Optimum Embankment Design for a Tailings Dam

Selection between thickened, paste and filtered tailings disposal

Behrooz Ghahreman-Nejad

ATC Williams

This paper discusses the method and results of an options study into selection of the optimal form for a 130 m high tailings/water retaining dam, located in a region of high seismicity in central Iran.

The proposed dam is part of a planned expansion project for Sarcheshmeh Copper Mine (SCM), which after construction will provide 550 million tonnes of additional tailings storage over the next 27 years.

Geotechnical investigation at the proposed site indicated that adequate suitable low permeability materials (ie clay) were not available in the immediate vicinity of the dam site and would need to be imported from a distance of well over 10 km (direct). Given the magnitude of the estimated quantity and construction cost it was considered prudent to compare the cost of alternative dam design options for the proposed storage. A total of five dam design options are considered including a conventional rockfill embankment dam with an upstream sloping earth core (ECRD), a geomembrane face rockfill embankment dam (GFRD), a sloping asphalt core rockfill embankment dam (ACRD), a roller compacted concrete dam (RCCD), and a filter rockfill embankment dam for tailings storage together with a smaller earthfill core rockfill dam (ECRD) for storage of decant water.

The risks, costing and design of all options are discussed in detail and the outcome of the study is presented.

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