318 
MALARIA 
DIAGRAM NO-2 
re-channeling crooked streams 
insufficient, these fills have been made with 
garbage, tin cans and other municipal 
wastes topped off with dirt. The tops of 
these fills should be sodded to prevent 
erosion, and a brick or riprap dam con¬ 
structed at the upper end of the cutoff to 
prevent the stream from following its old 
course. 
Junctions. Lateral ditches should always 
enter the main ditch at an acute angle in 
order that the flow shall take place with 
that of the main ditch and not across it. 
If possible, the lateral should enter the 
main ditch at an elevation above the grade 
of the main channel, and the grade of the 
lateral increased just before it enters the 
main ditch. 
Seepage. The drainage of seepage or 
marshy areas fed by springs presents a very 
serious problem to the novice, and may 
offer difficulties for the experienced and 
trained engineer. Deep, narrow contour 
ditches, located along the toe of slope of 
the hill cut at right angles to the direction 
of ground-water flow, are utilized to inter¬ 
cept and collect the seepage flow. The ele¬ 
vation of these ditches can be determined 
accurately by locating the level of the 
ground water causing the seepage outcrop 
with a post hole digger (Diagram No. 3). 
DIAGRAM NO-3 
HILLSIDE SEEPAGE DRAINAGE 
If the seepage is extensive, it may be neces¬ 
sary to construct several rows of contour 
ditches more or less parallel to each other. 
If the area is fed by a series of separate 
springs rather than a broad outcrop, nar¬ 
row individual laterals must be dug to each 
spring (Diagram No. 4). 
DIAGRAM NO-4 
DRAINING SPRING-PfcD MARSUfcS 
Construction Operations 
The general practice is to begin opera¬ 
tions on a new outlet ditch at the lower 
end in order that the crew may work in a 
dry ditch as long as possible. In cleaning 
out old channels, it is better to start work 
at the upper end in order that the trash 
and debris may be kept out of the ditch by 
floating it downstream as work progresses. 
Experience has demonstrated the wisdom 
of dividing large crews into separate units. 
Each unit is assigned to a particular type 
of work, such as, clearing, grubbing, rough¬ 
ing out, finishing and sodding. By using 
the same crew on the same type of work 
continuously, the labor becomes more pro¬ 
ficient and the work can be performed more 
economically. 
Cost Data 
The following is a table giving the actual 
cost of the different types of work: 
Type 
Cost per cubic yard 
Hand . 
$0.25-0.50 
Grader . 
0.19 
Slips . 
0.20 
Dynamite . 
0.13 
Dragline . 
0.10-0.18 
These figures were derived from actual 
field operations in Mississippi from 1928 
through 1931. The labor received approxi¬ 
mately $2.00 per day. 
