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i• J Blue Mountain Energy, Inc. WWTP Water Quality Assessment CO-0038024 residual chlorine is a pollutant of concern unique to Outfa11004, only the design flow of Outfall 004 will be used in the analysis. Using the mass-balance equation provided in the beginning ofSection IV, the acute and chronic low flows for the White River set out in Section III, the chlorine background concentration of zero as discussed above, and the in-stream standards for chlorine for stream segment COLCWRI2 shown in Section II, assimilative capacities for chlorine were calculated. The data used and the resulting calculations of the allowable dischazge concentration, Mz, are set forth below. Acute Chlorine 124 0.065 124.065 0 0.011 21 Chronic Chlorine 208 0.065 208.065 0 0.019 61 Fecal Coliform and E.Coli: The full assimilative capacity of the stream for fecal coliform was determined to equal the in-stream water quality standazd for stream segment 13a of 2000 colonies/100 ml (chronic). The full assimilative capacity of the stream for E. Coli was determined [o equal the in-stream water quality standazd for stream segment 13a of 630 colonies/100 ml (chronic). Metals: EPA reseazch and extensive effluent monitoring of the coal mining industry mine water discharges have determined that the only metals commonly found in Colorado mine water discharges aze iron and manganese. Iron is prevalent in such dischazges and manganese is infrequently found. Based on previous monitoring of the Blue Mountain Energy, Inc. discharges, iron is likely to be present and manganese maybe present. The full assimilative capacity of the stream for total recoverable manganese was determined to equal the in-stream water quality standazd for stream segment 13a of 200 ug/1(chronic). There aze no standards for dissolved iron, total recoverable iron and dissolved manganese for segment 13a. Thus, the assimilative capacities will be based on the downstream standazds and low flows for segment 12. Using the mass-balance equation provided in the beginning of Section IV, the low flows provided in Section III, the background concentrations contained in Section II, and the in-stream standazds for metals shown in Section II, assimilative capacities were calculated. The data used and the resulting calculations of the allowable discharge concentrations, M2, aze set forth in Table A-8. Note that them are no acute metals standazds for pollutants of concern. Appendix A Page 12 of 15