The Arizona sentinel. [volume] (Arizona City [Yuma], Yuma County, A.T. [Ariz.]) 1872-1911, 1908-11-11

so great, the water movement
toward the canal is slow, and
mostof the sediment is deposited.
1t is estimated that the capacity
of the sluice gates will be ap-
proximately 20. GOO cubic feet per
second each. This great volume
of water passing through the
sideways when the gates are
open, will carry out with the sed-
iment deposited above the intake
of the canals. The ordinary low
stage flow of the Colorado river
is from 5000 to 1900 cubic feet
per second, so the capacity Of each
of these sideways will be about
five times the low water flow OF
the river. The figures are given
for purposes Of comparison only.
AS the result of a number of
experiments, it has been found
that the principal quantity of silt
is carried along near the bottom
of the river, and that the surface
water is relative free from sedi-
ment. Il was planned, therefore,
70 take the water into the canals
by skimming process over a
long row of fash boards, so that
the entire capacity of the canal
can be furnished by drawing but
one foot in depth of water from
the surface of the river. AS
still further precaution, it was
decided to construct the first !, 900
feet of canal on each side Of the
river of such size that the move
ment of water through it will be
slower than one foot per second.
These settling basins, as they are
called, will be either cxcavated
from granite, or, where the Sec
ton is in earth, they will be
paved. At the lower end Of the
settling basins, gates were plan
ned to discharge into the river,
so that the water could be drawn
to the level of the stream.
The headworks as designed are
Of rock, concrete, or steel, with
the exception of the sheet piling
which is driven entirely below
the water level. and so will not
decay. Every portion Of the weir
is of what is known as peaman-
ent construction.
While the Laguna dam is 4, $50
feet, or nearly mile, in length,
its width is especially noticeable,
the maximum dimension being
no less than 272 feet, although
the height as stated is but 10 feet.
| These proportions are necessary,
however, because of the great
force of the flood current, and to
prevent the water from forcing
it's way beneath the dam and thus
undermining it.
The capacity of the canals at
their intakes is }, POO cubic feet
per second on the Arizona side,
and 200 cubic feet per second on
the California side. The amount
of the silt that would be daily de-
livered into the Arizona canal, if
diversion were made directly
from the structure, would APP
proximate 1000 cubic yards of
wet mud by volume.
Careful study was made of the
, existing canals in the vicinity OF
Yuma and Imperial, to determine
the shape that they naturally as
sumo, and the roughness of the
bottom and sides, which tends tC
retard the velocity. Based upon
these data, the new canals have
been so designed as to carry
5 water at a higher velocity
= throughout than will be found in
, the settling basins above theil
f head, and atsuch velocity as viii
= permit of minimum loss by
! tseepage and evaporation. The
] gates and droops of these canals
] and the Yuma bridges are stee
= fconcrete structures. One of The
most difficult problems in con
D nection with this project was th'
! crossing of the ella river. 1t wa:
G considered necessary to make thi:
= perfectly safe, and for this pur
pose a structure was designed
r that crossed beneath the bed 0
= the river, the top several fee
D below the lowest point of th'