Feasibility Study and Technical Report - Pretivm

testing should focus on samples within the VOK D1 domain, the weathered rockzone, and fault zones, as these geotechnical units are under-represented in thecurrent testing database.• Additional refinements are required for the 3D geological model of the VOKZone, and a 3D geological model should be developed for the West Zone.Further work should also be completed on the interpretation and modelling oflarge and intermediate scale faults. The presence of unknown major structuresor splays off the Brucejack Fault Zone has the potential to significantly affectrock mass stability. The updated model should be reviewed to determine ifupdates to the geotechnical assessments are required.• Numerical stress modeling has identified potential instability zones in stopeclusters around the sill pillars and the crown pillar. The model should beupdated with the West Zone geology model, in situ stress measurements, and adetailed stope-by-stope extraction plan, all of which are currently unavailable.The updated model should be calibrated using ground deformation observationsrecorded during the VOK Zone bulk sampling currently scheduled for thesummer of 2013. The calibration data can then be used to increase confidencein the modelling results. This will facilitate a more detailed study of the minesequencing effects on the rock mass stability, including pillars, stopehangingwalls, mine abutments, and excavations through the Brucejack FaultZone.The estimated cost for the above-mentioned recommended work is $1,800,000.26.4.2 HYDROGEOLOGICAL RECOMMENDATIONSBGC makes the following hydrogeological recommendations:• Further investigation of hydraulic conductivities (K) in the area of the BrucejackFault is recommended to support the current distribution of K in the model. Theadditional packer testing recommended above will be key to this investigation.• Inflow estimates are sensitive to the hydraulic properties of the project areabedrock as well as recharge applied to the model. Further consideration shouldbe given to, and potentially further investigation made of, glacial contributions tobaseflow and groundwater recharge.• The current model does not include the proposed lake outlet structure. The nextphase of modeling should include the effects of this structure, which will includean increase in the lake water level during certain times of year.• It will be important to continue the collection of hydraulic head data andpumping rate data from underground dewatering operations on a year-roundbasis at the project site, as these data will be important for future refinement ofthe conceptual hydrogeologic model and the numerical flow model calibration.Pretium Resources Inc. 26-4 1291990200-REP-R0012-02.1Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC