24
Geotechnical News • December 2017
GEOHAZARDS
who has insufficient data. Adequate
knowledge is a judgement call, and a
practical balance between effort spent
and diminishing returns is often neces-
sary. Nevertheless, there is a clear and
logical relationship between increased
data gathered through additional sam-
ples, boreholes, field work, LiDAR
or similar means, and the accuracy of
the result. Indeed, increased data was
the first recommendation of Abdula-
had et al. (2010) aimed at reducing
legal claims against the geotechnical
engineer, and it is the basis for the at
least some of the changes in the new
Canadian Highway Bridge Design
Code (CSA, 2014), the upcoming
seismic guidelines, and in general,
reliability assessments in geotechnical
engineering (Duncan, 2000).
Where knowledge is insufficient, the
uncertainty should be clearly com-
municated in such a manner that the
client knows and understands what
has been provided, but also what has
not been provided in the assessment.
Geotechnical baseline reports (GBR)
are sometimes used to communicate
the level of knowledge and reliability
of geotechnical assessments (ASCE,
2007; Parnass & Staheli, 2010). Base-
line statements may be in conflict with
the actual information gathered, but
may be a more accurate description of
what actual ground conditions could
be. GBR’s are not accepted by some
clients, however, we can still provide
clear communication about how our
studies are to be used or interpreted.
Finally, where residual risk is known
or assumed, that risk should be com-
municated as part of the information
provided to a client.
Code Bullet 6: Keep themselves
informed in order to maintain their
competence, strive to advance the
body of knowledge within which they
practice and provide opportunities for
the professional development of their
associates
For the first time in history, as profes-
sionals, we are limited not so much
by a lack of information as by an
excess of it. Part of the corollary to
the knowledge and training discussed
under Bullet 2 above, is the ongoing
need to continue to advance our under-
standing, to learn what new applica-
tions, tools, knowledge and software is
available to us to adequately perform
our jobs.
This is formalized through asso-
ciations as professional development
hours and opportunities to expand
one’s knowledge and understanding
will substantially improve one’s ability
to correctly assess hazard and risk.
In addition, where specialization
continues to occur, it behooves us
to learn what others can do, how it
differs from our own skill sets, and to
work in teams insofar as it is possible.
This helps us reduce the famous “not
knowing what we don’t know” portion
of the knowledge pie.
Code Bullet 8: Present clearly to
employers and clients the possible
consequences if professional deci-
sions or judgments are overruled or
disregarded
The human mind is notoriously bad
at understanding very large or very
small numbers. Further, we are inher-
ently drawn to a compelling narrative,
sometimes drawing completely false
conclusions about hazard and risk, and
we are subject to inherent biases based
on repeated experiences (Kahneman,
2011). For all these reasons and more,
humans in general are very poor
judges of actual risk, even when it is
explained to us.
Unfortunately, hazard and risk assess-
ments are routinely working with
abstractions of probability, while
individual human experience relates
better to the repeated instances where
nothing happened better than the
possibility that something unlikely
will occur. We are like the proverbial
thanksgiving turkeys the week before
the harvest, secure in our understand-
ing about the benign and caring nature
of the two legged creatures that bring
us daily food. There is a substantial
challenge communicating credible risk
scenarios to clients in a way that is not
a scare tactic, but represents instead a
genuine communication of probability,
uncertainty, and residual risk.
Moving away from statements that
discuss probabilities strictly in terms
of return intervals (1:100 years,
1:10,000 years) and toward the percent
probability of occurrence over a given
period (design life, 50 years or simi-
lar) frames these numbers in a way
that is more meaningful.
Similarly, we can articulate the ways
that infrequent probabilities accu-
mulate to better inform clients that
manage large areas, long linear infra-
structures or intend to build facilities
with a long design life.
Case studies or examples help
illustrate the credible consequence
scenarios for rare events that don’t
normally occur.
Ultimately, we have an obligation not
to make a risk decision on behalf of
the client, but to help the client under-
stand what that risk really entails, and
allow him or her to make an informed
decision.
Conclusion
An argument can be made that the
analysis of geotechnical risk is
increasing worldwide. Consequences
increase as the human footprint
extends further into marginal lands,
intersecting more hazards. Hazards
increase, in part, due to new interac-
tions between geomorphological
and anthropomorphic systems that
modify the surface of the planet and
change the processes that form it.
Our knowledge and understanding
about geotechnical, geological, or
geomorphological systems continues
to increase, but requires increased
specialization and training to use, and
considerable effort to remain current.
The issues are not new, just increas-
ingly complex. Possible solutions
should be taken seriously as part of the
service we provide, and to reduce our
own liability that may arise through a
failure of communication. Our Codes
of Ethics are intended to provide a
