, 1905-02-01
DIAMOND DR|LL|N
GOVERNMENT JOB
THE PART PLAYED BY THAT
TOOL IN THE CONSTRUCTION
OF RESERVOIR DAMS.
Surveyors and Determines the
Availability Of the Dam Site-Eye
Of Man Alone Unable to Determine
Location of Immovable Base.

Washington, Feb. 1.-One of the
most essential details connected with
the preliminary Investigations of a
large government irrigation project is
the work of the diamond drillers. AS
soon as the reconnaissance surveys in
dictate a feasible project the diamond
drill outfit is sent out to discover the
availability of the dam site In ali
cases where dams are to be built it is
absolutely impossible to determine the
number of yards Of excavation to bed
rock until carefully examinations have
been made with the diamond drill.
The final plans of a project, esti.
mates of cost. the kinds of structure in
fact nearly all the important feature
connected with the work, are Deepen
dent upon the results of the borings.
It frequently happens when the borings
are completed that all the preliminary
plans must be altered. Occasionally
the whole project is abandoned.
The high structures which the gov
is erecting must rest upon
solid foundations. Melting SHOWS or
cloudbursts on the mountains embrac-
ed in watersheds covering thousands
of square miles, rush down steep
slopes and onverge in the narrow
channels of these pent-up rivers. The
floods beat with almost resistless force
.gainst the ~impounding dams thai
block the way. They must be con
structed as firm and as enduring as the
everlasting mountains from which they
are being hewn.
The eye of man alone cannot safely
determine the location of the immov-
able rock upon which these great struc-
lures must be builded. Surface indi-
cations offer no safe guide, but the dia-
mond drill, penetrating the gravels.
b%oulders, shale and shattered forma
lions, finds at least the permanent
base.
An example of the fallibility of SUI
perficial Investigations of dam sites
was shown recently during the pre-
liminary reconnaissance of The h
shone project in Wyoming. At the
point selected for a dam the river had
cut through a deep n narrow gran.
tie canon and apparently flowed over
rock of the same formation. All indi-
cations were that bedrock would be
found at a depth of ten feet maximum.
On putting the drill at work, however,
il was shown that bedrock was IS feet
below the bed of he river. What look
ed to be a thin layer of gravel proved
to be IS feet of gravel and slabs that
had fallen from the canon walls, some
of these being 80 feet in thickness.
At one diversion site on the North
Platte river, where conditions seemed
favorable for bedrock at % feet, Dor
ings did show. however, that there
were 80 feet of gravel II boulders,
underlaid with soft material-quick-
sandwich would not permit the
building of a heavy structure.
vi lHc SoloIa u " h'sii -
site was discovered, so far as the sur
face conditions indicated, where a
point of rock stood 10 feet above the
water surface. Two hundred feet
away boring 100 feet below the river
bottom failed to ind a solid foundation.
In a great many cases a few hundred
dollars expended in borinss have re-
suited in changing the location of dam
sites and, of course, have saved many
thousands Of dollars.
The same conditions hold good in eA.
animation of reservoirs where natural
depressions are used to store waite.
Here it is necessary to determine
whether the bottom is impermeable, or
whether it has a subterranean outlet
which would let the water out after
it had been stored.