2014-08-01_REPORT - C1981014 - Laserfiche WebLink

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EM Southfield Mine — 2013 Annual Hydrology Report August 1, 2014 The mine and adjacent areas fall within the lower portions of the Magpie and Newlin Creek drainages and encompass the central portion of the Second Alkali Creek drainage, all of which are tributary to the Arkansas River. Newlin Creek is a perennial drainage above the mine permit area and to the diversion point for the City of Florence Municipal Water Supply. Within the mine permit boundary, flows in Newlin, Magpie, and Second Alkali Creeks are all ephemeral (refer to Section 2.04.7 of the Southfield permit application for more details). EFCI monitors any significant stream flows in Newlin, Magpie, and Second Alkali Creeks. In addition, EFCI monitors any storm water runoff discharge from the two remaining sedimentation structures, Ponds 4 and 5. In the mine site area, the current surface water monitoring program includes the following monitoring stations (refer to Map 12, Mine Area Surface and Groundwater Hydrology): Station Location Designation NC -2 E'hSE' /4, Sec 26 Newlin Creek (Upper) NC -1 WYNE' /4, Sec 19 Newlin Creek (Lower) MC -1 EV2NW' /4, Sec 30 Magpie Creek (Upper) MC -2 W %,NE' /4, Sec 30 Magpie Creek (Lower) SA -1 E' /2 W' /4, Sec 24 Second Alkali Creek, near MW-65 NPDES 002 E %zNW' /4, Sec 30 Pond 4 (outfall to Newlin Creek) NPDES 004 WV2SE' /4, Sec 19 Pond 5 (outfall to Magpie Creek) Two sedimentation ponds (Ponds 4 and 5) collect and allow sediment to settle from storm runoff from the reclaimed mine site. In recent years there has been less storm runoff reaching these ponds (observed as pooled water in the ponds) as vegetation improves on the reclaimed areas. Accordingly, no discharges have occurred due to storm events in recent years and during the reporting period (shown on Table 2). EFCI observed pond conditions on several occasions in 2013 following significant storm events. Thunder showers in mid -July left evidence of flow in ditches, but both ponds were found dry. In early August there were heavy rain showers at the mine site that resulted in about 1 foot of water pooled in Pond 5, and a small puddle - inches deep - in Pond 4. Heavy to intermittent rains again occurred during mid September, filling Pond 5 to within 32 inches of the top of the vertical primary discharge. Pond 4 had a pool approximately 1 foot deep following the same storm event. No storm events provided inflow to the ponds for the remainder of reporting period. At years end both ponds did retain a small amount of water; there was pool in Pond 5 a few inches deep, measuring approximately 30 by 50 feet. Pond 4 similarly had a small pool, several inches deep, remaining from the September storm. 2018AHR.doe Page 17