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An artificial form of recharge is occurring as a result of the irrigation ditch network and <br /> practices in the immediate vicinity of the mine. Were there not this source of recharge, <br /> the time required for the spoil to recharge from natural ground water flow and rainfall <br /> would be considerably longer. In conclusion, the mining operation will not diminish <br /> vertical or horizontal permeabilities and may increase them, thus there should be no <br /> significant impacts from the mining operation on ground water flow and recharge rates. <br /> The time period required for the spoil material to resaturate should be greatly reduced <br /> because of all the irrigation recharge (the Nucla East area will be revegetated for an <br /> irrigation type of postmining land use). <br /> Containment of Pit Inflow Pumpage and Impacts on Water Quality. All runoff and pit <br /> pumpage from disturbed areas are routed through sedimentation ponds. The ponds are <br /> designed and constructed to impound runoff and pit pumpage from areas disturbed by mining <br /> and provide sufficient residence time to insure that the pond discharge water chemistry <br /> meets the effluent requirements- specified in NPDES Permit No. CO-0000213 (see Tab 7, <br /> Appendix 7-6). Plans have been developed for water rights augmentation pumping from the <br /> ponds and minimizing erosion during the pumping (pagea 13-6 and 13-10 in Tab 13). In <br /> total, seven NPDES ponds are or will be constructed to contain runoff and pit pumpage from <br /> the two mining areas. Ponds 001 through 006 receive all runoff and pumpage from the Nucla <br /> mining area and Pond 007 is proposed to contain all discharges from the Nucla East mining <br /> area. To date, Ponds 002, 003, 004 and 005 have never discharged. All flow data for Pond <br /> 001 can be found in Tab 7, Appendix 7-5. Appendix 7-7 of Tab 7 presents all chemical data <br /> for discharges and monitoring at Ponds 001 and 006 as well as all flow data for 006. <br /> A review of the chemical and flow data indicates that the potential for any discharge from <br /> Pond 007 to exceed state receiving stream or federal standards is very minimal. Through <br /> 1987, only one NPDES standard has been exceeded at Ponds 001 and 006. The exceedence <br /> occurred in 1982 at Pond 001. The measured 30 day average for TSS was 45 mg/l and the <br /> NPDES standard is 35 mg/l. Also, there has been only one exceedence of the Colorado <br /> Department of Health receiving stream standards for Segment 5 of the San Miguel River. A <br /> total recoverable value of 140 ug/l for Ni was measured in the discharge from Pond 001 and <br /> the receiving stream standard is 100 ug/l. The significance of this is negligible as <br /> there is no Ni standard for Tuttle Draw, the associated flow was small and the impact to <br /> the higher flow San Miguel water quality would not be measurable. <br /> In the pit inflow section of this Tab, rates of ground water inflow by year have been <br /> calculated. The highest rate of inflow is projected to occur in year 5 of the Nucla East <br /> 17-29 Revised 08/19/88 <br />