Passaic Passage
New Jersey Department of Transportation
chooses precast over cast-in-place.
By Paul Heidt
General Manager, Garden
State Precast
Along the serene western bank
of the Passaic River in northern New Jersey
runs Route 21. This major feeder freeway serves
tens of thousands of commuters heading in and
out of New York City, Newark Liberty International
Airport and I-95. So when the New Jersey Department
of Transportation (NJDOT) decided to restructure
the old roadway to improve traffic flow and
safety, it encountered a major engineering challenge.
Going precast
Part of the project included
replacing the aging Newark brick combined sewer,
which was installed circa 1920. A high water
table combined with the expensive costs of sheeting
and dewatering motivated Dominic Salsa, project
engineer at J.H. Reid, the general contractor,
to propose an alternative precast concrete solution
– a first for the New Jersey Department
of Transportation (NJDOT). Upon obtaining NJDOT’s
approval, Salsa contacted Garden State Precast
of Farmingdale, N.J., to help fulfill the challenging
project requirements.
Rising to the challenge
After more than 200 hours
of engineering work, the precast concrete manufacturer
designed 15 structures including some unit weights
approaching 250,000 pounds.
To support the work, major
project requirements included flexible rubber
seals for 84-inch prestressed pipe, doghouse
units for redirecting existing sewers and reversible
sewage flows.
“The sheer size of these
units required careful planning and coordination,”
said Bruce Jamison, project manager for Garden
State Precast.
Units measuring 12 inches
and 15 inches thick with 11-foot-9-inch base
heights proposed serious production and shipping
challenges. The large base height was a major
factor due to the 100-inch outside diameter
of the pipe. To add further complexity, the
units needed to be installed directly alongside
the Passaic River with their top surfaces buried
10 to 20 feet below ground level.
The precaster coordinated
the efforts with various suppliers to propose
a workable solution to J.H. Reid and the NJDOT.
A.L. Patterson Inc. provided technical support
in selecting a proper lifting system, which
was crucial in ensuring safety and proper rigging
of all units. A.L. Patterson fabricated a large
insulated curing cover for the project that
provided a cost-efficient method for steam curing
the units.
Flexible cast-in seals measuring
84 and 66 inches in diameter met strict tolerance
requirements, ensuring proper compression and
a watertight seal.
The 11-man production team
constructed approximately one unit per week.
With some concrete pours in excess of 30 cubic
yards, project tolerances were a concern. All
riser sections were match-cast on top of the
base section, providing a perfectly matched
joint for both the four- and five-sided units.
Each section underwent vigorous quality control
inspections to ensure the tolerances were maintained.
The 15 structures were shipped
to the job on heavy lowboy trailers.
Tackling the unexpected
Several last-minute changes
due to site conditions were addressed during
production. Some sewers and building foundations
were located only by excavation since there
were no complete records of existing utilities.
Various revisions such as rerouting were coordinated
through on-site inspection of existing conditions.
Garden State Precast’s
on-site supervisor, who managed the offloading
and installation of the units and helped facilitate
workflow and communication during the precast
operation, immediately recognized that the rerouting
had caused a change in the job termination.
This last-minute change required the installation
of an additional unit, so the order was made,
completed and delivered in a timely fashion.
Had the job been cast-in-place concrete, much
more time would have been required due to forming,
setting and the continued stabilization of the
30-foot hole as well as creating safety issues.
Getting the job done
– on time, on budget
Regardless of the many
challenges the job posed, Garden State Precast
was able to complete the work to the satisfaction
of both J.H. Reid and NJDOT.
“Precasting was a logical
solution for a project of this magnitude,”
said Salsa. “By choosing precast over
cast-in-place, we were able to get the job done
more quickly and efficiently and under much
safer conditions.”
Each unit was installed in
only two days – quite a contrast to a
minimum 12 to 15 days for a cast-in-place unit.
This, combined with enhanced worker safety,
heralded precast concrete as an ideal solution
to the sewer replacement problem.
Project Profile
Project Name:
Passaic River Wastewater
Project
Owner:
New Jersey DOT
Contractor/Engineer:
JH Reid, South Plainfield,
N.J.
Precast Manufacturer/Installer:
Garden State Precast,
Farmingdale, N.J.*
*Garden State
Precast is a certified plant under NPCA’s
Quality Assurance/Plant Certification program.
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