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Geotechnical News • June 2016
WASTE GEOTECHNICS
An industry self-evaluation on geotechnical mine
closure objectives and planning teams
N. Slingerland, N. Beier, M. Baida
Background
In the spring of 2014, a survey con-
cerning various mine closure goals
and typical success rates was distrib-
uted internationally to mine closure
professionals working in industry,
academia, government, and/or some
combination thereof. The survey was
“high level” in nature, in order to iden-
tify trends over time, such as whether
certain objectives had evolved or
devolved, and also to gauge whether
closure goals were being successfully
achieved. This type of self-evaluation
on a global scale is important from
time-to-time in order to assess how
we are performing as an industry
and where more effort needs to be
expended. In a profession that alters
the earthly landscape on a scale visible
from space, this type of reflection can
have a sobering effect.
Nearly 20 years ago, the first known
widespread evaluation of closure goal
achievement was undertaken in the
form of a checklist completed during
the inspection of 57 mines in west-
ern North America and interviews
conducted with site staff (McKenna
& Dawson, 1997). The results were
variable, but some of the common
deficiencies found are as follows:
• Re-established drainage courses
such as rivers and channels had not
been designed and/or constructed
for large enough storm events, nor
had naturally occurring blockages
such as beaver dams or ice build-
up been taken into account.
• End-pit-lakes are still a reality for
many mines, and there were sev-
eral issues such as the reliability of
modeling, geochemistry, stratifica-
tion, and the hydrological perfor-
mance of these built structures that
were identified as requiring further
attention.
• Tailings dams that use coarse-silt to
fine sand as the primary construc-
tion material are highly erodible
and rills, gullies, and depositional
fans were repeatedly observed.
Ongoing maintenance to achieve
stabilization of these landscape
features is an unsustainable prac-
tice, and yet it was also the only
approach that was being employed
with success.
These deficiencies outline a need for
the perpetual maintenance of post-
mining landscape features, which is in
contrast to the overriding objective of
mine closure: that being to return land
in a self-sustaining, liability-free state
to the Crown. Since this inventory 19
years ago, there has been a steadily
increasing wave of environmental
activism globally, resulting in undesir-
able publicity directed towards mining
companies based on the land and
water quality degradation some have
left behind. This often overshadows
the positive economic contributions
that mining operations make to many
regions.
Fear of repeated environmental
degradation has fueled protests by the
public and NGO’s, who’s anti-mining
arguments have been strong enough to
keep mining operations from starting,
particularly in regions with a well-
versed, longstanding, and articulate
community (Kahn, Franceschi, Curi,
& Vale, 2001). This kind of attention
increases pressure on scientists, engi-
neers, and other closure professionals
to achieve their closure targets: not
only for the sake of a job well done,
but also to ensure they are building
a strong track record of success in
closure and reclamation works to more
easily achieve public license on future
projects.
In the authors’ 2014 survey, similar
issues to those found in 1997 were
uncovered. This tells us that while sci-
entists and engineers continue to build
on their ability to tackle the dynamic
geotechnical problems associated with
mine closure, the core issues such as
erosion control on tailings dams and
establishment of drainage courses
remain a challenge.
Survey methodology
The 2014 survey sought feedback
from mine closure professionals
around the world, and once complete
157 usable surveys were reviewed.
Respondents were solicited in a vari-
ety of methods including one national
land reclamation organization that
assisted by sending the online request
and web address to their membership,
and online mine closure discussion
groups on professional networking
websites like LinkedIn, for example.
Closure goals were grouped into four
categories: Technical, ecological, land-
use, and socio-economic. Along with
general population statistics includ-
ing years of experience and practice
region, professionals were asked
whether each of the 29 goals in four
