OZ Minerals engaged Exact Contracting to construct stage 1 of their cross valley tailings storage facility (TSF) at their recently established Carrapateena copper/gold mine, north-east of Port Augusta, South Australia. The TSF consisted of three primary embankment structures – decant dam embankment, TSF embankment and causeway totalling approximately 500,000m³ of imported general fill, select fill (crushed/screened) and clay. Pipe works were also completed in conjunction with earthworks including DN560 gravity decant line and multiple DN160 seepage collection lines, totalling approximately 4.5km of butt welded pipe and associated fittings/valves.
All earthen fill materials were site won from designated borrow pits, which were optimised through crushing and screening for select fill zones of the decant and TSF embankments. The supervised fill was imported utilising two truck fleets consisting of CAT 740 articulated dump trucks loaded by CAT 988 loaders, and CAT 777 dump trucks loaded by a PC1250 excavator and placed to design utilising GPS enabled dozers and graders.
Key achievements throughout the project:
The project was achieved on schedule, on budget and injury free – 293 days, with a peak manning of 60 personnel
Management of lining subcontractor to supply and install approximately 80,000m² of bituminous geomembrane on the decant dam and TSF embankment
Installation of 5.2km of LLDPE ballast tubes on the TSF embankment
High quality MDR and as-constructed survey package submitted containing all earthworks, liner, pipe information