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• POWDERHORN COAL COMPANY <br />1997 ANNUAL HYDROLOGIC REPORT <br />AND MINE INFLOWS STUDY <br />OCTOBER 1, 1996 THROUGH SEPTEMBER 30, 1997 <br />I • <br />I • <br />Introduction <br />During the 1997 Water Year, the Year, the Roadside South Portal operated one month <br />(October). The Roadside North Portal operated the entire Year. Production at the <br />Roadside North continued to be done using room and pillar mining with a continuous miner <br />and shuttle cars. Both mines had difficult geologic, hydrologic and gas problems. <br />The Peabody Western's hydrologic reporting system again was used as a tool for <br />compiling and reporting part of the information for this Year's report. The general format <br />of this report is the same as in previous years. <br />This reporting period includes monitoring requirements which were added to the Mining <br />and Reclamation Permit to include the new Rollins Sandstone monitoring wells. <br />Surtace Water <br />Water flow and quality on the Colorado River is monitored by the U.S. Geologic Survey <br />(USGS) at various locations. The closest location is Station No. 09095500 which is <br />located upstream approximately 7 miles north east of the mine site. Water quality and flow <br />from this site are used as a general representation of the Colorado River up gradient of <br />our mining operation. There is a diversion to the Government Highline Canal, the addition <br />of Plateau Creek and the addition of other minor drainages between the monitoring site <br />and the mine site. Data Pages SQ-18 and 19 include information supplied by USGS on <br />this site in 1997. The total flow at this site for the Year was 4,154,000 acre-feet which <br />amounts to 146°~ of the 1934-1997 average flow. The estimated TDS load for the Year <br />was 1.759 million tons. This estimate is made using the value for dissolved solids reported <br />on page SQ-19 times the monthly flow in acre feet. The low flow for the Year was <br />recorded as 1460 CFS on December 18, 1996. As can be seen on data page SO-19, the <br />river was carrying 0.77 tons of TDS per acre-foot on December 23`d. This flow and TDS <br />load equates to approximately 2,230 tons of Total Dissolved Solids, TDS, being carried <br />by the river past the mine that day. Mine discharges on December 12, 1996 (the closest <br />monthly analysis), were: 001 - 10 GPM @ 766 TDS; 002 - 70 GPM @ 1650 mg/I TDS; <br />and 004 - 200 GPM @ 1480 mgA TDS, resulting in approximately 2.52 tons of TDS being <br />