sections required use of a slide rail shoring system because
the more common trench box system was not viable at that
depth and in the poor soil conditions. Steel panels slide
into rails that are separated by strut carts, and as the earth
is excavated, the whole system is driven into the ground,
preventing the trench walls from caving in. The panels
then are lifted incrementally as backfilling proceeds and
then advanced to the front of the excavation in a leap-frog
manner.
A slide rail system, though popular in Europe,
is a relatively new technology in the United States,
explained Jeff Moore, senior project manager with Garney
Construction. The design team traveled out of state to
witness a slide rail system in use, determining it was a
viable solution for the CIPO project. Not only was this
system safer than a risky, closed-face tunneling approach, it
saved millions of dollars as well, Moore said.
Involving Garney Construction from the start was
essential to the design process, especially for determining
the viability of the slide rail technique, Fater said. “When
we were evaluating construction methods during the
design, we needed input from (Garney) on feasibility,” he
said. In a typical design-bid-build process “you can make
those kinds of decision on your own, but the risk comes
back to the owner.”
Moore said it would have been nearly impossible to
complete the CIPO project in a typical design-bid-build
Left: A transition structure to connect storm sewer.
Right: The 102-inch pipe installation with a slide rail shoring
system.
14│TRENDS
process. The project had 17 separate work orders and more
than 800 separate bid items. “I don’t even know how
you’d put it out to bid; it would have been a huge nightmare
for all parties,” Moore said. The combined project was the
largest project Garney’s Fort Collins office had undertaken
since its ongoing relationship with the City began in 1999.
“The way we carved out work orders over the four-year
construction period under the APDS system was by far the
best way to handle a large project like CIPO.”
Moore said it helped that the APDS team had worked
together on several other projects before CIPO. “We
worked together well, and we functioned as a team to start
with. That enabled us to get off the ground running in the
first design meeting,” he said. “To this day, I don’t know
anything major that we’d do differently.”
The project could not have been completed without
the cooperation of the entire APDS team, Randall said.
Anderson Consulting Engineers designed the ponds, and
Ayres Associates designed the storm sewer collection and
conveyance piping. “The group worked well together
all the way through,” he said. “With APDS, you take
advantage of each team member’s experience and make
decisions as a team in the best interest of the project.
Nobody has all the answers because it takes the whole team
to get the best solutions.”