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Surface Water Impacts: <br />Surface water features in the permit area are the perennial stream Trout Creek, and ephemeral <br />drainages that extend down the northwest facing hillslope in the northern part of the permit <br />azea. These ephemeral drainages drain to Middle Creek. The ephemeral streams have not <br />been impacted by Apex because the mine's surface disturbance is limited to the Trout Creek <br />valley, to the south. Sunland predicted the Apex Mine would cause no impacts to surface <br />waters (pages 190.4 and 190.5 of the permit application). Sunland has conducted long-term <br />monitoring in Trout Creek upstream and downstream from the mine. The monitoring <br />indicates long-term compliance with all surface water standazds. The sediment control pond <br />has not dischazged for several yeazs. The Division has verified compliance with all surface <br />water standazds each yeaz in its review of the mine's annual hydrology reports. Sustained <br />stream flows, and the compliance with NPDES discharge limitations and instream standazds, <br />indicate Sunland has prevented material damage to the surface water hydrologic balance <br />outside the permit azea. <br />Impacts to Alluvial Valley Floors (AVFs) <br />The Division determined in its review of Technical Revision 10 that Trout Creek within the permit <br />area does not meet the regulatory definition of an AVF. AVFs exist on Trout Creek downstream <br />from the Apex Mine, but aze beyond the influence of the mine. The Division has determined that a <br />segment of Middle Creek meets the regulatory definition of an AVF. The Middle Creek AVF is <br />located about 4000 feet northwest of the permit azea. The Middle Creek AVF was not undermined <br />by the Apex No. 2 and did not receive surface runoff from the mine. The mine has caused no <br />adverse impacts to the AVF. Based on these observations regazding the Middle Creek AVF, the <br />Division fmds that CYCC has preserved the essential hydrologic functions of AFVs not within the <br />permit area. The essential hydrologic functions have been preserved by maintaining the geologic, <br />hydrologic, and biologic characteristics that support those functions. <br />Findings on Protection of Hydrologic Balance <br />Based on the foregoing observations regazding hydrologic impacts, the Division fmds that Sunland <br />has minimized disturbance of the hydrologic balance in the mine plan and adjacent azeas, and <br />prevented material damage outside the permit area. The Division also fmds that Sunland has not <br />caused hydrologic changes that adversely affect the approved post-mining land use in the permit <br />azea. <br />Subsidence Impacts <br />Sunland predicted maximum subsidence of 10 to 28 inches over the mine workings. The subsidence <br />was predicted to not cause material aamage or diminution of reasonably foreseeable use of stuctures <br />and renewable resource lands. An extraction limitation and subsidence monitoring were required if <br />a neazby house was undermined. No structures were undermined, however, and no adverse <br />Apex No. 2 Mine Page 13 January 24, 2003 <br />Phases I, II, and III Bond Release <br />