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Technical Manual: Conduits through Embankment Dams (FEMA 484)

Technical Manual: Conduits through Embankment Dams (FEMA 484)

Technical Manual: Conduits through Embankment Dams (FEMA 484)

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<strong>Conduits</strong> <strong>through</strong> <strong>Embankment</strong> <strong>Dams</strong>Figure B-59.—The camera-crawler encountered fine sandy materials thatappeared to be entering the conduit <strong>through</strong> a defect in the sidewall. Thisview is looking upstream at the right side wall. The conduit had not beenoperated since the fall of 2003. These materials had collected within theconduit over the last 7 months.Figure B-60.—Just into the masonry conduit an open defect (crack), shownin the lower part of the figure, exists in the crown of the conduit. Thisdefect allowed sandy materials to enter the conduit.A contractor was mobilized to lower the reservoir level to elevation 4880.0 usinghigh capacity, low head pumps (12-inch diameter). The reservoir drawdown waslimited to 1 foot per day. After the reservoir was lowered to the desired elevation, asiphon was installed to provide downstream irrigation releases. Figure B-61 showsthe siphon discharge irrigation releases. Based on the deteriorated condition of theconduit, the BIA decided to abandon the outlet works by grouting it closed. TheB-78

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