Landfills are a common means of disposing waste. Approximately 95% of the world’s garbage is sent to landfill sites [1
]. This method is considered an economic and systematic way to manage garbage when compared to other methods of managing waste, such as the reuse and recycling of garbage and the burning and subsequent burial of garbage in dump sites [5
]. Inefficient landfill management systems in several countries are the cause of harmful impacts that affect both the environment and human health (e.g., surface water and groundwater contamination, gas emissions, and even human suffocation because of the spontaneous combustion of landfill waste) [2
]. In addition, the leachate that is generated within landfills is considered a prime cause of groundwater contamination. The liquid leachate includes different types of pollutants which filter through the landfill’s layers [2
]. In addition to the design process, landfill siting is also a complex task since several significant factors should be accommodated within any study area. These factors include general and local regulations, economic factors, environmental factors, population growth rates, increasing public awareness, human health, and, for local residents, the difficulty of finding land that meets the required conditions to be a landfill site in the face of growing official objection and popular dissent surrounding the idea of the establishment of landfill locations in their areas [2
]. This is also the case with respect to landfill siting in the Babylon Governorate in Iraq.
Landfill design broadly includes two systems: the base liner system and the final cover system. A base liner system is used to control pollution that results from waste in modern landfills. The liner system is intended to protect environmental parameters (soil and ground water) from contamination arising from landfill. In modern landfills, the base liner system is constructed to form a barrier between the environment and the waste and to drain the leachate to treatment facilities through leachate collection systems. There are many types of landfill liner systems, but they can broadly be described as the single-liner system, the composite-liner system, and the double-liner system [14
In contrast, the final cover system is used to separate the waste from the environment through placing layers of final cover over the waste. The final cover layers act to prevent water from infiltrating into the mass of waste, thereby reducing leachate generation [15
]. In addition, the system minimizes surface erosion by boosting drainage into the final cover layers. In theory, the final cover system should operate well during its life span, with the lowest cost for maintenance whilst accommodating settlement due to any decomposition of organic materials in the waste mass [16
According to [15
], the main designs used as final cover solutions for landfills in semi-arid and arid areas in the USA are the “RCRA Subtitle D Cover” and the “RCRA Subtitle C Cover” systems. However, there are alternative designs for a final cover system that can be used, and these include a geosynthetic clay liner cover, a capillary barrier cover, an anisotropic barrier cover, and an evapotranspiration soil cover [17
]. Indeed, in the literature, many studies have given environmental guidelines and recommendations for landfill design in various countries and in different regions, as can be seen below.
In New South Wales, Australia, for example, the land area west of the Great Dividing Range has an arid to semi-arid climate and average rainfall ranges from 15 to 50 cm per annum. The annual average rainfall in Eastern New South Wales ranges from 70 to 140 cm per annum, while the annual rainfall in the far northwest of New South Wales is less than 18 cm per annum [18
In New South Wales, the base liner system design for landfills involves either a primary barrier for municipal solid waste or a dual barrier system (primary and secondary barriers) for restricted (hazardous) solid waste landfills [19
]. The primary barrier liner system can be used in arid to semi-arid areas, and its layers are [19
] (i) a compacted sub-base, 20 cm thick, (ii) a compacted clay liner (barrier soil) ≤1 m thick, with a gradient of 3% transverse and 1% longitudinal direction and a hydraulic conductivity of ≤1.0 × 10−9
m/s, (iii) a geomembrane placed over the clay liner with a thickness of < 2 mm, (iv) a protective geotextile placed on top of the geomembrane to protect it from damage, (v) a non-woven separation geotextile placed over the drainage layer to decrease the entry of fine materials from the waste, (vi) a drainage layer (gravel) with a thickness of 30 cm, and with a hydraulic conductivity of ≥1.0 × 10−3
m/s. The leachate collection pipes are laid within the drainage layer, and the internal diameter of the pipes should be >15 cm with an interval of <25 m.
The recommended design for the final cover layers for landfills in New South Wales (from the top to the bottom layers) is as follows: (i) topsoil of 20 cm, (ii) a re-vegetation layer at least 1 m thick, (iii) a top barrier layer (compacted clay) with a thickness of 60 cm and saturated hydraulic conductivity of ≥1.0 × 10−9 m/s, and (iv) a 30 cm thick support layer.
In Kuwait, in the Arabian Gulf (an arid area), the suggested designs for landfill include both the base liner system and the final cover system [20
]. The layers of the base liner system (from bottom to top) are as follows: (i) a sub grade layer of native soil, with a minimum saturated hydraulic conductivity of 1.0 × 10−7
cm/s, (ii) a highly compacted barrier layer of 90 cm with four lifts (each lift is 22.5 cm) (the hydraulic conductivity of this barrier layer is 1.0 × 10−6
cm/s), (iii) a drainage layer containing coarse materials (gravel or sand) with a thickness of 30 cm, and containing the leachate collection pipes, (iv) a geotextile filter layer over the drainage layer to protect it from clogging by fine materials that might transfer from the waste mass above, and (v) a 60 cm deep protective layer, used to protect the leachate collection pipes from damage and to filter leachate before it is removed to treatment units.
The characteristics of suggested layers for the final cover system for landfill in Kuwait (from top to bottom) are as follows: (i) a topsoil layer, 30 cm thick, containing a mixture of silt and natural gravel, and with a slope of more than 3%, (ii) a drainage layer (30 cm) consisting of sand or gravel, with a slope of 3% at the bottom of the layer and with a hydraulic conductivity of ≥1.0 × 10−2 cm/s (drainage pipes are laid within the drainage layer to transfer leachate to the sump), and (iii) a top barrier layer comprising compacted soil with a hydraulic conductivity of ≥1.0 × 10−5 cm/s (the thickness of this layer is 60 cm with three lifts (each lift is 20 cm)), and (iv) a base layer (natural soil) used to collect gas released from landfill and as a foundation for the cover system layers.
Another example is the suggested design for the new phase of landfill in Southern Makkah, Saudi Arabia, which consists of the base liner system and the final cover (capping) system [16
]. Makkah, Saudi Arabia, is located in a hot, desert climate, and it is notable for high temperatures, even in winter. The average mean annual temperatures are between 24.7 and 38.1 °C, and the average rainfall reading for the years 1986–2000 is 111.8 mm [21
In Southern Makkah, the layers for the base liner system (from bottom to top) are as follows [16
]: (i) a base layer consisting of compacted original soil (natural materials) in situ (the soil is laid down as compacted layers after excavating to the required depth of approximately 1 m above the water table), (ii) a 30 cm thick cushion layer placed over the base layer and composed of compacted clean sand (maximum dry density should be more than 90% since this layer acts as a cushion to the geomembrane liner), (iii) a leachate collection system containing gravel and 30 cm in thickness, and (iv) a 2.5 mm geomembrane (HDPE) used to prevent the groundwater contamination by the leachate.
The final cover (capping) system in Southern Makkah has the following layers [16
]: (i) a foundation cover of sand material, 30 cm thick, placed over the waste mass, (ii) a cushion layer consisting of moderately compacted sand with a thickness of 30 cm (this layer is placed over the foundation cover, and the gas collection pipes are laid within this layer), (iii) a synthetic, bentonite (six mm thick) clay liner (GCL) positioned between two strong but thin layers of the unwoven geotextile as a sandwich to protect the bentonite barrier from cracks (the first unwoven geotextile layer is placed over the bentonite (as a drainage layer), while the second unwoven geotextile is positioned beneath the bentonite to reinforce the GCL liner), (iv) a 60 cm thick topsoil layer with a surface slope of between 3 and 5% to prevent surface erosion by runoff and water pools on the topsoil surface.
In countries that have a tropical climate (especially developing countries), annual rainfall is more than 250 cm and can be as much as 1000 cm in monsoon season [22
]. Mean temperatures in tropical are more than 18 °C [23
]. Both the base lining system and the final cover system are used in these regions.
In such climates, the base liner system consists of five layers as follows [5
]: (i) a base liner layer of clay with a thickness of 40–80 cm, which has a hydraulic conductivity of ≤1.0 × 10−9
m/s, (ii) a geomembrane liner (HDPE), 0.4–0.5 cm thick, placed on the clay layer, and (iii) a leachate collection system that includes the drainage layer (gravel) and leachate collection pipes that are placed within it (the drainage layer should be more than 50 cm thick, with a slope >2%, with a hydraulic conductivity of ≥1.0 × 10−3
m/s), (iv) an optional non-wave geotextile filter layer placed over the drainage layer to protect it from clogging by fine materials that come from the layers above, and (v) a protective layer consisting of compacted soft particles of waste (e.g., paper, organic materials, shredded waste, other smaller particles of waste), with a thickness of between 30 and 50 cm and with a hydraulic conductivity of ≤1.0 × 10−5
According to [5
], the recommended design for the final cover in tropical countries is as follows: (i) an intermediate cover layer (compost material or soil) placed on the waste zone to a thickness of 50 cm and with a surface slope of between 5 and 10%, (ii) an alternative option where the intermediate cover can be replaced by a top sealing system (clay liner) based on settlement progress after 5–20 years (the thickness of the clay liner is 50 cm with a slope of >5%), and (iii) topsoil placed on the clay layer with a thickness of more than 50 cm. Additionally, in tropical countries, dense vegetation is suggested for use in the final cover of the landfill.
In cold regions (e.g., Ireland), the components of landfill design for non-hazardous waste include the base liner system and the final cover (capping) system [24
]. The layers of the base liner system in Ireland are as follows: (i) subgrade, (ii) a composite liner (the lower component) that includes compacted clay, where the layer’s thickness is ≥1 m with four lifts (each lift is 25 cm), and the hydraulic conductivity of the compacted soil is ≤1.0 × 10−9
m/s, (iii) a composite liner (the upper component) consisting of a geomembrane liner (HDPE) with a thickness of ≥2 mm, (iv) a leachate collection system that contains the drainage layer (gravel) with a thickness of more than 50 cm, and where the hydraulic conductivity of the gravel is ≥1.0 × 10−3
m/s (the leachate collection pipes of 20 cm diameter are placed within the drainage layer), and (v) a protective layer laid over the leachate collection layer to prevent any fine materials from moving into the drainage layer and clogging it and to protect the geomembrane from damage.
The components of the final cover system in Ireland are as follows: (i) a topsoil layer, between 15 and 30 cm thick, consisting of uniform soil with a slope of more than 1:3 to prevent aggregation of water on the landfill’s surface, (ii) a sub-soil (topsoil support) layer positioned beneath the topsoil layer with a thickness of ≥1 m, (iii) a drainage layer beneath the support-topsoil layer with a thickness of 50 cm and a hydraulic conductivity of ≥1.0 × 10−3 m/s, (iv) a 60 cm thick compacted barrier layer with three lifts (each lift of 20 cm) and a hydraulic conductivity of ≤1.0 × 10−9 m/s, and (v) a foundation layer (optional) consisting of natural material with a thickness of more than 30 cm and a hydraulic conductivity of ≥1.0 × 10−3 m/s.
Despite these various working landfill systems that exist in the world, all processes regarding waste in the Babylon Governorate, starting from the collection to its disposal, lack proper management. At present, 16 locations for waste disposal are spread over the cities of the Babylon Governorate. All these locations are considered irregular according to Iraqi authorities, and these waste disposal locations have all failed to adopt the criteria used in developed countries when being selected [25
]. According to [15
], the composition of municipal solid waste (MSW) in the Babylon Governorate is 55% organic material. In the Babylon Governorate in 2013, the solid waste quantity was approximately 483 thousand (tonnes) [26
], and the estimated solid waste quantity in 2030 will be close to one million (tonnes) [25
]. In addition to this growth in MSW, landfill siting is complicated by the fact that the groundwater level (beneath the surface) in the Babylon Governorate is shallow. The maximum reading of groundwater depth is 15.97 m, while the minimum depth is 0.423 m [28
As part of an updated study, and in order to check the soil characteristic as well as the water level from the ground surface to the groundwater depth, soil investigations were done in the year 2016 on the selected sites for landfill in the Babylon Governorate. This investigation provided accurate information to enable planners to know the locally available soil materials that could contribute in the construction of the suggested layers within the landfill design. In addition, this information proved useful when selecting the height, types, and the number of layers above the surface, as well as the depth and type of layers that will be used beneath the surface. The information also gives planners a suitable method for selecting layers and other requirements in cases where groundwater depth is shallow in the study area [24
]. Criteria that conform to the requirements of international scientific and environmental standards were also employed in the process of selecting locations for landfill in all districts in the Babylon Governorate. Subsequently, multi-criteria methods (MCDM) and GIS software were applied together in order to establish the optimum location for landfills. The multi-criteria methods were used to obtain relative weights for the criteria in certain steps and different procedures. The main multi-criteria methods applied for this purpose were a pair-wise comparison method, ranking methods, and rating methods. Many previous studies have also used multi-criteria methods and GIS software to determine candidate sites for landfill such as [29
In the present study, the “Hydrologic Evaluation of Landfill Performance” (HELP 3.95 D) model was applied to check the suggested design for the selected sites in the Babylon Governorate districts. This was because the main additional source for the leachate that resulted from waste is the amount of water that infiltrates from rainfall. This model enables users to compute the amount of leaching into the suggested layers and the water level on the surface of barrier layers at various periods. The required information that should be entered into the HELP model to calculate the leachate and to select the proper soil materials and layer thicknesses are weather parameters and the soil characteristics for each layer. The main goal of this model is to know whether any leachate is coming from the waste zone through the layers located under it and thus causing groundwater contamination [35
]. To calculate the leachate throughout the layers in landfill sites, many previous studies have also applied the HELP model (e.g., [38
The aim of this study is to adopt a suitable design for landfills in the arid area which is distinguished by shallow groundwater depth. The Babylon Governorate was selected to be a case study for the arid area in order to validate the suggested design for landfill that will apply in the study area: the base liner system and the final cover system. The suitability of the three scenarios for the final cover system that will be used in the arid area were checked using the HELP model.
1.1. Study Area
The Babylon Governorate lies in the middle part of Iraq, about 100 km to the south of Baghdad (the Iraqi capital), between latitudes 32°5′41″ N and 33°7′36″ N and between longitudes 44°2′43″ E and 45°12′11″ E (Figure 1
). The area of the Babylon Governorate is 5337 km2
, and its population is about 2,200,000 [44
]. Administratively, the Babylon Governorate has five major districts (locally called Qadhaas). These districts are Al-Hillah, Al-Mahawil, Al-Hashimiyah, Al-Qasim, and Al-Musayiab. Each district is divided into small cities, and, in total across the five districts there are 16 small cities that are administratively linked to major districts.
The Babylon Governorate is located in the arid, hot region between the rivers Tigris and Euphrates [45
]. The winter is cold and rainy, with approximately 6.8 h/day of sunlight. The average daytime temperature is 24 °C and, although temperatures normally remain above 0 °C (10 °C), they can decrease below freezing during some nights. The summer season is particularly hot, with an average of approximately 12 h of sunlight/day and the weather is usually dry with no precipitation. The temperature during the summer can reach more than 50 °C in the shade. The average temperature ranges during the summer months are between 40 °C in the day and 24 °C at night. The annual average wind speed in the Babylon Governorate is 7.2 km/h, with the wind predominantly coming from the northwest and blowing throughout the year. For the years from 2005 to 2016, average annual precipitation was 102 mm. The average annual relative humidity is 45.8 [47
1.2. Selecting and Assessing the Candidate sites for Landfill
GIS software was applied using (MCDM) methods to choose the optimum candidate locations for landfill in each district in the Babylon Governorate. Using the GIS software (10.5 (Lulea University of Technology, Lulea, Sweden)), for the high vulnerability criteria, 15 final maps were produced for the study area. These criteria are discussed and explained in [51
]. Geologically, clastic (fertile) materials known as alluvial deposits extend from the surface to a depth of more than 50 m, and no rocks are exposed in this area [57
Two locations were chosen from the final map of each district (10 locations for the Babylon governorate), and these locations were compared with their positions on the satellite images of the governorate. Moreover, in 2016, the soil investigations and soil sample testing for the chosen sites were conducted by the National Center for Construction Laboratories and Research Babylon-Iraqi Ministry of Housing & Construction [58
shows the symbols of the chosen location in the Babylon governorate (two sites for each district). These symbols represent the Al-Hillah district (Location 1 (Hi-1) & Location 2 (Hi-2)), the Al-Qasim district (Location 1 (Q-1) & Location 2 (Q-2)), the Al-Hashimiyah district (Location 1 (Hs-1) & Location 2 (Hs-2)), the Al-Mahawil district (Location 1 (Ma-1) & Location 2 (Ma-2)), and the Al-Musayiab district (Location 1 (Hu-1) & Location 2 (Hu-2)) [52
Adequate landfill design is the main factor in environmental requirements to prevent the contamination of groundwater by the leachate produced from a landfill site, especially in a low groundwater level and arid area like the Babylon Governorate, Iraq.
Proposed designs for the selected landfill sites in Babylon Governorate using a Geographic Information System environment and MCDM methods consist of a base liner system and a final cover system. For three scenarios, the suggested design for the base liner system consists of a protection layer of sand material with a thickness of 30 cm positioned beneath the zone of waste. A drainage layer (gravel) of 30 cm was placed beneath the protective layer, and the leachate collection pipes are laid within this layer to remove and send the leachate to the treatment facilities. A 0.15 cm thick geomembrane liner (a type of high-density polyethylene) was placed directly over the bottom barrier layer. The bottom barrier layer consists of composite soil of sandy clay at a thickness of 60 cm. This layer is set in situ as four sub-layers (each being 15 cm thick) under high compaction.
To avoid crack forming in the clay layer when it is exposed to drying from below by heat that is released from the bottom of the landfill or from surrounding conditions [19
], a mixture of clay with granular materials (e.g., sand) is usually used to reduce the potential for swelling and shrinkage and to improve the shear strength of cohesive clayey soils [79
]. Mixing clay soil with granular materials is a soil improvement method. The mixture of green clay (70%) or red clay (80%), which are available in Iraq, with sand (in the bottom barrier) yields a hydraulic conductivity of 1.0 × 10−9
The compacted waste is put over the ground surface because of the low groundwater level in Babylon Governorate. The solid waste height was 2 m, with a density of 700 kg/m3 (after compaction) in order to reduce settlement and deformation on the bottom barrier soil surface under the cumulative loads of waste over the landfill surface. Then, the intermediate soil cover of 30 cm is used to cover the waste mass to conserve the environment in the surrounding areas.
In the current design of landfills, for the final cover system, three scenarios that are suitable for arid areas were suggested. The first scenario (evapotranspiration soil cover (ET), capillary barriers) contains the coarse-particle soil layer (coarse sand) with a 30 cm thickness, and this is placed over the intermediate cover layer. The fine-particle soil layer (moderately compacted loam) with a thickness of 75 cm is placed on the coarse particle soil layer. A 15 cm thick layer of topsoil is then placed on top of the fine particle soil layer, which consists of silty-clay loam.
In the second scenario, the “RCRA Subtitle D” cover design was used, but it was modified by adding the coarse sand layer (30 cm) as a foundation for the layers of the cover system, and which was placed over the intermediate cover. Then, the clay soil that is used in the “RCRA Subtitle D” cover design as a barrier layer was replaced by the highly compacted soil of sandy clay (45 cm), which is available in the Babylon Governorate. The topsoil layer of silty clayey loam is placed over the barrier layer with a thickness of 15 cm.
In the third scenario, the suggested design for the final cover system was based on combining certain layers from the first and second scenarios. This cover consists of the intermediate cover (30 cm) of moderately compacted silty-clay loam, and the foundation layer (30 cm) of coarse sand placed over the intermediate cover. The top barrier layer (45 cm) of highly compacted sandy clay, and with a saturated hydraulic conductivity of 1.0 × 10−7 cm/s, was placed over the foundation layer. The 0.5 cm thick geomembrane liner (HDPE) was placed on the top barrier. The supported vegetation layer of moderately compacted loam (fine particles) was placed on the geomembrane liner, and this layer is used to store water within it and on the top barrier layer until evaporation takes place. The topsoil layer (15 cm) of silty-clay loam is placed over the supported vegetation layer.
According to [41
], mixing sand with proportions of green clay (30–50%) and red clay (40–60%) yields a hydraulic conductivity of 1.0 × 10−9
to 1.0 × 10−10
m/s. Therefore, the top barrier layer of sandy clay is more suitable than the clayey soil for the final cover system of landfills in arid areas.
The top barrier layer (in the second and third scenarios) and the top uniform (monolithic) layer (fine practical) (in the first scenario) must be maintained for a certain time to avoid deformation on these layers’ surface (without a ripple) and cracks when the organic material within the waste zone degrades [5
]. The waste in the Babylon Governorate is composed of more than 55% organic material [80
]. Therefore, a similar amount of soil material was used to construct the top barrier layer and the top uniform layer, but this should be subject to monitoring and maintenance (if it is necessary) for a specific time until the settlement in these surface layers has completed before placing other layers of the final cover system over it.
In the current design, the HELP 3.95 D model was applied to check the suggested design appropriateness for the chosen landfill sites in Babylon Governorate. This model considers hydrology parameter data as well as the required data for evapotranspiration and soil layers for the proposed landfill design. In the current model, results showed that the mean yearly rainfall reading was 10.193 cm for the chosen period from 2005 to 2016. Actual evapotranspiration, runoff, and changes in water content in all soil layers are the results of mean yearly rainfall. The value of mean yearly runoff (22.39 mm) in the second scenario was higher than in both the first scenario (10.76 mm) and the third scenario (10.74 mm). The values of actual evapotranspiration in the first scenario (87.44 mm) and third scenario (87.97 mm) were more than that in the second scenario (77.25 mm). The mean yearly values of change in water storage were 3.74 (Scenario 1), 2.29 (Scenario 2), and 3.22 mm (Scenario 3) (Figure 6
For all scenarios, the mean yearly results obtained showed that there was no water percolation through the bottom barrier layer during the years from 2005 to 2016. In the first scenario, the amount of water drainage that was removed from the leachate collection system was 3.0 × 10−5 mm. In the second and third scenarios, there was no leakage through the soil layers that were positioned under the ground surface. In the third scenario, the mean water level above the geomembrane surface (Layer 3) within the final cover system was about 33 mm, and the amount of water leakage into the top barrier soil (Layer 4) was 0.011 mm.
In this model, annual runoff values in the second scenario were higher than the values in the first and third scenarios, which were close to each other. Furthermore, the values of the actual evapotranspiration for the first and third scenarios were almost equal and more than the values in the second scenario (Figure 7
). For all three scenarios, most values of actual evapotranspiration during the chosen period (2005–2016) were higher than runoff values, except for some years in the second scenario where the runoff values were higher than those of the actual evapotranspiration due to a high amount of rainfall.
In the second and third scenarios, the results of annual values showed that there was no water percolation into the bottom barrier layer for the years from 2005 to 2016. Moreover, in the first scenario, there was no leachate percolation through the bottom barrier layer during the study years apart from in 2013 and 2014. In these years, water percolation figures were 1.4 × 10−5 and 4.0 × 10−6 mm, respectively. These values are considered small, and they resulted from the high rate of rainfall during these years. In such cases, the layer (Layer 2) of fine particle soil (within the final cover) reached a limit of saturation, meaning that water infiltrated quickly into the layer of coarse particle soil, and through it to the under layers. Although, these values were small, they should still be considered when adopting this design in the study area.
The amount of water content in all soil layers for the years from 2005 to 2016 for the second scenario were more than that for the first scenario, and the first scenario was higher than the third scenario. This is due to the use of additional layers that acted to increase the final water content of the soils in each scenario. For the three scenarios, the values of water content change in the soil layers yielded a negative hydrological water balance in the last year of the selected period (2016). Therefore, the water interception was equal to 0.0 mm/year for the three scenarios.
In the HELP model, the maximum daily value of runoff in the second scenario (94.33 mm) was higher than in the first (65.62 mm) and third scenarios (65.47 mm). For all scenarios, there was no leakage of leachate from any layers of the landfill situated beneath the ground surface. In the third scenario, the average highest daily value of the water level above the geomembrane surface (Layer 3) was 156.65 mm. The value of water percolation through the top barrier soil (Layer 4) was 1.4 × 10−4 mm, but there was no water leakage through the layers beneath it.
The cost of the “RCRA Subtitle D” cover design (second scenario) was cheaper than the design for the final cover of evapotranspiration (ET) (the first scenario) [15
]. Therefore, the third scenario of final cover design is logically more expensive than that in the first and second scenarios because it used additional layers in its design.
For all layers, the value that resulted from subtracting the amount of final soil water storage from the initial soil water storage was 4.486 (first scenario), 2.75 (second scenario), and 3.863 cm (third scenario). For all scenarios, the value of interception water was 0.0 mm/year.
In the first scenario, the additional value in the final water content in all soil layers in 2016 compared to initial water content in all soil layers in 2005 resulted from the infiltration of surface water through the topsoil layer (Layer 1), the fine particle soil layer (Layer 2), the coarse particle soil layer (Layer 3), and the waste mass layer (Layer 5). In the second scenario, the value of final water content in the soil layers of the landfill increased in 2016 due to the infiltration of a quantity of rainfall that came from the surface through the topsoil layer (Layer 1) and the top barrier soil layer (Layer 2). In the third scenario, the value of final water content in all the soil layers in 2016 was higher than the initial value of soil water content in 2005. This is because surface water infiltrated into the topsoil layer (Layer 1) and the support vegetation layer (Layer 2), so a small amount (1.543 cm) infiltrated into the waste mass itself (Layer 7).