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Mine Water Quality Assessment <br />CO-0034142 <br />RAG Empire Corporation, Eagle Mine: The RAG Empire Corporation, Eagle Mine is located at <br />40 25' 41.69" latitude and 107 39" 11.12" longitude. The current design capacity of the facility is <br />4.03 MGD (6.2 cfs) for Outfalls 003, 022 and 024; the design capacity of Outfa11023 is 0.012 MGD <br />(0.019 cfs). The technical analyses that follow include assessments of the assimilative capacity <br />based on this design capacity. <br />Total Residual Chlorine: The mass-balance equation was used to determine the assimilative <br />capacity for chlorine. There are no sowces located immediatelyupstream or downstream oftheEagle <br />Mine dischazge. Since chlorine is rapidly oxidized, in-stream levels of residual chlorine aze detected <br />only for a short distance below a source. Ambient chlorine was therefore assumed to be zero: <br />Using the mass-balance equation provided in the beginning of Section N, the acute and chronic low <br />flows set out in Section III, the chlorine background concentration of zero as discussed above, and <br />the in-strearti standazds for chlorine shown in Section II, assimilative capacities for chlorine were <br />calculated. Outfall 023 represents the only sowce of chlorine from the Eagle Mine. Thus the efl]tient <br />flow, Q2, is set equal to the design flow of 0.012 MGD (0.019 cfs) for Outfa11023. The data used <br />and the resulting calculations of the allowable discharge concentration, M_~, are set forth below. <br /> Parameter Qt (cfs) Qi (Sfs) Q3 (Sfs) Mt (UgB) Ms (u8B) Mz (u$n) <br /> Acute Chlorine 11 0.029 11.019 0 19 11,275 <br />~~ Chronic Chlorine 20 0.019 20.019 0 11 11,860 <br />Fecal Coliform: No data for fecal coliforrn were available. Because there aze no nearby upstream or <br />downstream sources of fecal Coliform, the ambient concentration is assumed to be zero. Note that <br />this is consistent with the analysis conducted for the Rationale for Classif:cat:.ons, Standards and <br />Designations of Segments of the Lower Colorado River Basin and was likewise considered <br />appropriate for this WQA... °_ •-_ ~ ~' <br />It is the staddazd approach of the WQCD to perform a-mass balance check•based solely on the <br />individual discharger to determine if fecal Coliform standards ate exceeded.; And, a~ is standard <br />WQCD procedwe, the checks are only conducted on the chronic low flows assetout in Section IlL. <br />Using the equation provided in the beginning of Section N, the backgound concentration of zero, <br />and the in-stream standazds for fecal Coliform shown in Section II, checks for fecal Coliform were <br />conducted. Outfa11023 represents the only sowce of fecal Coliform from the Eagle Mine. Thus the <br />effluent flow, Q2, is set equal to the design flow of 0.012 MGD (0.019 cfs) for Outfa11023. The data <br />used and the resulting calculations of the allowable discharge concentration,.MZ;.aze.also set forth <br />below. • <br />Parameter Qt (cfs) Qz (cfs) Q3 (cfs) Mt (#/100 <br />ml) M3 (#/100 <br />ml) M2 (#/100 <br />tnl) <br />Fecal Coliform 20 0.019 20.019 58 2000 2,093,858 <br />Appendix A Page 10 of 13 <br />