The Emmett index. [volume] (Emmett, Idaho) 1893-1925, 1916-01-06
OPEN CUT PREFERABLE
TO TUNNEL
Engineer Horn Strongly Advises
That Tunnel Be Abandoned
Cost About Equal.

Below is given the report of F. c.
Horn, engineer, on the two PROPOSE
tions for the improvement of the
Plowman tunnel on the Canyon canal
lining the present tunnel with ce-
ment or making an open cut. Mr..
Horn advises making an open cut and
gives his reasons. The estimated cost
of each is given and also the bids of
three construction companies for the
work of making an open cut:
November "a, 1915.
president and Board of Trustees,
Emmett Irrigation District, EN-
NETT, Idaho.
Gentlemen: After thorough ex-
animation of your tunnel No. near
Montour, Idaho, l have come to the
conclusion that the condition of it is
a most serious one, as all of the tim
ber constituting the lining is in a
more or less advanced stage of de-
cay and may fail at any time. The
major portion of the posts and caps
are in condition of decay which rem
ders them impossible of performing
their proper service.
"The material through which the
tunnel was driven is a heavy gravel
mixed with sand and alternating
with a sandy clay in many places.
Towards the westerly or downstream
portal of the tunnel the prevailing
material is sandy clay, mixed with
a little gravel The failure of but
a few of these rotten timbers would
result in most serious condition,
both to the tunnel and to the project
as whole. The gravel and clay
through which the tunnel passes, is
not a self supporting material as is
rock or other sitter materials, con-
sequently the weight of earth above
the roof of the tunnel is enormous.
"a failure of the tunnel during the
irrigating season, would mean the
washing out of the canal bank above
the tunnel, and what would be more
the untold loss to the I
farmers, due to absence of water.
Expensive orchards could not be re.
placed for several years. Due to the
physical characteristics of the gravel,
its looseness, etc, great quantities OF
would have to be handled
n making repairs which could not be
made in short time.
With concrete in the first place, and
made larger enough to supply future
demands. The enlarging of the pres
mt tunnel under the most favorable
and also the lining of it ]
With concrete, would be an expensive
A means was devised for {
he temporary timbering to be used
n enlarging and lining the tunnel,
which contemplated using the pre-
ent timbering as far as possible to |
eep down the cost. l have appended !
cost sheet to this report showing {
he quantities and costs. The pro-
osed enlarged tunnel was figured to
ave discharge of any amount up to
thousand inches, but J
7ould require total difference in the \
levations of the water surface at the n
vo ends of the tunnel of four feet. :
here is at present a difference of 4
ovation of the floor of the tunnel at
le two ends of three feet in the
,tal distance of fifteen hundred feet.
he additional one foot would be re-
1ired to produce the necessary We
city to force the water through
lie tunnel in order to get the required
scharge. This is not desirable from
,ur point of view as it lowers the
ficiency to the canal from the tunnel
the dam, and also of the flash
ards placed on the dam to keep
e water flowing into the canal dur
g the period of low water in the
yer.
"My final conclusion is that this
ction of your canal system would =
improved greatly if an open cut =
IS made in place of the enlarged
mel. There are many advantages
favor of the open cut, which are
'tinct advantages when considerat-
2 the tunnel
'One of them is the less danger
I'M loss of life on construction.
ouble might be encountered by the
on the tunnel enlarging
ich would delay progress to such
extent as to cause the farmers to
fer from lack of water.
The main advantages lie, however,
the better hydraulic conditions to