Jacob
Douma
in Chicago -- not Acres.
Harza?
Harza. You're right. They had designed Reza Shah
Dam [for Iran], a high,
concrete arch dam, with a concrete flip bucket chute spillway. The first time the chute
spillway went into operation with high flows, a lot of erosion occurred on the chute invert.
Harza Engineering designed the dam, and followed through on the construction. Harza
wanted independent consultants to evaluate the erosion problem.
The spillway chute eroded and failed. Harza also had a man at
and they got in
touch with us there and asked us to stop by in Iran on our way back to the U.S. and
inspect the dam. We'd change airplanes at the capital of Iran, Teheran. That's where we
boarded another one-hour flight up to the northern part of Iran. Then we had to take about
a
car trip up the mountains to the dam site.
An Italian construction firm had just finished constructing the spillway for this dam when
a large flood occurred which filled the reservoir and caused the spillway to go into
operation with
to seven-foot depths of high-velocity flow in the lower part of the
spillway chute. This was about six months before Khomeini took over the Government
of Iran.
They called Jim Ball and me, and we both accepted the assignment. After being briefed
by the resident engineer and his assistants, we spent several hours inspecting the dam and
damaged spillway. and saw that the construction was poor. We concluded that the
construction people did a poor job of smoothing the floor of the high-velocity chute. It
was rough, particularly at construction joints. The invert joints of the chute at the lower
end were not smooth. There were places where the joints, either downstream or upstream,
would be as much as three-quarters of an inch out of place. With water velocities of about
a hundred miles an hour, negative pressures occurred at these joints. The negative
pressures caused cavitation erosion of the concrete. There were
or six-foot deep
holes through the concrete invert and into the rock. The concrete slab was only 18 inches
thick, and during the course of time, that slab failed, and then water got underneath at high
velocity and just ripped the whole thing out.
We wrote our report on what caused the erosion and what should be done to repair the
damage. Harza told the client that the construction was at fault, and he should repair the
damage at his cost. The damaged chute was repaired. A few years later another large
flood occurred, and the chute operated perfectly.
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