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i• <br />J <br />Blue Mountain <br />where: <br />Inc. WWTP Water <br />Assessment <br />CO-0038024 <br />Q~ =Upstream tow flow (1 E3 or 30E3) <br />Q1=Average daily effluent flow (design capacity) <br />Qa =Downstream flow (Ql + QZ} <br />Mi = In-stream backgound pollutant concentrations at the existing quality <br />Mz =Calculated maximum allowable effluent pollutant concentration <br />M3 =Maximum allowable in-stream pollutant concentration (water quality standards) <br />When Q~ equals zero, QZ equals Q3, and the following results: <br />Mz = M~ <br />Because the low flow (Q!) for the unnamed tributaries to Red Wash and Scullion Gulch is zero, the <br />assimilative capacity of the unnamed tributaries to Red Wash and Scullion Gulch for the pollutants <br />of concern is equal to the in-stream water quality standards. <br />The in-stream background pollutant concentrations used in the mass-balance equation will vary <br />based on the regulations definition of existing ambient water quality. For most pollutants, existing <br />quality is determined to be the 85u' percentile. For metals in the total recoverable form, existing <br />quality is determined to be the SO's percentile. <br />For non-conservative pazameters and ammonia, the mass-balance equation is not as applicable and <br />thus other approaches aze considered where appropriate. Note that conservative pollutants are <br />pollutants that aze modeled as if mass is conserved and there is no degradation, whereas non- <br />conservativepollutants degrade and sometimes are created within a receiving stream depending on <br />stream conditions. Amore detailed discussion of the technical analysis for these parameters is <br />provided in the pages that follow. <br />Pollutants of Concern , <br />The following pazameters were identified by the WQCD as pollutants of concern for this facility: <br />• Ammonia <br />• Fecal Coliform <br />• Chlorine <br />• Iron <br />• Manganese. <br />During assessment ofthe facility, neazby facilities, and receiving stream wafer quality, no additional <br />pazameters were identified as pollutants of concern. <br />Blue Mountain Ener¢y, Inc. WWTP: The Blue Mountain Energy, Inc. WWTP is located at <br />Sections 1-4, 10-12, T2N, R101 W; and Sections 29-36, T3N, R101 W; approximately nine miles <br />northeast ofRangely, CO in Rio Blanco County. The current combined design capacity of the five <br />subject outfalls (numbers 004, 023, 024, 026, and 029) is 0.79 MGD (1.2 cfs). Additionally, Outfall <br />004, which is the outfall containing treated domestic sewage, has fecal colifomr, total residual <br />Appendix A Page 10 of 15 <br />