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quite steep at disturbance perimeters. In some cases backfill material was placed against undisturbed <br />virgin ground at the top of a final highwall. As indicated in Tab 20 (Backfilling and Grading) of the <br />PAP, slopes may exceed 3(h):1(v) in these areas above the final highwall where the natural slope is <br />originally steeper than 3(h):1(v). Included in the postmine regrading operation was the construction of <br />small swales and hummocks to minimize erosion and to conserve soil moisture and to promote <br />revegetation. <br />SCC generated topographic maps, using photogrammetric methods, of backfilled and regraded areas on <br />an annual basis. The maps were used to determine whether regraded areas are consistent with the <br />approved postmining topography. There were no variances from approximate original contour (AOC) <br />requirements or highwall reclamation requested or allowed in the permit area. Exhibit "D ", Post Mine <br />Cross - Sections of the bond release application, provides representative cross- sections showing final <br />topography configuration within the Neck Pit and South Pit reclamation areas. Final topography in the <br />North Pit area had been previously reviewed and determined to be acceptable in the context of Phase I <br />Bond Release SL -1, in 2007, which applied solely to the North Pit area. A couple narrow corridors <br />associated with reclaimed light use roads and channels, and a small slide scarp area, were excluded from <br />the Division's SL -1 approval, but the major portion of the North Pit area was approved for Phase I <br />release within SL -l. These areas that had been excluded in SL -1 were all requested for Phase I bond <br />release with SL -2. <br />The approved Post - Mining Topography Map, Exhibit 20 -2, was compared with the Land Use Map <br />(Exhibit 4 -1 of the approved PAP), which depicts premining topography over the entire permit area, <br />with a 40' contour interval, and with the Premining Vegetation Map (Exhibit 10 -1 of the approved <br />PAP), which depicts premining topography within the Neck Pit and South Mine areas, with a 5' <br />contour interval. The maps were reviewed to verify that post -mine drainages were constructed in <br />appropriate locations with adequate drainage density. Pre - mining topography was also compared <br />with the approved Post - Mining Topography Map to verify that regraded slopes achieved AOC. All <br />regraded slopes were inspected and evaluated for erosional stability during the Phase I bond release <br />inspection and routinely during normal monthly inspections. Results of these evaluations are <br />discussed below in Section III Observations and Findings. <br />The Yoast Mine drains to Sage Creek on the west side and to Grassy Creek on the east side. Sage <br />Creek and Grassy Creek are perennial tributaries to the Yampa River. Annand Draw and Scotchmans <br />Gulch are intermittent drainages which drain from the northern side of the proposed permit area into <br />Grassy Creek. The Yampa River then flows to the Green River and eventually the Colorado River. <br />The final reclamation plan for the Yoast Mine includes retention of numerous ephemeral postmine <br />drainage channels that are ultimately tributary to either Sage Creek or Grassy Creek. The SL -2 <br />evaluation included assessment of drainage density, field check of channel compliance with design <br />specifications of the approved permit, and assessment of channel erosional stability. Based on <br />comparison of permanent drainages depicted on the pre -mine map Exhibit 4 -1 and post -mine <br />topographic maps, the density of postmining channels is higher than the density of pre - mining <br />ephemeral drainages. <br />Numerous permanent drainage channels have been approved and constructed, and were evaluated as <br />part of this Phase I bond release. The postmine channels are shown on Exhibit 20 -2 and certified <br />7 <br />