Volume 6 • Issue 6 • 1000259
J Civil Environ Eng, an open access journal
ISSN: 2165-784X
Yaya et al., J Civil Environ Eng 2016, 6:6
DOI: 10.4172/2165-784X.1000259
Research Article Open Access
Auscultation of a Dam for Mining Restoration in Quebec, Canada
Coulibaly Yaya, Li Zhen Cheng*, Tikou Belem and Sylvain Lortie
University of Québec in Abitibi-Témiscamingue, Canada
Abstract
The tailing management is a long term concern for environment and social security. Following the discovery of a
new gold mineralization, a mining company aims at reusing one of tailings storage facility at the mining site. However,
there is a small treated water reservoir (polishing pond) downstream of the Northwest dam. It is therefore important
to know the present state of the Northwest dam’s internal structure. Geophysical methods of electrical resistivity and
georadar were used for the auscultation of the Northwest dam. Numerical models were subsequently used to assess
the geotechnical behavior of the dam in different deposition situations by simulating the restoration.
The image processing results of georadar data show a layered structure near the surface. Changes in electrical
resistivity offer deeper information than georadar. The lateral variability of the electrical resistivity corresponds to
heterogeneity within each layer. As we cannot collect samples for the characterization of materials, the geophysical
interpretation results help to estimate the compositional structure of the dam; ultimately it helps in numerical modeling
on the safety factor estimation.
*Corresponding author: LiZhen Cheng, University of Québec in Abitibi-
Témiscamingue, Canada, Tel: +18197620971; E-mail: LiZhen.Cheng@uqat.ca
Received October 20, 2016; Accepted December 05, 2016; Published December
08, 2016
Citation: Yaya C, Cheng LZ, Belem T, Lortie S (2016) Auscultation of a Dam
for Mining Restoration in Quebec, Canada. J Civil Environ Eng 6: 259. doi:
10.4172/2165-784X.1000259
Copyright: © 2016 Yaya C, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited.
Keywords: Dam; Embankment; Electrical resistivity; Factor of safety;
Georadar; Internal structure; Tailings pond
Introduction
e Abitibi greenstone belt of Canada is a world well-known
region rich in mineral resources. By-products from exploitation of
those natural resources could cause acid mine drainage (AMD) due
to the interaction between water discharges, atmospheric oxygen and
sulphide minerals. In some cases, metals as nickel (Ni), zinc (Zn), cobalt
(Co), copper (Cu) and metalloids as arsenic (As) and antimony (Sb)
may generate contaminated neutral mine drainage (DNC). e AMD
and the DNC are considered the most important environmental issues,
as they may affect the population’s quality of life by contamination of
surface water and groundwater. To minimize environmental risks,
mining companies have developed some waste management strategies:
either 1) make cemented paste for backfilling underground; or 2) by
stacking them to the surface with impermeable cover; or 3) dropping in
the lake bottom around the operation site (tailings). Tailings dams play
an important role to separating contaminated and uncontaminated
areas. e stability of dams is thus a key element to be monitoring,
especially in intensive mining activities region as the Abitibi greenstone
belt. Tailings are a mixture of water and fine material from rocks aſter
concentrated minerals being removed and they are piped into a storage
facility (e.g. lakes) belted by dams. However, dams can sometimes
yield to different types of hazards and dumping of pulp residues and
cause extensive damage and major environmental impacts. Figure 1
shows the breakdown of the dam around tailings from Mount Polley
in Canada with over 24 million m
3
spilled [1]. Damage with the death
of 19 people is also recorded due to the bursting of tailings dam in
Mariana, Brazil in 2015 [2]. Figure 2 shows the socioeconomic impact
of disruptions in the world with the loss of life and on the environment
that was increased from 2000 to 2010. 76% of incidents worldwide were
related to the upstream construction method [3]. 51% of incidents
(breakdowns and accidents) identified by ICOLD (1996, 2001) are
due to slope instability of the dam following excessive stress in the
foundation soil, the embankment of the dam, inadequate control of
water pressure [4].
e causes of breaking dams are multiple. Apart from construction
problems, poor maintenance or unusual weather as cited by Azam
and Li [5], other vulnerability may also be the cause such as the excess
pore pressures accumulation due to rapid rising of the dam. e pore
pressure (especially in muddy areas) will reduce the effective stresses
and resistance to shear residues [6,7]. e static and seismic liquefaction
are also considered a common cause of levees broke particularly those
enhanced by the upstream method [8,9]. As the break is a physical
process (mechanical, hydraulic), in general, the breakdown for
embankments is made according to four classical mechanisms [10-12]:
external erosion, internal erosion, external instability and liquefaction
(Figure 3).
Runoff of rain water can be the cause of the external erosion. e
settlements on the crest cause cracks that promote water infiltration
into the dam and this could cause internal erosion or slippage in an
area of weakness.
Issue of study
A Canadian mining company discovered a new deposit of gold
mineralization around an old mining site in the Abitibi greenstone
belt of Québec, Canada. e restoration of a tailings lake to store waste
rocks is then planned. According to information gathered at the site,
a collapsing zone on the Northwest dam was observed in spring 2004
Figure 1: Illustration of embankment failure-cases of the tailings from Mount
Polley (Cariboo Regional District, Canada, 2014) [1].
J
o
u
r
n
a
l
o
f
C
i
v
il
&
E
n
v
i
r
o
n
m
e
n
t
a
l
E
n
g
i
n
e
e
r
i
n
g
ISSN: 2165-784X
Journal of Civil & Environmental
Engineering