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A Hole-in-One is
very rare, but, Montgomery County had 3 during the Holes Creek
Tunnel Project. The first, in employing Woolpert LLP of Dayton, OH
for engineering services, the second in awarding Bowen Engineering
Corporation of Fishers, IN the project, and the third, in
specifying centrifugally cast fiberglass reinforced polymer mortar
(CCFRPM) HOBAS pipe for approximately 4400 feet of new 36-in. and
48-in. diameter sanitary sewer.
The Holes Creek
Tunnel Project, in Dayton, Ohio, was established as part of a
comprehensive plan to eliminate sanitary sewer overflows in the
Holes Creek Drainage Basin. Sewer loads had increased in the basin
as a result of development in the surrounding areas and
consequently, during periods of heavy rainfall, overflows occurred
for many reasons including cracks & leaks in manholes and
pipes.
GAME PLAN
Initially,
this microtunneling project was designed to be open-cut, with
alternate routing to avoid depths greater than 25 feet. However,
due to the following factors:
- several locations had depths
greater than 30 feet
- construction crossed underground
and overhead utilities
- heavily used roads adjacent to
construction: impossible to close down traffic or reroute
- native material (limestone):
would make open-cut difficult and time consuming
- environmental concerns:
construction in wooded areas and across Holes Creek
- microtunneling was deemed
necessary for the entire project.
THE RIGHT
CHOICE
In addition
to being corrosion resistant, it was essential that the jacking
pipe materials be able to conform to the varied conditions. The
combined factors necessitated specifying vitrified clay pipe,
reinforced concrete pipe with coal tar epoxy lining, and HOBAS
CCFRPM pipe. Most important to Bowen in their pipe selection was
the overall lower installed cost and confidence in microtunneling
HOBAS pipe, which were attributed to the following:
- Low friction resistance (lower
jacking loads)
- High strength and durability (
predictable and reliable performance)
- Light weight (lighter, less
expensive equipment needed for handling)
- End-squareness (reduces the
possibility of point loading)
WHAT A
DRIVE
Only ten drives were required (1 drive
remaining) to complete this project that consists of over 1100 ft.
of 36-in. 300 ton and 3300 ft. of 48-in. 400 ton jacking pipes,
supplied in 10-foot sections with gasket-sealed flush bell-spigot
joints. Thus far, the average drive lengths reported are
approximately 362 ft. & 467 ft. for the 36-in. and 48-in.,
respectively, with average jacking loads of only 100 tons. The
longest drive reported was 688 ft (through weathered shale and
limestone) with a maximum jacking load of only 280 tons.
PAR-FECT
After Bowen’s last drive, the final
deflection test will confirm another successful and nearly
flawless project. Routine leakage tests of 5 psi for 28 minutes
were performed, with only one leak due to a rolled gasket during
assembly. The leak was easily and permanently repaired with a
fiberglass lay-up internally applied across the joint. Delighted
with the performance of HOBAS pipe, Bowen plans to use HOBAS on
another project, the Lillian Avenue/Ether Avenue in Fort Wayne,
which includes microtunneling approximately 1600 ft of 48-in.
diameter pipe. HOBAS pipe’s inherent jacking characteristics
result in the most reliable installations with longer drives,
lower jacking loads, and fewer pits. Specify HOBAS today for YOUR
next project, it’s sure to be a "Hole-In-One"!
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