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West Elk Mine <br />• The results of the flow measurements and stream channel surveys will be included the Annual <br />Hydrology report. If significant changes in the stream flow related to mining activities is noted, <br />the CDMG will be notified within three days of observing the flow anomalies. <br />Springs, Aquifers, and Ground Water Wells <br />Map 37 shows one decreed spring (Spring 21), three springs found flowing at every site visit (in <br />1975, 1977, 1979, and 1980), thirty-three intermittent springs, and two groundwater wells that are <br />currently monitored. Only a few springs in the West Elk Mine azea indicate a source from a local <br />bedrock aquifer. Most springs likely have sources from local aquifers in surficial material (debris <br />flows, colluvium, and possibly alluvium). <br />In contrast to surface water containment structures, such as reservoirs, ponds, streams and <br />ditches, springs and aquifers may have water sources that aze either in bedrock beneath the <br />blanket of clay-rich surficial material (debris flows, alluvium, and colluvium), or have a source <br />from within the surficial material. Subsidence may affect a spring or aquifer source located in <br />bedrock, whereas effects may or may not be expected where the spring source is within the <br />surficial material. Tension cracks produced in sandstone bedrock during the subsidence process, <br />for example, may divert water to a lower rock layer and therefore change the flow location. <br />However, local aquifers in permeable zones, which are interlayered with clay-rich zones <br />(Wasatch clays) in the surficial deposit, may yield to tensile stresses without cracking. There is <br />no field documentation known to Mr. Dunrud to either support or refute this statement. <br />• Therefore, it is important to monitor all known spring flows for a few yeazs (to account for <br />seasonal variations) prior to any mining in the azea. <br />Springs <br />Decreed Spring 21 is located within the areas of mining influence of un-mined longwall panels <br />E5, E6, and E9 in the NE'/4 of Section 5, (Township 14 South, Range 90 West). Maximum tilt <br />and strain is expected to occur in this azea, because it is located above the projected haulageway <br />and barrier pillaz to the haulageway. The overburden depth at this spring site to the E seam is <br />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, and outside of the area of <br />influence of longwall panel E8. <br />Of the springs mapped, only the decreed Spring 21 and the spring located along Dry Fork and <br />above longwall panel E2, may be impacted by longwall mining. The source of decreed Spring <br />21 may be a local aquifer in bedrock of the Mesaverde Formation, whereas, the source of the <br />spring along Dry Fork (above longwall panel E2) is likely to be a local aquifer in colluvium or <br />alluvium derived from debris flows. <br />• <br />2.05-l39 Revised November 1004 PRIO <br />