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EM Southfield Mine - 2010Annual Hydrology Report May 30, 2011 <br />Water levels for well MW-16, shown on Figure 3, indicate significant cyclic/seasonal fluctuations <br />prior to 2001. It was essentially dry beginning in December 2001 until June 2004, possibly <br />associated with drought conditions. The well has silted-up to approximately 110 feet below ground <br />surface leaving 4 feet of perforated casing above the current depth. Water levels for 2004 and 2005 <br />were between 97 and 106 feet but the well has been dry from 2006 through the reporting period. <br />Well MW-23 has demonstrated steadily declining water levels since July of 1984, shown on Figure <br />4. A slight increase in water level was observed at this well for both measurements taken during <br />2010. Water levels for Well MW-65, shown on Figure 5, have generally remained stable with minor <br />fluctuations of less than 10 feet through the reporting period. MW-NW has been dry since <br />monitoring was initiated in early 2003, shown on Figure 6 (the water level line represents the well <br />depth). <br />Water quality data for monitoring wells MW 16, MW-23, MW 65 and MW NW are included on <br />Tables 4, 5, 6, and 7, respectively. These tables provide any analytical results obtained during 2010, <br />and the minimum, maximum and average values calculated using all historical monitoring data. <br />Only wells MW-23 and MW-65 provided water sample data for the reporting period. <br />A review of the 2010 quality data for MW-65 indicates that sample parameters were close to <br />historic values, suggesting no significant changes to groundwater quality are occurring at this site. <br />Quality data for MW-23 indicates elevated values of dissolved Calcium and Magnesium relative to <br />historic values. This trend is similar to that noted for the previous (2009) monitoring period. EFCI <br />will monitor this potential trend by further sampling of the well in accordance with the monitoring <br />plan. <br />Loadout Area <br />In the Loadout Area, groundwater occurs primarily in alluvial/colluvial deposits in and adjacent to <br />the Oak Creek flood plain. Due to limited surface and groundwater 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 />groundwater source or aquifer, no groundwater monitoring is required at the Loadout site or <br />immediate vicinity. <br />3.2 Monitoring Well Inspections <br />The depth and general condition of monitoring wells are checked each time the wells are monitored. <br />EFCI replaced several well caps in 2001/2002 to assure ongoing access control and prevent any <br />surface-source contamination. Based on most recent inspections, Southfield's four monitoring <br />wells are in good condition and are performing as designed for obtaining representative water <br />samples. <br />2010 AHR text.doc Page 6