Underground Construction - November 2019 - 23

An Akkerman microtunnel boring
machine (MTBM) will help to
maintain a precise line and grade
for the new pipeline.

East Trunk Sewer Project Solves Weather Risk
Kimberly Paggioli, P.E.

While rain is often a welcome sight along the western shore
of Lake Michigan, some Mequon, Wis., residents and business
owners began to eye the prospect of precipitation with dread.
After numerous hazardous and costly sanitary sewer backups, it
was clear that a plan of action was needed in this picturesque city
just 15 miles north of Milwaukee.
A wet weather sewer relief study, commissioned by the
Milwaukee Metropolitan Sewerage District (MMSD) and
approved by the Mequon Common Council in 2016, prompted the
design of the East Trunk Sewer Project in 2017.
From the very beginning, collaboration between groups was
vital. In order to design a relief sewer that reduced negative
impact to residents, businesses, utilities and traffic, while
safeguarding the quality of life, the city of Mequon staff and
a consultant team coordinated efforts with Ozaukee County,
Wisconsin Department of Transportation (WisDOT), Wisconsin
Department of Natural Resources, Union Pacific Railroad (UPRR)
and the Milwaukee Metropolitan Sewerage District.
During both the design and construction phases, the district
reached out to individual residents and property owners and
hosted public information meetings. Of particular concern to
those affected was the potential increased cost of their utility
bills. The meetings gave district officials a chance to address
concerns and explain how this much-needed project would have
minimal impacts on the utility rate.
"Our design consideration was to help alleviate sewer and
basement backups within the affected portions of the city of

Mequon," said Troy Hartjes, P.E., senior project manager of
Brookfield WI-based R.A. Smith National's Municipal Services
Division. "We were design partners with the local office of
engineering firm AECOM, which did some of the structural
analysis and the sanitary sewer modeling."
WisDOT, UPRR, MMSD and Ozaukee County approved permits,
and private property easements were obtained for the sewer
tunneling underneath private property. Construction of the largest
public works project in Mequon's history was well under way by
2018, starting at the county line of Ozaukee and Milwaukee.

Challenges
Along the two-mile sewer route were two challenges: jacking at
a depth of 30 feet directly under the Union Pacific Railroad
track and jacking at a 22-foot depth under U.S. Interstate
43. Tunneling was also necessary beneath the public areas in
the eastern segment of Katherine Kearney Carpenter Park,
one of more than 20 parks in Mequon.
One goal of the East Trunk Sewer Project was to keep
interruptions to a minimum so that visitors to the park and
nearby areas could still participate in their usual activities. A key
decision involved tunneling for sewer construction. This would
be a more expensive alternative to open-cut sewer construction
with road restoration but, fortunately, not as disruptive.
"Hobas pipe was chosen because of its strength, thickness and
resistance to corrosion," Hartjes explained. "Joint integrity was an
important factor, and the pipe is also good for tunneling." For this
UConOnline.com | NOVEMBER 2019

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Underground Construction - November 2019

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