September/October 2023 - 20

geotechnical engineer suggested considering lightweight
foamed concrete, or cellular concrete, for the backfill, which
had been observed on a recent project. The lightweight
material allowed for relatively thick lifts to be placed, and the
lateral pressures, both during placement and when well
cured, were much less than with earthen fill. With its low
viscosity, the lightweight foamed concrete could easily flow
into windows cut into the pipe struts for a more efficient way
to abandon them in place. The reduced pressures on the wall
allowed the number of rows of tie rods to be reduced from six
to four, and deadmen could be used rather than trying to
connect the tierods directly to the temporary soldier piles.
The contractor found significant time and cost savings by
using the lightweight foamed concrete for this backfilling
application. The foamed concrete was produced on site and
was generally unaffected by the rain. It did, however, require
the construction of a tent to maintain the temperature above
40ºF (4ºC) for curing, which was a minimal inconvenience
compared to the advantages of using the foamed concrete.
Conclusion
The completed perimeter wall system included more than
650 soldier piles, each installed in a predrilled 30 in (762 mm)
diameter borehole and grouted in place. The wall is supported
by 2,400 tiebacks with a total drilled and installed length of
130,000 ft (40,000 m). The earth retention wall allowed for the
excavation of 680,000 cu yd (520,000 m3) of soil. The permanent
soldier pile and lagging wall offered the right solution for
this extremely fast-tracked and complicated project.
The transformation of Climate Pledge Arena was
comparable in scope to the construction of an entirely new
arena with the added complexity of having to work around
the existing roof and its temporary supports. Working within
a very short schedule, the project team faced a number of
Completed arena
challenges, including the design and construction of the
perimeter wall. But thanks to some innovative approaches
and solid collaboration, the Seattle Kraken NHL team was
able to open its home arena on time, and it enjoyed a very
successful first season.
Project Team
Project Owner/Developer: Oak View Group
Structural/Façade/Construction/Geostructural Engineer:
Thornton Tomasetti
General Contractor/Construction Manager: Mortenson
Design Architect: Populous
Civil Engineer: DCI Engineers
Geotechnical Engineer: Hart Crowser
Owner's Representative: CAA Icon
Meeok Kim, Ph.D., P.E., an associate principal in Thornton Tomasetti's
Boston office, has extensive experience in geostructural engineering,
specializing in the analysis and design of complex below grade systems.
Shawn Leary, P.E., is a principal at Thornton Tomasetti and leads
the construction engineering team in the firm's Boston office. He has a
broad background in the structural design, management and delivery
of complex projects.
Seth Knihtila, P.E., is a senior project engineer with the
geostructural engineering team in Thornton Tomasetti's Boston office.
His areas of specialization include geotechnical investigations and
designs, deep foundations, and support of excavations in urban
environments.
Michael Oakland, Ph.D., P.E., principal of Oakland Geotech, is a
former vice president at Thornton Tomasetti. He has extensive
geotechnical engineering experience in the design and construction of
foundations, retaining structures, slope stability, and ground
improvement.
20 * DEEP FOUNDATIONS * SEPT/OCT 2023
September/October 2023

Table of Contents for the Digital Edition of September/October 2023
