2019-06-28_REVISION - M1977004 (9)

Home Browse Search

Homestake Mining Company May 10,2019 Regular(112d)Operation Reclamation Permit Application Package 3.4.3.3. Survey Point Network 107 monitoring points were surveyed in 2018 in the North Pit and South Pit zones. Ninety two of the 107 monitoring points surveyed in 2018 had survey data from 2017 to compare with and determine displacement values (15 new monitoring points were added since the last survey). Table 3-2 shows the number of monitoring points surveyed each year, number of monitoring points with both data for the current year and previous year, number of monitoring points with movement above their associated potential survey error, and the percentage breakdown (BGC, 2019b). The 2017 survey program indicated that 32 of the 92 (35%) monitoring points had annual displacement magnitudes greater than the potential survey error. In contrast, the 2018 survey program indicates that 17 of the 92 (18%) monitoring points had annual displacement magnitudes greater than the potential survey error showing a decrease in the number of monitoring points with displacements above their associated survey error. Table 3-2. Number and percentage of monitoring points with movement above their associated survey error(BGC, 2019b). Number of Number of Monitoring Points Number of Monitoring Monitoring Surveyed that also has Data Points with Movement Year Points from the Previous Year as Above their Associated Percentage Surveyed well Survey Error 2012 87 - - - 2013 87 87 12 14% 2014 87 87 30 35% 2015 91 88 39 44% 2016 94 90 29 32% 2017 94 92 32 35% 2018 92 92 17 19% Note: 1. 2012 is the first year of data analyzed for this report and serves as the baseline for movement.Therefore,movement and a percentage cannot be calculated until a second year of data are available.Percentage is calculated as the 4th column divided by the 3`d column. The cumulative displacement vectors for each Pitch Mine survey location are shown in Drawing 04 for the 2012-2018 annual survey time interval. Drawings 5 through 10 show the annual movement of rate and cumulative movement for the monitoring points. An error bar (red) is included to show the associated potential survey error of each monitoring point estimated to be 0.1 ft for every 1,000 ft of distance from the control point to the monitoring point. Drawing 11 shows the annual precipitation (rainfall plus the snowfall's rainfall equivalent) versus the average movement of all monitoring points per year. The average movement of all monitoring points indicates the overall rate of movement of the slopes has been decreasing over the past two years and follows the similar trend in Table 3-3 (BGC, 2019b). EXHIBIT E-RULE 6 4.5(AMENDED RECLAMATION PLAN) Page 54 HOMESTAKE MINING COMPANY