Si decaster Dredges 



Sidecaster dredges employ a hydraulic system similar to hopper dredges. 

 However, instead of temporarily storing the dredged material in bins, it is 

 shunted to one side of the vessel by use of a side arm or short pipeline. In 

 some instances, it may be pumped ashore for beach nourishment or confined dis- 

 posal (Gren 1976). 



MECHANICAL DREDGES 



Bucket Dredges 



There are several kinds of bucket dredges including clamshell, dragline, 

 and orange peel. In their simplest form, they consist of a drop bucket attach- 

 ed by cables to a winch-equipped boom and lifting system generally mounted on 

 a barge (Pequegnat et al . 1978). They are used in both maintenance dredging 

 and new channel construction. 



Ladder Dredges 



A special type of bucket dredge is the bucket ladder dredge or simply the 

 ladder dredge. A continuous chain of buckets removes sediments from the bottom 

 and places the sediments aboard a barge for transport to the disposal area. 



The ladder dredge is used in the United States only for mining opera- 

 tions, however, it is a common component of European dredging fleets and is 

 being advocated for use in the United States (Mohr 1976). Mohr states that 

 the ladder dredge has the advantages over hydraulic dredges of using less 

 energy and creating less turbidity. 



Dipper Dredges 



The dipper dredge consists of a power shovel mounted on a barge and is 

 particularly useful for excavating hard bottom material in water depths less 

 than 10 m (33 ft). 



