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EFCI Southfield Mine - 2008 Annual Hydrology Report <br />April 15, 2009 <br />3.0 GROUND WATER AND SURFACE WATER MONITORING RESULTS <br />3.1 Ground Water Monitoring Results <br />Mine Area <br />In the Mine Area, ground water occurs in surficial alluvial/colluvial deposits and as water table <br />conditions in the sequence of sedimentary rocks corresponding to the Vermejo, Raton, and Poison <br />Creek formations. Due to semi-arid conditions and the limited extent and continuity of the <br />alluvial/colluvial deposits, these units do not store or transmit appreciable quantities of ground <br />water in the general mine area. There is limited lateral or regional continuity of potential water- <br />bearing units due to variable lithology and significant cross-bedding and inter-bedding within the <br />bedrock units. As a result, there are no units known to be an aquifer in this area and bedrock <br />ground water occurrences are limited to isolated units and zones that have sufficient local recharge <br />and characteristics that allow it to store and transmit water. Therefore, in this area, isolated shallow <br />perched ground water zones may develop. Additional "minor" ground water storage may occur in <br />abandoned and flooded mine workings, which serve as collection and storage reservoirs as well as <br />for origination of fracture flows (refer to Section 2.04.7 of the Southfield permit application for <br />more details). <br />In the Mine Area, the current ground water monitoring program includes the following monitoring <br />wells, located as shown on Figure 1, Mine Monitoring Stations: <br />Well Location Depth/Completion Zone Geologic Completion Zone <br />MW-16 E'/zNW'/4, Sec 30 136'/ 106-136' Jack O'Lantern Coal Seam <br />MW-23 E'/2SW'/4, Sec 19 179'/ 149-179' Red Arrow Coal Seam <br />MW-65 W'/2SW'/4, Sec 24 1448'/ 968'-988' Jack O'Lantern Coal Seam <br />MW-NW W'/2SW'/4, Sec 19 380'/ 360'-380' Red Arrow Coal Seam (mine void) <br />Monitoring wells MW-7A, MW-713, MW-8, MW-10, and MW-22 were previously included in the <br />monitoring program, but have since been mined-through and eliminated from ongoing monitoring. <br />Wells MW-7A, MW-713, MW-22 were mined-through by Dorchester Coal Co. prior to 1985. EFCI <br />collapsed wells MW-8 and MW-10 as a result of mining operations later in the period of active <br />mining. <br />A former dewatering well, referred to as the North Well, was originally used to dewater abandoned <br />mine workings in the Red Arrow Coal Seam north of the main mine entries. EFCI discontinued its <br />use as a dewatering well in 1994, later removing the pump and associated equipment. In 2003, it <br />was converted to and approved for use as a new monitoring well named MW-NW. <br />In Technical Revision 35 (TR-35), the approved groundwater monitoring schedule was reduced <br />from quarterly to semi-annually and is typically conducted in June and December at the four <br />monitoring wells. Field measurements and laboratory data for active monitoring wells are <br />summarized in the following discussions. Field and laboratory data for 2008 are provided in <br />Appendix A. Measured water levels for all Mine Area monitoring wells are summarized in <br />2008 AHR.doc WP Page 6