Spillway and Stilling Basin John Day Dam, Columbia River, Oregon and Washington. Hydraulic Model Investigation.
ARMY ENGINEER DIV NORTH PACIFIC BONNEVILLE OREG DIV HYDRAULIC LAB
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Two sectional models were used to check performance of the proposed spillway for John Day Dam and to develop improvements if necessary. A three-bay section of the 20-bay spillway was studied in a 141.14-scale model. A two-bay section of the 17 low bays to be used during second-step construction was reproduced in a 124-scale model. Modifications of the crest piers to reduce the danger of cavitation during unusually large spillway flows were recommended. Discharge ratings in the three-bay model indicated that capacity of the spillway was slightly greater than computed for the design flow of 2,250,000 cfs. A 185-ft-long stilling basin at elev 114 performed as well as a 210-ft-long basin at elev 118. Three 10-ft-high baffle piers produced desired flow conditions in bay 2 of the stilling basin.
- Civil Engineering