The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1880-03-28
THE WATER DISCHARGE.
What Smith & Doremus Say
About the Canals Capacity.

0 SALT LAKE CITY, March 81, 1880.
! Editors Herald:
In your issue of this date San &C
: dress to the voters of Salt Lake City
! By the Hon. the Mayor, and the Cit
Council contains the following:
1.-THE proposed canal, as surveyed an
{ now being excavated, begins with tn
. South Jordan Canal and separates from
1t BIT the hume across the kiver JordAn
and extends by the mos. feasible rout
to the fret workings on the old Churcl
Canal near Little Cottonwood, which
latter viii DO adopted and form the con
tinuation OF the Jordan and Salt LAX
City Canal into this ~. The canal /
twenty feet wide in the bottom, and hai
a cap 4city for carrying four feet in depll
of water. The fall Tor the first sever
miles is two and half feet to the mile
from that point to the Church Canal the
TALL is nineteen inches to the mile where
there is a drop Of nineteen feet; The fall
from that point to the Sugar House is
thirty inches to the mile, besides drops
amounting in the aggregate to fifteen
feet. From the Sugar House TO the
terminus in the city the canal is level,
the head and draft giving sufficient force
to The water for that distance.
The velocity of water flowing in q
canal twenty feet wide and four feet
deep, with fall Of thirty inches to the
mile, is three and one-half feet per
second, or two and one-third miles per
hour; the discharge in round numbers
would be 3261l cubic feet of water per
second, or J ,l76, 422 cubic feet per hour,
s, 1866 gallons of water, which affords
some idea of the amount of water which
such canal as the one now being con-
structed will supply"
Assuming the canal above des-
cribed to have sides sloping at an
angle of 450 our method shows 336
cubic feet per second to be its
theoretic disohsrging capacity-the
actual discharge being a variable
per cent. less depending upon evapor-
alton, character of soil, curvature,
etc. Were the size Of ditch and fall
per mile uniform through its entire
length, the above would undoubtedly
'aford some idea of the amount of
water which such canal as
the one being constructed
will supply. But from a point seven
miles down the canal. from its head,
"to the Church Canal the fall is nine.
teen inches TO the mile" and being,
under the same law, capable of dis
charging only 2754 cubic feet of water
per second. Then we have a section
from where we enter the Church
Canal "to the Sugar House." with a
tall of thirty inches to the mile,
which being the same as on the first
section of seven miles, must neces.
;srily have the same or equal die
charging capacity. It may be proper
10 here state that the drops" do not
ia the least effect the dlscharging
of the canal. And again
from the Sugar House to the ter
minus in the city the canal ia level,
the head and draft giving sufficient
iorce to the water for that distance.
That the above is only guess work the
most thoughtless, resort to figures
iully proves; for if the terminus of
Inc canal il this city was left entirely
lnobstructed by gates or other
wise, and the water allowed its free
course the discharge per second
could not possibly exceed 30 cubic
feet, assuming, as we have, that the
Did canal Is 80 feet wide in the bot
tom and will carry 8 feet depth of
water.
Now, the unavoidable question,
by the above, is how are We
to get the $50 cubic feet of water
delivered each second by our first,
or 80 inches to the mile section, to
pass through the second or 10 inches
to the mile section, which is capable
Of disposing of only 2753 cubic feet
Of water per second? Or through
our fourth or level section with its
dischargiDg capacity of
not more than so cubic feet per sec
ond?
From further hasty calculations We
find that in order to nave our canal
of uniform discharging capacity
throughout, and equal to that OF the
frat or 80 Inches to the mile section,
which we have taken as base (sup-
posing that to be of the size neces.
sary from the fact of its
being known and its
construction far advanced) il will be
to enlarge the whole of the
second or 10 inches to the mile sec
ton to about &c feet wide in the
bottom with 4 feet depth of water
while the fourth or level section must
be enlarged to more than 20 feet
wide in the bottom with 5 feet depth
of water.
Evidently the existing conditions
are unintenlional or the object very
obscure, and in either case should be
explained to the satisfaction Of voters
before they can be expected to say
"Yes" to the amount of $3.50, 600.
With q hope that other members OF
the profession will be troubled to
verify or disprove the correctness of
our statements. And q desire that
this may be the meaps of awakening
an interest in the matter equal to the
occasion. We are,
Yours truly,
SMITH d Do2EMUs,
Civil Engineers.