The twice-a-week Twin Falls times. (Twin Falls, Idaho) 1916-1918, 1917-12-06

/ IL immediately calls Tor reason lot /
providing the present banks and wing |
walls.
At the siphon. 800 second feet addi-
tional is called for by the 25 per cent |
excess capacity scheme, or in other
words, the capacity must be increased |
from 117S to 1872 second feet. In |
order to do this we must increase the /
difference between the elevation of |
water surfaces at intake and outlet |
as much as 3.8 feet, or increase the |
depth over the intake more than four
feet. This means raising the con-
crete abutment walls at the intake |
remodelling the recently completed |
concrete spillway about 200 feet above |
the siphon and raising the canal banks
for several thousand feet above this
point. An examination of the de-
! sign of the intake structure, might |
reasonably be expected to show lack |
of strength to carry such an increase. |
Although the entire distance from
the siphon up the forks" has been
examined by the writer, the consider
alton of required betterments, did not, |
at the time, entertain the idea of 1875
per cent delivery, and although an
estimate is included for betterments
between Perrine coulee and the 81
phon, the solution of the problem of
controlling the erosion which is TAX
ing place between the forks" and the
| Perrine coulee, requires more study
than has been devoted to it. The item
of most Importance here, is the elm
ination of the eroding agent which is
primarily, the mineral debris lossen-
ed from the channel itself This can
be overcome by the construction of
an artificial channel but no estimate
has been made as to the cost
For a distance of more than miles
below Perrine coulee, the banks are
in bad condition. 1t seems safe to
say that half the section of the banks
has been washed away, leaving a YER
teal face of earth from to 10 feet
high exposed to the high velocity of
this section. From 10 to 20 feet back
of these vertical faces, large cracks
speak for a thoroughly unsafe condi-
ton
High Line Canal
The high line canal not only lacks
capacity for 1875 per cent delivery, but
for 100 per cent delivery and though
considerably smaller than the low
line, it is the source of far more grief.
Beginning at the forks, or the
heading of this canal, cleaning is now
needed to the point of the concrete
lining.
From station 269 to station PTS, or
from a point about two miles above
the Cottonwood flues, to a point about
Il mile above, the upper bank must be
raised to prevent overflow.
At the fumes, the approach must
be modified to offer an easier en-
trance of the water, and below it a de-
, cided enlargement of the rock cut
+ must be made. In fact the whole can
nal from the fumes to Cedar Draw
must be enlarged.
In the report Of the general man
ager for 1917, it was pointed out that
in order to give the high line, the
, same relative capacity as the low line,
the fumes must carry 1867 second
! feet. In considering the t25 per cent
. delivery, the fumes must increase this
q amount of 1867 to 1854 second feet.
| 1t was tentatively planned in this an
nual report, to increase the capacity
of the canal, below the fumes build
q ing up the upper bank, because the
+ lower bank offers more freeboard
f than necessary, but in order to obtain
a necessary velocity of 7.3 feet per
+ second through the fumes, the water
Q surface below must be dropped, and
! therefore, the canal cross section in
, creased.
Below Cedar Draw. the high line
y was enlarged in 1915 and cross sec
i tions show sufficient capacity.
Y Main Canal
e Capacity revision of the high and
= low lines, brings about the following
condition at the FORKS" which is the
c lower end of the main canal:
s High line requirements 1886 second
v feet; lowline requirements. 1867 sec
ond feet, total requirements 1903 sec
ond feet.
T. To this amount we now add diver
: sions and transportation losses be-
; tween here and Miner and reach a
T. grand total of 4097 second feet, which
Il is 367 second feet over and above
j the largest amount diverted to the
main canal This calls for enlarge
y ment, but it is the opinion of the writ
er that an enlargement of this canal
> is in order regardless of whether this
+ 367 second feet is added or not. at
! least as far as Dry creek reservoir.
{ This report is not able to base an
i estimate of the cost of main canal
{ enlargement on the notes of a survey
:, for this purpose, but estimates the
Il cost as compared with cleaning oper-
= ations and the estimated cost of the
high line enlargement
= Another item for consideration on
the main canal, to which attention was
= called in the preliminary report OF
- the writer, last October, is the nee
- essity of a full capacity wasteway at
% the point where the canal is the short
q est distance from the Snake river
= canyon. This is found northeast OF
y Hansen 312 miles, at what is known
n as Hansen Point"
g General Remarks.
IS A more detailed inspection of the
: system since the preliminary report
II of last October deserves the express
If sion of opinion that the condition gen
orally, is considerably better than il