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COLORADO DEPARTMENT OF HEALTH Water Quality Control Division 4210 East 11th Avenue Denver, Colorado 80220 ZaTIONALE e4~1ENDMENT iJO. 5 WESTERN FUELS - UTAH, INC. PER?!IT NUMBER CO-0038024 RIO BLANCO COUNTY FACILITY DESCRIPTION: By letter of July 27, 1987, the permittee has requested an additional outfall, which would be used as an alternate discharge point for mine water. The mine water is currently pumped about 1.8 miles to pond PP-2 where it is commingled with shop and conveyor washdown, WTP reject water and W~TF effluent. The new outfall would serve as a discharge point strictly for mine water and would necessitate pumping only about 0.4 mile. Settling would occur in as 8 million gallon underground sump. The new outfall shall be numbered outfall 023. Discharge will go to Scullion Gulch at a point approximately one half mile above confluence with the White River. iIo livestock or wildlife typically use Scullion Gulch along this stretch. Access to the majority of the gulch is restricted by fencing. Sheep graze above the mine site, but not along or below it. EFFLUENT LIMITATION EVALUATION: Scullion Gulch is part of Segment 13a of the White River Sub-basin. Segment 13a has no metals standards. Thus, the discharge is evaluated against the neat Segment (12 ), which is the mainstem of the White River. The 7-day, 10-year low flow CQ7_10) for the White River is 140 cfs. The permittee has stated that a maximum of 79,200 gallons would be discharged per week, but he cannot estimate the daily maximum flow at this time. For a conservative approach, we will assume that the entire 79,200 gallons (0.123 cfs) could be discharged in a single day. This would yield a ratio of 1138:1. At this high dilution no specific metals limitations would be necessary. Appendix A shows calculations for a few parameters to illustrate this point. Appendix B shows the results of two analyses of this water. The only parameter of concern is total dissolved solids, which will be discussed later.