Feasibility Study and Technical Report - Pretivm

The data was collected over a relatively short time period (2.5 years, October 2009 toMarch 2012) and may not be representative of longer-term averages. To address thisconcern, AMC analyzed climatic data collected from the weather station adjacent to theEskay Creek Mine, located approximately 19 km northwest of the Brucejack site at anelevation of 900 m. Minimum, maximum, and mean daily temperatures were collectedfrom 1989 to 2010, yielding 21 years of comparative data. Figure 16.31 shows themonthly mean temperatures collected from the two weather stations.Figure 16.31Monthly Mean TemperaturesThe trend in temperature change over the course of a year at Eskay Creek parallels theBrucejack data, but is consistently higher in absolute value. It is probable that the 500 melevation difference between the two stations accounts for this differential value. AMCconcludes that the data collected from the Brucejack weather station is representative oflong-term averages.AMC has assumed the coldest temperature that can be anticipated at Brucejack Lake isapproximately -35°C.16.9.13 PROPANE SUPPLY AND STORAGEMine air heating will be the only consumer of propane for the underground operations.Surface infrastructure−for example the camp−will require propane, however, the storageof propane for this purpose will be independent of mine air heating. Based on theavailable climatic data from site, calculations were performed to estimate the annualPretium Resources Inc. 16-68 1291990200-REP-R0012-02.1Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC