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. ~~ Cv~eos ~pme ,' ~ cosroasroN A Cyprus Amen Company III IIIIIIIIIIIIIIII P.O. Box 6d Craig, Colorado 81626 (970) 824-8246 RECEIVED December 8, 1998 Mr. Byron Walker Em•iromnental Protection Specialist Colorado Division Of Minerals and Geology 1313 Sherman Street, Room 215 Denver, Colorado 80203 RE: EAGLE MINE, PERMIT NO. C-81-044 1997 Annual Hydrologic Report, Adequacy Review Dear Mr. Walker: DEC 0 9 1998 Division of Minerals & Geology In response to your request for fiuther e~plartation of the iMon»ation provided in Figures 16 and 17 of Ute 1997 Armual Hydrologic Report, I submit We following: FiCrrre 16 Figwc IG of the 1997 AHR (as well as previous AHRs) cl><arts Ute water discharged From Ure No. 5 and No. G nilnes, expressed as a constant rote of Oow Cor We reporting period of one year (We mean annual discharge rate). Historically these sources were ptmtped nearly continuously in order to maintain constant water levels at Ure underground reservoirs Urat each served. Under Utose conditions, Ure combined Oow of We two sources also served as a measurement of inflows into Ute mine. During 1997, wiW the rune in temporary cessation, Were pumps were run oiily intermittently (t}pically one week per monW or less). As you can see, We water discharged during Wese intemtiuent pwnping periods, particularly when projected as an equivalent constant tlow (the mean annual discharge rate), is muter insignificant pess Uuvr 0.5 gal/min) when compared prior years. Further, Were is no longer a correlation behceen the discharges and mine inflow-s. Fimire 17 Historically, discharges from mines No. 5 and No.6 were measured at Weir respective N.P.D.E.S. discharge points weekly. Since pumping was continuous (as explained above), flows at We discharge points were also continuous and nearly equivalent to We flow metered at We pwnps. In prior years, We weekly Oow roles, at Ilte N. P.D.E. S. sites, were graphed as Figtue 17. However iu 1997, druing temporary cessation. Wese pwnps were nw only internrinrntly. The water Wat was pumped to We surface, and Wen Uuough a series of ditches and treaunent pond:;, did not always produce a discharge at the N.P.D.E.S. sites. Weekly readings, therefor, did not provide meaningful data for We 1997 AHR. In lieu of the custonntry N. P.D.E. S. discharge data, in the 1997 AHR Figure 17 provides a montlily listing of the metered quantifies of water pwmped out of the mines.