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The biggest challenge was the
16foot-tall full pipe. "The structure of this full
pipe is unique its form, the way it mimics an ocean
wave," Wormhoudt says. "I don't know of another
structure like it. Normally a full pipe is cut off at
an angle perpendicular to its length. in this one, the
top peaks at 23 feet wide and falls, wavelike, to just
12 feet wide where it meets the deck. The pipe wraps
up and over in the same way that a wave breaks, giving
skaters transitions where they can perform lots of tricks.
"But," says Wormhoudt, "it is really
difficult to build. It is hard to get concrete to go
into these shapes."
Here Vasconi's engineering expertise really paid off.
He used bridge technology, steel beams and heavy timbers
to build curved joists. He covered this truss system
with sheet metal and placed the concrete on top of that.
Vascom used shotcrete that consisted of a 3/8inch aggregate
and high cement content (7.5 sacks), delivering 4,000
psi of strength. It also contained fiber mesh to prevent
shrink cracking during hydration. The shotcrete was
pumped with a 2-inch concrete pump and shot onto the
form through an airpowered nozzle. The finish was burned
in with small fresnos or "funny trowels."
The finish is important. Vascom says, "We're not
building the court to play on, we're building the ball
to play with. It has to be perfectly round. We burn
in the concrete so it is what the skaters call 'buttery'-
fast and smooth."
After the concrete was placed, it was turned over to
Tom Ralston for staining. Vasconi's crews helped power-wash
the concrete, and then Ralston got to work. The city's
Department of Parks and Recreation wanted warm colors
that evoked the ocean, and signed off on a bluegreen
called "Copper Patina" from L.M. Scofield
Co. for the pools and bowls and a rich sand color, "Malay
Tan" from Kemiko, for the decks. Acid stains were
selected over other coloring options because of their
vivid, permanent, penetrating colors.
For someone as experienced as Tom Ralston, much of
the staining for the 15,000-square-foot park was routine.
Staining the interior of the full pipe was another matter.
Ralston says he sat and thought through how to go about
staining overhead. He considered, and discarded, the
idea of scaffolding and settled instead on sprayers
with nozzles so the stain could be directed at an angle
away from the workers below. These workers would be
covered from head to toe in protective clothing. Crews
of four, sometimes as many as eight, worked every day
for two weeks to prep, stain, wash and neutralize, removing
the water and ammonia with a vacuum and hauling it away.
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