Design of the Pierina Waste Dump

CIM Vancouver 2002
X. Ochoa, R. Sharon,
Abstract Development of Barrick Gold’s Pierina Gold Mine in north central Peru requires construction of a waste dump for disposal of sub-ore grade materials stripped from the open pit to expose the ore. The waste dump site is located in a V-shaped valley adjacent to the open pit and is underlain by thin colluvial and morainal soils with locally thick peats and glaciolacustrine deposits. Bedrock underlying the site consists of variably weathered volcanics. The site is subject to moderately high seasonal rainfall and significant seismicity. The geotechnical quality of the waste rock is highly variable, ranging from poor quality, degradable, soil-like materials containing appreciable quantities of silt and clay, to good quality, hard, durable, blocky waste rock.

A hybrid dump design concept was developed that provides for in-pit segregation of good and poor quality waste, and selective placement of materials in the dump to maximize stability and enhance internal and subsurface drainage. The design includes a rock drain beneath the dump along the axis of the valley and a series of connected finger drains. Extensive peripheral diversions and measures to inhibit infiltration of precipitation are also included.

This paper discusses the unique challenges presented by the site and waste materials, the design methodology and stability analyses, planned monitoring systems and the experience with the early development phases.
Keywords: Rock, dump, Drainage, Waste, Stability
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