Mill-Race
Retaining Wall
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| Mill Race Wall that was Demolished |
The
main project at Hagley Museum entailed the demolition of a stone retaining wall
in the mill race. Work began by removing
several feet of mud from the by way of a fire hose, and wood skids were lowered
into the race by tractor to act as a working platform. The purpose for the retaining wall was to
block off a water pipe that fed a water turbine on the property years ago. Once the platform was in place, the stones were removed using a Hilti
hammer/drill. It was found that some of
the stones were too large and well bonded for the Hilti drill, so a jack
–hammer running off of compressed air was brought in to remove the larger
stones.
After the wall was lowered to water
level, a mortar mix consisting of Portland Type II was made to make a level cap
that would provide a sound bed for the new wall that was to be
constructed. The museum wanted to
install a new water turbine and reopen the water pipe that the existing wall
was closing off, so a wall with a garbage rack had to be constructed to keep
debris from flowing into the turbine.
The wall was constructed as two piers on each side and an open space in
the middle. The piers would provide
anchoring points for concrete lentils to be drilled and bonded to the stone
wall. Plywood was attached to the
lentils by the company carpenters to act like a temporary dam until the garbage
rack was constructed.
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| New Race Wall and Concrete Post and Lentils |
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