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<br />U <br />-lfl- <br /> <br /> <br />To aid in mitigating the affects of the irriyation return flows, the <br />operator proposed tv+o solutions. One measure used was to divert as much <br />surface water away from pits as possible. This has helped surface flows <br />somewhat but is not yreatly reducing the amount of interflow. A second <br />measure proposed was to concrete line ttre irrigation ditches <br />north-norttrwest of the mine. Although this would greatly remedy the <br />problem, the ditch owners have so far been unreceptive to the idea. The <br />operator is continuing to pursue this measure. <br />The monitoring data of water discharged from the mine shov+s seasonal <br />fluctuations in total dissolved solids and nitrate. This is expected due <br />to the high concentration of these parameters in the irriyation return <br />flows. Other constituants such as heavy metals and trace elements do not <br />fluctuate significantly throughout the year. This would seem to indicate <br />that leaching of the regraded spoil material by spring runoff or <br />irrigation water is having a minimal affect on the mine discharges. <br />Iron and maganese concentrations in mine discharges tend to fluctuate <br />with sediment loads. Hov+ever, manganese increases are mare delayed than <br />iron. Urre explanation nay be that manganese is released from sediment <br />muds at the bottom of ponds where anaerobic conditions increase its <br />solubility. Despite this situation all iron and manganese levels have <br />been helow E.P.A, effluent limitations. <br />Other water quality paramenters such as conductivity, hardness, calcium, <br />and sulfate increase due to mine discharges but do not significantly <br />change the quality of water flowing in Tuttle Draw. <br />Sediment loads increase so~nev+hat belov+ the mine but are probably <br />attributed to non-mining sources such as agriculture. The mine has <br />mitigated sediment impacts by utilizing a sediment control system and <br />promptly reveyetating mined out areas. <br />B. Ground Water <br />The primary probable hydrologic consequences of mininy to the ground <br />water will be the affects to the shallow bedrock aquifers by possibly <br />increasing recharye and thereby diluting poor ground water quality. <br />Deeper aquifers will probably not be impacted for the mining operation <br />will disturb only the top 100 feet of strata. I~lonitoriny wells and pit <br />observations show that the overburden is generally not saturated, <br />hov+ever, interflow in the overburden does occur during the irrigation <br />season. It can be concluded that the major source of v+ater in these <br />shallow aquifers is from irrigation. It therefore appears from <br />piezo~netric data drat the mine overburden is an area of recharge to <br />shallow aquifers. Uuriny periods of hiyh water tahle conditions, <br />discharge of this water would be to Tuttle Uraw on the south. <br />l <br />