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Contribution of Statistical Fracturation and Karstification Analysis to the Definition of
Quarry Faces Evolution and Restoration Policy
Tahar ALOUI 1 and Fredj CHAABANI
Laboratory of Mineral Resources and Environment.
Department of Geology. Faculty of Mathematical, Physical and Natural Sciences. University
Campus, 1060 - Tunis, Tunisia.
Abstract
The physical properties of the bedrock influence widely the spatiotemporal evolution of
the quarry faces, the exploitation, the productivity of the quarry as well as the type of the
ultimate rehabilitation. In this study, we propose a new method based on the statistical study
of the fracture - karstification couple of the bedrock, to initiate a harmonious exploitation
which simultaneously gathers the investor, the natural environment and the local community.
It does not only avoid the zones affected by fracture and karstification phenomena, but also
adapts a long-term planning policy in order to benefit from the natural bedrock state,
minimize the cost of extraction and the risk of eventual loss of high-quality materials.
Furthermore, the environmental works should be managed at the rate of the exploitation in
order to reduce the consecutive harmful effects of the excavation and to better integrate the
site in its local socio-economic context.
Keywords: fracture; karstification; quarry restoration; landfill
1 e-mail : [email protected]
2
1. Introduction
Since 1986, the beginning of the first industrial quarry, several specialized factories in
mineral industry have been established along Jebel Feriana (Fig.1). They have exploited
extra-white limestones of late cretaceous age for varied ends: dimension stone, white cement,
glass manufacturing, painting materials and pharmaceutical products. Both surface and deep
observations affirm that limestones are far from the homogeneity foreseen by anterior
geological exploration (Burollet et al., 1954; Trabelssi, 1989). During his study of the
irregularity of a clinker based on the limestones of Jebel Feriana, Sadran G. (1988) had the
merit of evoking, for the first time, the heterogeneity of the raw material itself. Indeed, the
envisaged limestones do exist, but they are often karstified and contain various impurities
limiting their use. The exploiter attenuates these difficulties by discarding more materials
which may be of good quality and by reorienting the phases that were foreseen by the initial
exploitation plan.
Although this approach satisfies national and international requirements in terms of
quantity, the hazard to the environment is still significant and the quality of the quarrying
operations remains to be improved. Throughout the present paper, we propose a model based
on the statistical study of the fracturation - karstification couple of the rock to initiate a
harmonious exploitation which gathers, at the same time, the stakeholders (investors, local
community...) and the natural environment requirements.
Fig. 1. Geographical situation of the study area
0 250 500 m
Tunis
Sfax
ALG
ERIA
L I BYA 35°
36°
34°
10°9°
FERIANA
0 100 km
124000124500125000
124000124500125000
115500116000
116500TUNISIA
3
2. Methodology
The study site was subdivided into elementary stations or measuring sites with square
mesh (Si). Each station is defined by the Universal Transverse Mercator (UTM) of one of its
diagonals. The identification of various families of fractures and the determination of their
geometric and spacial characteristics are based on the data acquisition by the Systematic
Linear Mapping Method (SLMM) along the measuring site (Si). This technique, which was
recommended throughout this work, enables us to get quantitative and qualitative information
that will be evaluated statistically. The visualization of the data on stereograms seems to be a
rather delicate process. If we suppose that the measuring surface is planar and the fractures
are vertical to subvertical, the recourse to rose diagram allows a satisfactory visual
appreciation of the directional data. A diagram briefly summarizes the main steps of the
procedure appears as Figure 2.
Fig. 2. Descriptive diagram showing main stages of the model
2.1. Statistical analysis of fractures
Statistical analysis of fracturation aims to identify quantitatively and qualitatively the
zones of great intensity of fractures. The observations carried out on the terrain and supported
by a mining method enabled us to highlight the particular importance of certain descriptors in
the dynamics of the faces as: direction, overlap, connectivity, openness, depth, slope and
length of fractures (Fig. 3).
Si Identification of the elementary measuring stations
Identification of directional classes
Checking of the model
D1, D2 … Dn’ n’≤n
Useful descriptors
Mapping
Identification of useful descriptors
n=0 or n’→n
- Morphology - Slop - Surface - Access conditions - Lithology - …
Study area
- Aerial photography - Visits on the terrain - Geological radar - Vertical walls - …
Systematic descriptors
D1, D2 … Dn
Model
Reconstituted phenomenon
Yes No
Optimization of the exploitation
4
Fig. 3. Conceptual model of fractured limestone showing studied descriptors
The quantitative study was achieved by representing in angular coordinates the frequency
(ƒ) of each directional class in the measuring site (Si). In contrast, the qualitative study tends
to classify fractures according to their impact on the exploitation. In addition to lithology,
only openness (o) and spacing (e) descriptors have a critical influence on quarrying
operations, that’s why they are considered in the model. Other parameters as (α) and (l), are
ignored because they are relatively constant on the scale of the measuring site (Si). The
compilation of these statistical indicators must define the dominant directional classes of the
fractures to be able to influence exploitation and safety.
2.2. Statistical analysis of karstification
Statistical analysis of karstification consists in the follow-up of the three-dimensional
behavior of the karstification generated by each fracture. This study is based on the results of
the statistical analysis of fracturing, vertical quarry walls and direct observations. Its final
goal is not only the identification of the fractures with high potential of karstification but also
the proposal of a karstification model of the site.
3. Description of the study area
The technique announced above was applied in the establishment of the exploitation plan
of Maastrichtian limestones of Abiod Formation (Burollet, 1956; M’Rabet et al., 1986; Saadi,
1991; Negra, 1994; M’ Rabet, 1996; El Euchi H. 1993) located at Jebel Feriana (Fig. 3).
Typically, those limestones are 150 m thick, sealed by the El Haria shales of the Upper
Maastrichtian and Palaeocene and their equivalents. They are organised in two bars separated
by grey-to-blue marls with intercalations of decimetric limestone beds member which is
missing only in Jebel Feriana (Negra, 1994; Aloui, 1999). Because of their high whiteness
p
l
e
o
r
α
e : spacing r : overlap l : length p : depth α : inclination o : openness
5
(Trabelssi, 1989; Kchouk, 1995; Aloui, 1999), this resource has widespread uses including
paper, painting as well as white cement manufacturing and tiling.
The measurement taken on the field and supported by aerial photographs show that Jebel
Feriana is a dissymmetrical conical fold with an axial plan E-W, a steep north flank and a
gently sloping south flank. Its total length is approximately 4 km and its openness is about 3°.
The weakest inclinations were observed in the deep fold at the level of Choubet Ettarf and
Choubet Si Ali (5 to 8°). The highest inclination is observed in the periphery. Indeed, it is of
20 to 25° on the northern flank and of 10 to 15° on the southern flank (Aloui, 1999).
4. Results and discussion
On the surface, the limestones are relatively karstic. The paleokarstic forms are in various
stages of lapiezation. These forms result from a progressive dissolution of the carbonate beds
during wet seasons. Some karstic forms have undergone a filling formed mainly of reddish
residual clay. The closed depressions of low altitude are sometimes filled by terra rossa soil
type.
In depth, the observations of the quarry faces highlight a significant network of
subvertical and parallel veins with inter-bed plans. The parallel ones are frequent in hard and
soft limestone alternations of the summit part of the Abiod Formation (Fig. 4).
At this stage, the variation of permeability involves a preferential infiltration of water in
depth. Indeed, in rainy weather, water follows the surface of the hard carbonated levels, its
speed of percolation decreases, the time of contact with the rock increases and the dissolution
of subjacent soft limestones becomes clearly marked (Aloui, 1999). The karstic vacuums are
approximately 20 cm in diameter, filled with rust clay and sometimes it is easy to observe a
thin film of calcite deposits in cavities and small faults.
Special care should be taken when drilling, blasting and detonating explosives for
breaking rock. Infact, during the loading of mines, the explosive accumulates in the karstic
pockets, which generates a bad distribution of the demolition energy; a raised blocometry
accompanied with a significant noise or even mine failures.
At the lower part of the Abiod Formation (Campanian pp.), the cavities are very often
localized and vertically lengthened with a more important diameter than that on the upper
part. The apogee of the karstification phenomenon is located approximately at 25 m depth.
The scarcity of silicification and dolomitization process indicates that the karstic vacuum
was not filled with stagnant and reduced water, but corresponds probably to percolation
zones. Under the electron microscope, these limestones are made up mainly of geared and
subhedral grains of micrite with a size varying between 5 and 10 µm. Inspite of the partial
6
cementation by sparite, the resulting porosity is that of an open channel-type (Negra, 1994),
which is very favorable for the installation of the karstification process (Aloui, 1999).
Fig. 4. Synthetic lithostratigraphic column of Jebel Feriana
In addition to the inclination of the layers, morphology and lithology of the rock, the
fractures exert a mere control over the definition of the karstic style in the area. The majority
of the mapped fractures presents free extemities (weak connectivity) and generally crosses the
totality of the Abiod Formation. The stratification is often blurred and when it is well
individualized, particularly in the upper part of the Formation, the plans of stratification are
increasingly tightened and the fractures are well highlighted. With the exception of the
measurements carried out in the vicinity of the deep northern side where the inclinations are
close to 30° S and rarely 60° S, the inclinations are subvertical to vertical. In general, the
fracture network is well developed in the vicinity of the hinge of the anticline. The vertical
observation of the quarry faces does not show any significant variation in the density of
fracturing with the depth.
Littostratigraphic log Formations Age
AB
IOD
A
LEG
Cam
panian to Maastrichtian
Santonian C
oniacian
Decimetric alternations of crystalline limestone and rather hard yellowish limestone with flint at the top
Saccharoid chalky white limestone with blurred stratification intercalating some metric siliceous limestone passages at the top
Soft limestones with nodulous appearance
Beige to white massive limestone
Alternations of beige to yellows deposits of bioclastic limestone and grey marls
0
50 m
25 Marno-limestone alternations
7
4.1. Contribution of the statistical analysis of the fractures
The experiment shows that the harmful effect which the spacing (e) can carry to the
exploitation grows with 1/e ratio, and that the critical value of spacing between two fractures
belonging to the same directional class of the station (Si) is often lower than the length of the
bench (Aloui, 1999). This critical value can generate hazardous effects for the exploitation
only under the effect of reducing the spacing. The observation of the evolution of some quarry
faces located on the left bank of the Wadi Errachih proves that the critical value - for which
openness can generate harmful effects to the exploitation only when (o) increases - is about
0.5 cm.
From surface and underground mapping in mines and quarry faces in Jebel Feriana, the
quantitative study (Fig. 5) of the fractures identified various styles and structural elements in
the area.
Fig. 5. Frequency distribution of the directional classes
The network of fractures comprising five classes of dominant direction was highlighted:
- the class NS is frequent in the vicinity of the Wadi Errachih, Choubet Ettarf and Choubet Si
Ali. They are fractures of weak openness (Fig. 6) and spacing (Fig. 7);
124000124500125000
124000124500125000
115500116000
116500
115500116000
116500
10
20
30 0
90
180
270
10
20
30 0
90
180
270
10
20
30
90
180
270 10
20
30
180
10
20
30 0
90
180
270 10
20
30 0
90
180
18
20
30 0
180
0 250 500 m
10
20
30 0
10
20
30 0
90
8
- the class N45 constitutes a secondary network of fracturing with weak frequency and which
appears in the axial zone of the anticline between the Wadi Errachih and Choubet Ettarf.
Those accidents are very isolated with slightly developed openness;
- the class N60 is frequent in the zone where concavity of the anticline axis changes. It is
characterized by weak spacing and openness;
- the class N90 is frequent in the axial zone. Those accidents have weak spacing and variable
openness often important southward;
- the class N130 constitutes a network of fractures very frequent in the massifs of the region
and the tertiary deposits of Maamoura synclinal. It is probably the relatively recent network
fractures. Its genesis seems to be irrelated to the local conditions of Jebel Feriana (Aloui,
1999).
Fig. 6. Aperture distribution according to the directional classes
124000124500125000
124000124500125000
115500116000
116500
115500116000
116500
10
20
30 0
90
180
270
10
20
300
10
20
300
90
180
10
20
30 0
90
180
270
10
20
30
90
180
10
20
300
90
10
20
30 0
180
0 250 500 m
10
20
30
90
180
10
20
30 0
180
9
Fig. 7. Reverse of the spacing distribution according to the directional classes
4.2. Contribution of the statistical analysis of the karstification
Karsts result from water circulation and its aggressive chemical and physical action in
cracks, joints and fractures along the layers of limestone over time. In few situations where it
is not possible or appropriate to recover the variation of the volume of dissolved limestones,
non-destructive cores were used. They show that the karstification phenomenon is
approximately 25 m in depth (Fig. 8).
The appreciation of the karstification state of the bedrock was deduced from the definition
of the karstification index (IK). For a single fracture network, IK is proportional to openness
and fracturing intensity that could be estimated as follows:
Ik=o.If (1)
in which (o) represents the average openness and (If) a term describing the characteristic
fracturing of the site. Here, we suppose - for simplicity - that the constant of proportionality is
equal to 1. In the particular case of a site with a surface (s), made of (nC) beds and including
(n) fractures which are spaced by (e) meters and have the same direction, this term can be
defined by the following relation:
124000124500125000
124000124500125000
115500 116000
116500
115500 116000
116500
0 250 500 m
0.01
0.02
0.03
90
180
0.01
0.02
0.03
90
180
0.01
0.02
0.03 0
90
180
0.01
0.02
0.03 0
90
180
0.01
0.02
0.030
90
180
0.01
0.02
0.03 0
90
180
270
0.01
0.02
0.030
90 0.01
0.02
0.030
0.01
0.02
0.03
90
180
270
10
If s.en.n C= (2)
After replacing the term (If) in the initial equation we get:
IKs.e
n.n. Co= (3)
The case of a simple site, in which fractures are mono-directional, seems to be rare. In
fact, the network of fractures is often extremely complex. The fractures are often poly-
directional. Each directional class is characterized by its relative frequency in the network, its
openness and its average spacing. In the same way, one or more networks interfere with each
other and contribute to increased fracture intensity. On the scale of the study area, the
observations of surface, as well as those of undersurface, affirm that karstification seems to be
a localized phenomenon and the intensity of fracturing is mainly generated by the cumulative
effect of each directional class in the measuring site. This simple procedure allows us to
estimate roughly the karstification intensity at Jebel Feriana by the following model:
i
j
1=i i
ic o e
s
n= ∑
fkI (4)
Where s : measuring surface or station expressed in km2 ƒ : frequency of the directional class in the measuring station
nc number of beds in the directional classes ei : average spacing of the directional ith class expressed in meter oi : average openness of the directional ith class expressed in meter i : positive integer between 1 and j [ 1, j ] j : positive integer indicating the number of directional classes
4.3. Generalization of the model
Not only can a mathematical model as i
j
1=i i
ic o e
s
n= ∑
fkI
be adjusted with the statistical
data of fractures in the vicinity of Jebel Feriana, but it is also probable that a model based on
the same observations could be applied to other localities. In this concern, we are led to adjust
the data with a simple model in which the following considerations were taken:
- the sampling must be representative and likely to give a non-deformed or reduced image of
the site from which it was carried out;
- the descriptors of IK present the same probability of being raised and implied in the
development of the karstification phenomenon.
11
Actually, no natural site corresponds to the plain scheme considered previously.
According to his experience, the exploiter should adjust this model to adapt it conveniently
with his case of study.
Basing on the karstification index IK, it is possible to appreciate the karstification degree
according to table 1.
The fractures of direction N60 and N90 would probably be the major cause of the
karstification in Jebel Feriana whereas the fractures of direction N130 seem to have a local
effect. The karstified zones are slightly at the South flank and at the change of concavity of
the anticline axis.
Fig. 8. Block diagram outlining the fractures and karstification characteristics of Jebel Feriana
Table 1. Degree of karstification according to Ik
Ik [0 , 250] ]250 , 750] ]750 , 1500] ]1500 , 3000] ]3000 , +∞[ State Not karstified Slightly karstified Fairly karstified Enough karstified Very karstified
These results enabled us to envisage a selective exploitation in three working floors with
a 12-m high bench. The evolution of the faces should follow the direction of the dominant
fractures (Fig. 9) and the zones of weak karstification (Fig. 10).
Har
d lim
esto
nes
with
low
por
osity
S
oft l
imes
tone
s w
ith
high
por
osity
Karstic pocket
25 m
Depth (m)
Importance of karstification
12
Fig. 9. Distribution of the fracture network
Fig. 10. Distribution chart of karstification
0 250 500 m
Fracture network
N130
N90
N60
N45
NS
123850 124100124350124600124850125100 125350
123600 123850 124100124350124600124850125100 125350
115400115650
115900116400
116150116650
Slightly karstified
Bedrock state
Very karstified
Fairly karstified
Not karstified
Enough karstified
0 250 500 m
123850 124100124350124600124850125100 125350
123600 123850 124100124350124600124850125100 125350
115400115650
115900116400
116150116650
13
In this concern, it is preferable to carry out the extraction in three phases of a total
duration of about 45 years. A grid surface in 3D was computed to illustrate the dynamics of
the faces during the three production phases (Fig. 11).
4.4. Rehabilitation of places
Feriana town, located at 1 km of the studied site, was marked during these two last
decades by a fast development of urbanization under the triple effect of the economic growth,
the demographic increase and the change in consumption modes. This is accompanied by a
domestic and industrial solid waste with unceasingly varied growth (Table. 2).
Table 2. Evolution of the quantity of solid waste in tons (Municipality of Feriana)
Year 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 Quantity (tons) 4329 4612 4957 5323 5723 6123 6623 7210 7708 8237
bi-annual 6.14 6.96 6.88 6.99 6.53 7.55 8.14 6.46 6.42 Increase (%) annual 3.07 3.48 3.44 3.49 3.27 3.77 4.07 3.23 3.21 3.33
14
Phase 1
Current state of the quarry after 9 years after 12 years after 15 years Phase 2
after 23 years after 26 years after 29 years after 33 years
Phase 3
Insertion of the site in its new socio-economic context
after 38 years after 41 years after 45 years
Fig. 11. Evolution of the faces based on the statistical analyses of fractures and karstification
15
Their collection and treatment constitute a major concern for the local community.
Currently, their evacuation is made towards two great wild landfills established on the flood
plains of Wadi Saboun and Wadi Bou Haya (Fig. 12).
Fig. 12. Air sight showing the situation of the wild landfills and the industrial quarries
Deposited in the natural environment without precondition treatment, these solid wastes
may cause serious potential problems (like soil contamination, groundwater and surface
water) that may occur as leachate produced by water or liquid wastes. For this reason, we
believe it is interesting to re-use the consecutive space to the excavation as a controlled
landfill (Qasim et al., 1994).
Several audits of the waste characteristics arriving in the domestic and commercial
collection vehicles at Feriana town have been undertaken since 1997. The daily production of
waste per inhabitant is about 0.47 kg/capita/day. It is 0.5 kg in large Tunis, 0.75 kg in Sousse,
1 kg in Sfax and can reach 2.5 kg/capita/day in other communes as Sidi Bou Said (Souissi,
2000).
Out of dustbin and without being compressed, the specific mass (ρ) of wastes is about 32
kg/m3. From the composition perspective (Fig. 13), the wastes of Feriana town, like in most
Tunisian towns, are very often wet (the water content varies from 60 to 70%) and most of the
wet weight (65 to 70%) consists of organic matter (70%); paper accounts for 11% and plastic
approximately 7%.
1
2
3
Industrial quarries
Wild landfills
Feriana town
Bou Haya Wadi
Saboun Wadi
1
2
3
16
72.15
11.27
7.072.445.1 1.98
Organic matter paper Plastic matter
Alloys Glass Others
Fig. 13. Average composition of a representative dustbin of Feriana town during 2002
(Municipality of Feriana, 2002)
4.5. Lifespan of the landfill
The estimated quantity of waste poured by the commune of Feriana was deduced, based
on its high linear correlation (R2 = 0.989) with the time (t) expressed in years (Fig. 14).
qt = 219.42t - 431661 (5)
Fig. 14. Linear correlation between the quantity of solid waste and time
We assume that the projected growth rate per annum (Γ) between two years (i-1) and (i) in
the quantity of waste is given by the equation below:
100.q
q-qΓ
i
1-ii= (6)
4000
5000
6000
7000
8000
9000
1985 1990 1995 2000 2005
Time (year)
Qua
ntity
of w
aste
Qn
(tons
)
17
Where (Qi-1) and (Qi) are, respectively, the quantities of waste generated during the year (i-1)
and (i). Multiplying the equation (6) by (Γ
iq) and grouping (qi ) term, we get:
1-ii q.100
100qΓ−
= (7)
Note that each term after the first is found by multiplying the previous term by a fixed
number. Consequently, the quantity of solid waste describes a geometric sequence of common
ratio 1100
100r >Γ−
= and starting value Q0. By successive substitution applied to equation (7),
we easily get:
( ) 0i
0i
i q1.033=q.)100
100(=q
Γ- (8)
If we suppose that the excavation starts from the point of coordinates (124600, 116650)
and that the landfill is in use from year (n) and finishes at the end of year (n+d), n and d are
two natural numbers. The equation (8) can be written as follows: ndn
n q)033.1(q ++ =d , where
Qn (first term of the sequence) corresponds to the quantity of waste during the year in which
the landfill is in use and Qn+d (last term of the sequence) represents the quantity of solid waste
collected during year (n+d).
In order to optimize the stability of the slope, we suppose that the landfill will be
exhausted after a lifespan (d) which corresponds to the filling of T% of the excavated volume
v(m3). Here, the lifespan (d) indicates the number of years necessary so that the cumulated
quantity of solid waste between the (n) and (n+d) years takes the value (v.T). If we ignore the
contribution of the materials intended for the covering and the compaction effect, (d) must
check the subsequent relation:
∑=
+
d
1iinq=v.t (9)
or:
v.t = n
1+d
qr-1
r-1. (10)
from which we can conclude:
nn
1+d
.rqr).v.t-(1-1=r (11)
After the application of the log function to the two terms of the equation (11), we find:
18
).rq).v.tr -(1-log(1=1).log(r)(d n
n
+ (12)
The lifespan of the landfill expressed in terms of year could be estimated by equation (13):
1-)r log(
).rq
)r -(1v.t-log(1=d
nn
.
(13)
At an annual tonnage of excavated limestones of 200000 tons/year, we estimate that the
first phase will be spread out over a period of 15 years. It is highly recommended that the
excavation be planned with the intention of conserving and enhancing the quality of the area
for an ultimate use of the site. Besides, the operators should integrate environmental works
into all daily operations at the rhythm of the quarry faces in order to facilitate the
rehabilitation into a landfill.
Similarly, it would be beneficial to all partners (local authorities, elected officials,
operators, environmentalists …) to begin the handing over of the controlled landfill from the
end of the first phase of exploitation (Aloui, 1999). Ultimately, if we suppose that the density
of the rock is 2.1 tons/m3 and on the basis of the particular case:
v = 171 8646 m3 r = 1.033 T = 0.66 n = 2020 Γ= 3.43 Qn = 219.42n - 43 1661
The lifespan of the landfill will be about 15 years.
4.6. Alternative treatments and special considerations
The ceaseless progress of the transformation techniques and conditioning of materials
does not consider waste as garbage to be systematically eliminated, but as secondary raw
materials in order to be highly-valued to release surplus (Scholtz et al., 1994; Merchant et al.,
1995; Stessel, 1996; Nyamwange, 1996; Aloui 1999). Authorities can, also, encourage new
techniques and try to adapt them to their local context like waste reduction such as source,
resource recovery or differentiated collection (paper and cardboard, glass, plastic, aluminum,
durable goods and electronic devices, car batteries…). These alternative solutions should be
considered in priority (Alexander, 1996; Stessel, 1996; Calaminus et al., 1998).
19
The quantity of the buried waste must be controlled, road traffic ought to be harmonized
and access roads must be adequately maintained. However, special considerations should be
evoked:
- in order to combat the throwing of papers and plastic materials, a permanent and a mobile
barrier whose height ranges from 3 to 5 m should be placed perpendicular to the dominant
direction of the wind;
- traffic lanes should be filled by inert or recuperated materials in rainy weather. These
materials will be handy to the rolling facilities;
- the future landfill will be located at less than 1 km of the agglomeration, watering will
represent an adequate solution to control the emanation of dust in dry time;
- certain dangerous waste can be neutralized by lime or a coating in butine or plastic films
(Fig. 15).
- the final cover system must maximize surface water run-off and prevent its pending.
Fig. 15. Block diagram showing briefly the adjustment of the landfill and the treatment under
consideration for each type of solid waste
Front mask
Hazardous wastes neutralized by butine
Hazardous wastes neutralized by lime
Hazardous wastes in plastic sachets adapted
Impermeable cover
Impermeable clays and marls of the Aleg Formation
Karstic fill materials or marls of the Aleg Formation
Inert harmful wastes
Limestone of the Abiod Formation
Final cover
leachate collection system
20
5. Conclusions
The statistical analysis supported by observations on surface as well as in depth of the
fracturing-karstification couple, has enabled us to identify the networks of discontinuity and
to propose a model of karstification in Jebel Feriana. In the light of the compilation of these
results, a model of the quarry faces evolution is defined. This formalism is too simplistic to
allow the development of models other than those necessary to guide the exploitation of
limestones in the studied area and those similar to it. Nevertheless, this study has the merit to
show the role of the main parameters widely controlling the exploitation.
Considering the potential risk that the waste poured in non-made-up places can generate,
we propose to re-use the consecutive vacuum to excavation as controlled landfill. Such
restoration should constitute a capital priority in matters of local authorities, elected officials,
developers, and conservationists.
By taking into account of the quarry face evolution, the volume of the excavation and the
socio-economic development of Feriana town (waste generation rates per annum), a simple
mathematical model was developed to estimate the quantity of waste poured annually. This
model will evolve over time into a dynamic one, being able to estimate the lifespan of the
controlled landfill.
Actually, no natural site corresponds to the simplistic plan previously foreseen. According
to their experiences, the operators and their partners are led to adjust this method so as to
adapt it with its case of study.
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