Geotechnical engineering for heap leach

The authors present a geotechnical primer especially oriented to heap leach operators, as well as geotechnical engineers new to heap leaching. The geotechnical behavior of leach heaps and pads can have important impacts on a wide range of key issues, from leach kinetics to environmental and safety risks. The failure to properly predict, incorporate, or react to changed conditions has led to a long list of serious problems: dramatic capital and operating cost overruns, inability to achieve economically viable extraction rates, physical instability of the heap and the related risk to the environmental and human health or safety, excessive leakage through the liner system and the resulting environmental risks and legacy issues, as well as regulatory violations being a few of those. Four key stages of projects are addressed: design and construction, commissioning, operations, and closure. For each stage certain weaknesses or gaps in the geotechnical data collection and analyses tend to reoccur from project to project. This paper will address these deficiencies, giving real-world examples, and provide some operational guidance for recognizing these issues and best using geotechnical resources to avoid negative consequences.