Filling System for Lower Granite Lock

The Lower Granite dam will be the last of four Snake River dams designed to bring slack water navigation to eastern Washington and northern Idaho. The lock dimensions are 86 ft wide by 675 ft long with maximum lift 105 ft. A lock filling system has been developed that is different from systems previously used in the United States. Advantages are faster lockage time, greater uniformity of filling conditions, reduced hawser forces and lesser danger from nonsynchronous valve operation. Water introduced at the center of the lock is divided equally upstream and downstream, then passes through several subculverts which admit it to the lock chamber simultaneously through symmetrically located ports. This arrangement minimizes longitudinal and transverse flow in the chamber. Model studies were conducted at a scale of 1:25. The lock can be filled in 9.6 min at maximum head, using a 1-min valve opening time; average maximum hawser forces are only 2.5 tons.