Figure 123.-Dam river outlet pipes-Profiles and installation details. Plate thicknesses 3-12-59 Jul REVISED AND REDRAWN TO AGREE WITH FINAL DESIGN UNITED STATES DEPARTMENT OF THE INTERIOR BUREAU OF RECLAMATION COLORADO RIVER STORAGE PROJECT MIDDLE RIVER DIV-GLEN CANYON UNIT-ARIZONA-UTAH DRAWN... Pat. TRAGED...B.Re. CHECKED... 9PM. BUBMITTED...N.Noonan .... APPROVED. DENVER, COLORADO, NOV. 10, 100 557-0-97 The outlet pipes have an inside diameter of 8 feet. They begin at the downstream ends of cast iron bellmouths in the upstream face of the dam at centerline elevation 3374.0 near the left abutment. Each pipe runs level for about 90 feet, then slopes downward and emerges from the dam and passes around the powerplant to the outlet structure. Outlet pipes No. 1 and 2 emerge from the dam at centerline elevation 3168.5, run level to the outlet structure and there lift to centerline elevation 3175.0. Pipes No. 3 and 4 emerge from the dam at centerline elevation 3179.0, run level to the outlet structure and there drop to centerline elevation 3175.0, in line with the other outlet pipes. A ring-follower gate is installed in the first level run of each pipe. The outlet pipes terminate at hollow-jet type discharge regulating valves. Each outlet pipe is approximately 930 feet long. Minimum and maximum outlet pipe plate thicknesses are 9/16 and 7/8 inches. The outlet pipes are totally embedded in dam and encasement concrete except where they are exposed at expansion joints and at hollow-jet valves. The outlet pipes have 6-inch gate bypass and filling piping systems at the ring-follower gates. These systems provide complete flexibility of outlet pipe filling and ring-follower gate bypass for each pair of outlet pipes. That is, pipes No. 1 and 2 may be filled from each other, and pipes No. 3 and 4 may be filled from each other; but there is no connection between pipes No. 1 and 2 and pipes No. 3 and 4. A teetering section with double-end expansion joints was installed in each outlet pipe across the joint between the dam and the adjacent mass concrete. Sleeve-type coupling joints were located at each contraction joint in mass concrete encasements and discharge valve structure. (b) Design.-The outlet pipes were designed for static head when the reservoir water surface is at maximum elevation 3711.0. For design considerations no water-hammer head was superimposed on static head because the outlet pipe gate and valve controls do not operate rapidly enough to cause significant water hammer. The maximum designed discharge through each outlet pipe is 3,750 cubic feet per second. The corresponding average velocity in the 8-foot-diameter pipes is 74.60 feet per second. The pipe diameter was chosen for best balance between factors representing desired discharge, energy dissipation, and maximum allowable velocity short of destructive cavitation and vibration. The maximum designed velocity of 74.60 |