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|Title:||Navigation conditions at Mitchell Lock and Dam, Coosa River, Alabama : hydraulic model investigation|
|Authors:||United States. Army. Corps of Engineers. Mobile District.|
Myrick, Carolyn M.
|Keywords:||Mitchell Lock and Dam|
|Publisher:||Hydraulics Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical report (U.S. Army Engineer Waterways Experiment Station) ; HL-84-12.|
Abstract: Mitchell Lock is the second navigation structure proposed for the development of navigation in the Coosa River waterway. The 84- by 600-ft lock will be located at Mitchell Dam and powerhouse about 37.3 miles upstream of the mouth of the Coosa River near Verbena, Alabama. A fixed-bed model reproducing about 4 miles of the Coosa River and adjacent overbank areas to an undistorted scale of 1:120 was used to provide some general information on navigation conditions with the proposed designs and to develop such modifications as might be required to eliminate conditions that would adversely affect navigation. Results of the investigation revealed: (A.) With medium to high flows, navigation conditions at the Highway 22 Bridge were hazardous for both upbound and downbound tows due to the high velocities and limited width provided through the navigation span with the existing piers and low superstructure. Navigation conditions were acceptable at the bridge for low flows. (B.) With the first lock alignment (Plans A and A-1), navigation conditions were acceptable with the 35,000-cfs flow only. With flows greater than 35,000 cfs, navigation conditions were hazardous in the upper pool due to the upstream guard wall perpendicularly intersecting the currents. (C.) With the second lock alignment (Plans B, B- 1, B-2, and B- 3) , navigation conditions were acceptable for the 35,000- cfs flow. With flows higher than 35,000 cfs, navigation conditions were hazardous in the lower pool due to the current alignment, high velocities, and the short maneuvering distance between the lock approach and the Highway 22 Bridge. (D.) With the third lock alignment (Plans C and C-1), navigation conditions were acceptable for all flows evenly distributed through the gated dam up to and including the 90,000-cfs flow. With the modifications in Plan C-1, the navigation conditions were improved in the lower lock approach with the low flows and the 65,000- cfs unevenly distributed flow. Navigation conditions were hazardous with flows greater than 90,000 cfs due to the current alignment, high velocities, and the limited clearance at the Highway 22 Bridge. (E.) Flows unevenly distributed through the gated dam could cause navigation problems in the lower pool. (F.) Navigation conditions would be hazardous for tows in the upper lock approach canal during lock filling. (G.) Navigation conditions would be hazardous for tows at the end of the lower guard wall when emptying the lock into the lower approach with no riverflow. The problem was eliminated by a riverflow of 35,000 cfs or by emptying the lock into the river.
|Appears in Collections:||Technical Report|