Asbestos soil materials

The common asbestos containing materials that may be found in contaminated land and brown field sites are therefore pieces of cement boarding, insulation boarding, fibrous insulation or occasionally free fibre depending upon the previous usage of the site, bitumen felt, vinyl floor tiles and gasket materials. These materials may have been mixed in with demolition rubble and soil, crushed as hardcore and utilised on site, or simply buried to raise the level of the land prior to redevelopment. 

If the soil material is due to be removed from site for disposal, then the waste disposal carrier and site accepting the waste will require a certificate of analysis determining how much asbestos is present. If the asbestos content is equal to or greater than 0.1% w/w (1000 mg/kg), then the material is classified in the UK as special waste (SI 972 1996) and can therefore only be disposed of... 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials Can catch fire when in contact with porous materials such as wood, asbestos, cloth, soil, or rusty metals Stability During Transport Stable at ordinary temperatures, however when heated this material can decompose to nitrogen and ammonia gases. The decomposition is not generally hazardous unless it occurs in confined spaces Neutralizing Agents for Acids and Caustics Flush with water and neutralize the resulting solution with calcium hypochlorite Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

MSO is unsuited for treating materials with high inert content, such as asbestos, concrete, soils, and rubble. There is concern over emissions from MSO relating to particulate mercury content and radioactivity. MSO is inappropriate for wastes with high tritium levels. MSO pilot programs have encountered problems with carbon monoxide (CO) emissions. The corrosion of reactor materials by molten salt has remained a concern for the long-term operability of the system. The viscosity and volatility of the melt have to be controlled. There have been problems with material from the melt plugging air exhaust and feeder systems. 

Soil may be contaminated with asbestos by the weathering of natural asbestos deposits, or by land-based disposal of waste asbestos materials. While disposal of waste asbestos to landfills was a common practice in the past, current regulations restrict this practice (see Chapters 5 and 8). 

Constantopoulos et al. (1985, 1987a, 1991) attributed the pleural calcifications to the domestic production and use of a tremolite-asbestos-containing whitewash ( luto ) made from a local soil. Analysis of samples of the whitewash material by light microscopy, transmission electron microscopy, and x-ray dispersion analysis indicated that it contained predominantly asbestiform tremolite (Langer et al. 1987). 

Using the optimized run protocol, different amount of samples were run to establish the reproducibility. Samples with low proportions of combustible material such as concrete, brick, metal, asbestos etc. show a good H-3 reproducibility for sample masses up to 10 g. However, for samples having high organic contents, such as biota, plastic, organic-rich sediment/soil etc.,... 

If a site has a history of previous buildings being abandoned, demolished or any industrial processes that may have used asbestos, or led to waste materials being deposited on the site, then it is very likely that asbestos debris or materials will be present within the soil or fill material. 

This method is generally applicable for the analysis of building materials that contain asbestos, however, if the material submitted for analysis comprises of a quantity of soil or fill type material, then careful screening will have to take place to remove all suspect ACMs from the soil. These suspect materials should be separated from the soil and washed if necessary prior to being analysed in accordance with MDHS 77 (1994) as detailed below. 

If these materials are weighed and were detected from within a 1 kg sample of soil, then it is possible to calculate (using density correction factors) a result that can be expressed as a percentage weight-to-weight of asbestos in soil. Using this method, it is possible to achieve a detection limit of between 0.001 and 0.01% w/w (10-100 mg/kg), depending upon the sample matrix. 

In the case of soil or fill type materials that are submitted for analysis, there is no definitive guidance on what level of asbestos in soil might be considered safe or what usages may be permitted where low quantities of asbestos contamination are determined to be present. 

At present, there is no official guidance defining what percentage of asbestos in soil would constitute a health risk and how this figure might depend upon the asbestos type, product, material, friability or moisture content etc. However, the UK HSE is also reviewing the test methods for asbestos materials in contaminated land and may provide additional guidance as part of this future documentation. 

Soil plays an integral part in our lives and is inherently linked to public health. For example, many of the essential trace elements which we require in our diet to remain healthy are derived from soils and parent rock material, and low concentrations or the unavailability of these elements in soil can cause dietary deficiencies. Soils can also be contaminated with a range of potentially hazardous substances (both chemical and biological) which, if present at sufficiently elevated levels, can present a potential public health problem. For example, soils may contain elevated levels of heavy metals such as cadmium and lead which can have measurable and often severe effects on local populations. The soils of Cappadocia in central Turkey are naturally rich in fibrous asbestos-like minerals that are thought to be the cause of a rare cancer in local communities1 while exposure to the bacterium Clostridium tetani in soils can cause tetanus. Despite such examples, the effects of contaminated land have, until recently, been relatively ignored and, even today, our understanding of the mechanisms and level of risk associated with contaminated land is poor in relation to air and water. 

A solution or suspension must be prepared from bulk material or soil contaminated with asbestos fibers in a suitable liquid. In the case of contaminated soil a few kilograms should be taken as the minimum for analysis. Insoluble bulk samples of 2-3 g are ground to fine powder and mixed with distilled water. The way of filtration is the same as for simple water samples. 

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