Underground Construction - November 2020 - 38

Emergency Large-Diameter Lining Repair in Louisville

Project owner was Louisville and Jefferson County
Metropolitan Sewer District (MSD). The primary contractor
was Ulliman Schutte and subcontractor was Boyer Inc. for the
lining portion of the repair.
" MSD needed a proven system that was fully engineered
to be a structural solution because failure in downtown
Louisville was not an option, " Cassel said. " Ulliman Schutte
and Boyer were able to address the problem immediately.
The Danby PVC Lining system has zero known failures over
30-plus years of installation nationwide. "
Because of the shape of the tunnel, a standard spiral-wound
Danby lining system could not be used.
" The lining was custom-designed and -built, and man-entry
installed, " explained Cassel. " The arched structure required
the use of our modular system. It is the same Danby product,
but custom panels were used to match the shape of the arch.
Panels are semi-rigid with enough deflection to conform to
such shapes, which makes it highly versatile.
" It fit the needs of the project owner for a fully structural
system and a custom fabricated ring beam safety cage to keep
the workers safe in case more of the tunnel collapsed. "
When describing the multiple steps to complete the job,
Cassell pointed out that an entry pit was not required.
Access to the tunnel was available from an existing sluice gate
and junction box.
" Danby PVC lining can be fed through standard manhole
openings, which is an important part of our trenchless
system, " she added.
It was necessary to divert traffic flow around the work area.
An 18-inch HDPE bypass line was constructed that could
handle as much as 40 million gallons per day during
construction. It was laid along curbsides to minimize
possible traffic disruption.
Next came thorough cleaning of the section of tunnel to
be relined. Boyer personnel installed a conveyor system to
move debris, and a bucket-equipped crane was used to remove
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NOVEMBER 2020 | UCONonline.com

material from the tunnel. Following cleaning, the tunnel
segment was carefully inspected.
" Once the structure was hydro blasted and we knew the
dimensions, " said Cassel, " Danby produced custom kits
which were sent directly to the job site. "
Before the lining panels could be put in place, structural rebar
was installed to reinforce the tunnel to design requirements.
A key element in the process was the arch safety support cage.
Components of the cage ware bolted together inside the tunnel
and positioned every four feet as work progressed.
The cage was left in the tunnel and became a structural
component. Panel installation followed.
" There were 1,400, 12-inch panels installed as a semi-elliptical
arch through the full length of the rehabilitated section of
tunnel, " Cassel explained. " Installing each panel and securing
it to the adjacent panel took from 15 to 20 minutes. Danby
accessory pieces were used to anchor panel ends to the floor of
the structure to firmly lock panels in place.
" Standard cordless cutting tools, drills and pneumatic air
hammers were the basic tools used to install the panels.
Crews ranged from six to eight men working single shifts
six days a week for approximately eight weeks. "
A ventilation system, including air monitoring equipment,
maintained safe air quality in the tunnel during construction.
The final step in rehabilitation was pumping structural grout
to lock everything in place. Cassel said Boyer used its custombuilt grouting rig to pump in structural grout at 5,000 psi in
12-inch lifts from the bottom to the top of the structure.
" Pumping ports, " Cassel said, " were drilled upstream and
downstream in 12-inch increments, in a stair-step manner, to
ensure solid lifts that didn't place too much weight on the liner.
" With the completed job, the lining acts as an inner casting
with the structural grouting in the annular space from the
existing structure. The new liner, which is mechanically
anchored in place, is a protective barrier to prevent H2S sewer
corrosion from attacking the concrete. "
The Louisville and Jefferson County MSD provides sanitary
sewer and stormwater drainage service for more than 200,000
residential, commercial and industrial customer accounts
throughout Louisville and Jefferson County. It also provides
sanitary sewer service to Oldham County residents and
wastewater treatment service to a state facility in Shelby County.
Ulliman Schutte is a national leader in the construction and
renovation of water and wastewater treatment plants, pump
stations and associated utility work.
Boyer Inc. is known for its expertise in completing some
of the most difficult and complex infrastructure projects
in the public sector.
Danby PVC linings, available in coils or flat panels, have been
installed in pipes and vertical structures in diameters ranging
from 36 inches to 20 feet. *
FOR MORE INFORMATION:
Danby LLC, (281) 598-1126, danbyrehab.com
Boyer Inc., (713) 466-5395, boyerinc.com

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Underground Construction - November 2020

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