Feasibility Study and Technical Report - Pretivm

16.10.1 DISTRIBUTION SYSTEM DESIGNThe pipe routing for the underground distribution system (UDS) was developed withconsideration given to site conditions and client preferences in combination with pipelineoperation experience and hydraulic modelling. Some of the conditions that were takeninto account in the design include:• the availability of the conveyor ramp down to the 1,300 Level, which is isolatedfrom vehicle traffic• the difficulty foreseen in accessing any trenched pipelines on surface due to siteconditions, especially during winter months• the mining schedule, which defines that the VOK Zone will be developed in theearly years while the West Zone will only be developed in the second half of themine life• the long distance from the paste fill plant to the underground workings (morethan 800 m)• the location of the paste fill plant below the elevation of the top third of the VOKore zoneThe mining schedule breaks down the Brucejack orebody into six areas: VOK-U, VOK-M,VOK-L, GAL, WST-U, and WST-L, as shown with their respective elevations in Figure 16.7and Figure 16.8. The first areas to be mined are the VOK-U, GAL and VOK-M; coming onlinein Years 1, 2 and 3, respectively. Production in VOK-L will start in Year 6, while theWST Zones will only come on-line after Year 15. The VOK zones have continuousproduction scheduled until Year 20. The paste fill distribution system was designed withthis schedule in mind.The main challenge for the Brucejack paste fill distribution system is that a portion of theorebody is located above the elevation of the paste fill plant. A balance in strategy isrequired to ensure that paste can be pumped to this section of the orebody withoutcompromising the quality and proper flow distribution to the rest of the mine.16.10.2 DISTRIBUTION APPROACHThe philosophy developed for the paste fill distribution system is a dual pumping system.This will optimize the pumping capacity and minimize wear on the paste pumps. Apositive displacement pump in the paste fill plant will provide paste to all of the WestZone (WST-U and WST-L) and the lower VOK (below the 1,330 Level). The paste plantpump will also feed a booster pump located near the crusher station at the bottom of theconveyor ramp, and near to the main entrance to the VOK Zone area on the 1,330 Level.This booster pump will pump paste up to the Galena Zone and the upper VOK Zone(1,330 Level and above). Figure 16.33 shows the breakdown of the Brucejack ore zoneby the paste pumps feeding them: single pump zone and dual pump zone.Pretium Resources Inc. 16-72 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC