EXCAVATING MACHINERY USED IN LAND DRAINAGE. Pes 
Of the various sizes of fioating dredges, most operators agree that 
the 24 or 3 cubic-yard dredges are the most economical in cost per 
cubic yard. 
SELECTION OF DREDGES. 
The floating dipper dredge is admirably adapted to the excava- 
tion of drainage ditches having sufficient width and depth and the 
necessary supply of water for floating the machine, especially where 
the ground is swampy or covered with trees or stumps rendering 
impracticable the use of teams or dry-land machinery. No other 
type of excavator is so well fitted for digging ditches in timbered 
country or where large stumps will be encountered. The dipper 
dredge, however, is not well adapted to digging channels of less 
than 100 square feet in cross-section, although it is used in the 
construction of smaller ditches. Standard types of dipper dredges 
are not adapted to digging ditches more than 1,200 square feet in 
cross-section, although ditches with 123-foot base and 11 feet deep 
have been dug with a 90-foot boom, vertical-spud dredge. As ordi- 
narily operated, the dipper dredge constructs a more or less ragged 
and irregular ditch, yet in the hands of a skilled operator very 
good results can be obtained. 
Tn the construction of ditches in the Piedmont section of the 
southern Atlantic Coast States, floating dipper dredges equipped 
with #-yard dippers and 30-foot booms and mounted on sectional 
steel hulls are used rather extensively. The ditches have ordinarily 
a top width of from 14 to 20 feet and a length of 5 or 6 miles, 
involving the removal of 100,000 cubic yards or more of earth. 
Since the ditches frequently cross an old channel, the floating dredge 
is better adapted to this work than dry-land machines. Contractors 
state that the cost of installing a dredge of this size on a job is about 
$5,000. To justify the installation of this size of machine, a job 
should cost about $20,000 or more. 
A 14-yard dredge having a 40 or 50 foot boom, a hull 20 to 22 feet 
wide, and a draft of 3 feet is an economical machine for digging 
small ditches. A dredge of this size will excavate a ditch through 
timbered land cheaper than any other type of small excavating 
machine. On a project adapted to floating dredges, with plenty of 
water for flcating the machines, and where there are a few small 
laterals with bottom widths of 4 or 5 feet and ranging in depth 
from 7 to 8 feet, the construction of these smal] laterals, if dug by 
the machine used on the larger ditches, will invariably cost more 
per cubic yard than ditches with 14-foot bottoms, owing to the excess 
yardage which must be removed by the dredge. 
The size of the dredge that should be used depends upon various 
factors. Not only the greatest and least, but the intermediate cross- 
