PUZZLE IN PANAMA — BOWMAN 417 



have to be provided. This, however, would be a part of the required 

 channel deepening and not lost motion. 



Finally, with respect to any of the stage-lowering plans, there is one 

 special requirement to be met that would involve extra cost and con- 

 struction difficulty. This is the provision of salt-water pumping plants 

 to make up a deficiency of water for lock operation after Gatum Lake 

 is lowered to elevation 50. Estimates indicate that such plants might 

 have to aggregate over 4,000 second-feet in capacity. 



DEEP-DREDGING PLAN 



All the expense and trouble of conversion locks could, however, be 

 eliminated if dredges could dig as deep as 135 feet below the water 

 surface, i. e, from elevation 85, existing lake level, to elevation — 50, 

 the required sea-level chaimel depth. It is the great appeal of this 

 plan, as to simplicity and to probable lessened cost, that has led the 

 investigators to award the special dredge-development contracts. 

 Should this plan prove feasible it would only be necessary to dredge 

 channels in Gatun and Miraflores Lakes to elevation —50, and then 

 knock out the protective plugs in the third locks cuts, draining the 

 lake. There would be 8 to 10 days interruption to canal traffic while 

 the plugs were being removed and the channels cleared of debris, but 

 after that the sea-level canal would be a going concern. 



Simple in concept though it is, the deep-dredging plan raises some 

 puzzling questions. One of these is basic : Can dredges be designed 

 and built to dig at 135-foot depths, and fast enough to be practicable 

 from a cost standpoint ? To find out, two contracts have been awarded, 

 and to date the results are encouraging. 



One of the contracts, covering both the design of a hydraulic cutter 

 head dredge and studies and estimates of a construction plan, is held 

 by a combination named Panama Contractors and consisting of 

 Gahagan Construction Co., Standard Dredging Co., and the Atlantic, 

 Gulf and Pacific Co. Their contemplated dredge is said to have a 

 46-inch suction and a 40-inch discharge, and to incorporate the unique 

 feature of a booster pump set about 65-foot down on the 185-foot long 

 boom. Lifting and swinging gear would be of unprecedented size, 

 and large buoyancy tanks would help support the boom. The spuds 

 on this huge machine would be 150 feet long, the lower 80 feet of which 

 telescopes into the upper part as required for adjustment. 



The second deep-dredge contract covers design only of a bucket 

 ladder dredge and is held by the Yuba Manufacturing Co., specialists 

 in these types of dredges. Although ladder dredges with %-yard 

 buckets have operated at 124-foot depths in California gold-mining 

 work, nothing approaching the high capacity and 135-foot depth 

 required for the Panama dredging has ever been built. Buckets as 

 large as 6 cubic yards were investigated, but it is believed that the 



