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A 10 foot by 12 foot prefabricated wood frame and metal pumphouse was bolted to the concrete slab enclosing the pumps and flowmeter system. The house is equipped with base board heating, insulation, a lockable door, and a removable ceiling partition to facilitate pump removal. Wiring of the pumphouse and the controls for the pumps was completed by Homestake electricians. A 2000 foot, 600 volt ►2, 0 cable buried power supply line was brought into the pumphouse at its southwest corner and connected to a ■■! main supply switch. Each of the pumps is also fitted with a power switch, and on -off -automatic switches. When on automatic, the pumps are controlled by limit switches which are suspended in the sump, thereby allowing the sump water level to control the pumps. As currently configured, the #1 pump works alone, and cycles on and off to maintain the sump water level between eleva- tions 8827.7 and 8830.9 (see Figure 3). If water enters the sump faster than it can be removed by the d1 pump, limit switches cause the #2 pump to go on when the water level reaches an elevation of 8831.4 feet. Control of on-off pump cycle time can be controlled through adjustment of the butterfly valves in the discharge line to control the pumping rate of each or both pumps. 3.5 PERFORMANCE OF THE SYSTEM The performance of the cutoff wall and pump -back system can be assessed through evaluation of seepage collection rates and changes in downstream water conditions. Since the installation of the slurry wall cutoff on July 17, 1982, the downstream water conditions have significantly changed. The ground water seepage which emerged into the drainage channel in this area prior to cutoff 1 construction were eliminated and the drainage channel is now dry. The ground 1 3-7 hack to the pond. The totalizer is mounted on the north wall and records total flow in gallons. A strip chart recorder maintains a continuous record of flow rate in gpm versus time. The recorder was set at 1 inch per hour and will last approximately 1 month on a single roll of paper. A 10 foot by 12 foot prefabricated wood frame and metal pumphouse was bolted to the concrete slab enclosing the pumps and flowmeter system. The house is equipped with base board heating, insulation, a lockable door, and a removable ceiling partition to facilitate pump removal. Wiring of the pumphouse and the controls for the pumps was completed by Homestake electricians. A 2000 foot, 600 volt ►2, 0 cable buried power supply line was brought into the pumphouse at its southwest corner and connected to a ■■! main supply switch. Each of the pumps is also fitted with a power switch, and on -off -automatic switches. When on automatic, the pumps are controlled by limit switches which are suspended in the sump, thereby allowing the sump water level to control the pumps. As currently configured, the #1 pump works alone, and cycles on and off to maintain the sump water level between eleva- tions 8827.7 and 8830.9 (see Figure 3). If water enters the sump faster than it can be removed by the d1 pump, limit switches cause the #2 pump to go on when the water level reaches an elevation of 8831.4 feet. Control of on-off pump cycle time can be controlled through adjustment of the butterfly valves in the discharge line to control the pumping rate of each or both pumps. 3.5 PERFORMANCE OF THE SYSTEM The performance of the cutoff wall and pump -back system can be assessed through evaluation of seepage collection rates and changes in downstream water conditions. Since the installation of the slurry wall cutoff on July 17, 1982, the downstream water conditions have significantly changed. The ground water seepage which emerged into the drainage channel in this area prior to cutoff 1 construction were eliminated and the drainage channel is now dry. The ground 1