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EM Southfield Mine - 2008 Annual Hydrology Report April 15, 2009 <br />Table 3, Monitor Well Water Levels, for the years 2000-2008. Previous well water level data for <br />all monitoring wells are documented in AHR's on file at the Division. All historic water level data <br />are presented graphically for the four monitoring wells on Figures 3, 4, 5, and 6. <br />Water levels for well MW-16 have shown some cyclic/seasonal fluctuations. It was essentially dry <br />from December 2001 until June 2004, possibly associated with drought conditions. The well has <br />silted up to approximately l 10 feet below ground surface leaving 4 feet of perforated casing above <br />the current depth. Water levels for 2004 and 2005 were between 97 and 106 feet but the well has <br />been dry from 2006 through the period of this report. Well MW-23 has demonstrated steadily <br />declining water levels since July of 1984. Water levels for Well MW-65 have generally remained <br />stable with minor fluctuations of less than 10 feet. MW-NW has been dry since monitoring was <br />initiated in early 2003. <br />Water quality data for monitoring wells MW-16, MW-23, MW-65 and MW-NW are provided on <br />Tables 4, 5, 6, and 7, respectively. These tables provide any analytical results for 2008 and the <br />minimum, maximum and average values calculated using all historical monitoring data. Only wells <br />MW-23 and MW-65 provided water sample data for the reporting period. Review of 2008 data and <br />historic water quality monitoring data compared to the Colorado Groundwater Standards <br />(Regulation no. 41 - Basic Standards for Ground Water) indicated the following exceedances. <br />MW-16: The historic averages for dissolved Iron and Sulfate exceed the Secondary Drinking <br />Water Standard although no historic sample parameter averages exceed the Agricultural Standards. <br />MW-23: The historic average for dissolved Iron exceeds the Secondary Drinking Water Standard. <br />The May 2008 sample for dissolved Iron exceeded both Secondary Drinking Water Standards and <br />Agricultural Standards. In addition, the same sample exceeded Secondary Drinking Water <br />Standards for dissolved Manganese. Analytical results for the December 2008 samples indicated <br />that concentrations of both Iron and Manganese were below detection limits. <br />MW-65: The historical average of dissolved Manganese exceed the Secondary Drinking Water <br />Standard. Both samples in 2008 exceed Secondary Drinking Water Standards for dissolved <br />Manganese; although neither the 2008 samples or historic sample parameter averages for dissolved <br />Manganese exceed Agricultural Standards. <br />Loadout Area <br />In the Loadout Area, ground water occurs primarily in alluvial/colluvial deposits in and adjacent to <br />the Oak Creek flood plain. Due to limited surface and ground water flows and recharge and the <br />character of the alluvial/colluvial deposits, these deposits do not appear to store or transmit <br />significant quantities of water, as indicated by the lack of sub-irrigation. A 2003 evaluation at the <br />site, performed by the Fremont County Soil Conservation Service, concluded that no AVF areas <br />exist within the Loadout permit boundary. <br />Because the alluvial/colluvial deposits associated with Oak Creek do not represent a significant <br />ground water source or aquifer, there is not ongoing ground water monitoring in the Loadout Area <br />or immediate vicinity. <br />2008 AHR.doc WP Page 7