MEMORANDUM FOR THE SECRETARY OF WAR:
An increase in the width of the locks of the Panama Canal will increase the cost, increase the time of filling and empty the locks, thereby reducing the capacity of the Canal and affect the sufficiency of the water supply.
The cost of all the locks 100 feet wide in the clear is estimated at $52,580,011. This cost is increased approximately 10 percent for an additional width of 10 feet; 15 percent, for an additional width of 15 feet; 30 percent for an additional width of 20 feet and 25 percent for an additional width of 25 feet. Assuming that the resolution of the Commission be adopted fixing the width of the locks at 110 feet in accordance with the wishes expressed by the General Board of the Navy, the cost will be $57,690,850, a difference too small to be considered, assuming the necessity for the increased width be as stated by the Navy.
The increased time of filling and emptying reduces by just so much the number of lockages per day and to that extent reduces the capacity of the Canal. Increased with of locks necessitates larger gates and heavier machinery for their operation, thereby reducing the facility of operation.
The Board of Consulting Engineers fixed the maximum elevation of the lake level at plus 86 and the minimum elevation at the end of the dry season at 82, giving storage of practically 4 feet in the lake for lockages. With locks 100 feet wide and allowing 250 cubic feet per second as necessary for operating the power plant, it is found that for the year of minimum discharge, 1903, 22 lockages in 24 hours will be the maximum number permissible. During the year of average discharge, the maximum number of lockages will be 31. Under these circumstances, the depth of the water at the end of the dry season in the Culebra Cut will be 42 feet. There is no reason why the maximum level in the lake should not be maintained at 87 feet and if the lake were drawn off 7 feet, reducing the level in the Culebra Cut to 40 feet, which will be ample depth for any battleship built or contemplated, there will be sufficient water for 30 lockages per day, the number fixed on as the maximum by the Board of Consulting Engineers. If it be desired to obtain this number of lockages for every year, then additional storage capacity will have to be provided by a dam at Alhajuela or the operating plant will have to be moved to that locality and a dam constructed necessary to give sufficient head for generating the power required. The latter method is the more economical and by an additional expenditure of $2,000,000 will give a water supply ample for locks of 125 feet in width.
It is the opinion of the Commission that the present width of locks, 100 feet, is ample for all commercial vessels that are now building or that may be contemplated and that locks are sufficient in size for any battleship now constructed, building or at present projected. As however, that the Navy General Board desires a width of 110 feet and state that “the width of locks as now fixed is not sufficient for probable ships of future construction and that sound policy would dictate a clear width of 110 feet,” the Commission felt that it should be guided by the wishes of the Navy and adopted the resolution fixing the size of the locks at 1,000 feet in length and 110 feet in width.
GEO. W. GOETHALS
Chairman and Chief Engineer
From: The Panama Canal Spillway
September 6, 1996