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APR-20-2000 THU 04:48 PM FAX N0. P. 04 from the outflow window. The primary justification appears to be that M-341ics outside the current conivuination plume, as viewed by B;ufItl. This fact, if Uve, is largely irrelevant. Colorado law reyuires that the alluvial aquifer be protected at all points --not just downgradient from the cun'ent pollution plume. The critical point is the window, the point where the outflow from the Wcst Pit enters the 1Zito Scco alluvium. AMR[ admits drat "[t]he expected long-term concentration of manganese in groundwater flowing from the West Yit may be approximately 2mg/I,." TR-2$ at pp. 1 1-13. The fact that natural processes may attenuate these levels down to the standard ol•0.05 mglL by the time the plume reaches M-34, even i f true, does not mean that BMRI has complied wish its duty to protect ground water when it first enters the alluvium at the window. Thus, BMRI's conclusion that "manganese concentrations arc not expected to exca~d the (able value standard of O.OSmgJL", TR-28 at p. l2, is incorrect. BMRI would only be in cotttpliance with the law if such a statement applied in the entire Rito Seco alluvium. In fact, the DMG's April 11, 2000, adequacy -etter, at p. 3, aekttowledges shat M-34 will only "provide adequate demonstration that the lower segment of the alluvial aquifer is not being ndvcrsely affected by fire existing contaminant plume." Protecting only tltc lower segtncnt, rather than the entire segment, does not comply with state law attd cannot form the basis for DMCdr approval. Since that is trot the case, BMRI's proposals tnust be rejected and appropriate water quality protections must be regttircd. Accordingly, one or Wrote of the wells in the window {M- 18, 19, 28, andlor 29) should be used to ascertain whctltcr BMRI is protecting the alluvium ground water. li should 6e noted drat BMRi's reliance on "elevated" "natural concentrations of manganese" at M-26 attd M-30, TR-28 at p. 12, is misplaced. These two wells are either significantly downgtadicnt front dtc window (Nt-2G), or above the window (M-30). They an not rcpresentativo ofpre-mining conditions in the alluvial window. Regarding surface water contpliattce points, BMRI's proposal to tttove the critical point downstroam to RS-5 is also very troubling, The trot measure of the Wcst Pit's inflwence upon the Rito Scco is in the vicinity of tltc window, not far dowttstrc:utt. State law does not al low standards to be stet by i3MR1 downstream -- it requires all standards to be met at th4 point of discharge. In addition, the treated efFluent should be discharged downstream of an appropriate instreattt compliance point, well downstream of the compliance aztd tttonitoring locations setup to ascertain the impacts of the West Piton the stream and stream alluvium. Accordingly, the DMG must notify BMRI that RS-2A, or a point even closer to the window, will be the point at which compliance with surface water standards must be established.