2016-05-04_REVISION - C1982056 (12)

Home Browse Search

predicted conductivity would be well below the 3 mmhos/cm material damage suspect level for sub -irrigation. Water quality measured in well 006 -AW -2 exceeds the suspect level in both the existing and predicted case, but mine discharge water would actually dilute the salinity of 006 -AW -2 water, resulting in an improvement in water quality due to mining. Following mining and reclamation, the mine workings would fill with ground water, and water passing through the mine workings would again discharge to the stream/alluvial aquifer system. This water would be expected to have a degraded water quality (3200 mg/l TDS at the source), but concentrations would decrease as the affected water flows to the discharge area. The ground water discharge would be further diluted by flow in the stream/alluvial aquifer system. Because of the low flows involved (0.02 cfs), water quality degradation in the stream/alluvial aquifer system would not be sufficient to cause material damage to the waters which supply the Fish Creek Alluvial Valley Floor. 3. The proposed operation will preserve, throughout the mining operation, the essential hydrologic functions of the Alluvial Valley Floor. The essential hydrologic functions of the Fish Creek Alluvial Valley Floor have been identified as having the capacity to support subirrigated and flood irrigated agricultural activities. Mining beneath the Fish Creek AVF has occurred in panels 5, 6 and 7 of the Southwest Mining District and did not result in dewatering of the stream/alluvial system. Also, as discussed previously, no material damage would result from changes in the quality of surface and ground water that supply the Fish Creek Alluvial Valley Floor. The essential hydrologic functions of the Fish Creek Alluvial Valley Floor would not be affected by the proposed operation. Monitoring of Fish Creek above and below this area continues as per the approved plan. Undermining of Fish Creek was approved in Permit Revision No. 5 in Longwall panels 13L, 14L, and 15L in Section 19, Township 5 North, Range 86 West, and Sections 24 and 35, Township 5 North, Range 87 West. Similar response to undermining of Fish Creek is expected as observed when other portions of Fish Creek were undermined previously. PR -10 proposes to mine under Fish Creek in panels 6RT, 7RT, 8RT and 9RT in the Wolf Creek Reserve. Fish Creek will be monitored upstream and downstream from the under -mined area, as required in the approved plan. Trout Creek- The reek The boundaries of the Trout Creek Alluvial Valley Floor which would potentially be affected by the proposed operation and to which these findings apply include irrigated pasture 8S, which encompasses the Middle Creek/Trout Creek Confluence, and all alluvial deposits downstream on Trout Creek to its confluence with the Yampa River, Page 46 of 52