Graham guardian., 1908-07-10

| rainfall upon the territory to be
irrigated ranges from 3 to 10 inches;
and the rapid evaporation of mois-
ture is indicated by the fact that
the temperature in summer ranges
as high as 100 degrees, although
the elevation varies from 900 to
| 1900 feet altitude. The damswill
impound So iiic,ent water to fully
irrigate 270, 900 acres of soil. This
soil is known to be fertile when
water in sufficient quantities is
applied; the Department of Agri-
culture having tested II few ex-
perimental tracts, with the result
that the crops have been remark
able for their quality and yield.
A feature of the undertaking is
the power canal Water power or
electric curren, has before been Sc
cured from dams intended for ir-
rigatiDg purposes by utilizing the
waste water. Such power, how
ever, is only available when the
flow of water into reservoir is
more than sufficient to fill it. The
power at Roosevelt is obtained in
dependentiy Of the irrigating
scheme, the canal being seperate
from the reservoir and one of the
first works completed The head
OF water secured by means of the
canal actuates waterwheels con.
nected to electric generators at
present developing over 1900
horse power. From the power
station extends transmission
line conveying current TO the plant
for the manufacture of cement, the
stone crushing plant, for lighting,
operating the aerial railway, and
for other purposes, Under head
Of 900 feet, hydraulic jets with
pDzzles of II inches have been used
to wash away the loose formation
and accumulation Of sgmp above
the bedrock upon which the dam
proper is being built, and have
greatly facilitated progress. Much
of the gravel thus secured has
been utilized for construction
material. To remove the gravel,
elevators have been PLACED in
| seryi,e.
This canal, which is twenty
miles in length, is one of the per-
manent works. Most of it is lined
with concrete, and it includes sev,
eral extensive tunnels, aggrera.: ::
ing nearly 10000 feet in length.
1t is carried over gulches by con
crete pipes. The dams used for
diverting the water to the power
canal represent a cost of $4,000,
while the canal, including Its pres
sure pipe and auxiliarY structures,
represents q total of nearly $1,000.
900. When all of the generating
sets to be installed are in service,
it will develop no less than 4,4O0
horse power, which will be used
for pumping water for irrigation.
A cement mill has capacity
for manufacturing 10000 barrels
month when the machinery is
working to its complete capacity.
Much of the raw material neces-
sary for cement has been found in
abundance locally, and cement is
manufactured at a cost Of S2.25 per
barrel, less than half the cost Of
cement from the outside. The
mill is operated entirely by electric
power, as already intimated, the
current being transmitted from the
power house at the end Of the
canal.
Work upon the construction of
the dam proper has been in pro-
gress only since September 20,
1906, owing to the immense
amount of labor required in max.
ing the excavations to bedrock.
When it is remembered that the
height of the dam above the rock
is 2S4 feet, the length at the bot.
tom 235 feet, and the length at the
top 1850 feet, the time and labor
required in preparing the site for
the wall do not seem excessive.
The work is what is technically
known as Il masonry arch dam
with Il gravity section arising from
the foundation. 1t will range in
thickness from nearly IT'S feet at
the bottom to l6 feet at the top
sufficient 10 provide u highway for
vehicles. 1
AS soon as the blocks of stone
are quarried, they are carried to
the site and placed iu position by
boom derriclks, while the aerial
tramway conveys the cement in
which they are set. An enormous
quantity of rock, set in concrete.
is required for filing in behind the
face, and boulders us large as can
be handled are used, Nearly 400
600 cubic yards of masonry will be
placed in position when the dam
is completed, and the reservoir
which it will create will form
lake twenty. five and one half
square miles in area. As soon as
the dam is finished, the cement
mill and other construction plants
will be stripped of all machinery
which can be profitably removed,
and the buildings abandoned, as
they will be many feet under
water when the reservoir fills.