DFI Magazine November/December 2020 - 84

Excavating Above Deep Utilities

Cutoff Wall Through Norwood Ave

The contractor installed the SCCB cutoff
wall above three deep utility crossings that
were below the bottom design depth of the
cutoff wall. For the 66 in (167.6 cm) sewer
line, which was crossed at two different
locations, installation was done of two
monitoring rods that were surveyed daily to
ensure that the installation process did not
cause any deflection to the pipe. All survey
results indicated no deflection in the pipe
after the cutoff wall was installed within 5 ft
(1.5 m) of the utility. The contractor also
installed a cutoff wall above a high-pressure
gas line that required advanced coordination
with PG&E, review and confirmation of asbuilt information, and standby support from
PG&E personnel. All work was completed
safely with zero utility conflicts.

The North Area Streams Levee Improvement Project also required installing cutoff
walls through busy thoroughfares
including Norwood Avenue and the
Sacramento Northern Bike Trail. The
contractor coordinated the work with the
City of Sacramento (including a bike trail
detour) and implemented flagging and
traffic control while the work crossed
Norwood Avenue. Forgen installed slurry
splash guards consisting of visqueen tied to
chain-link fence panels to ensure safe
vehicular passage during construction
activities. Following the completion of
each working shift, steel plates were also
placed over the trench to allow both lanes
of traffic to safely open during nonworking
hours. In addition, the viscosity of the

SCCB construction around a live utility protected in place

modifying admixture was adjusted while
working in the road to ensure a quicker
setup of the panel prior to the tie-in.

Conclusion
The North Area Streams Levee Improvement Project presented multiple challenges
that primarily involved construction around
existing utilities and structures. Collaboration between the owner, stakeholders,
design engineers and contractors allowed
for unique solutions to be developed to
complete the project with zero incidents and
within tight environmental requirements
and flood season scheduling constraints.
Some of the key challenges that were
overcome included:
* Realigning the SCCB cutoff wall to pass
under the Rio Linda Bridge rather than
through the road. This required
stepped SCCB panel construction.
* Having a protect-in-place utility
construction strategy that worked for
numerous conflicts, including highpressure gas lines, fiber optic utility
banks, water mains and sewer mains.
* Adjusting each SCCB mix depending
on in situ soil conditions.
* Constructing an SCCB cutoff wall
through an active roadway.

Acknowledgments
Stakeholders who were instrumental in
successful project completion included
Sacramento Area Flood Control Agency
(owner), California Department of Water
Resources, U.S. Army Corps of Engineers
and City of Sacramento and Sacramento
County. Nordic Industries served as the JV
partner that performed the SB cutoff walls,
earthwork and utility installations; AECOM
and Peterson Brustad served as the project
engineers; MBK Engineering and WSP, as
the construction managers; and GEI Consultants provided environmental consulting.
Jared Williams is a project director for Forgen who
has managed California levee programs that include
over 50 mi (80.5 km) of levee rehabilitation and 12
million sq ft (1.1 million sq m) of slurry cutoff wall.
The civil engineer holds a professional engineering
license in California, presented at DFI's 41st Annual
Conference on Deep Foundations, and has received
the 2013 ASCE Outstanding Younger Civil Engineer
Award, and its 2018 Charles Pope Construction Award.
DFI Magazine November/December 2020

Table of Contents for the Digital Edition of DFI Magazine November/December 2020
