2
artificial landforms that will change and evolve over time
just as their natural counterparts do.
Within the last few years there has been a growing rec-
ognition by NGOs and industry organizations that some
mine facilities may require long-term care and mainte-
nance (ANCOLD 2012, ICMM 2019, MAC 2019). This
Acknowledgment is primarily addressing the long-term
risks posed by closed tailings facilities, but certainly could
be applied to most any reclaimed mine facility. While rec-
ognizing some closed mine facilities may pose long-term
risks or may require long-term monitoring, what appears
to be missing is an answer to, how long is long-term? This
lack of a working definition underscores the regulator’s
dilemma: How do you calculate financial assurance if you
don’t know how long to apply costs? The federal mining
regulations do not address this conundrum, and current
guidelines struggle to provide a precise definition (ICMM
2019, MAC 2019). Without a common understanding of
what long-term means, it is difficult to address mine closure
in a meaningful way.
A start to defining long-term in the context of mine
reclamation could include addressing the following three
questions,
1. How should one think of long-term care and
maintenance?
2. What should be included in long-term care and
maintenance?
3. Why is long-term care and maintenance important?
The answer to how one should think about long-term
care and maintenance (LTCM) requires accepting that
we should view it in terms of geologic time and not sim-
ply in engineering time. Consider the time a mine will be
in a closed state will be far, far longer than it ever was in
operation.
Mining creates landforms, whether they be waste
dumps, tailings impoundments or some other constructed
mine feature. These, however, are artificial landforms, dif-
ferent from those that have evolved through natural pro-
cesses, yet both types will continue to change in shape and
size in response to climatic and environmental forces. The
most recognizable landforms on a mine site are tailings
impoundments, waste dumps, and open pits. Certainly,
these have the potential to pose significant risk to human
health, safety, and the environment, but many other lesser
landforms also inhabit the mining landscape: diversion
ditches, portals, sediment ponds, and roads, to name a
few. While a mine is in operation, these facilities are main-
tained as part of the normal mining cycle, as part of regu-
larly scheduled maintenance, or in response to some system
failure. After closure, when the regulator has determined
the operator has met the requirements of the closure plan
and the intent of the regulations have been satisfied, the
operator’s bond may be released and the permit retired. At
this point there is no longer a designated responsible party
to maintain these facilities, and they become part of the
surrounding landscape where they are subject to the same
natural forces and processes that have driven geomorpho-
logical change for millennia. Indeed, regulators and NGOs
have recognized that some reclaimed mine facilities, specifi-
cally tailings dams, may need care and maintenance exceed-
ing 1,000 years (ICOLD, 2013). As mine closure guidelines
(ANCOLD 2012, ICOLD 2013) extend the time frame
for post-reclamation care and maintenance, companies
should begin preparing for a much longer site presence and
financial commitment at their closed properties.
What should be included in LTCM requires thinking
beyond water treatment, and while a significant feature of
any post-closure regimen where it may be required, it is not
necessarily the only system that requires long-term over-
sight. Reclaimed mine facilities and their components can
be highly engineered with very narrow construction and
operating tolerances. Water balance covers, underdrains
and seepage collection systems, pipeline valves, couplers
and gauges, electronic monitoring arrays, filters and passive
treatment systems, and dewatering devices, are commonly
found as part of reclaimed mine facilities. Some systems
include synthetic or reactive materials like geomembranes
or metals that may degrade over time, while natural pro-
cesses such as settlement and slope creep can compromise
buried components. Inclusion of these elements in the rec-
lamation design implies they are necessary for that facility’s
proper function whether during operations or in post-
closure. To assume these systems will function as designed
indefinitely is misguided.
The answer to why LTCM is important can be reduced
to simple economics: it can be really expensive.
RISK-BASED CLOSURE
While many mining risk analysis exercises concentrate on
the operations phase, applying it to the post-closure envi-
ronment can highlight potentially vulnerable facilities and
reclamation components that may not otherwise be flagged
during operations.
Reclaimed mine sites can be a complex of integrated
systems where each component may have a specific func-
tion in support of another dependent system: an underd-
rain must work to prevent the build-up of a phreatic surface
in an embankment to ensure embankment stability is not
compromised a diversion ditch must function to prevent
artificial landforms that will change and evolve over time
just as their natural counterparts do.
Within the last few years there has been a growing rec-
ognition by NGOs and industry organizations that some
mine facilities may require long-term care and mainte-
nance (ANCOLD 2012, ICMM 2019, MAC 2019). This
Acknowledgment is primarily addressing the long-term
risks posed by closed tailings facilities, but certainly could
be applied to most any reclaimed mine facility. While rec-
ognizing some closed mine facilities may pose long-term
risks or may require long-term monitoring, what appears
to be missing is an answer to, how long is long-term? This
lack of a working definition underscores the regulator’s
dilemma: How do you calculate financial assurance if you
don’t know how long to apply costs? The federal mining
regulations do not address this conundrum, and current
guidelines struggle to provide a precise definition (ICMM
2019, MAC 2019). Without a common understanding of
what long-term means, it is difficult to address mine closure
in a meaningful way.
A start to defining long-term in the context of mine
reclamation could include addressing the following three
questions,
1. How should one think of long-term care and
maintenance?
2. What should be included in long-term care and
maintenance?
3. Why is long-term care and maintenance important?
The answer to how one should think about long-term
care and maintenance (LTCM) requires accepting that
we should view it in terms of geologic time and not sim-
ply in engineering time. Consider the time a mine will be
in a closed state will be far, far longer than it ever was in
operation.
Mining creates landforms, whether they be waste
dumps, tailings impoundments or some other constructed
mine feature. These, however, are artificial landforms, dif-
ferent from those that have evolved through natural pro-
cesses, yet both types will continue to change in shape and
size in response to climatic and environmental forces. The
most recognizable landforms on a mine site are tailings
impoundments, waste dumps, and open pits. Certainly,
these have the potential to pose significant risk to human
health, safety, and the environment, but many other lesser
landforms also inhabit the mining landscape: diversion
ditches, portals, sediment ponds, and roads, to name a
few. While a mine is in operation, these facilities are main-
tained as part of the normal mining cycle, as part of regu-
larly scheduled maintenance, or in response to some system
failure. After closure, when the regulator has determined
the operator has met the requirements of the closure plan
and the intent of the regulations have been satisfied, the
operator’s bond may be released and the permit retired. At
this point there is no longer a designated responsible party
to maintain these facilities, and they become part of the
surrounding landscape where they are subject to the same
natural forces and processes that have driven geomorpho-
logical change for millennia. Indeed, regulators and NGOs
have recognized that some reclaimed mine facilities, specifi-
cally tailings dams, may need care and maintenance exceed-
ing 1,000 years (ICOLD, 2013). As mine closure guidelines
(ANCOLD 2012, ICOLD 2013) extend the time frame
for post-reclamation care and maintenance, companies
should begin preparing for a much longer site presence and
financial commitment at their closed properties.
What should be included in LTCM requires thinking
beyond water treatment, and while a significant feature of
any post-closure regimen where it may be required, it is not
necessarily the only system that requires long-term over-
sight. Reclaimed mine facilities and their components can
be highly engineered with very narrow construction and
operating tolerances. Water balance covers, underdrains
and seepage collection systems, pipeline valves, couplers
and gauges, electronic monitoring arrays, filters and passive
treatment systems, and dewatering devices, are commonly
found as part of reclaimed mine facilities. Some systems
include synthetic or reactive materials like geomembranes
or metals that may degrade over time, while natural pro-
cesses such as settlement and slope creep can compromise
buried components. Inclusion of these elements in the rec-
lamation design implies they are necessary for that facility’s
proper function whether during operations or in post-
closure. To assume these systems will function as designed
indefinitely is misguided.
The answer to why LTCM is important can be reduced
to simple economics: it can be really expensive.
RISK-BASED CLOSURE
While many mining risk analysis exercises concentrate on
the operations phase, applying it to the post-closure envi-
ronment can highlight potentially vulnerable facilities and
reclamation components that may not otherwise be flagged
during operations.
Reclaimed mine sites can be a complex of integrated
systems where each component may have a specific func-
tion in support of another dependent system: an underd-
rain must work to prevent the build-up of a phreatic surface
in an embankment to ensure embankment stability is not
compromised a diversion ditch must function to prevent