Predictive assessment of the asbestos content in the Western Italian Alps: an essential tool for an effective approach to risk analysis and management in tunneling operations and muck reuse

The modern approach to the design and management of tunnel excavation, and muck reuse, can be influenced to a great extent by the possible presence of rock formations containing asbestos minerals. This situation creates problems concerning the protection of the workers’ health and the expectable environmental criticalities, while a drastic re-consideration of the muck destination is necessary. Since, in the case of carcinogens, corrective action following exposure or dispersion is not acceptable, detailed knowledge of the characteristics of the material to be excavated is all the more essential. Only on this basis it is possible to design the tunneling operations in a prevention through design approach, so that the tunnel driving techniques, fittings and technologies, and special equipment and modus operandi, can grant, where necessary, minimized risk conditions, and make a correct decision on whether, how and when these measures must be fully activated, since such an approach involves a remarkable impact on costs and work organization. In the Western Alps a detailed identification and quantification of the asbestos content in rocks is a difficult task, due to the fact that the asbestos in the host rocks, mainly serpentinite, shows a highly variable distribution, typical of ophiolitic belts throughout the world, as it is mostly associated with joints and shear zones. The possibilities of a predictive assessment of the asbestos content in the formations to be excavated are here discussed, with special reference to the reliability of the achievable results.