Payette enterprise. (Payette, Canyon Co., Idaho) 1909-1935, 1915-09-23
ARROWROCK DAM
NOW COMPLETED
MASTERPIECE OF THE EN-
GINEERlNG PROFESSION ITS
CONSTRUCTION MEANS THE
IRRIGATION OF AN EMPIRE.

1
completed today, masterpiece o
the engineering profession, in tn
formal dedication of which Bois
and all Idaho will joyfully participate
on October 4th with proper ceremon,
will be of interest to readers of thu
Enterprise. Its construction mean:
the irrigation of an empire, 0,00(
acres of land in western Idaho:
The Arrowrock dam stands 348.5
feet high, 90 feet of which is below
the bed of the river anchored to
solid granite, through which series
of holes were bored to a depth OF
from 80 to 40 feet and grouted with
concrete under pressure to prevent
possible seepage The river was
diverted from its normal channel in
which the dam sits into tunnel
put through a cliff. A Golfer dam
left the river bed dry and in it
were placed lotion Atlantic shovels,
derr: cks, hoists, etc. With the as
sistance of men to operate them
and work in the pit the excavation
was gradually sunk down, the grout-
ing took place and the foundation
| for the towering dam laid 24O feet
wide at the base and HOO feet long.
Each day thereafter saw the struc-
ture 1000 cubic yards nearer COM
pletion A line of open holes to
catch possible seepage bored just
below the holes for grouting to-
gether with grouting holes was
carried up through the dam and
connected with galleries built in
side of it from which the outlets
are operated partly by water pres
sure and partly by electricity. In
these galleries additional groutmg
can be carried on deep below the
base of the dam If necessary The
thickness of the structure was
gradually reduced until at the crest
il stands but 16 feet wide, forming
a roadway, guarded on either side
by a parapet wall four feet high.
Mounted at intervals on this are
rows of pedestals crowned with
arc lights, power for which is furn-
ished by the electric plant
To the one side of the dam has
been cut a gigantic spillway through !
cliff of solid granite 1t us 400 !
feet long following the contour of
the ground in a direction at right
angles with the DAM In flood sea
son water from the reservoir will
enter the spillway over the lip
ON which are specially con-
gates. 1t will be carried off
around the dam and allowed to cas-
cade down the mountain side back
into the river. In an extreme flood
year, should the spillway be unable
70 handle the water, the dam is so
as to permit 1T to plunge
over it's crest dropping over 2oO
'eet to the river below. A total of
10 900 second feet of water can rush
through this spillway at its normal i,
and could it be harnessed
t would develop vast amount OF
electrical energy. !.
To the opposite side of the dam,
concrete log chute has been built
o permit the passage of logs from
he reservoir to the river below.
he estimated stand of timber tribu- t
ary to the reservoir is three billion V
aet valued at thirty-six million dol d
ars. 1t will take so years to pass 1t t.
YER the dam On the same side, Ii
hould 1t be deemed advisable TO fl
uild an additional hydro-electric b.
liant a tunnel can be bored through
,e mountain side to tap the reser- in
Dir and provide the water to gen. fo
rate as high as $4,000 horsepower. ly
The reservoir is IS miles long lie
it'll a maximum depth of 200 feet be
$ capacity is 244,300 acre-feet
hich If spread one foot deep would ed
yer $50 square miles, or it would In
yer the city of New York includ- tn
g Manhattan Island, Bronx, Brook tn,
n, Queens and Richmond to the Sta
me depth; cover Chicago with two er;
ct of water; Boston with eight thu
ct; the District of Columbia with tie
'e feet and the state of Rhode on,
and with four inches. Law
The dam itself weighs over a nil to
n tons. If loaded ton to each the
foot wagon, the wagons would the
ach from San Francisco to New for
rk and double back to Cleveland me
e project is located tributary to
Use from 40 to 60 miles from the
m. Every acre with the exception
about 1000 has been filed en- by +
tiers. I
The delegates from 10 states now +
attendance upon the Western )