The watchman and southron. [volume] (Sumter, S.C.) 1881-1930, 1909-09-25
TILE DRAINAGE IN FOUR CAP
TIERS.
Chapter Nv.
(Continued.)

II
| "The most important part of every
business Is to know what ought to be
DONE" About A. D., 10 Columbia.
In laying out, on the ground. sys-
tenn of underdrainage, a field having
one slope presents the simplest prob
In the choice Of outlet for the main
drain. This should generally be at
the lowest point of egress from the
field. but circumstances may make 1t
necessary to go much beyond the
limits of the area to be drained in
order to get to q water course that
may be relied upon to remain at all
times unobstructed. A drop Of sew
eral inches from the end of the pipe
into which it discharges. is always de-
sirable. The end Of the pipe should
pass through pier of masonry hav-
ing a foundation we'll below the bot
tom Of the channel and the mouth
| of the pipe should be closed by a
shackle valve, opening outward, to
prevent the entrance of vermin.
In the case We have under consid-
Grafton, the main drain, after reach
ing the field. would probably run
| along the foot of the slope receiving
In its course branch drains running
down from the higher ground; an ex-
ptional case being one in which by
c-tting for a few rods through q
| slight hill. we could more than Offset
the additional cost of the deeper
trench by the saving affected in the
large and more costly pipe of the
main drain.
At proper points for receiving the
lateral or branch drains, Y functions
should be laid tn the course Of the
main drain. The outer or branch
prong of the should be turned up
ward somewhat. In order that the
water from the lateral may enter the
main drain near the top of the latter.
BY connecting the lateral with the
main through Y, the water from
the lateral Is made to enter the main
drain at an acute angle, which serves
to accelerate rather than to retard
the flow Of water In the main.
AS far as the working of the sys-
tenn Is concerned, 1t makes no differ
ence what angle the course of the
lateral makes with the course of the
main drain. If the course of the lat
eral is perpendicular to that of the
main. 1t is only necessary to connect
the lateral with the branch by an
appropriately curved pipe known as
q 45-degree bend The prong or
branch of the ITSELF sets off from
the main at an angle of about Is
degrees and the addition of the bend
further sets off 45 degrees, thus caus-
ing the lateral to assume a direction
which is at right angle to the cours
Of the main drain.
AS to the direction the lateral
drains should take with reference tC
the topography, they should. where
! possible lie perpendicular to the con.
tours that is to say, straight up and
down the slope. In this position they
draw water from equal distances or
, either side.
The difference of elevation between
the channel into which the mair
Grain is to discharge, and the lanC
through which this drain is to b,
laid. controls both its depth and it,
inclination. But If we can not ge
the desired depth for the main drain
. in its course through the field, w,
5 can run our branch drains on grades
. Halter than the slope up which the,
g pass. uatll We shall have received tn,
, desired depth. and then continu
!. them on grades parallel to the gen
I eral surface Of the ground. The lat
eral drains constitute. by far, tn,
: greater portion of a drainage system
The main drain receives directly from
!. the soil but small per cent of tn,
/ aggregate carried by it, and i'm tn
simple problem we are now cXamin
ing the question of depth is not
, serious one provided the pipe be deer
enough for safety.
A case more complex than the on,
which we have just considered, would
be one I'm which the land slopes in