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Therefore, South Portal discharge capacity was increased through the <br />installation of a pipe from the No.2 South Mains sump to outfall 001. The <br />routing of this "South Portal" 4-inch diameter pipe is presented on Figure <br />14-6. The capacity of this discharge pipe was about 75 - 100 gpm. See <br />Figure 14-6 Roadside South Portal Mine Water Discharge System and <br />Figure 14-7 Roadside South Portal Dewatering Schematic. <br />The Northwest Intake Pool (see Figure 14-7) must be maintained between <br />elevation 4755 and 4762 to assure the siphon continues to function. The <br />level of the pool is measured through monitoring well N-1 which is located <br />at the reclaimed North Decline. This 7-foot elevation range equates to <br />about 2.3 million gallons per foot or about 16.1 million gallons (ref. AHR <br />Table M-3). The discharge from the siphon was increased or decreased, <br />by adjusting a valve, depending on water level measurements in well N-1. <br />Changes in the elevation of the Northwest Intake Pool were gradual <br />because each foot of increase or decrease represents 2.3 million gallons. <br />The Operator considered the siphon and 4-inch dewatering pipe a reliable <br />mine dewatering system. However, a high level of monitoring and some <br />periodic maintenance was required. Therefore, the Operator identified a <br />location where an angled hole could be drilled into the mine and water <br />would flow by gravity from the mine. <br />An angled hole was drilled into the mine so water flows by gravity from the <br />mine. This system is presented on Figure 14-8 Mine Dewatering -Plan <br />and Profile. The "North Decline" mine dewatering pipe is 8-inches in <br />diameter and has a flow capacity of 350 gpm (see figure 14-10). <br />Installation of this system was complete and operational April 1, 2002 and <br />discharge began on April 3, 2002. <br />The average and maximum flows through the North Decline mine <br />dewatering pipe, CDPS Outfall 016, are as follows: <br />Water Year Average Flow Maximum Flow <br />2004 276 gpm 310 gpm <br />2005 291 gpm 305 gpm <br />2006 290 gpm 295 gpm <br />14-30 (Rev. 08/07) <br />