November/December 2022 - 95

* May provide additional reductions of
time or labor-intensive operations
such as over-water construction,
cofferdam construction, site dewatering
or environmental protections
(silt fences, barriers, fish
protection, etc.).
* Incorporating an existing foundation
into the footprint of a new
foundation may reduce underground
congestion, eliminate the
need for foundation removal or
allow a more robust combined
foundation than an independent
new foundation for a similar cost.
Foundation reuse often involves reuse of
the whole bridge substructure and it has
been used in br idge widening,
replacement and repurposing (such as
local to state highway) projects. Despite
the potential for a wide variety of project
benefits, as a current state of practice in
the U.S. transportation sector, foundation
reuse is relatively uncommon.
While the reuse of foundations is not
discouraged, it is also not generally proactively
encouraged. Perhaps with an
outlook to sustainability benefits, foundation
reuse may be recognized more as
an opportunity than a challenge.
Challenges and Opportunities
It is recognized that there are both
challenges and opportunities associated
with foundation reuse and that
some amount of incentivization or
disruptive innovation is likely needed
to encourage a significant shift to
sustainable designs favoring lowest
material use, carbon emissions and
energy.
Foundation reuse often involves reuse of the whole bridge substructure
Challenges include:
* Current design codes do not address
foundation reuse.
* Current design code requirements
are written for new construction
with little or no practical code
guidance or commentary for application
to existing foundations, particularly
for integrity assessment.
*
In-place foundations were constructed
by 'others' and are unlikely
to be warrantied by the owner for
new projects.
* High-quality as-built plans and
records about installation, materials,
construction control, inspection and
foundation locations and dimensions
often do not exist or cannot be
located.
* Foundation construction is not generally
a large cost component of most
typical bridge projects (simple span
crossings of roadways or rivers).
* Design codes and owner construction
practices, or other requirements,
may have changed or been
updated since the time of foundation
installation; this could be of particular
significance in areas with seismic
design requirements.
* No guidance or procedures for
accounting for complete life-cycle
environmental impacts (energy,
resource consumption, CO2 emissions,
etc.) of geo-structures or foundation
construction is in place,
which makes it difficult to evaluate
the sustainability benefits.
* Effective testing for in-place foundations
may be deemed impractical
due to potential risks of cost,
schedule or other impacts if reuse is
found to be unfavorable. Evaluation
of existing foundations is often
impractical until the existing
structure is removed, particularly
with respect to integrity or load
testing existing piles or shafts.
DEEP FOUNDATIONS * NOV/DEC 2022 * 95
November/December 2022

Table of Contents for the Digital Edition of November/December 2022
