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I• <br />Summary. The anal yaia of geochrnicel controls on ground water quality suggests tfiat <br />the water charm atry and eoneantratl one of most al ements of concern ors eontroilnd by <br />mineral ogle reaeti ons eh at will real sL ehenges'in water chemistry. Boron coneen[rati ono <br />do not appear to be controll ad by mineral solubility. Production of acid may occur in <br />very local settings (and is Drobably most prevalent In the coal, whl ch wi it ba mi nod); <br />ealcul ati ons indicate that neutral lzati on of the acid nt 11 occur rapidly with mixing of <br />water, or with movement of acidic water into calcite-bnari ng rocks. <br />Additionally, the methodology developed by Hounslow et al. (t 978) also indicates that <br />chemical changes are not likely to occur. Although the approach is not spectffe to the <br />se[ting et Nuela, it was developed by using data from many mi nee in a variety of settings, <br />ine lading minas of similar character. <br />Last, the water aenpled from apolls st Nuela is typical of ground water in the Nucla and <br />Nuela Eest areas, end is of better quality than most. There is no evidence of the <br />production of acid, increased mobility of toxic el ealents, or even increases in TDS. <br />Boron, the el rnent not addressed by the geochemi gal modelSng, showed no evidence of <br />increased concentratf ons. <br />• In auomery, nlning is not ii kely to cease significant changes in grouiM-water quality <br />(reawvsl of Che ooal may actually iapreve water quality), arW certainly wf 11 not impact <br />its use, .ditch is liefted by its naturally poor quellty. <br />Potential Impacts of Reol aced SDOile on Surface Nater puati ty. For purposes of assesai ng <br />the mining impacts on the receiving stream surface water chemistry, seasonal impacts were <br />eospared against mean annual Smpacta to daterml ne which analysis Drovided the worst case <br />scenario. For the seasonal analyaf s, sane day flows ware measured and samples were <br />collected trap the San Niguel Ri var above the Calamity Draw confluence and Del ow the <br />confluence With Tuttle Draw. At the enure time flow meeaurements and samples were taken at <br />Monitoring Sites SN-N3, SN-N7 and SN-N/03 an Tuttle and Calamity Draws, respectively. <br />Same day saeyles and meaaurrnenta were obeaf Wed on 4/3/87 and 10/5/87 representing the <br />ends of the non-S rri gati on aM irrigation peri ode, respecttvel y. Tables 17-15A and 17-758 <br />show the flaw, TDS end ChrnT Cal load input parameters measured and used Sn the same day <br />(seasonal) a~ mean annual Tmpaet analyses, resDecti valy. <br />1 <br />Since Calamity Draw, at the present time, does not represent impacted water quality, the <br />17-81 Revised 84/11/88 <br />1~ <br />u <br />REVISED MARCH 2006 Attachment 2.05.6(3)-2-71 <br />