2017-02-03_REVISION - C1980004 (6)

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mining resumed, additional area in the saturatedportion of the graben was opened, and inflow increased to approximately 3.9 gpm in 1990. In April, 1990, the mine section from which inflow had originated was sealed, and in July, 1992, all areas to the north of the East Mains were sealed and are now inaccessible. No water has been produced in other areas of the mine since the section which had originally produced water was sealed in 1990. Further dewatering of the mine from areas which previously produced water is not projected to be necessary until water in the originally sealed area backs up to the seals, and is drained to a dewatering sump to be used in the mining process. At the 1990 inflow rate, this would not occur for approximately 60 years. The source of inflows to date is believed to be a mix of water infiltrating the graben along the faults and water in the coal seam. The mine was largely idle between 1992 and 1999; operations resumed in early 2000. As projected, additional mine inflows have been encountered since operations resumed, as the workings have extended further to the east into the predicted saturated portion of the Cameo seam. In April 2000, seepage was observed in the mining faces developing to the east. Current estimated inflow rate as documented in the 2005 Annual Hydrologic Report (AHR) is approximately 31.4 gpm, which is in line with PHC projections indicated in Appendix N of the application (30 gpm inflow predicted for 0.5 million ton per year production rate. This does not include the inflows into sealed portions of the mine north of the East Mains discussed in the previous paragraph. The inflow wateris collected in mine sumps and used for dust control in the mining process and for haul road dust control. Initially following resumption of operations in 2000, inflows were entirely consumed by dust control operations, but beginning in May 2002, discharge via CDPS Outfall 002 was resumed. For the purposes of projecting the effect mine discharge will have on East Salt Creek, PHC projections in Appendix N have assumed a conservative maximum mine flow rate of 100 gpm, or 0.22 CFS. The quantity of inflows which have been observed to date and are projected upon resumption of mining in future permit terms are considered to be insignificant with respect to effects on flow in the ephemeral surface drainages, or with respect to recharge of the coal seam. Based on information provided in the permit application, ground water intercepted by the mine does not appear to be in communication with any aquifers being put to beneficial use, and there are no registered wells within two miles of the permit boundary. The quality of water discharged from the mine is similar or higher quality than water in East Salt Creek at the confluence with McClave Creek, and any discharge is required to meet NPDES discharge standards. For these reasons, no detrimental impact to ground water resources or to surface water quality downstream of the permit area is expected. Original ground water flow patterns in the mined area will ultimate ly be reestablished after the mine is sealed and the abandoned workings slowly fill with water. An alluvial aquifer has been identified along East Salt Creek. Monitoring wells established in the alluvium indicate that alluvial water levels fluctuate seasonally in response to flow in East Salt Creek. Data collected by the applicant from the Salt Creek alluvial aquifer indicate a carbonate -sulfate type water, similar to the characteristics of 26