Feasibility Study and Technical Report - Pretivm

16.3 MINING METHOD AND SEQUENCE16.3.1 BLOCK DEFINITIONThe orebody was divided into six logical blocks, defined by elevation, that facilitate2,700 t/d of production through the creation of multiple working areas. Miningprogresses upward from the lowest elevation in the block.A number of factors that impact value and cash flow were taken into consideration whendefining the block elevations:• Three of the six blocks contain sills: Mining these sills will expose the cementedbackfill of the stopes in the block immediately above. They will be relativelymore problematic to mine due to the effects of increasing ground stress and theoverhead fill, with lower recovery, higher dilution, and higher costs anticipated.Therefore, the block elevation selection tended toward minimizing the grade andcontained metal within the sills.• Pre-production development requirements: The first block to be scheduled forproduction is the VOK Zone is 1,360 Level to 1,540 Level. The block is close tothe existing workings. This will allow the production ramp-up schedule toproceed in a reasonable time.• Grade profile: Block definition impacts grade accessibility over time. Thearrangement provided for the feasibility study assists with achieving highergrades earlier in the mine life.16.3.2 STOPE CYCLEThe primary mining method will be transverse LHOS based on a standardprimary/secondary sequence. No permanent pillars will be required and maximum oreextraction will be targeted.The hanging wall drives will be completed, and a through ventilation circuit will beestablished before mining begins between any two levels.A cross-cut will be driven from the hanging wall drive, through the centre of the stope, tothe far ore contact on the undercut and overcut levels. The undercut level will havealready been developed if stoping has progressed beyond the block starting level.Cross-cuts on both levels will be cable-bolted from the central access to pre-support theroof prior to full-width slashing of the entire stope footprint. Slashing to the adjacentstope boundaries will expose paste fill walls in the case of secondary stope extraction.Full width slashing will permit parallel production hole drilling across the entire width ofthe stope, and will reduce the potential for ore in stope corners to fail to break to designdue to inadequate free face or poor explosives distribution. Ore recovery will be higherthan a fan drilling alternative (in the absence of full-width slashing). Given the significantvalue of Brucejack ore, high recovery was an overriding criterion in the design.Pretium Resources Inc. 16-11 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC