Geotechnical Challenges faced when raising the tailings dam at the Lisheen Mine
About the event
The Lisheen Mine, an underground lead and zinc mine in North Tipperary, was discovered in 1994 and has been in production since 1999. It is fully owned by Vedanta Resources Plc. and is currently scheduled to close in April 2015. The Lisheen Tailings Management Facility (TMF) has an internal footprint of approximately 64 Ha and is located on an area of peat bog adjacent to the mine site. The TMF embankment was constructed with glacial till and rockfill and utilised a combination of low density polyethylene (LLDPE) and geosynthetic clay liner (GCL) systems. On closure, the facility will contain approximately 10 million tonnes of tailings. In January 2008, Lisheen commenced a progressive rehabilitation programme on the Lisheen Mine TMF and by June 2010, approximately 8.5 hectares of the facility was rehabilitated.
Due to the discovery of a new ore body in 2010, additional TMF capacity was required to meet revised life of mine requirements and consideration was given to raising the height of the remaining operational area of the TMF. This entailed forming an internal embankment on the beached tailings to form one wall with the other three walls being formed using the upstream method. A trial area on the previously formed rehabilitation area was identified and instrumented to assess settlement under loading. This solution proved to be technically and commercially advantageous and was approved by the Irish regulatory authorities. In June 2011, a 12 month program to deliver a two meter raising of the facility commenced and the project was successfully completed in June 2012. Progressive rehabilitation of the facility is scheduled to re-commence in 2013 and rehabilitation of the entire facility is expected to be completed by 2017.
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About the speakers
Sean Callery Chartered Engineer, Principal Tailings Engineer - Vedanta Resources plc
Paul Quigley Chartered Engineer, IGSL Ltd
Admission
Free - all welcome!