Laserfiche WebLink
Table 2.05.6.(3)-1 <br />Summary of Consequences of the Life -of -Mine Mining Plan for the New Horizon Mining Area <br />July 2016 (TR -74) 2.05.6(3)-12 <br />Probable Hydrologic Consequences <br />Analysis Results <br />Significance <br />Ground <br />Water <br />I <br />Interruption of ground water flow and <br />Maximum projected pit inflow rates will be approximately 5,230 <br />Short term impact of minimal significance. Any injury to surface <br />drawdowns. <br />ft3/day during year 5 of mining at the New Horizon 2 mining area. <br />water rights will be mitigated according to the surface water <br />The maximum extent of the 1 foot drawdown contour is estimated to <br />augmentation plan. Wells proximate to mining areas are <br />be 4,000 feet from the center of the pit. <br />completed in deeper units and are not likely to be injured (little <br />significance). Ground water rights mitigation plan addresses <br />alternative ground or surface water sources should they be <br />needed. No short or long term significant impacts. <br />2 <br />Removal of wells and ponds by <br />No water righted wells are projected to be removed in the <br />No impact. <br />mining. <br />remaining areas to be mined except the Garvey Well (water Right <br />42) and the Ernest Well (Water Right 1). These wells and the land in <br />which they are located, have been bought by the permittee. <br />3 <br />Impact of replaced spoil material on <br />Horizontal hydraulic conductivities will be higher in the spoil as a <br />Short term impact to topsoil structure but of little significance <br />ground water flow and recharge <br />result of higher percentages of interconnected porosities. <br />as far as infiltration rate changes because of plowing and disking <br />capacity. <br />Existing and reclaimed topsoil infiltration rates are similar except <br />practices in the reclamation. Vertical hydraulic conductivities in <br />for some loss of soil structure in the reclaimed topsoil. Vertical <br />the spoil will improve because they are no longer dependent on <br />hydraulic conductivities in the overburden are principally limited to <br />fracture flow. Horizontal hydraulic conductivities should also be <br />interconnected fractures. Flow impeding ledges of consolidated <br />higher. <br />rock are absent in the spoil but there is poorer sorting of grain sizes. <br />4 <br />Containment of pit inflow pumpage <br />Only one exceedence of an NPDES standard has occurred as a <br />There is very little chance of federal or state receiving stream <br />and impacts on water quality. <br />result of pond discharges since 1979. Pit pumpage impacts to <br />water quality standards being exceeded in any pond discharges. <br />Calamity Draw and San Miguel water quality are 1.5 percent and <br />If any problem were to occur, the discharge could be <br />.08 percent increases in TDS, respectively. <br />stopped from the pond and the problem could be remediated. <br />Pit pumpage impacts in terms of TDS increases in Calamity <br />Draw and the San Miguel River will be very slight. No short or <br />long term significant impacts. <br />5 <br />Impact of spoil water quality on <br />Geochemical controls on water quality suggest that the water <br />No indication of significant long or short term impacts to the local <br />ground and surface water quality. <br />chemistry and concentrations of most elements of concern are <br />ground water quality. Impact to San Miguel water quality is of <br />controlled by mineralogic reactions that will resist changes in water <br />little significance. Impacts to Calamity and Tuttle Draw water <br />chemistry. Irrigation water will enter the spoil and will increase <br />quality are measurable, but are of little significance in terms of <br />in TDS and will discharge from spoil springs but the quality <br />water use. See detailed discussion in Probable Hydrologic <br />will be essentially the same as the current overburden water <br />Consequences under Item 5) Potential impacts of replaced spoil <br />quality. This will occur for at least hundreds of years and the spoil <br />on groundwater quality. <br />water quality will gradually improve to the quality of the irrigation <br />water as pyrite is oxidized and dissolved solids are flushed out. <br />July 2016 (TR -74) 2.05.6(3)-12 <br />