DRY-LAND DREDGING 



247 



The second class of dredges used for dry-land excavation are 

 machines designed and built for this particular kind of work. 

 One of the best known of these machines is the Austin Drainage 

 Excavator, built by a company of that name, in Chicago, 111. This 

 machine straddles the ditch or canal and excavates a clean ditch 

 with sides sloped to any desired angle, see Fig. 82. Digging with 

 this machine is often termed "excavating a ditch to a template." 



FIG. 81. Bucket for Dry-land Dredging. 



A steel framework upon which the two buckets operate is made 

 to conform to the bottom of the ditch and extend to either side, 

 so that the earth is carried away from the sides of the ditch, leaving 

 a berm that is free of earth, and thus preventing it from running 

 back into the excavation. In this manner two regular levees are 

 built, one on each side of the ditch, that act as banks to confine 

 the water in case of floods. The berm left is from 10 to 15 ft. wide. 

 The frame under the machine is lowered as the ditch is deepened. 



