34 



BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. 



and cost $115,000. Once dining this season the dredge was sunk to 

 the bottom of the canal; otherwise, the work was done under favor- 

 able conditions and the excavation made was representative of the 

 capacity of the machine in ordinary clay soil. 



Cost of excavation by hydraulic suction dredge on the New York Barge Canal for the 



season 1908. 



Month. 









Total 



Labor. 



Plants 



Material. 



for 

 month. 



Dollars. 



Dollars. 



Dollars. 



Dollars. 



3,670.95 



408. 30 



1,900.62 



5,979.87 



5, 169. 29 



1,367.60 



2, 558. 88 



9, 095. 77 



5, 615. 75 



1,677.85 



2, 263. 16 



9, 556. 76 



5,835.14 



1,735.50 



2,446.45 



10. 017. 09 



5, 985. 87 



1,631.15 



2,320.92 



9, 937. 94 



4,993.11 



1,692.85 



2, 430. 05 



9,116.01 



4, 834. 14 



1,791.15 



2, 573. 50 



9, 198. 79 



Yards 

 exca- 

 vated. 



April 



May 



June 



July 



August 



September 

 October... 



120,673 

 204, S38 

 203,474 

 207,520 

 174,395 

 231,473 

 214,438 



1 Interest and depreciation at 15 per cent per annum. 

 Average cost for trie season, $0.0464 per yard. 



USE IN CONSTRUCTION OF LEVEES. 



It formerly was considered that the hydraulic dredge was not 

 applicable to levee construction for the reason that the large amount 

 of water pumped made it difficult to keep the solid material from 

 spreading over a wider base than desired for the levee. It was gen- 

 erally thought necessary to build ridges to form the toes of the em- 

 bankment, with earth dry enough to hold the wet material within 

 the desired limits until the solid matter had been deposited; in this 

 manner one layer was added to another until the desired height of 

 levee was reached. The need of this dry material is avoided by 

 methods now in use by which the entire section of the levee is built 

 in one operation. 



Plate VIII and Plate IX, figure 1, illustrate the method of forming 

 the desired slopes by means of steel boards about 18 inches wide and 

 10 feet long, made of No. 14-gauge steel with angle-iron top. These 

 boards are not too large nor too heavy to be easily moved by one man. 

 In Plate VIII, figure 2, the slope boards are easily seen; they are 

 placed at the intersection of the side slope with the natural slope of 

 the end of the fill under construction. Several men equipped with 

 shovels are necessary to distribute the material evenly and to move 

 the slope boards ahead as the levee is built up. 



On a section of levee built along the Mississippi River near Bur- 

 lington, Iowa, a hydraulic dredge consisting of a hull 24 by SO by 

 4£ feet, upon which was mounted a centrifugal pump having a 12-inch 

 suction pipe, a 14-inch discharge pipe, a 200-horsepower engine, and 

 a boiler nominally rated at 150 horsepower, was used for the con- 

 struction. The discharge pipe was carried from the dredge to the 



