The Oroville weekly gazette. [volume] (Oroville, Wash.) 1905-19??, 1920-04-23
Massive Dam Will Stay
Course of Turbulent
River Generate
5000 II. p.
lFrom the seattle Post.InteIlIgencerl

portant hydro-electrie power develop
ment in this part OF the state h pro-
jected in the plant that is being In
stalled by the okanogan Valley Power
on the Similkameen river
about five miles west of here. Con
struction work is being rushed by the
company I'm a race against time To
provide electric power for pumping
plants along the lower valley. partieu-
larry for the lands under the govern
ment irrigation project between River
side and Okanogan. in order that the
fruit owe may be insured against
the danger of an insufficient water
supply due to the light snow fall OF
the past winter.
While this enterprise cannot be
compared with a number OF other
hydroelectric power plants In this
state so far as the amount of horse
power that will be generated or the
cost of construction and installation
are concerned. it involves engineering
features comparable in their magni-
tude and the ingenuity required in
their solution to any that have been
met with in similar undertakings In
the country.
The plant which will consist of
TWO turbines, will generate 5000
horsepower. In order to provide this
amount of energy. the waters OF the
turbulent Similkameen are being Inn
pounded by a massive concrete dam,
containing $4,000 yards OF
eighty feet through at the bottom, six
feet through at the top and AIS feet
across from buttress to buttress. This
dam, of the arch type with a 200-foot
radius, will create a lake two and one
half miles long with a total surface
area Of 900 acres and will give a head
at the turbines of los feet. Two i'm
mense concrete conduits, each 1000
feet long, will convey the water from
the dam to the turbines. "A trench Is
feet deep through the bed rock under
the river anchors the base of the dam
and its wings are moulded into the
solid rock of the p%recipitous cliffs that
rise abruptly on either side of the
river and confine the stream in a mar
row gorge at this point. The conduits
and the generating plant are also built
into solid rock. Thus the entire con-
struction is made durable and design
ed to resist the assaults Of time and
the elements.
The dam is located about 100 yards
upstream from the Similkameen falls,
= which have a drop Of about IL or IA
feet. The turbines will be located
about 200 yards below the falls. Ac-
cording to government measurements
conducted over a number of years, the
average volume of water that flows
with impetuous momentum through
the narrowly confined channel Oh the
Similkameen at this point is 1000 sec
ond feet at extremely low water and
$4,000 second feet during high water.
At this time the dam is rapidly near
ing completion and is. already advanc-
ed to a point where it can safely resist
the tremendous force of high water
in case of an early rise in the river
should one occur. The foundations for
the conduits and the generating plant
are now being prepared, and the en-
gineer in charge, d. j. Frederick, who
has had years of experience in similar
work in this state and in Alaska, con-
fidently expects to deliver electric
power Tor use in the valley by the lat
ter part of July.
Preliminary surveys n ~soundings
for the location of the dam were start
ed in July, 1919, and actual construc-
ton began in October last year. When
completed in July of this yea the
total cash outlay will amount to a lit
tie over 100000. The rapid progress
and the comparatively low cost are
due in no small part to the practical
ingenuity of the engineer in charge
who has taken full advantage of the
situation and has devised working
methods that have minimized the labor
and resulted in large economics
Gravel for the concrete is washed
from a hill 400 feet ABOVE the dam and
conveyed by gravity to the mixer at
it's base. Concrete is delivered by rail,
the tracks of the Great Northern u n
ming along the cliff above the site of
the PLAN. A tower 1913 feet in height
rises above the mixer and when pre-
pared the concrete is lifted up this
tower and poured into the forms, the
conveyor from the tower having suf-
ficient radius to reach from side to
side of the dam. An electrically driven
compressor, with a steam auxiliary
plant, provide power, and thus a small
force of men have been enabled to per-
form what appears to be a prodigy OF
labor within a few months time.
When the Similkameen plant is CON-
pleted connections will be made with
q smaller plant located on the Methow
river and owned by the same company.
This will give service to the entire
Methow and Okanogan valleys. The
company is now furnishing electric
power for the towns along the two
rivers, but the increased demand aris-
ing from irrigation development has
made the installation of the larger