Journal of Water Resource and Protection, 2013, 5, 440-445 Published Online April 2013 (
Assessment of the Impact of the Landfill on Groundwater
Quality: A Case Study of the Mediouna Site, Casablanca,
Driss Smahi, Ouafa El Hammoumi, Ahmed Fekri
Department of Geology, Faculty of Sciences Ben M’sick, Casablanca, Morocco
Received January 23, 2013; revised February 25, 2013; accepted March 9, 2013
Copyright © 2013 Driss Smahi et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
A local case study for the environmental impact of landfill leachate on groundwater quality along and across the Medi-
ouna landfill is presented, based on physicochemical and statistical approaches. The landfill has been operational since
1986 and it receives municipal solid wastes produced by the city of Casablanca, whose the daily waste output exceeds
4000 t. This waste is stockpiled in old sandstone quarries; the site has never been sealed before its opening. The aim of
this study is to update the knowledge about groundwater quality around the landfill, to determine the factors controlling
the extent of groundwater contamination and compare the results with those of 1989 and 2001. To evaluate groundwater
pollution due to this landfill, piezometric level and geochemical analyses have been carried out on 19 wells. The phys-
icochemical data of groundwater down-gradient of the landfill site is showing a deterioration of its quality, to the point
that the wells have become unusable. The statistical treatment of physicochemical data by principal components analy-
sis allowed the mapping of three areas downstream of the landfill. The first is hardly polluted, the second is moderately
polluted and the third is characterized by mineralization through their waters and the almost absence of organic matter.
The extent of groundwater contamination from an area with a radius of 200 m in 1989, to an area with a radius of about
1 km in 2001 to more 2 km as of today. This extension is controlled by the structural factor of faults, by the lithology of
aquiferous and the intensity of water pumping; the wells equipped with pumps exert pressure against the advanced front
of the pollution.
Keywords: Leachate; Landfill; Groundwater; Pollution; Morocco
1. Introduction
The consequences of solid waste disposal in landfills are
gas and leachate generation due primarily to microbial
decomposition, climatic conditions, refuse characteristics
and landfilling operations. The quantity of leachate gene-
rated is site-specific and a function of water availability
and weather conditions as well as the characteristics of
the refuse, the landfill surface, and underlying soil [1-6].
The quality of landfill leachate is highly dependent upon
the stage of fermentation in the landfill, waste decompo-
sition, operational procedures, and co-disposal of Indus-
trial wastes [7-10].
Mediouna’s landfill receives waste from the entire Ca-
sablanca metropolis, whose population and growth are
constantly increasing. Indeed, the daily quantity received
by the landfill has increased from 2.1 T in 1989 to 2600
T in 2000 to more than 3200 T in 2008 of wastes of dif-
ferent types, ranging from organic to inorganic, hazard-
ous and non-hazardous [11-14]. The site is considered
the largest nationally and it has no waterproof device or
any leachate drainage system and biogases collection.
The quantity estimated daily amount of leachate is 1277
m3/d in 2007. While the leachate poses a threat to under-
lying groundwater [14-17], the site selection was how-
ever dictated by the availability of public land, and the
fact that it didn’t have to conform to any environmental
regulations at the date of its opening.
The objectives of this study are to update the current
data on groundwater pollution, and that will eventually
be compared to those of 1989 [16], and 2001 [17] in or-
der to examine the extent of pollutants and to determine
the factors controlling the advancing front of pollution
after more than two decades of implementation of this
landfill, and to establish a baseline of water quality on
the eve of the closure of the landfill in order to designate
opyright © 2013 SciRes. JWARP
a network for monitoring pollution. This study discusses
the hydrogeochemical aspect of groundwater, which were
the subject of physico-chemical measurements as well as
parameters indicative of organic pollution, such as COD
and DO, the results were the subject of statistical proc-
essing by principal component analysis.
2. Field Site Description
The location is situated on the south of Casablanca, one
mile north of the municipality of Médiouna (Figure 1)
and adjacent to a national road (RP 7).
Currently, the landfill receives 4000 t of daily waste of
various natures, which accounts for about 1300 m3/day
[13] of landfill leachate with high polluting load.
This landfill is composed of 13 quarries along 60 of 78
hectares are assigned to the landfill, which give a volume
of 3 million m3. The area is a part of the geological unit
knows as the Moroccan coastal meseta bordered by the
Atlantic Ocean and the massive plains of central Mo-
rocco [18]. Indeed, the Paleozoic bedrock of the landfill
are formed of Cambrian and Ordovician marine sedi-
ments modified by the Hercynian orogenesis, marine for-
mations overlain by Plio-Quaternary lumachelle and con-
glomeratic facies covered with sandstones [19-22].
There is a bidirectional flow [15], one from the West
with a hydraulic gradient around 2% indicating bad water
circulation and another from the East with a low hydrau-
lic gradient about 1%. So we have a good flow of ground-
water in this area.
The small depths of the groundwater table are con-
trolled essentially by the variation of the topography [15].
The presence of zero meter piezometric level in the area
indicates another potential source of pollution: agricul-
tural and industrial activities.
Figure 1. Geographical situation of landfill site.
3. Materials and Methods
Two sampling campaigns were conducted, the first in
October 2010 in the period of low tide and the second in
April 2011 in the period of high tide. The sampling net-
work was composed of 19 wells, of which 3 (W1, W2
and W3) were upstream of the landfill (control wells).
The other 16 remaining wells were downstream of the
landfill (Figure 2). The majority of wells are used for
drinking water supply, irrigation, animal feed and for in-
The temperature (T), electrical conductivity (EC) and
pH were measured in situ using a multiparameter con-
ductimeter (USP 645) and pH meter HANNA (HI 9126).
The concentration of chloride (Cl), sulfate (SO2
), cal-
cium (Ca2+), magnesium (Mg2+), carbonates (3
oxydability and chemical oxygen demand (COD), were
determined using the volumetric method (AFNOR, 1990).
The biochemical oxygen demand (BOD5) was measured
by BOD meter HANNA (HI 98186). Nitrate (3
) are
analysed by colorimetry method using spectrophotometer
(Spectronic 20D). The heavy metals (Fe, Zn, Pb, Al, Mn,
Cu, Cd, Cr) were determined using atomic absorption
spectrophotometer (Unicam 929 AA Spectrometer).
The piezometric level and thematic maps were gridded
using the inverse distance weighted.
4. Results and Discussion
The results of physicochemical analysis and indicators of
pollution of two campaigns are presented in Tables 1 and
In this study, the relationship between various elements
has been studied using the Pearson correlation matrix. The
result matrix shows up the strong positive correlation of
EC with most of the variables. EC shows significant rela-
tionship with 3
(0.74), COD (0.91) and also with
the chemical elements Cl, Na+, Ca2+, Mg2+ and K+ (r
range 0.70 and 0.83) and a negative correlation with DO
(0.65). The correlation between K+ and 3
does in-
dicate the anthropogenic pollution source and some ag-
riculture related solid waste in the area which is being
dumped at the landfill site.
The results of the factors analysis based on the three
most significant factors indicate that these factors justify
about 86.6% of total sample variance. The variance ex-
planation of the factors, are 65.33% for factor 1, 13.4% for
factor 2 and 7.88% for factor 3.
The variables of EC, Cl, Na+, 3, COD, K+,
Mg2+ and Ca2+ have high positive loading for factor 1,
this factor represents the water mineralized and enriched
in organic matter, and that the variables 3 and 4
NO 2
have high positive loading on factor 2 and 3 with pH and
The projection (Figure 2) of the wells on the principal
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Table 1. Physico-chemical characteristics of groundwater in October 2010 (mg/l unless otherwise stated).
Well pH EC (µs/cm) DO COD
Cl Na+ Ca2+ Mg2+ K
W1 6.9 1250 324.50 5.67 0 264.50 72.70 132.4048.40 220.74 11.10 2.30
W2 7.37 544 279.00 4.4 0 198.60 23.10 105.6038.20 177.81 10.06 2.40
W3 7.71 623 237.60 4.23 0 172.10 19.80 90.20 32.50 151.97 8.50 2.10
W4 6.82 10,100 1021.00 0.71 275 334.20 156.301922.80591.60883.38 121.4069.70
W5 7.47 8900 1234.00 0.83 234 450.10 158.202616.20927.301132.96 163.30104.20
W6 7.7 1772 487.00 3.1 43.4 424.50 53.80 455.70113.40434.19 26.90 3.40
W7 8.01 2840 335.50 4.2 0 742.00 154.80406.90 81.90 561.99 20.40 2.70
W8 7.25 1135 658.20 1.6 0 132.60 107.10515.20150.40420.50 46.40 3.80
W9 7.32 2370 649.10 1.75 67 251.40 109.201048.80362.50524.20 55.90 6.20
W10 7.5 931 633.00 3.6 0 401.20 103.60318.20189.90317.90 32.60 4.50
W11 7.1 1830 488.40 3.4 0 311.40 181.30420.60162.70373.28 42.50 4.50
W12 6.76 6550 536.80
1.96 83 101.40 106.401272.80309.70640.09 79.70 4.70
W13 7.15 3440 531.30 2.5 79 1005.90127.60972.70193.30874.11 60.80 6.30
W14 7.24 1364 486.80 2.6 65 493.20 124.80907.40209.40630.49 59.60 4.90
W15 7.35 2070 382.00 4.2 0 372.40 139.90476.40125.40377.26 38.40 3.60
W16 7.24 4570 522.00 0.88 54 458.40 256.50470.20207.80436.69 44.60 6.80
W17 7.03 6050 494.50 2.67 113 107.90 23.40 632.50256.90255.12 38.90 62.50
W18 7.42 2320 297.10 4.6 37 345.30 180.60275.50129.90262.50 36.70 3.20
W19 7.85 2940 296.60 5.2 0 242.70 122.40212.4076.40 242.80 21.40 2.40
Table 2. Physico-chemical characteristics of groundwater in April 2011 (mg/l unless otherwise stated).
Well pH EC (µs/cm) 3
Cl Na+ Ca2+ Mg2+ K
W1 6.7 1096.0 384.7 6.4 0.0 189.1 54.7 153.9 51.9 208.6 8.3 2.3
W2 6.8 502.0 341.4 5.9 0.0 156.6 19.3 127.3 42.0 171.6 7.7 2.5
W3 7.3 571.0 282.1 6.0 0.0 129.5 15.9 105.2 34.7 141.8 6.3 2.0
W4 6.7 11560.0 1004.9 1.8 289.5 138.5 57.4 1709.2531.3 706.1 74.8 32.3
W5 7.5 7990.0 1413.5 1.6 323.8 183.1 90.8 2132.6778.4 1032.4 110.8 34.9
W6 6.9 1532.0 199.5 4.9 55.7 132.2 6.2 255.5 60.5 120.3 5.4 2.8
W7 7.0 2540.0 158.3 5.0 0.0 264.9 5.6 395.9 40.0 357.9 10.2 2.7
W8 7.1 1076.0 339.3 1.3 0.0 101.5 35.9 240.1 112.3 172.3 11.9 5.5
W9 6.5 5870.0 177.8 3.9 89.0 179.1 21.7 381.1 139.2 150.1 12.4 5.2
W10 7.1 1084.0 114.2 5.1 0.0 166.9 6.9 228.5 98.8 86.9 6.8 1.9
W11 6.7 1833.0 333.2 5.8 0.0 155.1 68.8 278.4 130.8 202.2 14.7 5.9
W12 6.3 8110.0 204.1 2.0 112.0 163.1 27.1 676.1 145.2 295.5 28.6 5.7
W13 6.7 3570.0 125.7 1.8 74.2 426.0 48.3 542.4 127.3 366.8 19.8 13.5
W14 6.9 1288.0 209.2 3.1 82.0 250.2 35.4 469.7 112.1 281.1 20.8 7.3
W15 6.9 2110.0 297.7 4.6 0.0 161.5 30.9 190.6 63.7 181.1 14.2 2.7
W16 7.2 4290.0 341.8 5.1 66.4 153.4 54.2 315.3 157.9 216.7 9.1 9.4
W17 7.0 5160.0 265.6 2.2 254.0 167.9 57.2 1198.8232.2 305.3 36.4 34.6
W18 7.2 1938.0 318.6 2.8 53.0 210.1 116.2 279.8 122.3 217.7 23.2 2.9
W19 6.8 1881.0 276.4 6.2 0.0 132.0 64.8 182.6 60.5 176.0 11.7 1.5
-1-0.75 -0.5-0.2500.250.50.751
F2 ( 13.40 %)
F1 (65.33 %)
W1 0
W1 3
W1 4
W1 8
F2 ( 13.40 %)
F1 (65.33 %)
Figure 2. Projection of physicochemical parameters and
wells on the principal plane of the P CA.
plane of PCA shows a wide dispersion reflecting the
variability in their physicochemical parameters. However,
four groups are identified:
Group I: located at the extreme positive side of factor
1, contains two wells W4 and W5. This group is cha-
racterized by its high organic matter content (COD
between 234 and 275 mg/l) is also characterized by
its strong mineralization (EC between 8.9 and 10.1
ms/cm). These two wells are located on the front and
down-gradient of the landfill.
Group II: positioned on the positive side of factor 1, it
consists of the wells W9, W12, W13, W14, W16 and
W17. This group is characterized by presence of or-
ganic matter content (COD between 67 and 113 mg/l)
and also by the relatively high electrical conductivity
data of 1.4 and 6.5 ms/cm indicating the water miner-
alization. All wells of this group are located down-
gradient of the landfill.
Group III: located in an intermediate position on a
factor 1, concern the wells W6, W7, W8, W10, W11,
W15, W18 and W19. It is characterized by high val-
ues of electrical conductivity reflecting the water mi-
neralization and a total absence of organic matter ex-
cept W6 and W18 which have respectively 43.3 and
37 mg/l of COD.
Group IV: located on the negative side of a factor 1.
Concern the wells W1, W2 and W3 located upstream
of the landfill. These wells are characterized by the
complete absence of organic matter and low mineral
content of their waters.
Results obtained in this study show that the ground-
water quality underlying Mediouna landfill site has been
differently impacted. They also allow us to plot a map
showing the advancing front of the pollution (Figure 3):
An intact area located upstream of the landfill in-
cludes W1, W2 and W3.
An area hardly polluted by the strong presence of
organic matter and very high mineralization and the
brown color of their waters.
A moderately polluted area characterized by the pre-
sence of organic matter and a significant mineraliza-
tion but lower than in the first area.
An area characterized by mineralization through its
waters and the near absence of organic matter, since the
values of COD were not detected in almost all of its
wells. It should be noted that the matrix of the aquifer
Figure 3. Typology of pollution obtained by PCA.
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Figure 4. Evolution of the front of the pollution between 2001 (left) and 2011 (right).
moves from a quartzic facies to schale facies downstream
of the landfill, the change of lithologic facies may con-
tribute to the mineralization of water.
Evolution the Extent of Pollution from 1989,
2001 to 2011
Comparing these results with those of 2001 [17] and
those of 1990 [23], we are able to predict the rate of pro-
gress of the front of the pollution more than two decades
of commissioning landfill, identify factors controlling
this progression (Figure 4), and make the following con-
The area contaminated by organic pollution and min-
eral (GI and GII) has undergone extensions in differ-
ent directions depending on the structural control ex-
erted by fracturing on one hand and the pressure ex-
erted by the pumps at the water points on the other. In
fact, this area has reached more wells between 2001
and 2011, the difference of electrical conductivity
data varies from 1000 μs/cm for W9 over 5000 μs/cm
(W4 and W5) proximal to the wells of the landfill.
We also note that the W16 has increased by more
than 3000 μs/cm even if it is positioned distal to the
landfill, this increase is probably due to another source
of mineralization.
The front of the pollution increased, it spent an area
with a radius of 200 m in 1989 [16] to an area with a
radius of about 1 km in 2001 [17] more 2 km now.
This growth is controlled by fracturing [14,15] and
the pressure on water demand. In fact, the faults af-
fecting the area functioning as channels transporting
the leachate discharge downstream.
The impact of the landfill gradually fades one moves
downstream, this attenuation is marked by the decrease
in the content and electrical conductivity of organic mat-
5. Conclusions
Hydrochemical data of all samples do indicate an em-
pirical relation between landfill leachates and groundwa-
ter sampling. The results of factor analysis indicate that
pollution source is dominated by natural process in the
vicinity of this landfill site. Moreover, positive loading of
most of the factor for chemical elements and indicators
of organic pollution clearly show landfill leachates im-
pact the groundwater quality especially in the down gra-
dient of the landfill and in the direction of groundwater
flow which is further supported by PCA finding of three
groups of wells under the influence of landfill leachates.
The first group contains wells with very EC and organic
matter load, the second includes wells that have high EC
and organic matter content but more or less than the first
group and the third group including wells of water min-
eralized without organic matter.
Mapping of this data shows the impact of the sur-
rounding geological advancing front of the pollution and
also of the impact of human activities, the wells equipped
with curtain hydraulic pumps against the advancement of
contaminants downstream.
The comparison of data obtained with those obtained
in 1989 and 2001 shows an increase in the front of the
pollution, from an area with a radius of 200 m in 1989
[17], to an area with a radius of about 1 km in 2001 [18]
to more 2 km as of today. This growth especially is con-
trolled by fracturing and the pressure on water demand.
Indeed, the faults affecting the area functioning as chan-
nels transporting the landfill leachates downstream.
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