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ditch as the trench underdrain. It should be noted that the final trench location was <br />determined in the field as conditions dictated. <br />Culvert J -7 was moved from the proposed design location to the location, shown on Exhibit <br />13 -2, Surface Hydrology to fit the final overall topographic configuration. <br />Shrub Plot Slump Remediation <br />All monitoring and study indicates that the instability results from saturation of overburden <br />material in a final pit and piping as the water surfaces at the lip of the final pit along a <br />possible pit ramp. Channel PM -2 was relocated to capture the flow nearer the point of origin. <br />The slump area was regraded with the majority of the slump material removed and the area <br />sloped to Channel PM -2. The only discharge point from the slump area was developed and <br />rocked and discharges directly into Channel PM -2. <br />Pond 016A Removal <br />A portion of the embankment on Pond 016A was removed to allow the impounded water to <br />drain and to allow the construction of Channel PM -2. The remainder of the original <br />embankment was left inplace. The pond area was backfilled using material excavated from <br />the slide area. <br />Once the pond was drained, an under drain was constructed through the bottom of the pond. <br />The saturated material in the bottom of the pond was removed and spread on a selected <br />location on the nearby surface to dry. The dryer material excavated from the slide area was <br />placed and compacted over and around the underdrain and then the remainder of the area was <br />backfilled and compacted to the current configuration. <br />Postmine Drainage Channel PM -2 (relocation) <br />The PM -2 postmine channel was relocated through the shrub plot slump area and the Pond <br />016A area discharging to the existing channel that empties into Pond 016. <br />The design specifies a ten (10) foot bottom width with nine (9) inch riprap or vegetated TRM <br />and a minimum depth of 1.5 feet (the final ditch configuration is extremely conservative <br />compared to the approved design). The relocated portion passes through the shrub plot <br />slump area, through the slump area on the southwest edge of Pond 016A and continues <br />through the original embankment at Pond 016A and into Pond 016. The new location of PM- <br />2 will allow the subsurface and surface waters causing the instabilities to be captured and the <br />flow directed away from the areas susceptible to saturation and movement. It should be <br />noted that the final channel locations (PM -2, 2A, 2B and 3) were determined in the field as <br />conditions dictated. The final locations and configuration are shown on Exhibit 20 -2, <br />Postmining Topography and Drainage. <br />Previously Abandoned Wells <br />Regrading was conducted in the vicinity of the abandoned wells; however, extreme care was <br />taken not to cause any disturbance to the wells or drain. <br />TR -79 20 -D.2 10/12 <br />