2011-02-14_PERMIT FILE - C1980007A (3)

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Subsidence Evaluation for the Exhibit 60E South of Divide and Dry Fork Mining Areas Page 34 zone. Most springs likely have sources from local water - bearing zones in surficial material (debris flows, colluvium, and possibly alluvium). In contrast to surface water containment structures, such as reservoirs, ponds, streams and ditches, springs and water - bearing zones may have water sources that are either in bedrock beneath the blanket of clay -rich surficial material (debris flows, alluvium, and colluvium), or have a source from within the surficial material. Subsidence may affect a spring or water - bearing zone source located in bedrock, whereas effects may or may not be expected where the spring source is within the surficial material. Tension cracks produced in sandstone bedrock during the subsidence process, for example, may divert water to a lower rock layer and therefore change the flow location. However, local water - bearing zones in permeable zones, which are interlayered with clay -rich zones (Wasatch clays) in the surficial deposit, may yield to tensile stresses without cracking. There is no field documentation known to Dunrud or the current author to either support or refute this statement. Therefore, it is recommended to monitor all known spring flows for a few years (to account for seasonal variations) prior to any mining in the area. 11.4.1 Springs Decreed Spring 21 is located within the areas of mining influence of un -mined E -seam longwall panels E5, E6, and E9 in the NE' /+ of Section 5, (Township 14 South, Range 90 West). Maximum tilt and strain is expected to occur in this area, because it is located above the projected haulageway and barrier pillar to the haulageway. The overburden depth at this spring site to the E -seam is about 650 feet. Springs mapped in the South of Divide mining area, which have been found flowing at every site visit, include: 1) a spring located 800 feet west, southwest of the Minnesota Reservoir dam — outside the area of any planned mining influence; 2) a spring located along Dry Fork 700 feet west of the confluence of Poison Creek and Dry Fork, above projected longwall panel E2 in about 650 feet of overburden to the E -seam; 3) a spring located south, and outside of the area of influence of longwall panel E8. Of the springs mapped in the South of Divide area, only the decreed Spring 21 and the spring located along Dry Fork and above longwall panel E2, may be impacted by longwall mining. The source of decreed Spring 21 may be a local water - bearing zone in bedrock of the Mesaverde Formation, whereas, the source of the spring along Dry Fork (above longwall panel E2) is likely to be a local water - bearing zone in colluvium or alluvium derived from debris flows. There are seven springs that are identified as perennial in the Dry Fork mining area. Springs 2 -1 and 2 -2 are adjacent to each other and located above the bleeder entries in E -seam longwall panel E5 where there is about 1,200 feet of overburden These springs should not be affected by mining. Springs 2 -3 and 2 -4 are adjacent to each other and located above the center of panel E-4. The overburden is about 1,000 feet thick at this location. These springs may be minimally impacted. Spring 35 -1 is located above the center of panel E3 along Deep Creek. The overburden is about 1,000 feet think at this location. Springs 36 -1 and 35 -2 are located along a tributary of Deep Creek and have overburden depths of 950 and 1,000 feet. These springs may also be • minimally impacted. 831 - 032.810 Wright Water Engineers, Inc.