Feasibility Study and Technical Report - Pretivm

18.13 BRUCEJACK LAKE SUSPENDED SOLIDS OUTFLOW CONTROLApproximately 2.3Mt of waste rock and 9.5 Mt of tailings are anticipated to be depositedin Brucejack Lake over the projected 22-year mine life. The estimated final footprint ofthe waste rock and tailings is shown in Figure 18.10. Stringent discharge criteria (basedon the Metal Mining Effluent Regulations (MMER)) state that the TSS concentrations inthe outflow at Brucejack Creek must be less than 15 mg/L.The tailings deposition system has been developed to minimize the concentration of finesuspended solids in the outflow to Brucejack Creek by discharging near the bottom of thelake (at 80 m depth) and under the accumulations of tailings solids. On the other hand,waste rock with a wide range of particle sizes is to be deposited in the lake by surfacedumping from causeways raising the possibility that fine granular material will beintroduced to the surface layer of the lake and to the outflow.It will be necessary to control the TSS concentrations at the outlet of Brucejack Lake tomeet the MMER regulations. The following three possibilities were proposed anddiscussed, and an allowance has been included in the capital cost estimate:• washing waste rock before depositing in the lake• turbidity curtain surrounding tailings deposit and waste rock• outlet control structure for temporary control of the lake outflow.Further work regarding the TSS mitigation strategy is required during subsequent stagesof design.18.14 COMMUNICATIONS18.14.1 SITE TELECOMMUNICATION SYSTEMA complete site-wide telecommunications system will be installed in two phases. The firstphase will include the base installation of the communication system during theconstruction phase. The second phase will allow for expansion of the system to includethe operating plant. Major subsystems include:• a VoIP telephone system for buildings, camps, and offices• satellite communications for critical voice and data needs• Ethernet cabling for site infrastructure and wireless internet access• very-high frequency (VHF) two-way radio system with eight public channels• four remotely located VHF repeaters• satellite TV and Internet for the camp at the mill site and the camp at thetransfer station, including a wireless access tower for communications to thetransfer station and airport location.Pretium Resources Inc. 18-38 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC