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approximate original contour and stability of the reclaimed landscape. To determine compliance <br /> with Colowyo's approved approximate original contour(AOC) in the SL-15 areas, elevation data <br /> provided in the SL-15 Bond Release application was compared to GPS data collected by the <br /> Division. A total of twenty one points were taken along the West Pit, East Pit and The Gulch A <br /> Ditch. A total of fourteen points were taken along the West Pit and six points were also <br /> collected along the East Pit (see Figures 3 and 4). For the East and West Pit, points were placed <br /> at selected transects at approximately 200 feet intervals and along contour elevations in ArcGIS <br /> and those points were then downloaded on ArcGIS for ESRI Collector (Collector). During the <br /> bond release inspection, the Division navigated to the points using the data in Collector and a <br /> GPS data point was collected at each site with a Bad Elf GNSS (Bad Elf) surveying unit. Each <br /> reclamation parcel was also visually inspected to ensure the area was graded and blended in with <br /> the adjacent reclaimed areas. During the inspection, small erosional features were observed <br /> along the West Pit however, the Division determined that these features will self-heal over time <br /> with additional vegetation establishment. No issues were observed at the visually inspected <br /> reclamation parcels. <br /> The static accuracy of the Bad Elf is approximately 1 meter with SBAS+PPP and is on a <br /> localized geoid. For comparison reasons, a known point was collected at the Colowyo Mine <br /> office to determine a correction factor for the elevation of the bond release areas collected with <br /> the Bad Elf. In Colowyo's coordinate system (UTM NAD 27 Colorado State Plane) the <br /> elevation is 7,261' at the known base station and was measured by the Division at an elevation of <br /> 7,286' with the Bad Elf. The difference between the elevations was -25 feet which will be used <br /> as the correction factor. <br /> The elevation data collected for the East and West Pits by the Division was compared to <br /> elevation information provided in the SL-15 Bond Release application. After comparison, all <br /> elevation points taken by the Division were found to have an average deviation of 3.5 feet from <br /> the elevations shown on SL-15 Map 2. Given the expanse of the mine site and the steepness of <br /> the terrain at Colowyo, as well as the error contributed by the user, the Division determined that <br /> the difference in elevation is acceptable. <br /> One additional point was collected along the Gulch A Ditch (See Figure 5). This point was to <br /> mark the location of the ditch measurement that was taken during the June 12, 2019 inspection. <br /> Measurements were taken to ensure the ditch was constructed as approved in Volume 2C, <br /> Exhibit 7-14G of the PAP. The measured section of ditch had a bottom width of 12 ft., top width <br /> of 41 ft. and a depth of 3.5 ft. Based on the measurements of the widths and depth, the side slope <br /> for the ditch is calculated to be at approximately 4H:1 V at that point of the ditch. The <br /> measurements approximately match what is approved in the Colowyo PAP. No signs of erosion <br /> or cutting was observed throughout the length of the Gulch A Ditch. The ditch is stabilized with <br /> rip rap as well as vegetative growth within the channel. <br /> For the West Pit, East Pit and Gulch A Ditch, the Division finds that the Colowyo Mine has <br /> achieved a post-mining surface that conforms to the approved post-mining topography and <br /> resembles the general surface configuration of the land prior to mining. All highwalls have been <br /> Proposed Decision and Findings of Compliance August 6,2019 <br /> Partial Phase I,II and III Bond Release SL-15 Page 8 <br />