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EFCI Southfield Mine - 2012 Annual Hydrology Report April 18, 2013 <br />-* 4/17/2012: 1 inch water in Thompson culvert, flow receding. <br />-� 4/24/2012: Flow in Thompson road culvert barely a trickle. No visible snow in the uplands <br />drainage area. Water flow did not reach the lower sample point, NC 1 during the report period. <br />Given that there was not sufficient water runoff in Newlin Creek to reach the lower sample point <br />during the reporting period; comparison of the upper (NC2) and lower (NC 1) sample points could <br />not be obtained. <br />Historic field and laboratory water quality data for the surface water monitoring stations on Newlin, <br />Magpie, and Second Alkali Creeks are summarized in Tables 9, 10, 11, 12 and 13. Ongoing <br />monitoring of surface flows for Newlin, Magpie, and Second Alkali Creeks provides for <br />identification and evaluation of any future changes in water quality that may result from mining and <br />related activities. The same trends of the surface water quantity and quality as monitored during <br />previous years continued during the report period of 2012. <br />Loadout Area <br />The Loadout and adjacent areas fall within the lower sections of the Oak and Chandler Creek <br />drainages, both of which are tributary to the Arkansas River. Oak Creek is a perennial drainage <br />above the municipal well field for the Town of Rockvale. Dependent on water demand and <br />withdrawal levels for Rockvale, flows in Oak Creek below the well field in the 4.7 mile section <br />above the Loadout area may be either perennial or ephemeral. In areas adjacent to the Loadout <br />Area, flows in Oak Creek are frequently ephemeral, and Chandler Creek is considered an ephemeral <br />creek (refer to Section 2.04.7 of the Southfield permit application for more details). EFCI monitors <br />any stormwater runoff discharge from the two active sedimentation ponds, Ponds L -1 and L -2, in <br />the Loadout Area. <br />In the Loadout Area, the current surface water monitoring program includes the following <br />monitoring stations: <br />Station Location Designation <br />NPDES 001 W' /2NW1/4, Sec 17 Pond L -1 (outfall to Chandler Creek) <br />NPDES 002 E1/2NE1/4, Sec 19 Pond L -2 (outfall to Oak Creek) <br />Monitoring locations on Oak Creek, both upstream and downstream, were eliminated in accordance <br />with approved Technical Revision No. 37. Oak Creek flow measurements made from 1998 through <br />2009, are presented for the two stream monitoring locations on Table 8. Stream flow data from <br />previous years are documented in AHR's on file at the Division. <br />Field and laboratory water quality data (prior to 2010) for surface water monitoring stations on Oak <br />Creek are provided in previous AHR submittals on file at the Division. <br />The two Loadout area sedimentation ponds have historically held only a small amount of water, and <br />have never discharged to the stream system. Similar to previous years, both ponds remained dry so <br />there was no pond discharge during 2012. <br />2012 AHR text doc <br />Page 20 <br />