Feasibility Study and Technical Report - Pretivm

in the workshop/crusher/mine offices area. In review of crew numbers during the life ofthe mine, it is estimated that the maximum number of personnel underground workingduring any shift will be 86. It is estimated that 36 people will be working predominantlyin the workshop area.The remaining personnel working underground, namely the production development andservice crews, will be provided refuge by means of five, 12-person mobile self-sufficientrescue chambers. These will be independent of a compressed air supply, withappropriate provisions for safe refuge. They will be located in areas where a secondaryegress is not, or has not yet been established, and will be sited relative to the activeworking areas in order to be within the average walking pace duration of a personal selfrescuerdevice.An automatic stench gas warning system will be installed on the supply side of thesurface vehicle portal and conveyor portal. When fired, this system will release stenchgas into the main fresh air system allowing the gas to permeate rapidly throughout themine workings. Once stench gas is released, underground mine personnel would reportimmediately to the nearest mine refuge station or surface, whichever is closer.The primary purposes of fire doors are to prevent noxious gases from reaching workersshould they be trapped underground and to prevent fire from spreading as much aspossible.Fire doors will be required to isolate the following areas:• workshop• fuel bay• conveyor decline.Portal doors will also be designed to meet fire door criteria.16.9 UNDERGROUND INFRASTRUCTURE16.9.1 MINE DEWATERING AND SOLIDS HANDLINGMine dewatering must accommodate groundwater inflows from the VOK Zone workings,the West Zone workings, and inflows from drill and other operating equipment. Totalinflows are estimated to be approximately 100 L/s; however, to accommodate foruncertainty in the water inflow model, the design capacity for the pumping system isbased on maximum inflows of 139 L/s.Mine dewatering will be handled by a combination of submersible and horizontalcentrifugal pumps located throughout the West Zone and VOK Zone working levels. Thepumps will handle mine water via multiple lifts throughout the mine to minimize pumpsize and power. Lift stations will be designed with consistent vertical intervals of 60 m tomaintain similar pump head characteristics. This reduces the amount of different pumpsizes required, which will simplify maintenance.Pretium Resources Inc. 16-50 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC