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POWDERHORN COAL COMPANY <br />1986 ANNUAL HYDROL06IC REPORT <br />January 1, 1986 through December 31, 1986 <br />• <br />Introduction <br />This 1986 Annual Hydrologic Report is being prepared in accordance with the <br />approved Mid-term Review Response Technical Revision TR-86-02. The period <br />of time being covered is the calendar year 1986. To reduce duplication of <br />effort, the mine inflows study is included in the report. <br />Reporting, in the past, has been for flows on Cottonwood and Rapid Creeks and <br />mine inflows - consumptive use (ground water). This report will be structured <br />to report surface water, ground water (piezometers), mine water, and consumptive <br />use. The data sheets generally cover 1986 with the exception of the unit train <br />loadout water levels which qo back to 1984. <br />The mines went into temporary cessation during October 1986 and remain in that <br />status. Technical Revision Request 86-04 was submitted November 14, 1986 to <br />request elimination of monitoring requirements on Cottonwood and Rapid Creeks. <br />The T.R. was approved as a reduction in monitoring requirements. Another T.R. <br />request will be submitted in early 1987, to request further monitoring reductions. <br />Surface Mater <br />Three types of surface water monitoring were done during the year: The quality <br />of the Colorado River above and below the minesite, the flow on Cottonwood <br />• and Rapid Creeks, and the flow and quality of the CDPS discharge points. Previous <br />information on the Colorado River was submitted with the Mid-Term Review response <br />June 30, 1986. Previous information on Cottonwood and Rapid Creeks was submitted <br />as a 1983 report and a 1984-85 report. Previous CDPS information has been <br />submitted as copies of discharge monitoring reports submitted to the Colorado <br />Department of Health. <br />Data pages SB-1 and SC-1 are a tabulation of monitoring done in 1986 on the <br />Colorado River. Average values of TSS, TOS, TFe and TMn were not calculated <br />because flows are not available to calculate more meaningful mass averages. <br />The values for TSS and TDS are typical of stream flow with low TDS and high <br />TSS during high runoff from snowmelt and precipitation events. The TFe and <br />TMn were both more related to the TSS than the TDS indicating high amounts <br />of undissolved iron and manganese when their values are high. The variation <br />between the upper and lower monitoring stations is small. The projected maximum <br />increase in TDS in the river from this operation according to the findings <br />document was 0.1%. This small of increase is difficult to measure in normal <br />laboratory procedures. <br /> <br />Again, due to above normal precipitation, Cottonwood and Rapid Creek flowed <br />all year. Tables S86-1 through 12 show a daily average flow as recorded on <br />upper Rapid Creek (SWGS-03), Cottonwood Creek (SWGS-02) and lower Rapid Creek <br />(SWGS-O1 and 04). A fifth column on these tables is a combination of SWGS-02 <br />and SWGS-03 when both were recorded. Diagrams S86-1 thru 5 are a graphical <br />L J <br />