Feasibility Study and Technical Report - Pretivm

all modelling exercises, the accuracy of the predictions was limited by the informationavailable. The model will continue to be updated as new information becomes availableand updated water quality predictions will be provided in the EA report for the Project.Lorax Environmental Services Ltd. is currently developing a hydrodynamic model toassess the stability of the water column. The results of this model will be used to predicttotal metal and TSS concentrations. As a result, total metal concentrations and TSSestimates have not been evaluated at this time.Predicted concentrations were compared to the MMER, the Canadian Council ofMinisters of the Environment’s (CCME) Canadian Water Quality Guidelines for theProtection of Aquatic Life, and the BC Ministry of Environment (MOE) Contaminated SiteRegulation (CSR) Standard for the Protection of Freshwater Aquatic Life. Brucejack Lakeand the immediate downstream environment are not considered fish habitat (Price2005). Guidelines for aquatic life are likely considered stringent; however, site-specificguidelines have not yet been developed for the Project. Dissolved parameters that couldexceed guidelines at the outlet of Brucejack Lake are outlined in Table 20.3.Table 20.3Summary of Predicted Potential Exceedances of Water Quality Guidelines forthe ProjectCCME BC CSR MMERParameterMinimumGuideline(mg/L)PotentialExceedanceMinimumGuideline(mg/L)PotentialExceedanceMinimumGuideline(mg/L)PotentialExceedanceDissolved Aluminum 0.005 X - - - -Dissolved Arsenic 0.005 X 0.05 - 0.5 -Dissolved Cadmium 0.000017 X 0.0001 X - -Dissolved Copper 0.002 X 0.02 - 0.3 -Dissolved Iron 0.3 X - - - -Dissolved Lead 0.001 X 0.04 - 0.2 -Dissolved Mercury 0.000026 X 0.001 - - -Dissolved Selenium 0.001 X 0.01 - - -Dissolved Silver 0.0001 X 0.0005 - - -Dissolved Zinc 0.03 X 0.075 - 0.5 -Note: “X” indicates parameter exceed lower limit of guidelines. If a guideline is provided as a range, theresults are compared against the minimum value of that range. Dissolved metal concentrationsare compared to total concentrations if no guideline for totals exists.All of the parameters listed in Table 20.3 have previously exceeded guidelines at somepoint during baseline sampling events in mine seepage water. Water quality predictionswill need to be re-evaluated once additional information (such as an updated waterbalance and mine plan) is incorporated into the water quality model and site-specificguidelines are established. For additional details on the water quality modeldevelopment and methodology, please refer to BGC’s report entitled “Draft BrucejackProject Feasibility Study – Geochemistry Report” and dated June 2013.Pretium Resources Inc. 20-12 1291990200-REP-R0012-02.1Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC