EXCAVATING MACHINERY USED IN LAND DRAINAGE. 37 



SUMMARY. 



Power machinery is now available which will construct outlet 

 drainage ditches of all sizes, and under all conditions of soil and water, 

 cheaper than can be accomplished by any other method. 



The floating dipper dredge is more widely used in drainage work 

 than is any other type of excavating machine. For work through 

 wet land no other excavator will equal it hi cheapness of construction 

 of ditches having a cross section of from 100 square feet to 1,200 

 square feet. It is by far the most efficient machine to use where 

 many stumps will be encountered. Owing to its limited reach it is 

 not generally applicable to levee construction. Dipper dredges as 

 constructed for drainage work range hi capacity from one-half 

 cubic yard to 4 or 5 cubic yards; the sizes most commonly used 

 vary from 1 to 2 cubic yards. The smallest dredge costs about 

 $5,000; the cost increases rapidly with the capacity of dipper. The 

 floating dipper dredge should be operated downstream, where 

 practicable. 



In general, the clam-shell or orange-peel dredge is not well adapted 

 to ditch construction, especially if there are stumps to handle. 

 Certain types of soil, such as the muck of southern Louisiana, can, 

 however, be handled to advantage with this machine. It is also 

 suited to levee building when equipped with a long boom. 



The drag-line scraper excavator is constantly increasing in favor 

 in drainage work. It is especially suited to the construction of ditches 

 and levees of large cross section, where the ground is sufficiently 

 stable to support the machine. The scraper excavator is also suit- 

 able for ditch cleaning. 



The various forms of so-called dry-land machines find quite exten- 

 sive use in drainage. The dipper and orange-peel dredges of the 

 dry-land type are suitable for use where sufficient water can not be 

 had to float a dredge. The templet and the wheel types of excavat- 

 ors are applicable to open land where the soil is neither too hard 

 nor too wet. The ditches cut by these latter machines are superior 

 in hydraulic efficiency to those of similar section cut by any other type 

 of excavator. The dry-land machines should be operated upstream. 



The hydraulic dredge is not suited to ordinary drainage ditch 

 construction. It has been used to some extent in cleaning ditches, 

 and, with the use of slope boards, has in at least one instance made a 

 satisfactory record in levee construction. 



