CHAPTER XXVII 

 DRY-LAND DREDGING 



WITHIN the last decade dry-land dredging has been done exten- 

 sively in America. This is not in reference to excavation work by 

 steam shovels, but to excavation done in a manner somewhat 

 similar to ordinary dredging. This work is done for various purposes, 

 as the building of dykes or levees, the excavation of canals, power 

 ditches, dams and reservoirs, irrigation and drainage ditches. 



The machines used for such work may be divided into two classes. 

 First, types of machines similar to those used in ordinary dredges. 

 These are mostly the dipper, grapple and hydraulic suction type, 

 although a few dredges of the ladder type have been used. One 

 such has lately been used in the state of Idaho, in excavating irriga- 

 tion canals. The dredge is of a fair size, and is operated by a gasoline 

 engine. At first its work was indifferent, but after being rebuilt 

 it has done efficient work. 



Hydraulic dredges are not used extensively, but more so than 

 the ladder type for dry-land work. To use it a hole large enough 

 to float the machine must be excavated by other means and be 

 filled with water. A supply of water must be furnished to allow 

 the dredge to work. Unless the work is situated close by a river or 

 large body of water the needed water is difficult and expensive 

 to obtain, hence it is only possible to work the hydraulic dredge 

 under special conditions. Land however is sometimes flooded and 

 excavated with such dredges. This was one of the methods suggested 

 to excavate the Culebra cut on the Panama Canal but it was not 

 adopted. Other objections to the use of hydraulic dredges for 

 dry-land work are the necessity of rinding a place to deposit the 

 dredged material and the great volume of water necessary to carry 

 it. On harbor and river work this material is either pumped into 

 another part of the harbor or river, or else used to fill up adjoining 

 lowlands so the water does not do any damage, but for dry-land 

 work, even if there is a place to deposit the dredged material, yet 



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