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<br />Williams Fork Mines Prepared by: R. Reilley M.S. GISP <br />C1981044 5 November 2018 <br /> <br /> <br /> 21 <br /> <br />Monthly: Temperature, Conductivity, pH, Suspended Solids and flow rate. <br /> <br />Quarterly: Temperature, Conductivity, pH, Suspended Solids, flow rate, Acidity, Dissolved <br />Solids, Suspended Solids, Chloride, Iron and Manganese. <br /> <br />The Yampa River monitoring stations, Y-1 and Y-2 were monitored in conjunction with the No. <br />9 Mine and are no longer monitored. These stations will be re-established prior to the <br />development of the North Mains. <br /> <br />E. NPDES Discharge Monitoring <br /> <br />Monitoring locations covered under NPDES permit CO-0034142 include No. 5 Mine (NPDES <br />No. 003), No. 1 Strip Pit (NPDES No. 022), 7 North Angle Well (NPDES No. 024) and Sewage <br />Treatment Ponds (NPDES No. 023). The first three locations are monitored weekly, bimonthly, <br />monthly, and quarterly for the following parameters: <br /> <br />Weekly: Temperature, Conductivity, pH, Flow Rate, and Oil/grease. <br /> <br />Bimonthly: Temperature, Conductivity, pH, Suspended Solids, Flow Rate, Oil and Grease and <br />Total Suspended Solids. <br /> <br />Monthly: Temperature, Conductivity, pH, Suspended Solids, Flow Rate, Iron and Zinc. <br /> <br />Quarterly: Temperature, Conductivity, pH, Suspended Solids, Flow Rate, Total Dissolved Solids. <br /> <br /> The sewage treatment ponds (outfall 023) require weekly analyses for oil and <br />grease (visual), residual chlorine, pH, and flow rate weekly, plus monthly analyses for BOD <br />(five-day), suspended solids, and fecal coliform. Total dissolved solids are analyzed quarterly. <br /> <br />F. Probable Hydrologic Consequences <br /> <br /> <br />Projected Impacts <br /> <br />Section 2.05 of the permit application includes an assessment of the probable hydrologic <br />consequences of the mining operation. Those consequences are summarized as: <br /> <br />1) Maximum inflow of ground water into the mines during mining was estimated <br />at 2490 gpm. <br /> <br />2) Continued drawdown in the Middle Sandstone was expected to be the most <br />significant impact caused by Mines 5 and 6. <br /> <br />3) About one-half square mile of the Twentymile Sandstone was expected to be