10 Defining Probabilities of Events
141
Probabilities are perishable goods. They change as the system evolves, hence
they require updates. Frequencies, which are linked to “long-term averages” of occurrences vary too, but are slower to change. In mining we may well consider an horizon
of two to five years and assume initially probabilities will remain “fresh” that long,
but we need to keep an eye on this and perform updates as soon as needed.
TSFs oftentimes have service lives that span over multiple decades and their
closure and post closure lives may very well span over respectively another set
of multiple decades and centuries. There are plenty of cases where the “P” word,
“perpetuity” is used. Just remember, perpetuity is way longer than a long time! Below
we try to give a sense to the scale of time using an excerpt from a book chapter we
recently wrote (Oboni and Oboni 2016).
If our mining company had existed:
45000 years ago: we would have been mining hematite at Bomvu Ridge in Swaziland.
Our mine would have produced insignificant waste and no societal concerns.
3000 years ago: we would have been bidding for the rights to mine silver at Laurentia
just east of Athens. Slaves would have worked to our command to provide the money
to build the Parthenon.
1000 years ago: we would probably have been asked to sponsor the crusades. Total
world population was around 300M souls. Languages used then have since disappeared.
500 years ago: we could have learned about Mr. Columbus’s recent discovery. Total
world population had increased to 500 M souls.
200 years ago: we would have been concerned by the Battle of Trafalgar, Napoleon’s
retreat from Moscow, and the Battle of Waterloo. The world’s population had reached
950M souls.
If we had closed our mining tailings facility 1000, 500, or 200 years ago, would
we have expected that the tailings (mining wastes) should still be right there where
we dumped them, unattended, not maintained, not monitored? Oh, we are forgetting
one thing: had we left a Standard Operating Procedure and Maintenance Manual
for “future generations,” now the manual would be in a language difficult (if not
impossible) to understand. The documents might have turned to dust or have been
heavily damaged. In addition, if we think digital transcriptions of our documents may
have saved us, the solar flare of 1859 (the Carrington event) would probably have
erased them all if fires, floods, and wars had not destroyed them earlier.
Keep this information in mind as you go through the rest of this section.
We detailed the theme of the long term survivability of TDs at TMW 2014, where
attention was focused on modeling the aging process of a geo-structure as a series of
discrete hits by hazardous conditions (these could be anything, from an earthquake to
flooding, etc.). In Oboni et al. (2014) an attempt was made to draft a multidimensional
estimate of future consequences. We stated:
… Should the value of consequences increase… then the “excellent dam” would soon pose
a societally unacceptable risk even for shorter terms. Any dam that starts its life with a
small initial FoS or reduced standards of care… would see its risk evolve towards intolerable
141
Probabilities are perishable goods. They change as the system evolves, hence
they require updates. Frequencies, which are linked to “long-term averages” of occurrences vary too, but are slower to change. In mining we may well consider an horizon
of two to five years and assume initially probabilities will remain “fresh” that long,
but we need to keep an eye on this and perform updates as soon as needed.
TSFs oftentimes have service lives that span over multiple decades and their
closure and post closure lives may very well span over respectively another set
of multiple decades and centuries. There are plenty of cases where the “P” word,
“perpetuity” is used. Just remember, perpetuity is way longer than a long time! Below
we try to give a sense to the scale of time using an excerpt from a book chapter we
recently wrote (Oboni and Oboni 2016).
If our mining company had existed:
45000 years ago: we would have been mining hematite at Bomvu Ridge in Swaziland.
Our mine would have produced insignificant waste and no societal concerns.
3000 years ago: we would have been bidding for the rights to mine silver at Laurentia
just east of Athens. Slaves would have worked to our command to provide the money
to build the Parthenon.
1000 years ago: we would probably have been asked to sponsor the crusades. Total
world population was around 300M souls. Languages used then have since disappeared.
500 years ago: we could have learned about Mr. Columbus’s recent discovery. Total
world population had increased to 500 M souls.
200 years ago: we would have been concerned by the Battle of Trafalgar, Napoleon’s
retreat from Moscow, and the Battle of Waterloo. The world’s population had reached
950M souls.
If we had closed our mining tailings facility 1000, 500, or 200 years ago, would
we have expected that the tailings (mining wastes) should still be right there where
we dumped them, unattended, not maintained, not monitored? Oh, we are forgetting
one thing: had we left a Standard Operating Procedure and Maintenance Manual
for “future generations,” now the manual would be in a language difficult (if not
impossible) to understand. The documents might have turned to dust or have been
heavily damaged. In addition, if we think digital transcriptions of our documents may
have saved us, the solar flare of 1859 (the Carrington event) would probably have
erased them all if fires, floods, and wars had not destroyed them earlier.
Keep this information in mind as you go through the rest of this section.
We detailed the theme of the long term survivability of TDs at TMW 2014, where
attention was focused on modeling the aging process of a geo-structure as a series of
discrete hits by hazardous conditions (these could be anything, from an earthquake to
flooding, etc.). In Oboni et al. (2014) an attempt was made to draft a multidimensional
estimate of future consequences. We stated:
… Should the value of consequences increase… then the “excellent dam” would soon pose
a societally unacceptable risk even for shorter terms. Any dam that starts its life with a
small initial FoS or reduced standards of care… would see its risk evolve towards intolerable