Page 9 - May-June2019 Vol37 No1
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of 48-inch diameter brick and reinforced Gaining Stakeholder Buy-In innovative solution for bypass pumping
concrete pipe. A replacement via open Before finalizing the design, KUB on the upstream end of the project,
cut excavation or tunneling method was decreasing the project footprint size and
considered, but would delay the project and Barge met with stakeholders at UT, allowing for construction during football
by requiring new easements, resulting TDOT, and the City of Knoxville to obtain season. The original design concept was
in possible long-term disruptions to concept buy-in. Because a greenway has to install a new vault for pumping while
UT parking facilities. It also was cost- the same requirements as a roadway for using the existing vault for plugging. The
prohibitive. Sliplining appeared to be the minimum widths and traffic control, proposed pumping vault would close a
obvious choice, since additional hydraulic the bypass pumping plan design ran the vital sidewalk between UT’s campus and
capacity was not required, and the work piping along the greenway to maintain downtown Knoxville. KUB’s Herschel
could be performed without significant these features. Hall recommended installing a new vault
bypass pumping. for plugging within the project footprint
TDOT did not allow excavation in the (rather than in the sidewalk) so that
However, after Barge developed a plan recently resurfaced Neyland Drive, which pump suction lines could be run into the
and profile of the existing system so was the location of a siphon inlet box existing vault. The vault was installed in
that KUB could utilize their hydraulic and downstream terminus of the project. the location of the spring, so it eliminated
wastewater model, additional inspections TDOT lane restriction requirements had to the problematic infiltration.
revealed that the brick pipe was arched be incorporated into the bypass pumping
as opposed to being round. This meant plan. This requirement impacted the Hobas pipe was installed leading in
sliplining was not a viable rehabilitation bypass pumping and liner installation since and out of the vault, for better sealing
technique for the entire segment. the discharge piping had to be installed and structural elements at the vault
into the siphon inlet box (to bypass the and pipe interface. The plugging vault
KUB and Barge worked to identify entire rehabilitation segment). The size of provided a more consistent surface
potential solutions that would address the bypass piping was too large to fit into (rather than brick) for sealing plugs
the leaking and structurally- deficient a standard manhole frame and cover, so which provided for better reliability for
trunkline. The alternatives considered different bypass setups were required. worker safety.
were lining (geopolymer, epoxy, PVC
or cured-in-place pipe); sliplining the Although it is preferred to have access With this innovative thought and
reinforced concrete pipe and lining the to both ends of the pipe for better worker collaboration, UT approved a project
brick sewer; sliplining the reinforced comfort and application environment, schedule that extended into football
concrete pipe and installing a new sewer the contractor, Garney Construction, was season. Construction occurred during two
via open cut excavation to replace the able to bypass the siphon completely and UT football games with no issues along a
brick sewer; or tunneling. plug the last section at the siphon inlet. major pedestrian way into campus.
However, for this segment, the liner had to Multiple Fixes Led to Successful
A matrix and weighted scoring system be applied from only one end of the pipe. Completion
was developed to analyze the alternatives Bypass design and contractor flexibility
based on the project success factors. enabled the project team to accommodate Additional project successes were first
Project success factors included cost; TDOT’s requests and requirements while noticed with the nose. A turbulent section
public impacts to parking, pedestrians still delivering a successful outcome. existed near the siphon inlet. Soon after
and traffic including the greenway; Limited Space, Limited Time construction, a previously undetected
lifecycle (operations and maintenance odor was noticed at this location and was
requirements as well as product life The University was the most impacted strong enough to require mitigation. By
expectancy); schedule for easement stakeholder. KUB and Barge met with eliminating the infiltration from the Creek
acquisition, permitting and construction; UT representatives to obtain the multiple and spring, and sealing up the system, a
and constructability (difficulty, risk, need levels of approval required to proceed with small odor control unit was installed to
for bypass pumping, and potential for the project. Working space was limited eliminate nuisance calls due to a stronger
utility conflicts). so, outside of easements, UT required all wastewater concentration.
Best Alternatives Chosen work, (including bypass pumping and
laydown area), to occur in a footprint of Infiltration from the ‘gusher’ was
Spray-on lining systems provided the 75 x 200 feet. conservatively estimated at a constant 300
best alternative for meeting the project gallons per minute. This flow calculates
needs, with epoxy ultimately chosen for Five parking spaces were negotiated to 432,000 gallons per day or 157 million
the project. The epoxy liner is internally and granted in UT parking areas for gallons per year of extraneous water to
applied by workers inside the trunk sewer. contractor access. Schedule became the convey and treat. KUB has reinstalled
This recommended alternative set itself biggest project driver as the goal was to a flow monitor on the trunkline and is
apart with less public impacts, fewer construct the project during UT’s summer currently evaluating the impact of this
schedule impacts and less risk during semester, their least populated season on project to their system.
construction. campus. With the approval process slower
than anticipated, it became apparent KUB’s project is a strong example of
Moreover, manholes could be lined with that the project would run into the fall how managing project constraints, such
the same product, eliminating manhole semester and possibly conflict with UT’s as schedule, location, and stakeholder
replacements. However, the main football season. involvement, can ultimately lead to
drawback to this scenario was the need for Construction During Football Season innovative solutions and a more successful
bypass pumping at peak wastewater flow outcome.
of 24.5 million gallons per day. The project team brainstormed an
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