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Mountain Coal Company 1999 Annual Hydrology Report West Elk Mine <br />• Adequacy of Monitoring Program <br />MCC continued to monitor the same resources as in WY98. Many of the sites in the monitoring <br />progam have been monitored since the eazly 1980s, so there is extensive data for many of the <br />sites. in addition, with the approval of Minor Revision No. 208 on January 21, 1998, MCC <br />began to report water quality samples from mine water inflows. <br />During WY99, surface water continuous flow data were recorded on dataloggers in addition to <br />the Sevens Type F recorders at the flume stations. The dataloggers helps to eliminate errors in <br />transcribing the data. The strip charts remained in place as a backup system. <br />The Upper and Lower Deep Creek stations did not have flumes installed in order to minimize <br />impacts. Control sections were constructed from natural materials and a pressure transducer with <br />a datalogger was installed at both locations. Although the channel continues to be dynamic, <br />there were enough instantaneous flow measurements to develop a rating curve for WY99 and <br />convert the stage readings to flows for most of the water year. <br />in WY99, MCC conducted an evaluation that involved closely reviewing all springs and <br />remaining goundwater wells in the monitoring program. This investigation performed a <br />comprehensive hydrogeologic characterization of the West Elk Mine permit and adjacent areas. <br />The characterization is based on a syntheses of existing hydrogeologic information, isotopic data, <br />and the results of an in-mine, fault related, groundwater inflow investigation. This report, <br />Characterization o~ Groundwater Systems in the Vicinity of the West Elk Mine, Somerset, <br />• Colorado (January 1999) by Mayo and Associates was submitted as support for revising MCC's <br />monitoring program in Technical Revision No. 88. <br />Technical Revision No. 88 proposed to delete seventeen springs and nine wells from the <br />monitoring program, and was approved by the Division on August 24, 1999. The springs and <br />wells removed from the monitoring program are identified in Tables 2 and 3, respectively. <br />Technical Revision No. 88 fully explains the basis for these wells being deleted from the <br />monitoring program. <br />In 1996, MCC installed two groundwater wells to collect baseline data in the area where the <br />Refuse Pile Expansion (RPE) would be constructed. These wells were known as LRP-1 and <br />LRP-4. With the construction of the RPE, LRP-4 was destroyed, but LRP-I (now identified as <br />RPE-]) has continued to be monitored. The data for RPE-1 is included in this report. MCC <br />installed a replacement well for LRP-4 during WY99; this well is called RPE-7. <br />Da831-0321520jm1:11999 AHft1I999 AHR doc <br />• <br />83/-032.520 Page26 Wright Water Engineers <br />