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Pitch Reclamation Project Colorado Mined Land Reclamation Board — 2012 Annual Reclamation Report cumbersome and confusing. This report uses the former naming scheme, which omits the "year" from the monitoring point identification. Therefore, MP- 99 -85, reverts back to MP -85. During the most recent survey, monitoring point P -04 was replaced with a new monument due to settlement of well backfill. There are currently 92 monitoring points in the North and South pits to monitor surficial slope movement. Of these 92 monitoring points, eight had annual displacement magnitudes that were greater than survey error, as shown on the summary table presented on Appendix A. By comparison, 27 points had annual displacement magnitudes greater than survey error for the 2010 -2011 monitoring period. Displacement for monitoring points where displacement was not detected, or was less than calculated survey error is indicated as "ND" or non - detectable. The current maximum displacement at the east wall of the North Pit is 0.24 ft/yr at MP -39. During the previous monitoring period, there was 0.39 ft/yr displacement at MP -66 and MP -69. The current maximum displacement at the east wall of the South Pit is 0.10 ft/yr at MP HS-4. 4.2 Inclinometer Evaluation Three slope inclinometers were installed in 2003 to monitor areas of the North Pit. Annual survey data has been collected since July, 2003. Two slope inclinometers (198 -2 and 198 -2) are located on the south wall of the North pit and the other (198 -3) is above the crest of the east wall of the North Pit, a shown on Figure 3. Results from the inclinometer survey in 2012 indicate that the inclinometer displacement data are all below the threshold of error for the three installations. Total error, the sum of systematic and random error, associated with the slope inclinometer probe is +/- 0.3 inches per 100 feet of depth according to the manufacturer (Durham - Slope Indicator, Inc.). The error associated with inclinometer 198 -2 is 0.75 inches, 198 -2 is 1.27 inches, and 198 -3 is 1.5 inches according to the depth of each installation. The data collection system was repaired, tested and calibrated by Slope Indicator, Inc. in 2011. Baseline data for these inclinometers were initially collected on July 29, 2003. The initial baseline readings for these installations were corrupted due to data collection equipment failure and subsequently replaced in 2011 with more recent surveys. The inclinometer data collection equipment was tested on site prior to collecting data for the 2012 surveys. The revised baseline survey date for 198 -1 is August 8, 2007. The revised baseline survey date for 198 -2 and 198 -3 is August 1, 2006. The impact of using more recent baseline surveys is essentially inconsequential, because any displacement indicated by the surveys has consistently been below error tolerances. In addition to the loss of baseline surveys, all other surveys prior to 2006 are no longer available. The inclinometer data reflects that all are below the threshold of error for the three installations. The non- linear features on the plots for 198 -1 may indicate very minor displacement, but the magnitudes of the non - linear portions of the plots are below the error threshold for this installation. Therefore, it is more accurate to interpret the data as not indicative of slope displacement. The plots for 198 -2 and 198 -3 also indicate no slope displacement at these locations. However, given the isolated slope displacement on the northeast corner of the North Pit and the resaturation of the Pinnacle underground mine workings in the area of the south wall of the North Pit as discussed below, these inclinometers will continued to be monitored at the end of each summer. 4.3 Pinnacle Mine Workings Monitoring A concrete plug was constructed in the Pinnacle adit in September 1995. Authorization for the placement of the Pinnacle adit plug was requested by Homestake in April 1995, through Technical Revision #4 Pitch 2012 Reclamation Report 04 -16 -13 Doc 17