May/June 2022 - 107

" I Don't Have X-ray Vision: "
Risk-Informed Site Investigation
I don't have
x-ray vision
We didn't have time to
do more investigation
No one really knows
what is down there
It's always
a known
unknown
How often phrases like these have been
made by project managers and project
teams trying to explain why there has
been cost growth, project delays and
differing site conditions claims.
But does it really take x-ray vision?
Do we really approach geotechnical
construction projects unprepared for
the subsurface that may be encountered
because we can't get the answer?
Too often our industry seems to
think the answer is, " yes. " However,
this is not because we can't understand
the subsurface. All too frequently it is
because a choice is made to save money
or time by foregoing or shortchanging
upfront subsurface investigations. This
is accepting a risk at the beginning of
the process and realizing it during
construction.
Case histories have proven time and
time again that upfront investment in
site exploration and constructing a
ground model mitigates risk in design
and construction. But how much do we
prepare? What level of investigation (or
investment) is appropriate? The answer
of course, is it depends; how much risk
are you willing to take for your project
and what are the potential consequences?
FEATURE ARTICLE
Differing
site
conditions
are just
the cost
of doing
business
IT$
M NEYO
Risks and Uncertainties
It is the geoprofessional's job to
understand the risks and the potential
consequences presented by the
subsurface. They must understand both
the level of uncertainty associated with
the risk and the tools available to lower
this uncertainty. Geoprofessionals must
effectively communicate the risks and
consequences of poor site investigations
to the client, owner and project team.
Further, they must effectively communicate
to clients and project teams
the advantages and benefits of the
upfront investment. Not cost, investment.
The geoprofessional has a vital
role in ensuring project teams accurately
understand risks and consequences of
site investigation decisions. Riskinformed
decision making is only as
good as the information used to make
the decisions. Leave out this important
team member when contemplating construction
on, in or with the ground and it
can radically affect the bottom line.
Money, Money, Money
Conducting a good site investigation
and constructing a good ground model
is an upfront investment. It starts with
the desktop studies of the regional and
local geology and continues with
subsurface drilling and sampling,
geophysical exploration, laboratory
testing, and even instrumentation and
moni toring. These are the very
activities that help geoprofessionals
put toge ther the pi eces of the
subsurface puzzle. It is these activities
that provide an " x-ray vision " of the
subsurface by constructing a " ground
model " of the subsurface scaled to the
risk and consequences of the project.
Too often, this work is seen as only a
cost rather than a foundational element
of the design and construction process.
Too often, a choice is made to minimize
the preparation and accept the risk
associated with the project. In some
cases, this may be an appropriate
decision, but in others, it can have severe
consequences. These consequences can
include construction cost growth, time
delays, inadequate design, overdesign
and claims for alleged damages based on
" differing site conditions. "
The decision to forego an upfront
cost of site investigations often results
in a high cost paid out later in the
project life cycle. A 2006 survey of the
AUTHORS Georgette Hlepas, Ph.D., P.E., and Vanessa Bateman, P.G., P.E., D.GE, U.S. Army Corps of Engineers; Mary Nodine, P.E, GEI Consultants
DEEP FOUNDATIONS * MAY/JUNE 2022 * 107

May/June 2022

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