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EFCI Southfield Mine - 2014Annual Hydrology Report February 12, 2014 3.0 GROUNDWATER AND SURFACE WATER MONITORING RESULTS Mine Area In the Mine Area, groundwater occurs in surficial alluvial/colluvial deposits and as water table conditions in the sequence of sedimentary rocks corresponding to the Vermejo, Raton, and Poison Creek formations. Due to semi -arid conditions and the limited extent and continuity of the alluvial/colluvial deposits, these units do not store or transmit appreciable quantities of groundwater in the general mine area There is limited lateral or regional continuity of potential water- bearing units due to variable lithology and significant cross - bedding and inter - bedding within the bedrock units. As a result, there are no known aquifers in the mine area, and bedrock groundwater occurrences are limited to isolated units and zones that have sufficient local recharge and characteristics that allow it to store and transmit water. Therefore, only isolated shallow perched groundwater zones may develop. Additional "minor" groundwater storage may occur in abandoned and flooded mine workings, which serve as small collection and storage reservoirs as well as for origination of fracture flows. Additional supporting information may be found in Section 2.04.7 of the Southfield permit application. In the mine area, the approved groundwater monitoring program includes the following monitoring wells, shown on Map 12, Mine Area Surface and Groundwater Hydrology: WELL I.D. LOCATION DEPTH/COMPLETION GEOLOGIC COMPLETION ZONE ZONE MW-16 E %?NW' /4, Sec 30 136'/ 106' -136' Jack O'Lantern Coal Seam MW -23 E %:SW' /4, Sec 19 179'/ 149' -179' Red Arrow Coal Seam MW-65 W /2SW' /4, Sec 24 14481/9681-9881 Jack O'Lantern Coal Seam MW-NW W' /2SW' /4, Sec 19 380'/ 360' -380' Red Arrow Coal Seam (mine void) The approved groundwater monitoring schedule requires semi- annual well sampling, typically conducted during the second and fourth quarters at the four groundwater wells listed above. Field measurements and laboratory data for active monitoring wells are summarized in the following discussions. Field and laboratory data for 2014 are provided in Appendix A. Measured water levels for all wells are summarized in Table 3, Monitor Well Water Levels, for years 2000 -2014. Past well water level data for all monitoring wells are documented in AHR's on file at the Division. All current and preceding water level data are presented graphically for the four monitoring wells on Figures 1, 2, 3, and 4. Water quality data for monitoring wells MW-16, MW-23, MW-65 and MW-NW are included on Tables 4, 5, 6, and 7, respectively. These tables provide all available analytical results obtained during 2014, and the minimum, maximum and average values calculated using all preceding monitoring data Only wells MW-23 and MW-65 produced water and thus provided sample data for the reporting period. 2014 AMR iaAfte Page 5