6.6 Synthesis of the Forensic Analyses, Public Opinion, Institutional Reports
77
6.6 Synthesis of the Forensic Analyses, Public Opinion,
Institutional Reports
In this section we build a “table” of specifications for twenty-first-century tailings
dams management. The left column (Table 6.1) bears the “management” specs distilled from the previous chapters and sections, the right column the “risk evaluation” specs we have defined over the years. As a matter of fact, the right column is strongly inspired by a 2013 document entitled “Twenty rules for good
Table 6.1 Twenty rules for good risk assessment
Management specs
Risk evaluation specs
Start early with a comprehensive management
system. Do not wait to see the first errors or
near misses to start!
Start early. Often the best competitive
advantage is brought by developing risk
assessments already at pre-feasibility stage
There is the need for a rigorous and
disciplined risk-based approach by the
regulator in keeping with the objective to
protect the public from significant risks
Hazards are anything that can go wrong
You have to understand the context of the
study and what constitutes the system you
have to assess
Time spent on defining the system is very well
spent
Time spent making sure the logic of your
hazard register is correct is very well spent
The largest and costlier mistakes are generally
made when defining the system. Shortcuts and
logical confusion (which are very common)
are very expensive!
Regulators need to be informed, permit
applications need to be justified on the basis of
risk tolerance and designs and operating plans
must explicitly identify and address residual
risks
In modern society, he who hides risks dies,
sooner or later
If you want to stay out of jail, never use 0 or 1
for probabilities
Zero risk does not exist
Certainty does not exist
Always explicitly deal with uncertainty. A
range is far better and more credible than a
single number
Factor of Safety is not an indication of
soundness of design, resilience of the
structures, reliability or risk exposure
The same hazard can provoke widely different
risk because consequences can vary in time
and location, even if the FoS is constant
FoS can even mislead if applied to mitigation
decision making
You need something else and that something
else is: comprehensive assessments of
potential geotechnical problems, a detailed
evaluation of all potential failure modes, and a
management scheme for all residual risk
Evaluate mitigations’ risks, not only their
reliability. Mitigations reduce probability of
occurrence of scenarios, but they do not
change consequences. Alterations of the
system alter consequences
(continued)
77
6.6 Synthesis of the Forensic Analyses, Public Opinion,
Institutional Reports
In this section we build a “table” of specifications for twenty-first-century tailings
dams management. The left column (Table 6.1) bears the “management” specs distilled from the previous chapters and sections, the right column the “risk evaluation” specs we have defined over the years. As a matter of fact, the right column is strongly inspired by a 2013 document entitled “Twenty rules for good
Table 6.1 Twenty rules for good risk assessment
Management specs
Risk evaluation specs
Start early with a comprehensive management
system. Do not wait to see the first errors or
near misses to start!
Start early. Often the best competitive
advantage is brought by developing risk
assessments already at pre-feasibility stage
There is the need for a rigorous and
disciplined risk-based approach by the
regulator in keeping with the objective to
protect the public from significant risks
Hazards are anything that can go wrong
You have to understand the context of the
study and what constitutes the system you
have to assess
Time spent on defining the system is very well
spent
Time spent making sure the logic of your
hazard register is correct is very well spent
The largest and costlier mistakes are generally
made when defining the system. Shortcuts and
logical confusion (which are very common)
are very expensive!
Regulators need to be informed, permit
applications need to be justified on the basis of
risk tolerance and designs and operating plans
must explicitly identify and address residual
risks
In modern society, he who hides risks dies,
sooner or later
If you want to stay out of jail, never use 0 or 1
for probabilities
Zero risk does not exist
Certainty does not exist
Always explicitly deal with uncertainty. A
range is far better and more credible than a
single number
Factor of Safety is not an indication of
soundness of design, resilience of the
structures, reliability or risk exposure
The same hazard can provoke widely different
risk because consequences can vary in time
and location, even if the FoS is constant
FoS can even mislead if applied to mitigation
decision making
You need something else and that something
else is: comprehensive assessments of
potential geotechnical problems, a detailed
evaluation of all potential failure modes, and a
management scheme for all residual risk
Evaluate mitigations’ risks, not only their
reliability. Mitigations reduce probability of
occurrence of scenarios, but they do not
change consequences. Alterations of the
system alter consequences
(continued)