2013-10-08_REVISION - C1982056 (22)

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The Camellettis use these lands as undeveloped rangeland. The landowner estimated that 1% of the ranch production is attributed to the Fish Creek AVF. Twentymile Coal owns a significant portion of the lands in and adjacent to the Fish Creek AVF. Twentymile Coal Company operates a cattle operation on these lands and manages the land, through its ranch manager, Trout Creek Ranch, as undeveloped rangeland. TCC does not utilize the Fish Creek AVF as cropland. TCC projects that impacts to the Fish Creek AVF will not significantly impact the cattle operation. Technical Revision No. 14 (TR14) approved the undermining and subsidence of a small portion of Fish Creek due to longwall extraction in panels 5, 6 and 7 in the Southwest Mining District. No farming activities are currently undertaken along Fish Creek in this area. Subsidence did not preclude the farming of this area. The Fish Creek AVF was the only AVF approved to be undermined as a result of Permit Revision No. 6 (PR6). No stream pirating or loss of flow was experienced during the mining approved by PR6. 2. The proposed mining operations will not cause material damage to the quantity and quality of surface and ground water that supply the alluvial valley floor. The only significant degradation of the stream water from TC’s mining operations has been caused by pumping of underground mine water into Fish Creek and Foidel Creek. Data in TC’s annual hydrology reports document this degradation. Pumping occurs at two sites 115 (Fish Creek borehole) and 109 (portal area). The pumping loads the streams with dissolved solids, mainly sulfate. The operator has maintained stream water quality below the material damage threshold by limiting the pumping rates at both sites and treating the pumped water at one of the sites, 115. The operator will continue to limit pumping rates and treating water as in the past; therefore, mine pumping can be expected to not cause material damage to the quality of surface or alluvial water. Water in Fish Creek could see a slight increase in sediment load as subsidence creates slight changes to the stream channel gradient and minor erosion occurs at the head cuts in the stream. This increase in sediment load is anticipated to be no more than the sediment increase observed during spring runoff and after large rainstorms. An increased sediment load was not detected during past subsidence of Fish Creek, Foidel Creek, or Middle Creek. No impact to groundwater quality is predicted. Ground water could flow between aquifers through subsidence fractures. The Fish Creek alluvium and the Twentymile Sandstone have the greatest potential for such interstitial flow, but the stratigraphic separation of several hundred feet between the two units would prevent any significant amount of flow between them. 39 Foidel Creek MineOctober 8, 2013