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2004 Geologic Hazard Field Observations <br />South of Divide Mining Area <br />• bedrock water-bearing zone. Most springs likely have sources from local water-bearing zones in <br />surficial material (stratified debris flows, colluvium, and alluvium). <br />In contrast to surface water containment structures, such as reservoirs, ponds, streams and <br />ditches, springs and water-bearing zones may have water sources that are either in bedrock <br />beneath the blanket of clay-rich surficial material (debris flows, alluvium, and colluvium), or <br />have a source from within a permeable zone within the surflcia] material. Subsidence may affect <br />a spring or water-bearing zone source located in bedrock, whereas effects may or may not be <br />expected where the spring source is within the surficial material. Tension cracks produced in <br />sandstone bedrock during the subsidence process, for example, may divert water to a lower rock <br />layer and therefore change the flow location. However, local water-bearing zones in permeable <br />zones, which are interlayered with clay-rich zones (Wasatch clays) in the surficial deposits, may <br />yield to tensile stresses without cracking. There is no subterrain field documentation known to <br />the author to either support or refute this statement regazding interlayered sealing or leaking <br />when subjected to the effects of subsidence. <br />9.4.1 Springs <br />Decreed Spring 21 is located within the areas of mining influence of projected longwall panels <br />E5, E6, and E9 in the NEY, of Section 5, Township 14 South, Range 90 West). Maximum tilt of <br />3 to 5 percent and tensile and compressive strains 4 to 5 percent are expected to occur in this <br />azea, because it is located above the projected haulageway and bamer pillaz to the haulageway. <br />The overburden depth at this spring site to the E Seam is about 650 feet. <br />Springs mapped in the South of Divide mining area, which have been found flowing at every site <br />visit, include: 1) a spring located 800 feet west, southwest of the Minnesota Reservoir dam- <br />outside the azea of any planned mining influence; 2) a spring located along Dry Fork 700 feet <br />west of the confluence of Poison Creek and Dry Fork, above projected longwall panel E2 in <br />about 650 feet of overburden to the E Seam; 3) a spring located south of, and outside of, the area <br />of mining influence of longwall panel E8. <br />L_I <br />831-032.621 Wright Water Engineers, Inc. Page 36 <br />November 2004 <br />