Managing Asbestos Soil Contamination
Section 7 of the "How to Safely Remove Asbestos Code of Practice 2011" titled 'Controls for specific asbestos Removal work' lists the procedure for handling soil contaminated by asbestos. Soil is contaminated when Asbestos Containing Material (ACM) is dumped on the top soil, or buried ones are disturbed during activities like farming, road construction or natural weathering.
Guidelines :
1. Assessment : This step is necessary so that the assessor recommends the best and most relevant steps to be taken in decontaminating the site. It is fairly short and should only be done by professionals, in line with the Environmental Protection Heritage Council criterion.
2. Site Plan : The acreage, shape, areas of highest contamination and their boundaries must be marked on the plan, which has to have a key to act as guide.
3. Removal : After assessment, samples may need to be taken to an accredited lab for determination of the type of asbestos present, whether bonded or friable. The wet method must be used, as damp soil clumps together. No fibers will float into the air this way.
4. Licensing : A class B license holder should only be involved where the asbestos on the soil has been correctly identified as non-friable. A class A license holder only should work on friable asbestos.
5. Safety :
- Air monitoring : it has to be done at adequately spaced intervals as the work proceeds. The level of fiber in the air should not exceed 0.01 fibers per square milliliter.
- Barricade : an enclosure must be put up around the work area and cordoned off by a 200 micrometer thick plastic sheeting.
- Personal Protective Equipment (PPE) : Full face respirators with constant air supply are best to protect the face. Disposable thick overalls should be used since thin asbestos fines can float through thin or ordinary garment material. Inside the enclosure, a negative air supply unit must be used.
6. Clearance : A clearance certificate is to be issued after the removal of friable asbestos by a certified inspector, who certifies that the area is safe for use once again. The process involves monitoring the air inside and outside the enclosure immediately before and immediately after the removal of the enclosure. The route used to transport the asbestos should additionally be cleared.
A suspected site whose soil is suspected to have been contaminated by asbestos can vary in degree, in terms of description and classification, from contaminated to decontaminated. In between, it could be contaminated requiring investigation, requiring restricted use, cleaned up but for restricted use and non-contaminated. That is according to the Contaminated Sites Act of 2003. A site whose use is restricted implies that the full extent of the contamination is hard to establish, and only the cleared areas can be used. Most of the time, the usable area is demarcated.
When soil is contaminated, it poses a risk when it is agitated and fibers float in the air, or when edible plants grow on it, absorb it when it is and leached and it may end up in the human bloodstream.
