2014-12-19_REVISION - C1980005 (2)

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finds that the revegetation on the Seneca II Mine reclaimed areas is capable of supporting the approved post- mining land use. Evaluation of Hydrologic Impacts In accordance with Section 3.03.2(2), the Division has evaluated whether pollution of surface or subsurface water is occurring, and the probability of future occurrence of such pollution. The evaluation considered information in the following documents: the Probable Hydrologic Consequences section of the permit application, Annual Hydrology Reports submitted by the operator, the Division's Annual Hydrology Report review memoranda, and documents in the SL -06 bond release application and file. The results of the evaluation are summarized below. Basic Standards Interim Narrative Standard for Ground Water (CWQCC Regulation 41.5(c)(6)) The Seneca II Mine alluvial ground water point of compliance ( GWPOC) is well SFAL72, located in the Fish Creek alluvium less than one mile downstream from the Bond Creek confluence with Fish Creek. A review of the statistical summary of the water quality of SFAL72 was completed based on water quality data presented in the Annual Hydrology Reports for the Seneca II Mine. Well SFAL72 was permitted as the GWPOC in Technical Revision No. 47 (TR -47) approved in 2009. Based on the data collected, ambient values for SFAL72 were found to be higher than the Reg. 41 standards for iron, manganese, nitrate, and sulfates. For the past three years (2011 to 2013), the only standard that was exceeded was iron (0.35 mg /1, dissolved), with values ranging between 2.88 and 5.16 mg /1. However, total recoverable iron values, which should be greater than or equal to total dissolved values, were less than 0.32 mg/l for the last three years upstream at all spoil springs (SSSPG9, 0.28 mg/1) and in the NPDES discharge (NPDES8, 0.31 mg/1). Therefore, the high iron values observed at Well SFAL72 are not likely to be the result of discharges from the Seneca II Mine. The Seneca II Mine does not have a groundwater point of compliance for ground water in bedrock stratigraphic units, based on the absence of the potential for the mine to negatively impact the quality of bedrock ground water. Based on the decision of TR -47, the low hydraulic conductivities of the bedrock units and confining layers isolate mine - impacted water bearing units from the nearest usable aquifer, the Trout Creek Sandstone, which lies approximately 300 to 400 feet below the Wadge Coal seam and approximately 60 to 100 feet below the Wolf Creek Coal seam. Instream Numeric Standards (CWQCC 33) The Seneca II Mine discharges surface runoff and spoil leachate into Segment 13b (Fish Creek and tributaries) of the Yampa River in CWQCC's Region 12 of the Yampa River Basin. The Seneca 11 Mine is required to monitor 17 of the parameters in Segment 13b per CWQCC and CDRMS. A review of the statistical summary of the water quality data provided in Seneca II Mine's Annual Hydrology Reports and specifically for the past three years was conducted for the mine's NPDES Outfall (NPDES8) and stream sites SSB12 (Bond Creek above the confluence with Fish Creek), SSF11 (Fish Creek above the confluence with Bond Creek), and SSF13 (Fish Creek downstream of