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3-7 <br />back to the pond. The totalizer is mounted on the north wall and records <br />total flaw in gallons. A strip chart recorder maintains a continuous record <br />of flow rate in gpm versus time. The recorder was set at 1 inch per hour and <br />will last approximately 1 month on a sirxgle roll of paper. <br />A 10 foot by 12 foot prefabricated wood frame and metal pumphouse was bolted <br />to the concrete slab enclosing the pumps and flowmeter system. The house is <br />equipped with base board heating, insulation, a lockable door, and a removable <br />ceiling partition to Facilitate pump removal. <br />Wiring of the pumphouse and the controls for the pumps vas completed by <br />Homestake electricians. A 2000 foot, 600 volt #2, 0 cable buried power supply <br />line vas brought into the pumphouse at its southwest corner and connected to a <br />main supply switch. Each of the pumps is also fitted with a power switch, and <br />on-off-automatic switches. When on automatic, the pumps are controlled by <br />limit switches which are suspended in the sump, thereby allowing the sump <br />water level to control the pumps. As currently configured, the dl pump works <br />alone, and cycles on and off to maintain the sump eater level between eleva- <br />cions 8827.7 and 8830.9 (see Figure 3). If eater enters the sump faster than <br />it can be removed by the dl pump, limit switches cause the d2 pump to go on <br />when the water level reaches an elevation of 8831.4 feet. Control of on-off <br />pump cycle time can be controlled through adjustment of the butterfly valves <br />in the discharge line to control the pumping rate of each or both pumps. <br />3.5 PERFORMANCE OF THE SYSTEM <br />The performance of the cutoff wall and pump-back system can be assessed <br />through evaluation of seepage collection rates and changes in downstream water <br />conditions. <br /> <br />1 <br />~• <br />Since the installation of the slurry wall cutoff on July 17, 1982, the <br />downstream water conditions have significantly changed. The ground water <br />seepage which emerged into the drainage channel in this area prior to cutoff <br />construction were eliminated and the drainage channel is now dry. The ground <br />~.~~~~~~ <br />