The Providence news. (Providence [R.I.]) 1891-1906, 1893-12-12

A MONSTER iRRlGAToR.
The Highest Overflow Dam In the world
Building In California.

Butiding In Snifiornios
Stanislaus county, Cal, is to have the
highest overflow dam in the world. ID is
called the La Grange dam and is being
constructed Tor the Modesto and Turlock
irrigation districts. Its location Is In the
canyon Of The Tuolumne river, threo miles
from the town OF In Grange. Work onthd
project was commenced in June, 1921, and
has been prosecuted continuously ever
since. A force Of 200 men has been en-
ployed on the work, the total cost OF which
will be 5000 900.
The annals OF engineering have hitherto
recorded as the highest the Vyrnwy dam,
which retains the water supply for the city
Of Liverpool. It's height from base TO sum
nit is l27 feet, but theta Grange viii be
two feet higher. Other celebrated dams,
such as tho Bear Valley, in San Bernardino
county, and the Swectwater, near San Dt-
| ego, are properly known as reservoirs, and
| the protection OF their basins as retaining
walls.
The La Grange il being built by r. w.
| Gorrill and will be 800 feet long on top,
the plan being curved on radius of $50
feet. Its maximum height above the foun-
dation will be l27 feet o inches. The front
face OF tho wall is made to conform to the
curve described by the water in overflow
! ing, and 10 defect il into the basin in
front OF the dam.
The dam il built Of "cyclopean rubble"
| and il a model OF solidity. Huge rocks,
weighing from six to ten tons, were first laid
on the bottom. All their projecting pieces
were cut of, and fat but rough surface
wug prepared for the lower bed. Before
being placed i'm the bottom, all stones,
whatever their size, were scrubbed and
subjected 20 the action OF numerous jets
| OF water under pressure Of rs feet.
The process OF construction was as fol-
| lows:
GA level bed was first prepared in the
rock and covered with two inch layer OF
cement mortar, which was beaten to free
! IL OF air. A large stone was then lowered
| into position by steam crane, and was
beaten down into the mortar by blows from
! heavy handmauls. Other large stones were
similarly placed, but so as not to touch
| each other The spaces left between them
| were filed with concrete, which was thrust
into the narrow spaces with tampers.
"The work within the reach Of each
crane was brought up from six to eight feet
| before the crane was moved In each course
the immense stones were laid 40 as to
bind with those in the course below. No
horizontal joints passed through the wall,
as the top Of each course was left with pro-
| iecting stones and hollows. which permit
| it to 10 well bound with the next course.
To make the back face thoroughly water
tight, the vertical joints were filed with
mortar alone, and into this broken stone
was forced"
Tho La Grange dam will distribute
! water over a territory embracing 276, 900
acres. The Turlock district comprises
about los, 900 and the Modesto district
7s,000 acres. The water will how over
the dam into two bitches. One will be 80
miles long and 100 feet wide, the other 20
miles long and 80 feet wide. The waters
of the T TttelaHfae- river will be banked up
| by the dam in the rocky canyon. A lake
| will thus be formed four miles long and
half mile wide. An idea Of the solidity
| OF the dam may be gathered from the fact
| that Mt its base il is lit feet o inches
1 thick, and that Of solid stone, forming an
\ indestructible barrier to the lake OF water
behind Pacific I.umberman.