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(c)(i) Mine inflows will not be impounded above the normal ground level at the lowest portal. In <br />the Roadside South Mine, water was allowed to fill abandoned areas below an elevation <br />of approximately 4762 feet; the ground elevation of the Northwest Intake portal. A siphon <br />was installed in this portal seal to allow discharge through outfall 002 of the CDPS <br />permit. <br />During March of 2000 a 4-inch diameter pipe was installed from the No. 2 South Mains <br />Sump to outfall 001. The pipe penetrates the South Portal seal as shown on Figure 14- <br />2. The pipe intercepted water that flows to the Northwest Intake Pool and therefore <br />increased the overall mine discharge capability. <br />The siphon and 4-inch dewatering pipe was a reliable mine dewatering system. However, <br />a high level of monitoring and some periodic maintenance was required. Therefore, the <br />Operator identified a location where an angled hole could be drilled into the mine and <br />water would flow by gravity form the mine (see figure 14-10). <br />During 2001 the operator drilled the angled hole into the Roadside South Mne. The hole <br />was completed with and 8-inch diameter pipe during March 2002. The North Decline <br />dewatering system was put into service during April 2002 with discharge through outfall <br />016 of the CDPS discharge permit. Outfall 016 has proved to be a reliable mine <br />dewatering point. During the 2004 through 2006 water years, flow from the mine has <br />averaged about 285 gpm with a ma>amum flow of 310 gpm. <br />The North Decline gravity dewatering system is the primary dewatering system for the <br />mine. The siphon will be the backup system. The South Portal dewatering pipe will be <br />plugged. <br />The Roadside North Mine is entirely below the portal elevation and will fill to the normal <br />groundwater level which is approximately 50 feet below the reclaimed surface at the <br />portal area. <br />VOL 5 Tab 17 17-6 (Rev 08107) <br />