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COI,URAUO DEFAlt1'MENT OF III?ALTII <br />Wafer I~ualiCy Contru.l Division <br />42.L0 East 11th Aveuue <br />Ucnver, Colorado 110220 <br />IlA'1'1UNAI.E <br />AMENDI•fEN'l' N0. .1 <br />PIiAI)ODY COAL - NUCI.A COAL MINE <br />PIsILMiT NUMDIiR CO-0000213 <br />MON'TROSE COUN'l'Y <br />By letter of April 10, 190J,.tlie permittee I~as informed us of a new source of <br />wastewater being discharged through outfall U01. Spoils spring water I~as <br />begun emanating and Peabody lies touted it into tl~e 001 pond. 1'he permit was <br />written wltli Cederal DAT limitations to cover discharges of surface runoff <br />only. Phis new source necessitates a reassessment to determine whether <br />additional limitations are needed to cover this mostly continuous source. <br />For continuous sources, State water quality standards (WQS) must be met. Tlie <br />division uses a mesa balance formula to calculate limits, then compares the <br />limits to monitoring data to determine whether the limits must be imposed in <br />the permit. Tl~e calculations for several parameters for this outfall are <br />shown in Appendix A. <br />Tlie stream segment (Segiaent 12) which includes Tuttle Draw (immediate <br />receiving water for outfall 001) has no metals standard e. For this reason the <br />division looks at maintaining the standards in ttie next segment (Segment S, <br />San Miguel River Subbasin, Gunnison River Dasin). The 7-day, 10-year low flow <br />for the San Miguel River at confluence wltl~ Tuttle Draw (1.0 cfs) is used. <br />'1'Y~Ss looks at a worst case situation, that being w)iere the entire flow in <br />Tuttle Draw emirates from outfall U01 and tl~e flow in the San Miguel River Ss <br />at the Q7_10. 1'lie effluent flow wlticl~ .ie used is tl~e highest reported flow <br />on file. <br />'i'lls permittee subml.Cted monitoring results from seventeen samples of the <br />spoils spring prior to mixing with any waters in tl~e pond 001. This data is <br />nse~l ley tl~e division for comparison. It is expected that effluent <br />cc»icentrations wll.l be leas than or equal to tl~ls data, due to se[tling wl~icl~ <br />occurs in the pond. <br /> <br />7-6-33 <br />