Feasibility Study and Technical Report - Pretivm

• Although road access exists to the old Granduc Mine site, the best route for thetransmission line is higher on the slopes. No road access exists from theGranduc Mine site to the terminus of the Knipple Glacier. Given the lack of roadaccess along the route, helicopter construction is a means to eliminate the needfor road access along the route.• Helicopter construction and near-surface bedrock are favourable constraints fora steel monopole design for the transmission towers. Such a design will alsolengthen the conductor span between towers and eliminate the need for roadaccess, thus reducing the construction costs.• A review of the site conditions along the route concluded that the subsurfaceconditions and upslope snow avalanche hazards can be mitigated throughdetailed design and construction measures, as well as operationalrequirements.25.4.3 GEOTECHNICALBGC completed geotechnical designs and recommendations for the foundations of theproposed mill building and ancillary buildings based on site investigations in 2011 and2012 (BGC 2013). Recommended allowable bearing pressures were provided forfoundations on bedrock and on structural fill. Based on the foundation loadingrequirements for the mine site infrastructure, all facilities located within or adjacent tothe mill building must be founded on bedrock, whereas lightly loaded ancillary buildingscan be founded on either structural fill or bedrock.A large cut, made primarily in bedrock, will be required to bring the mill building to itsdesign elevation. Geotechnical recommendations have been provided for this cut, alongwith general recommendations for other excavations and fills required to bring the site toits design elevations.Additional investigations (e.g. geotechnical drilling and test pit excavations) will berequired for subsequent stages of design to further evaluate subsurface conditions withinthe footprints of the mine site facilities. Laboratory testing of rock and overburdensamples will also be required to further evaluate the properties and behaviour of thesematerials.25.4.4 WASTE ROCK DISPOSALA conceptual layout was developed for the disposal of approximately 2.28 Mm 3 of PAGwaste rock in Brucejack Lake (BGC 2013). Waste rock will be end-dumped from haultrucks onto a platform/causeway and then, either a dozer will be used to push it over theside or an excavator will be used to cast it over the side. All PAG waste rock disposed inBrucejack Lake must be placed more than 1 m below the low water elevation of the lake.Construction of the platform/causeway will require NAG material to be advanced out overthe submerged PAG waste rock. Therefore, a source of NAG rock will be quarried andstockpiled for this use.Pretium Resources Inc. 25-3 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC