Part
of the rock-crushing plant, December 1961.
Thomas E. Petermann Collection (S-2005-89-100)
The
concrete mixing plant, December 1961. A railroad flatcar
with buckets of concrete is seen in front.
Thomas E. Petermann Collection (S-2005-89-105)
Concrete is made of aggregate,
sand, water, Portland cement, and sometimes flyash, a filler material that
is a by-product of coal-burning plants. To keep costs down, the aggregate quarry
was located at the top of the bluff.
Rock was blasted
to a depth of 90 feet and hauled to the rock-crushing plant near the bluff’s
edge. After it was crushed and screened into various sizes, the rock was
stored in recovery tunnels and moved by conveyor belt to the mixing plant.
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