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West Elk Mine <br />entrance at the NSSA on the north side of Highway 133. Locations of the various stockpiles <br />are shown on Map 53. <br />Landslide Corrective Measures <br />In 1997 and 1998, MCC employed several corrective measures to stabilize the landslide at the <br />main mine facilities area, as surges of movement had been experienced in 1996 and 1997. The <br />corrective measures included the installation of rock buttresses, stone columns, horizontal <br />drains, pins (micro- piles), and the expansion of the roller compacted (RCC) buttress. These <br />structures are described in detail, and their effectiveness in improving the stability of the <br />facilities area is discussed in Exhibit 14C, 1998 Landslide Corrective Measures Report by Barr <br />Engineering /Harding Lawson Associates. The purpose of the corrective measures was to <br />prevent catastrophic failure, which MCC was successful in doing. MCC will continue to <br />evaluate the effectiveness of the corrective measures over time to evaluate their effectiveness <br />for the long term (i.e. post - reclamation). MCC collects water level data and movement data <br />from various piezometers, inclinometers, and survey mirrors around the mine site on a <br />scheduled interval. Based on the data collected, MCC will reevaluate the slope stability <br />analyses after spring runoff each year and where appropriate, update Exhibit 14C. The update <br />will include an evaluation of the relative change in the factor of safety during the previous year <br />and since the installation of the corrective measures in 1998. A revision including the updated <br />information will be provided to the CDRMS by July 30'' of each year. <br />In the spring of 1999, MCC drilled two horizontal holes from the surface, at the abandoned <br />main mine site substation, to intercept small sumps in the F -Seam to drain the water that <br />accumulates in these sumps. The water that accumulates in these sumps is primarily surface <br />water and near surface groundwater that infiltrates through the colluvium above the F -Seam <br />and into the F -Seam workings. Once the water is in the sump, it then infiltrates through the F- <br />Seam floor and into the unstable surface soils within the main mine site landslide. It is <br />important that water sources to the surface soils be controlled in order to improve the local and <br />global stability. These two holes are a test to determine if this method of draining the sumps is <br />feasible. These sumps are located near the main F -Seam portals. They are not part of MCC's <br />mine water handling system. These sumps have not been nor will be used to handle a large <br />inflow event. The sumps are too small and if they overflow, they will flow into the belt and <br />travel -ways. Drain A will be drilled approximately 1,100 feet and into the floor of one of the <br />main collection sumps. Drain B will be drilled approximately 1,400 feet, and into the bedrock <br />fracture zone below the F -Seam sumps. If the holes are successful, MCC estimates that <br />approximately 22 gpm will flow from the two holes and into pond MB -1. If the holes are <br />successful, MCC will permit and construct additional drains that will remain upon final <br />reclamation. In addition, MCC will update Exhibit 14C to include these drains and evaluate <br />them for the final reclamation plan. <br />2.05 -29 Rev. 06105, 01106. 03106. 04106 & 05106- PRIG; 01109- MR350; 04109- TR116; 04109- MR353; 05109- MR354; 08109- TR118; <br />08109- TR119; 05110 & 08111- MR366 <br />