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<br />• <br />Executive Summary <br />This annual hydrologic report is the eleventh <br />annual report submitted (or the West Elk Mine <br />(formerly the Mt. Gunnison No. 1 Mine) and <br />covers the period from 1 October 1991 [hrough <br />30 September 1992 (water year 1992). The report <br />describes and interprets hydrologic monitoring <br />data collected at the West Elk Mine during water <br />year 1992 and assesses hydrologic impacts. <br />The report is divided into two sections. The first <br />section describes monitoring activities for water <br />year 1992. The second section interprets the <br />hydrologic data collected during the year and <br />relates this information to mining and reclama- <br />tion activities at West Elk to assess the impacts, <br />if any, on the hydrologic balance. This section <br />also addresses hydrologic impacts that might be <br />expected to occur during water vear 1993. <br />An extensive baseline monitoring data base has <br />been developed for the West Elk Mine. Opera- <br />tional monitoring started in August 1981 with <br />commencement of construction activities at West <br />Elk. <br />Monitoring data for the period 1 October 1991 <br />through 30 September 1992 show no significant <br />adverse impacts to the hydrologic balance from <br />mining activities at the West Elk Mine. <br />Mine inflows during water year 1992 were more <br />than during water year 1991. The volume of <br />water discharged from the underground workings <br />in 1992 was abou[ 71 acre feet. Areas being <br />mined during water year 1992 were about as wet <br />as during 1991. <br />The quality of mine water sampled in L992 was <br />good. All discharges were well within NPDES <br />effluent limitations without treatment. There <br />were two isolated incidents of effluents exceeding <br />permit limitations on domestic water polishing <br />discharge number 007A. During monitoring <br />period 91/l0/Ol - 91/12/31, actual residual chlo- <br />rine 0.65 vs. permit 0.5; and during monitoring <br />period 92/07/01 - 92/09/30, actual total suspended <br />solids was 76.1 vs. permit 15. <br />Mine water discharge in 1992 was from Portal <br />No. 2 into pond MB-1. No water was discharged <br />from the Sylvester Gulch underground sump nor <br />from Portal No. 5. Discharged water had no <br />measurable effect on the quality of the North <br />Fork of the Gunnison Ricer. <br />Activities at the Lower Refuse Pile also had no <br />measurable effects on surface or groundwater <br />quality during water year 19''2. <br />Underground mining activities did not produce <br />any significant effects on springs, groundwater <br />wells, or surface water monitoring stations during <br />water year 1992. <br />Water year 1993 is expected to be similar to 1992 <br />relative to hydrology at the mine. No significant <br />impacts are expected. <br /> <br />ViSv!,',.li Gi ~ I ~ . ~ /a aLt'E <br />:v <br /> <br />~. <br />) r~. ~I,O ~i t <br />L <br />