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• Powderhorn's discharge permit No. CO-0027146 includes 4 mine dewatering <br />discharge points. Outfall 001 is located on the southeast bank of the Colorado <br />River under the conveyor suspension bridge. Outfall 002 is located on the <br />southeast bank of the Colorado River approximately 1200 feet north of Outfall 001. <br />Outfall 004 (now inactive) discharged to Coal Canyon near the Roadside North <br />Portals dip section and allowed discharge of Roadside North Portals inflows after <br />being routed through pond 12. Outfall 015 (inactive) was permitted at the Roadside <br />South Mine's 2 West Portals. Discharge from 015 would be to an unnamed canyon <br />leading to the Colorado River. <br />Mine inflows fill abandoned portions (Northwest Intake Pool) of the Roadside <br />South Portals to an elevation of approximately 4760 feet. Water is siphoned and <br />gravity discharged from the mine to prevent water from reaching the old Northwest <br />Intake Portals. See Figure 14-6 Roadside South Portal Mine Water Discharge <br />System and Figure 14-7 Roadside South Portal Dewatering Schematic. The siphon <br />• is installed at the Northwest Intake and the water discharges through outtall 002. <br />Water is piped from the updip No. 2 South Mains Sump to Outtall 001. Flow meters <br />are installed on mine discharge points to accurately measure quantities of water <br />being discharged. Water quality of the mine discharge water will be tested annually <br />using the list shown on Table 18-2 for Surface Water. <br />Monitoring on Rapid Creek and Cottonwood Creek was initially discussed in <br />the Plan for Surface Water Monitoring of Rapid and Cottonwood Creeks and a <br />Contingency Plan for Rapid Creek submitted January 28, 1983, Stipulations <br />Response 4 and 5. A minor revision (MR01) in March 1983, extended the <br />compliance date for SR04. Crest stage gauges were installed at three (3) of the <br />monitoring sites according to minor revision MR02 in that year. In 1986, technical <br />revision TR09 eliminated monitoring on SWGS-04 and reduced monitoring on <br />SWGS-02 and 03. Flow measurements will be taken bimonthly on SWGS-02 and <br />03 during periods of low flow (June through November). Flow measurements on <br />SWGS-01 will be taken with a continuous flow record when the creek is not frozen. <br />-• <br />VOL 5 Tab 18 18-2 3/01/00 <br />