Beadell Resources Limited appointed SRK to prepare a feasibility study of the Tucano project located in the north of Brazil, in Amapá State, where the mean annual precipitation is approximately 2.4 metres.
The feasibility study included surface water management for the pits (Taperebá AB, Taperebá C, Taperebá D and Urucum) and the associated waste dumps. The main focus was to divert clean runoff upstream of the facilities and collect potentially impacted water downstream.
SRK identified three elements that required special consideration in this project:
• With the type of soils on site and constant rainfall year-round, finding the ideal scenario to manage sediment problems
• Locating surface water infrastructure with limited space and the existing and proposed mining facilities on site
• Given the proximity of the facilities to William Creek, identifying the minimum do-not-disturb area near the creek
SRK analysed the minimum particle size to be held in each of the retention ponds, using the results of site monitoring and geotechnical laboratory tests. Based on the results of the calculations, the expected values of total suspended solids (TSS), in most cases, were lower than the maximum TSS threshold; however, only approximately half of the turbidity values complied with the requirements, so adding flocculants was recommended.
The size of the surface water infrastructure was reduced by focusing on minimising the inflow of water from outside of the mine footprint boundaries, to deal with the limited space available. Additionally, including various lining materials, such as high-density polyethylene and riprap, minimised the design sections to optimise the land use.
Location of the sedimentation ponds was a high priority to reduce the project’s impact on William Creek. Criteria included use of minimum catchment areas and minimum disturbance to the natural environment. The contacted water was collected in sedimentation ponds to allow solids to settle and, if needed, to add chemicals and flocculants. Clarified water from the sedimentation ponds will be discharged into the natural creek system that flows into William Creek.
