2012-10-05_REVISION - M1977342 (13)

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spillage from the face of the dam. Although the system is limited in tailing retention capabilities, several precautions have been taken to keep tailing from entering the seepwater pumps. Any small spills resulting from a brsak In the crest line would be localized and directed toward one section of the moat. Barriers have been constructed in the canal to contain settled tailing in the area of the spill and still allow seepwater to the flow through tie rest of the canal. Two delivery ditches have been constructed, exiting From the canal at different points, which will also tend to isolate tailing swills. Each ditch is equipped with a control slide gate which enables the operator to shut off one ditch while maintaining flow in the other. The gates are datailed on Drawing No. 5 -2 -384. Finally, at the point where the two ditches meet, • stoplog structure has been built to isolate any tailing which might get )ast the gates. Therefore, if a spill was to occur, it must be isolated to oie portion of the canal by closing a control gate and by utilizing the stoplog structure. Once the cause of the spill has been corrected, the moat and ditch should be cleaned out as soon as possible to provide full capacity once again. Although tailing spill retention is an important consideration, the main purpose of the canal Is to collect and convey the seepwater generated by the subdrains and prevent this water from discharging into the Williams Fork. Although there Is no method of determining the expected flow, tests condicted at the North Robinson tailing dam near Climax in 1962 resulted in a meas.ired seepage rate of about 2,000 gpm. Therefore, it was estimated that the lower pond at Henderson would generate about 3,000 gpm. As a safety precautioi, especially during start -up, all facilities were sized to handle 9,000 gpn. As a point of consideration, If the seepwater pumps were to fall, there is about 20 acre -feet of storage behind the seepwater delivery ditches, 14