EXCAVATING MACHINERY USED IN LAND DRAINAGE. 35 
top of the levee by small towers mounted on 14 by 40-foot barges. 
A strip about 30 feet wide along the center of the site of the levee was 
grubbed and ploughed. No muck ditch was prepared. The levee 
was about 14 feet high with an 8-foot crown and 3 to 1 slopes on both 
sides. The number of men usually employed was about 14, and the 
fuel used was about 5 tons of good coal in each shift. Two 11-hour 
shifts built 100 linear feet of completed levee, or 2,700 cubic yards. 
A dredge of this type costs approximately $15,000, not including 
the discharge pipe, the barges, and other necessary appurtenances 
which will add about $5,000, making the total first cost about $20,000 
for a plant to build levees by this method. 
With hydrauhc-fill levees a wide foreshore can be left. There are 
no borrow pits to aid in probable seepage and consequent failure of 
the levee. Any side slope wanted for a levee can be built. There 
is no shrinkage after the embankment is first completed, for the 
material is thoroughly compacted. The fine material is deposited 
in the base of the levee where it is most needed to prevent seepage. 
By using the hydraulic-fill method, a levee can be built across an old 
bayou or lagoon with as little trouble as on dry ground, which can 
be done by few machines. Wet, soggy ground gives no trouble in 
construction. Hydraulic-fill levees, being composed mostly of sand, 
are proof against damage by burrowing animals. 
On the other hand, a 20-foot head with about 600 to 800 feet of 
discharge pipe are the maximum conditions under which a plant de- 
veloping only 200 horsepower can operate; greater heights and dis- 
tances must be overcome by a corresponding increase of power 
equipment. The dredge must always be in about 8 feet of water to 
prevent air from being drawn into the suction pipe. It would hardly 
pay to put such an outfit on a project of less than 250,000 cubic yards. 
It has been observed in hydraulic fills made with clay that the 
tendency to settle is not so marked as when sand alone or sand 
mixed with some silt is pumped. The tendency of the sand to settle 
in the bottom of the discharge pipe permits the building of levees 
having any slope between the natural slope assumed by moist sand 
and that of a semifluid. By using the slope boards, however, a greater 
range of side slopes can be had. 
MACHINES FOR CLEANING OLD DITCHES. 
A floating dredge as a rule is unsuited to cleaning old ditches unless 
the amount of material to be excavated is large. It is also imprac- 
ticable to dam up the channel on account of possible damages to the 
landowners. Moreover, all bridges must be removed if a machine 
of this kind is used. 
A type of the stationary scraper excavator which straddles the 
ditch has been used quite successfully on the smaller ditches. On 
