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mining topography, Maps 29 and 29A show the backfilling and grading schedule, and Maps 41 <br />and 41A show the location of the permanent, post -mining drainage channels. The pre -mining <br />and post -mining cross-sections are shown on Maps 20 and 20B, and the permanent drainage <br />channel profiles are shown on Maps 33 and 33B. Exhibits 2 of the SL -09 application show <br />cross-sections of the SL -09 area, including approved post mining topography alongside the <br />constructed topography. <br />IV. OBSERVATIONS AND FINDINGS <br />The following discussion of observations and findings focuses on the results of backfilling and <br />grading work and drainage reestablishment in West Pit for the partial Phase I Bond Release. <br />The evaluation of the bond release application included the bond release inspection, an office <br />review of the permit requirements and regulatory criteria, and review of past inspection reports. <br />The bond release inspection was conducted on May 11, 2016. Several items were reviewed by the <br />Division during the technical evaluation of the bond release application before, during, and after <br />the inspection, including: the post -mining topography and cross-sections of backfilled and graded <br />areas. <br />During the partial Phase I Bond Release inspection, participants walked through most of the <br />bond release request area to allow for visual assessment of compliance with pertinent <br />requirements. <br />Backfilling and Grading <br />For the SL -09, observations were made during the bond release inspection with regard to <br />approximate original contour and stability of the reclaimed landscape. To determine compliance <br />with Colowyo's approved approximate original contour (AOC) in the SL -09 areas, elevation data <br />provided in the SL -09 Bond Release application was compared to GPS data collected by the <br />Division. Thirteen points were selected near the cross-sections provided with the SL -09 <br />application as well as additional cross-sections created by the Division. These points were <br />selected utilizing Exhibit 1 of the SL -09 application. Points were placed at selected contour <br />elevations in ArcGIS (to try to cover the majority of the area), and those points were then <br />downloaded into a Trimble Yuma. During the bond release inspection, Zach Trujillo navigated <br />to the points using the data in the Trimble, and a GPS data point was collected at each site. The <br />points collected at the site were downloaded from the Trimble into Pathfinder office and <br />converted into a point shape file to utilize in ArcGIS. <br />Elevation data using the Trimble Yuma is not exact. The Geoid used in the Trimble GeoXT is <br />DMA l OX 10 Global, which is a global elevation Geoid and not as accurate as a localized Geoid. <br />For this reason a known point was collected at the Colowyo Mine office to determine a <br />correction factor for the elevation collected in the Trimble Yuma. The elevation at the base <br />station was 7234.1' on Trimble Yuma, which utilizes a projected coordinate system of UTM, <br />NAD 83, Zone 13 North. In Colowyo's coordinate system (UTM NAD 27 Colorado State Plane) <br />Proposed Decision and Findings of Compliance September 2016 <br />Partial Phase I Bond Release SL -09 Page 5 <br />