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can be detected once subsidence began. In addition, major planimetric details such as roads and <br />rivers were compiled on the map. <br />This map was used for location purposes, and was generated from the original photography only. <br />(6) Subsidence Contours Ascribed drawing was made at 1"=200' showing "subsidence <br />contours" at one foot intervals. These contours were based on the difference between the original <br />digital terrain model and subsequent models. BME proposed to provide three subsidence contour <br />maps, one for each survey following the baseline survey. <br />(7) CrossSections Cross-sections were generated along grid lines between X, Y coordinates, <br />showing the terrain profile. Profiles from different flights could be combined on one cross-section plot. <br />These were plotted on paper at 1"=200' H and 1"=5' V, automatically on acomputer-driven flatbed <br />platter. A separate vertical scale was selected along the subsidence profile to allow a visual <br />recognition of the amount of subsidence. <br />Various cross-sections were produced, each to show the first and subsequent subsidence intervals <br />compared with the baseline data. <br />(8) Accuracy A total of 22 ground control points were monitored immediately prior to each <br />flight. BME completed a Third Order survey on the 22 ground control points, certified by a <br />registered land surveyor, licensed to practice surveying in the state of Colorado. The root mean <br />squared error of the difference in elevations determined from the aerial methods and from <br />on-the-ground surveys was within +/- 0.25 feet. 95% of the elevations differences at these 22 points <br />was within +/_ 0.8 feet. <br />(9) Coordination with Surface Observations and Other Monitoring Programs DMG had <br />expressed concem regarding probable impacts to the hydrologic characteristics of Red Wash. To <br />alleviate this concem, BME proposed to install nine alluvial wells in Red Wash to define the alluvium <br />characteristics and any changes that might occur in Red Wash as a result of subsidence. The nine <br />hole installation project was described as part of BME's first mid-term technical revision request. Map <br />137 shows the location of the nine alluvial wells. This monitoring program is discussed further in <br />Section II.C. <br />(10) Resort Preaaration Reports to DMG included the following: <br />• Brief description of analytical photogrammetry, including references on accuracy. <br />• Description of the monitoring program. <br />• Permit Renewal #3 (Rev, 8/99) III-25 <br />