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<br />and chemical eoncentra tf ons will allow for a rrorst case analyst a, Tables 17-t 9, 77-20A, <br />antl 17-20g aro presented to show the impact asaessnent computations for Lhe eombi ned Nucie <br />and Nucla East aDOil di seherges into the San Miguel, Nucla East spoil dT schargea into <br />Calamity Draw, and Nuela spoil discharges into Tuttle Oraw, respeeti vely. Assumptions <br />that were necessary Tn performing the computations era explained in Table 77-21. The <br />results of the water quality impact computaLf ons era, 7) The eonbi netl impact from the <br />Nucla and Nucla East spoil dT ache rges on tfie San Miguel water quality is only a 3 percent <br />increase in mean annual TDSI 2) The fmpacC of Nucla Ea at spoil dl schargea on Calamity Draw <br />hater quality is a 12 percent increase Tn TDS from 2,250 mg/7 to 2,533 mg/ll and 3) Ths <br />impact of the Nuela spoil discharges on Tuttle Dran is a 70 percent increase in TDS from <br />7,213 mg/1 tc 2,O6t mg/1. <br />The affects of the spoil di ache rges on Cha surface water quality in Calamity Draw and <br />Tuttle Draw appears to ba significant only when taken in the context of perttnt TD5 <br />increase over background. Coneantratf ons of Fe, Mn, 504 as wall as pH render the <br />baek9found surface hater 1n both of these draw9 unsuitable for use as domestic drinking <br />water. Concentrations of Mn and pH levels also render the water unauf table For use es <br />• irrigation water. The signs fi canes of t7m 7D5 increases to~2,500 and 2,700 ng/1 in terms <br />of water use is very minimal ac the changes will not affect the Dresent and ppLeniial use <br />of the water nhi ch is 1Svestoek drinking water. Hi ni ng impacts on the San Niguel water <br />quaff ty era vary minimal (3 percent 7D5 increase) and will in no way preclutle any of the <br />present or potential uses of Chia water. <br />At the request of HUt (9/22/08 latter from Catharine lieyaj to Ted Smith) addf Lionel Batt <br />loading projaeti one Nava been pefforned and era ineT Udad as Appendix 77-2 to this tab. <br />The additf oval analywa utilize only the 07_10 low flaw value for the San Hi goal and <br />include combined during mining impacts frao Nucla and Nuela East. <br />According to Irons et al ., 7965, Dage 131, the 07_10 flow value of 6.48 efa at Haturita <br />has a prababf lity of being exceeded 99.9 Dement of the time. Peabody questions the <br />relevanw a9 using such a low flow value for PHC pu rposea, particularly conai daring tM <br />fact that soon of the input parameters may have aignifieant (in terms of the ongni tude of <br />Lhe flow va fuse being used) amounts o/ error aeaoeiated with them. My conclusions <br />derived iron this additional analysis should be carefully qualtif ad. <br />17-68 Revised 10/07/88 <br />• <br />REVISED tv1ARCH 2006 Attachment 2.05.6(3)-2-78 <br />