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Subsidence Evaluation for the <br />Exhibit 60E Southern Panels, Apache Rocks West, & Sunset Trail Mining Areas Page 34 <br />11.0 EFFECTS OF SUBSIDENCE AND MINE -INDUCED SEISMIC <br />ACTIVITY ON MAN-MADE STRUCTURES AND RENEWABLE <br />RESOURCES <br />Man-made structures and renewable resources in the Southern Panels, Apache Rocks West, and <br />Sunset Trail mining areas basically consist of 1) a reservoir (Minnesota Reservoir), 2) stock <br />watering ponds, 3) streams (primarily Dry Fork and the upper part of Lick Creek) and Deep Creek <br />Ditch, 4) roads, and 5) local cabins. Minnesota Reservoir, the ponds, and the Deep Creek Ditch <br />diversion to Dry Fork serve the dual purpose of being both man-made structures and containment <br />structures for the valuable water resources in the area. Based on annual subsidence observations <br />in the Jumbo Mountain, Apache Rocks, Box Canyon, and South of Divide mining areas since <br />1996, the following information is considered appropriate for the Southern Panels, Apache Rocks <br />West, and Sunset Trail mining areas. <br />11.1 Minnesota Reservoir <br />Minnesota Reservoir, which provides storage water primarily for irrigation, is located between two <br />landslides—one beginning at the north shore and the other beginning at the south shore. As <br />explained in Section 10.1.1 (above), landslide movement on Jumbo Mountain occurred during <br />unusually wet periods before mining began, during mining, and after mining and subsidence was <br />complete. The conclusions were that landslide movement occurs in response to ground saturation <br />and is not noticeably affected by subsidence and seismic activity produced by longwall mining <br />beneath, or near, landslide areas. <br />Both the landslides on Jumbo Mountain and those north and south of Minnesota Reservoir occur <br />in surficial material (loose rock, gravel, sand, silt, clay, and soil) and local bedrock outcrops. <br />Dunrud therefore expects that the mining of longwall panel E9 will not noticeably affect the large <br />landslide south of Minnesota Reservoir. <br />Mining of the longwall mining panels in the Southern Panels, Apache Rocks West, and Sunset <br />Trail mining areas, as currently planned (Map 1) will not affect Minnesota Reservoir. The <br />reservoir is located outside the area of mining influence of both the B- and E -seam panels, using <br />an extremely conservative 45 -degree angle of draw. Monitoring data is presented in the annual <br />Fall Subsidence Reports to verify and demonstrate the accuracy of the predictions. <br />11.2 Stock Watering Ponds and U.S. Forest Service Water Resources <br />The stock watering ponds in the Southern Panels mining area are located in debris flows or <br />colluvium derived from the debris flows (Dunrud 1989). Some of these ponds are also classified <br />as U.S. Forest Service water resources. The debris flows consist of a heterogeneous mixture of <br />clay derived from the Wasatch Formation and boulders and gravels derived primarily from the <br />Mount Gunnison intrusive (granodiorites and quartz monzanites). Based on observations made <br />during geologic mapping in the area, these debris flows are even less likely to be affected by <br />longwall mining than the alluvium. The debris flows have a very low permeability and, because <br />the clay matrix is armored by the interstitial gravel and boulders, are resistant to erosion (the Deep <br />Creek Ditch locally flows in this material at steep gradients). Based on the above-mentioned <br />observations, no effects are expected when ponds in the Southern Panels, Apache Rocks West, and <br />831-032.816 Wright Water Engineers, Inc. <br />October 2018 <br />