the asbestos-contaminated soil using additional fill or concrete is achievable for bonded and friable asbestos. Encapsulation is a fast and effective method for minimising the risk of asbestos exposure. However, it’s not as effective as removing the risk and could become a future problem. In addition, the site must be registered with the EPA and the local council, recorded in an asbestos register, and managed in an asbestos management plan.
Global Asbestos Audits is committed to protecting the health and safety of the Australian population from exposure and contamination. If you suspect you may have a problem, please contact us for consultation.