2015-12-23_PERMIT FILE - C1982056 (2)

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Water quality in Middle Creek above Mine 3 (U.S.G.S. Station 09243700) is of magnesium- calcium sulfate - bicarbonate type. Total dissolved solids ranged from 434 mg/l in April 1992 to 920 mg/l in September 1992. Field pH ranged from 8.6 units in June 1992 to 8.9 units in September 1992. Concentrations of total recoverable iron ranged from 0.9 mg /l in April 1992 to 9.7 mg /l in September 1992. Total recoverable manganese concentrations ranged from 0.8 mg /l on September 16, 1992 to 7.9 mg /l on September 23, 1992. Total recoverable zinc concentrations ranged from below detection limit in April 1992 to 0.2 mg/1 in September 1992. Other metals analyzed were consistently below detection limits. (3) Alternative Water Supply Information The application shall identify the extent to which the proposed surface coal mining operations may approximately result in contamination diminution or interruption of an underground or surface source of water within the proposed permit area and adjacent areas for domestic, agricultural, industrial, fish and wildlife, or other legitimate use. If contamination, diminution, or interruption may result, then the description shall identify the alternative source of water supply or sources of augmentations water that could be developed to replace the existing sources. The alternate or substituted water shall be of a qualfty and quantity so as to meet the requirements for which the water has normally been used. (See Articles 83 and 92 of Title 37 of the 1973 Colorado Revised Statutes. RESPONSE The adjudicated water rights in the Foidel Creek and Fish Creek watersheds are listed in Table 9, Summary of Ground Water Rights, and Table 12, Summary of Surface Water Rights. Included in these tables are water right names and I.D. numbers, source information, locations, adjudicated amounts, and use(s). Those rights owned by TC are highlighted in yellow. In general, adjudicated water rights are used for industrial, commercial, and domestic purposes; or agricultural and domestic use. TC holds significant senior adjudicated flow and storage rights, which are used to meet mine water requirements, and are available to address any mining- related water impacts under an approved Water Adjudication Plan. Potential water quality impacts are addressed by TC's extensive drainage and sediment control system, targeted water treatment, and ongoing water quality monitoring and compliance under the applicable terms of active CDPS discharge permits. Irrigation ditches are utilized in the Twentymile Park Basin to support production of forage crops such as grass hay and alfalfa. The ditches are equipped with headgates, which divert natural flows from perennial and intermittent streams, for irrigation during the latter part of the growing season (July through September). The adjudicated irrigation ditches are listed in Table 12, Summary of Surface Water Rights. Some of the ditches are no longer active, however, TC has developed a ditch inventory and maintenance plans, and is proceeding with ongoing ditch maintenance activities to both maintain and rehabilitate those ditches which are practically functional, and can be used to support agricultural activities as part of TC's land management programs. The extent of potential impacts of mining and related operations on surface and ground water resources in the Permit and adjacent areas is identified and analyzed in the Protection of the Hydrologic Balance Section under Rule 2.05.6 (3). The potential for mining- related impacts on the registered water rights listed in Tables 9 and 12 is based on this assessment. There are two aspects of the planned operations, which may affect sources of water for beneficial use; 1) Partial dewatering of the overburden aquifer; and 2) Handling and treatment of excess water. The overburden aquifer will be partially dewatered by inflow and subsequent pumping from the underground mine workings. Inflow to the mine may cause drawdown of water levels in adjacent water supply and monitoring wells. Quantitative estimates of inflow and drawdown are presented in the Protection of the Hydrologic Balance Section under Rule 2.05.6 (3). Because of the confined non - tributary nature of the overburden aquifer previously discussed under Rule 2.04.7 (1), dewatering is not expected to result in any significant noticeable depletion of private wells within the general area, as documented under Section 2.05.6(3). TR 13 -83 2.04-38 11/03/14