November/December 2021 - 17

Columbus Crew Stadium construction in 100-year floodplain (credit, Aerocamera/Bill Walmsley)
elevation (>722 ft, or 220 m) drove the decision to raise the
pitch (playing field) to an elevation of 705 ft (215 m), placing the
stadium's service area at 709 ft (216 m) and its concourse at
727 ft (222 m). The pitch, however, would be below the
floodplain as a result. A solution for preventing high water
table levels from flooding the new venue was needed.
Cutoff Wall Design Assist
Shortly after groundbreaking, TSJV issued a request for
proposal for a design assist subcontractor specific to cutoff wall
design, a preliminary cost estimate, preconstruction services
and construction documents. Following some negotiations, the
subcontractor moved forward with preconstruction,
construction and close-out services for this project aspect.
Richard Goettle (Goettle) was chosen as an engineering and
construction firm specializing in design-build deep
foundations, earth retention systems and marine construction.
Based in Cincinnati, Goettle also satisfied the publicly and
privately funded project goal of using local subcontractors and
labor. Goettle's proposal favored a secant pile cutoff wall
instead of a slurry wall for efficiency and cost. The main
obstacle to slurry wall construction at the site was the presence
of cobbles and boulders, which could negatively impact trench
excavation and stability. To augment Goettle's in-house design
capabilities, the firm engaged Dan Brown and Associates.
Cutoff Wall Design, Construction
The secant pile cutoff wall surrounds the stadium perimeter
and acts as the back form of the stadium foundation walls. In
addition to being a groundwater cutoff wall, the wall also
retains the overburden soils for the pitch level grading. Its
design was governed by a cantilevered temporary condition
with a wall height of 24 ft (7.3 m) and a maximum of 6 ft (1.8 m)
of hydrostatic load. The wall consists of interlocking 46.5 in
DEEP FOUNDATIONS * NOV/DEC 2021 * 17
(1,180 mm) piles, with alternating piles reinforced with a
W36x210 steel beam to provide structural resistance.
Using this technique, the unreinforced primary piles were
constructed using low-strength (2,000 psi, or 13.8 MPa) auger
cast pile grout. The reinforced secondary pile was then drilled
between existing primary secant piles, cutting into them. The
pile spacing was adjusted to provide the design overcut or
secant depth into the primary piles. The secondary pile was
then finished using higher-strength (4,000 psi, or 27.58 MPa)
grout. In the stadium area that did not require a retaining
wall, the secant pile wall lacks steel reinforcement.
Construction of the 2,300 lft (701 m) secant pile cutoff wall
began in November 2019, with rain and snow as
impediments. From top to bottom, drilling conditions for the
Building information modeling of secant pile cutoff wall and CFA shafts

November/December 2021

Table of Contents for the Digital Edition of November/December 2021