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III. CRITERIA FOR BOND RELEASE <br />Rule 3.03.1(2)(a,) states, "Up to sixty percent of the applicable bond amount shall be released <br />when the permittee successfully completes backfilling, regrading, and drainage control in <br />accordance with the approved reclamation plan." <br />SL-11 requests partial Phase I bond release for 57.8 acres reclaimed in 2008 (this acreage is the <br />amount left after 6.1 acres was removed due to the slide at parcel E-AB-08). The requested <br />areas are associated with pits F and Z. The post-mining land use for all 57.8 acres is rangeland. <br />IV. OBSERVATIONS AND FINDINGS <br />The initial bond release inspection was conducted on April 20, 2010. A follow-up inspection <br />was conducted on November 8, 2010 to check completed repair work on areas noted by the <br />Division on the initial inspection. <br />Compliance with Approximate Original Contours <br />In order to determine compliance with Approximate Original Contours (AOCs) for SL-11, <br />elevations of points collected in the field with a GPS unit were compared to elevations <br />provided in the SLI I Bond Release application. Using ArcGIS, 20 locations were selected <br />from the SL-11 Bond Release map and downloaded into a Trimble GeoXT GPS unit. The <br />points were selected at approximately equal distances apart and generally at 50-foot elevation <br />intervals to represent the entire SL-11 Bond Release area. During the bond release <br />inspection, inspectors navigated to the points using data in the Trimble unit, and another <br />point was collected at each location with the Trimble unit. The points collected at the site <br />were downloaded from the Trimble into Pathfinder Office and converted into a point <br />shapefile to utilize in ArcGIS. <br />Elevation data using the Trimble GeoXT is not exact. The Geoid used in the Trimble GeoXT <br />is DMA 10X10 Global, which is a global elevation Geoid and not as accurate as a localized <br />Geoid. For this reason, a point was collected at the Trapper Mine base station (on the office <br />roof) to determine a correction factor for the elevation collected in the Trimble GeoXT. The <br />elevation at the base station was 6513 feet above sea level compared to 6527 feet on the <br />Trimble, which indicated the need for a correction of plus 14 feet. The main purpose of the <br />elevation collection was to determine if the elevation data showed any anomalies, such as <br />drastic elevation changes or fluctuations in elevation. All elevation points were found to be <br />between 13 feet and 19 feet above the elevations of the approved post-mining topography. <br />Given the correction factor of plus 14 feet at the Trapper Mine base station, the variances of <br />13 - 19 feet in elevation between the approved post-mining contours and the elevations <br />recorded by the Trimble unit are not significant. The backfilling and grading of the SL-11 <br />Trapper Mine Page 6 January 2011 <br />SL-11 Phase I Bond Release