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2004 Geologic Hazard Field Observations <br />South of Divide Mining Area <br />• <br />with which to definitively verify or discount a connection between subsidence of the <br />MCC mine workings and this active landslide." <br />b On August 6, 1997, Dave Nicewicz (Mountain Coal Company surveyor) and the <br />author visited the landslide aeeas on the north side of Jumbo Mountain located above <br />longwall mining panels 8 and 9. The author mapped the landslide area from on-site <br />investigations and with the use of aerial photos, which were dated in 1963 and in <br />1975 and were published by the USGS in 1989 (Coal Investigations Map C-115, 2 <br />sheets). Landslides of various ages and extents had occun•ed prior to any mining in <br />the area. <br />c The landslides observed were reactivations of slides in the mid 1980s (during very <br />high levels of precipitation) that had existed prior to the late 1970s and early 1980s. <br />However, these slides now exhibited cracks, scarps, depressions, and bulges that are <br />typical of landslide processes, but not typical of subsidence processes above longwall <br />• mines. Mr. Nicewicz reported that this was the wettest time that he had witnessed <br />during his time of surveying in the azea. The author estimated that there was roughly <br />a three-fold increase in the volume of flow and in the azeal extent of seeps since he <br />had mapped the area. <br />2. On September 10, 1998 Ron Hanna and the author revisited the observation site in <br />landslide areas on the north side of Jumbo Mountain above mined longwall panels 8 and <br />9. In his annual summary of major findings, the author reported, "Cracks estimated to be <br />only a few weeks to months old were observed above longwall Panels 8 and 9. However, <br />longwall mining influence in the crack area (of the new cracks) would have been <br />complete in Mazch or April 1997. Therefore, these cracks aze very likely not mining <br />related at all, but are only landslide related" (see the memorandum to Mountain Coal Co., <br />dated November 19, 1998 for further details). <br />3. In 1999, landslide-related cracks, as much as 1.5 feet wide and deep, were observed in the <br />basal area of the landslide located north of Minnesota Reservoir and Monument Dam, and <br /> <br />831-032.621 W right W ater Engineers, Inc, Page 41 <br />November 2004 <br />