Wilson dam is being built not to
last 10 years, or 50 years, but for
ever. This requires the rock founda
tion for the dam proper to be very
carefully tested. Holes are drilled
at designated intervals and air pres
sure is applied. Very rapid dropping
of the air pressure is proof that the
hole has passed through a seam iu
the rock, in which case the test hole
is filled with liquid cement under
pressure, thus filling up the hole. If
the air pressure does not drop very
rapidly the hole is filled with cement,
but not under pressure. The impor
tance of this work in obvious If the
holes were not filled the thousands
of tons of concrete would not be able
to resist permanently the force of
the water flowing through the seams
beneath the foundation of the dam
when completed, and would even
tually cause thre fall Tests being
completed and forms being in place,
the first course of concrete is placed.
During the week ending October IS
about 3,000 cubic yards or 6.000 tons
of concrete were placed in coffer
dam No. 5 alone.
Every effort within human possi
bility is being taken that there may
be no weak places in the huge dam
when it is completed. The engineers
who have charge of this work are
accomplishing much and the work is
being pushed forward as rapidly as
is consistent with care and efficient
labor.
o o o
Five Thousand Feet Long.
