GEOTECHNICAL CONSIDERATIONS IN SURF ACE MINE RECLAMATION

Abstract

Most attention in surface mine reclamation is given to agronomic soils and revegetation, but reclamation success depends on the geotechnical characteristics of the underlying earth. If the soil and rock that underlie the surface are not stable, surface treatments lack the dependable foundation needed for them to succeed. Reclamation practitioners need to understand those geotechnical considerations - material properties, structures, and processes - that affect stability. Properties of rock and soil are altered by mining, and those altered materials together with water and processing waste form often-complex mixtures of materials that must be stabilized in reclamation. Surface mining alters existing landforms and creates new ones such as pit walls, spoil and waste rock piles, tailings impoundments, and earthfills. Those structures need to be constructed or stabilized so that they can endure and support successful reclamation. Processes that affect material properties and landforms include mechanical breakage, accelerated weathering, erosion, and mass movements. Mechanical breakage and the resulting accelerated weathering combine to change material properties, usually expressed as degraded strength, that can lead to instability of landforms. Erosion, especially that related to extreme storm events, and mass movements in the form of slope failures are the most problematic processes that must be taken into account in reclaiming mined lands. These geotechnical considerations are essential in successful reclamation, and practitioners who overlook them may find their work literally sliding down a slippery slope.