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LORENCITO CANYON MINE <br />ANNUAL HYDROLOGIC MONITORING REPORT - 2007 <br />SECTION I - INTRODUCTION <br />To fulfill the requirements of the Regulations of the Colorado Mined Land Reclamation <br />Board, the following report has been assembled in compliance with Rule 2.04.7. Since the <br />beginning of 1996, substantial work has been performed at the Lorencito Canyon Mine site <br />to interpret the hydrology of the area. Specific methodologies employed for this work are <br />described below. Field work accomplished during the baseline period has included the <br />installation and testing of 12 alluvial wells, 16 consolidated aquifer wells, along with the <br />monitoring of 11 surface water sites, 11 springs and seeps, and 19 pond sites in the area. <br />From the field data collected, insight has been gained into the recharge and discharge <br />characteristics of aquifers, hydraulic properties, potentiometric and water table surfaces, and <br />water quality for each of the hydrologic units. The program was reduced following issuance <br />of the permit in August 1997, resulting in a reduction of monitoring stations, frequency of <br />monitoring, and water quality parameter analyses. A revision to the program was also <br />approved in early 1999 to reduce the frequency of monitoring during the pre-mining period <br />until disturbance activities begin. <br />In early 2001, a Permit Revision was submitted for approval of mining operations in the <br />• surface mining area. As a result, the monitoring program was adjusted to use only those <br />stations that would detect potential impacts of these operations. This revision eliminated all <br />deep aquifer wells from the monitoring program. In 2002, alluvial monitoring wells <br />MWLO-E and MWLO-W were completed to monitor potential impacts from the coal <br />loadout area. <br />The surface mine ceased operations later in 2002. Phase I bond release for all areas of <br />active mining in Jeff Canyon was approved in 2005. Also in 2005, quarry operations <br />conducted by the surface owner destroyed MWLO-W. The well was not replaced as the <br />loadout had ceased operations was was being reclaimed. In 2007 the Division approved a <br />permit revision reducing the frequency of field measurements to semi-annually in the <br />second and fourth quarters. Analytical sampling. was reduced to an annual sampling event in <br />the fourth quarter. These stations and water quality parameters are listed on Table 1-1 <br />Hydrology Monitoring Requirements and Tablel-2 Water Quality Parameter Sample <br />Suites. <br />This report presents the results of monitoring for operations in 2007 and a summary of data <br />from previous monitoring periods. <br />1 <br />0