192 A TREATISE ON DREDGES AND DREDGING 



all the cars have been loaded, the float is towed to some distant 

 point and moored to a convenient place where there are tracks 

 in continuation and flush with those located on the float. At 

 the landing pier a locomotive pulls out one row of cars at a time 

 and after the train is formed it is sent to the dumping place, while 

 empty cars are replaced on the float and towed back to the drcd::,. 

 to be filled with dredged material. This method of transportation 

 can be used onty in connection with the dipper and clamshell 

 dredges, and although it can be found convenient in some cases 

 it has the great disadvantage that it is difficult to load the cars, 

 part of the material falling between the tracks and must be 

 removed by hand. 



Deck Barges with Cargo Box. The dredged materials can be 

 transported also on deck barges with cargo boxes, when the barges 

 will be unloaded by means of clamshell or orange-peel buckets. 

 This method of transportation is commonly used in connection 

 with gravel and sand dredging for commercial purposes. The cargo 

 box is formed by fitting side boards about 3 ft. high and arranging 

 hopper ends, inclosing nearly all the deck area, leaving but a small 

 space at each end for handling lines. The barges used for carrying 

 sand on the Mississippi River are subjected to severe strains, and so 

 several steel-deck barges have been placed in service by one of the 

 largest sand companies on the river. These barges are 130 ft. long, 

 30 ft. wide and 1\ ft. deep. A complete steel deck is fitted, and on 

 this a wood box is arranged, by fitting timber side boards 3 ft. high. 

 The deck beams are framed longitudinally so as to better care for 

 the impact of the grab bucket, which is used with its cutting edges 

 across the barge. 



Dumping Scows. The transportation of the debris from the 

 dredging point to the dump in high seas, when not made by the 

 dredge itself, is done by means of dumping scows. These are usually 

 composed of an ordinary deck scow with one large or several small 

 holds having the floors formed by the trap doors. The ddbris is 

 deposited into these compartments and when the doors are opened 

 the contents fall out by gravity. It is more convenient to have 

 the scow divided into many separated compartments instead of 

 one large one. Such an arrangement will greatly facilitate the 

 operation and prevent the great weight of the load from straining 

 the mechanism controlling the doors. 



Dumping scows are constructed of different shapes and sizes. 



