This is where the concrete starts its journey to the walls. The Glacier truck is feeding the green pump which injects the concrete into the hose which came off the reels on the left.
One hose for concrete, the other for compressed air.
Once everything is running smoothly, it can be a bit boring.
Compressed air is used to clean off any debris on the re-bar just before the concrete is placed.
The pressurized concrete is shot emphatically into the re-bar and against the back wooden form.
In order to be assured the shot-crete process is done properly, the City contracts an inspection and testing entity. Here the on-site inspector closely monitors the placement of the concrete. He will also take a sample of it back to the lab in order to test the mix for required strength.
A long wooden screed knocks the concrete into a smooth, vertical face. Strings running across the face guide the screeder. Excess concrete drops to the footer below.
Using a short wooden trowel, the finish face is carefully gone over, pushing any stones in, filling any voids with cement, and pulling out a tight, smooth surface.
Since a tall wall must be done in different sections (called "lifts" in the trade), excess concrete ("overshot") is cleaned off and the top of the lift is trimmed to a 45 degree angle, providing a base for the next lift when it comes along. The excess of course drops down to the footer below.
Which is where the low man on the totem pole, literally and figuratively, toils with a shovel, throwing the overshot into a container to be disposed of.
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