Foundation design for tucano gold project
The Tucano project is located in Amapá State in northern Brazil. This area has an equatorial climate, with year-round high humidity and rainfall. Mean average precipitation is 2,387 mm. Average annual evaporation is 1,400 mm. Groundwater occurs at shallow depths (typically 0.5 to 30 m below ground level).
Decommissioning of former facilities and ground improvement were required for the installation of the mill, primary crusher, transfer bin, thickener and carbon-in-leach tanks. An amphibolite-granite contact was identified in the area, which caused heterogenic subsoil conditions. The relocation of structures and optimisation of cost and performance were guided by considerations of pre-consolidation pressures due to the pre-mining topography, and precise identification of the contact zone. It was determined that embankment construction could only be conducted during the dry season. The natural moisture of borrow materials was close to optimum. Vibrating wire piezometers allowed pore pressure build-up to be controlled, and ensured a safe embankment rate of rise was achieved.
SRK’s geotechnical team was engaged to undertake the following scope of work:
- complete drill holes, SPT, CPT and test pit investigation: design, technical supervision, geotechnical logging and soil sampling for laboratory testing
- evaluate ground improvement options for SAG mill foundation
- assess allowable design bearing pressures for the foundations of various structures such as the thickener, processing tanks (carbon-in-leach and detox tanks), mill, bin and primary crusher
- calculate consolidation settlements
- prepare design parameters for vibratory equipment foundations such as mills and crusher
- prepare design parameters for the construction of a retaining wall at the run of mine/crushing station, assumed to be made of reinforced concrete
- provide design recommendations for haul and plant roads
- select fill sources and construction specifications for engineered fills, embankments and roads
- provide compaction controls for improvement of thickener and carbon-in-leach tank foundations and embankment construction
- provide design and construction supervision for 15 embankments up to 33 m high and 465 m long
- compile as-built reports.
