Site wide water management for a large coal mine expansion

The Bulga Coal Complex, managed by Glencore, includes existing open cut and underground coal operations. The existing open cut mine was approved to operate until 2025 and the existing underground mine until 2031. The Bulga Optimisation Project, which received government and regulatory approval in 2014, allows for the extraction of an additional 230 Mt of ROM coal and extends the life of the mine to 2035. The optimisation project enables coal resources to be maximised within the existing development boundaries while reducing noise and dust impacts on near neighbours. The main function of the new surface water management system is to capture and treat runoff from new visual bund emplacement areas located to the southern and north-western sides of the site; and runoff from new haul roads and infrastructure areas. The project includes the development of 13 sedimentation dams ranging in storage capacity from 5ML to 193ML, two mine water dams, modifications to an existing mine water dam; 38 mine water and 16 clean water drains; and 23 pump stations with associated piping infrastructure for new and existing dams. The system will deliver water to an existing 3000ML mine water dam, as well as a new dam, which will store and release up to 2000ML of water from site under the Hunter River Salinity Trading Scheme. The overall water management system design reduces the risk of mine water discharge compared to similar historic mines, increases on-site water storage capacity and improves opportunities for controlled offsite release. The improved risk profile represents a step improvement in surface water management when compared with existing coal mines in the Hunter Region, and the wider Australian coal industry. Specific topics discussed in this paper include the use of value engineering techniques to improve capital and operational cost efficiencies; designing for a relatively complex brownfield site; and designing for future underground mine subsidence.