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this slope. This concern is listed in the adequacy section at the end of this <br />document. <br />The permanent drainage imprint has not been established in the southern portions of <br />the 720 pit. The topsoil pile is directly in the path of the final drainage location. <br />Erosion was noted on the steep section just before entering pond A. The slope of <br />this drainage was measured at 6% and 8%. The operator stated that this slope <br />would be graded to a lesser angle prior to topsoil placement. However, the Division <br />would like hydrologic calculations to show that final ditch will handle the expected <br />velocities and if needed appropriate ditch protection should be proposed. <br />Additionally, the south perimeter channel should be brought into the low area of the <br />720 pit at a direct angle rather than obliquely along the south side; this configuration <br />would be more natural and ultimately more stable (720 pit drawing). The highwall <br />cross diversion terrace and ditch B-1 could be probably be removed on the south <br />side of the highwall notch and the north terrace should be reviewed for removal. The <br />final drainage control should bring all native drainage through a reinforced channel <br />down the highwall area. The upland drainage should not be routed laterally across <br />the reclaimed slopes. The plan should be certified as needed. <br />The location of the former overburden pile was inspected. Premining topography <br />maps show that there was a ridge with concave slopes. The current topography has <br />a ridge with convex slopes. This creates two lenses of fill on either side of the center <br />ridge with a maximum thickness of 30 feet. At the top of the ridge roots were noted <br />on the surface, thus indicating that the overburden had been .removed to original <br />ground. The premining topographic map taken from the 7.5 minute USGS <br />quadrangle had a contour interval of 20 feet. This would create a margin of error of <br />+ or - 10 feet. These two pods should be used for fill material in final grading if <br />necessary. <br />In general the 720 pit backfilling and grading conformed closely to the approved post <br />mining topography. The mine must do additional work to reduce the grade of the <br />western slopes of the pit. Final drainage imprints must be established. <br />Pit 1 Reclamation <br />The final configuration of Pit no. 1 was close to the approved postmining topography. <br />There were several areas that will require additional work to reduce the slopes to <br />3:1. The areas noted in the inspection are diagrammed on the map below. <br />Marr Strip, Bond Release 3 May 24, 1994 <br />