Draft Report

Solid Waste Disposal at Reppi (issues, and

concerns for planning)

Addis Ababa City Administration

Addis Ababa City Cleansing
Management Agency
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

School of chemical Engineering, Addis Ababa Institute of Technology

&
Center for Environmental Engineering, Collage of Natural and
Computational Science
Addis Ababa University

Draft Report
Solid Waste Disposal at Reppi
(issues, and concerns for planning)

Addis Ababa City Administration Office of the City Manager/ Addis

Ababa City Cleansing Management Agency

January, 2024
Addis Ababa

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Solid Waste Disposal at Reppi (issues, and concerns for planning)

STUDY TEAM MEMBERS

Project Core Management Team
Name Institute Address
Prof. Seyoum Leta, CES, CNCS seyoum.leta@aau.edu.et
Dr. Shimelis Kebede SCBE, AAiT Shimelis.kebede@aait.edu.et
Prof. Zebene Kiflie SCBE, AAiT zebene.kifile@aau.edu.et
Dr. Berhanu Assefa SCBE, AAiT berhanu.assefa@aait.edu.et
Dr. Ahmed Hussen CES, CNCS ahmed.hussen29@aau.edu.et

Study team
Dr. Ing Mebruk Mohammed SCES, AAiT mebruk.mohammed@aau.edu.et
Dr. Wangari Furi CES, CNCS amenwako2010@gmail.com
Dr. Sileshi Degefa ES, ECSU sileshi.degefa@gmail.com
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Executive Summary

This study aims to provide an overview of the impacts and evaluate the current situation
and future possibilities regarding the capacity of Reppi for disposal of municipal solid
waste. The primary concerns related to Reppi are public health and safety, which have
significant implications beyond the immediate vicinity of the dumpsite. This study also
highlights the environmental risks associated with groundwater, and surface water,
which extend beyond the Reppi's location. Additionally, the structural safety of Reppi
becomes a major concern in its surrounding area, particularly regarding the potential for
sliding. To ensure the safety of the dumpsite, it is crucial to consider geotechnical-
engineering factors that influence the stability of the accumulated waste and the
underlying soil or geology throughout its lifespan. Accurate understanding and
conservative estimation of these factors are essential in addressing local safety issues.

The Reppi solid waste disposal site contains untreated rubbish consisting of various
types of waste materials. These include biodegradable solids like vegetables, paper, and
metal, as well as inert solids such as glass and plastics. Additionally, there are other
unclassified materials that pose a significant threat to the quality of underground water.
The impact of dumping solid waste on open ground is most evident in the high levels of
COD (Chemical Oxygen Demand) found in the groundwater. While the groundwater
meets the quality parameters set by the World Health Organization (WHO) for most
aspects, the COD levels exceed the WHO standard. It is important to note that even though
the parameters within the WHO standard are met, it does not guarantee the absence of
groundwater contamination from leachate. Instead, it indicates the current ability of the
soil layer beneath the Reppi solid waste disposal site to attenuate the contaminants.
However, this attenuation capacity of the soil layer may gradually decrease as excessive
leachates continue to be released into the soil, ultimately leading to contamination of the
groundwater zone.

The existing landfill site, situated less than 50 meters away from the highway and less
than 100 meters away from the residential area (Fig A), does not comply with
internationally recommended standards. The waste management practices currently
implemented at Reppi are likely to incur hidden costs associated with pollution and the
contamination of surface and groundwater.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

The stability of the waste slope is crucial in determining whether additional waste can be
disposed of. The potential for slope failure at the site was thus also evaluated. This study
focuses on the potential vulnerability related to the physical stability of the site. The
analysis of slope failure was carried out by three-dimensional slope stability analysis
software developed by USGS (Scoops3D). The possibility of slope failure (with a factor of
safety less than 1.5) was assessed considering groundwater and seismic activity. The
slope stability analysis was conducted using estimates of water table levels, using
unconfined aquifer system modelling. Unfortunately, the stability analysis has indicated
a potential risk of slope failure at the site (Fig B). The analysis of slope stability was
conducted for both wet and dry season situations. The analysis has revealed that there is
a possibility of slope failure due to factors such as natural occurrences like rising
groundwater levels and seismic activities. This issue poses an even greater threat to
overall stability if these loads coincide.

Fig. A Reppi Waste topography

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Fig. B. 3D Factor of safety distribution across the waste disposal site for seismic + wet
season

The results of the slope stability analysis reflect groundwater level configurations during
wet season is found to dictate the stability than seismic activities expected around the
site. This risk becomes more significant during the wet season, necessitating regular
monitoring of tension crack development along the top of the accumulated waste.
Monitoring the leachate level will also contribute to enhancing stability. Appropriate
drainage methods should be implemented to control the leachate level within the waste
complex, as natural causes of instability such as seismic activities are difficult to manage.

Based on the analysis carried out on the active waste disposal area in the Reppi
compound, it is projected that the site will reach its maximum capacity within a
timeframe of 10 to 16 months if the current management practice is maintained
exclusively over the active waste disposal site. Nevertheless, if the current management
practice is expanded to encompass the active and already capped waste disposal site, the
site's capacity will be reached within a period of 20 to 26 months. However, if effective
waste management is implemented and the waste-to-energy plant operates efficiently,
the duration could be prolonged up to 31 months. Urgent measures must then be taken
to address this issue before it becomes insurmountable.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

The available equipment and resources for solid waste management will determine the
most viable approach for waste collection and disposal. The allocation of budget,
personnel, machinery, and services will determine the availability of resources and
equipment. Providing training to personnel on various aspects of solid waste
management, including proper landfilling procedures and the identification and handling
of special waste, is a significant consideration.

The historical information on accumulated waste disposed in Reppi demonstrates a

decrease in height over time due to waste decomposition, which in turn leads to an
increase in waste density. This decrease in height and increase in waste density
contribute to the stability of the waste slopes. On contrary, the current machinery and
trucks used for waste disposal could further destabilize the slope stability. The existing
bulldozer, in particular, creates a larger live load that can hinder the slope's stability. To
mitigate this, lightweight machines for waste spreading may be necessary.

To ensure proper monitoring of leachate quality at the Reppi waste disposal site, it is
essential to have an analytical laboratory with the recommended minimum capacity. This
laboratory should be able to measure various parameters, including pH, electrical
conductivity, chloride ion, ammonia nitrogen, nitrate nitrogen, total phosphorus, zinc,
BOD5 (biochemical oxygen demand), and heavy metals such as cadmium, chromium,
copper, mercury, lead, iron, magnesium, manganese, and nickel.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Contents
Executive Summary ............................................................................................................................................i

Figures and Tables ........................................................................................................................................... vi

Table of Abbreviations .................................................................................................................................. vii

1. Introduction ................................................................................................................................................ 1

2. Description of the Site ............................................................................................................................ 4

2.1. Site Topography ............................................................................................................................... 4

2.2. Site Geology ........................................................................................................................................ 6

2.3. Soil types ............................................................................................................................................. 9

2.4. Groundwater occurrence and movement ...........................................................................10

2.5. Site Seismicity .................................................................................................................................11

2.6. Resources and Equipment .........................................................................................................13

3. Surface Water and Groundwater of the Site ...............................................................................13

3.1. Surface Water Drainage ..............................................................................................................14

3.2. Groundwater ...................................................................................................................................15

4. Physical (Slope) Stability.....................................................................................................................19

4.1. Waste Mechanics ...........................................................................................................................20

4.2. Geotechnical Characters of the Site: ......................................................................................21

4.2.1. Unit Weight .............................................................................................................................22

4.2.2. Shear Strength........................................................................................................................23

4.3. Physical Stability of the Site: .....................................................................................................24

5. Future Use of Reppi ...............................................................................................................................30

5.1. Expansion of Reppi Solid Waste Site .....................................................................................34

6. Conclusion .................................................................................................................................................35

Annex A: Groundwater Quality Data for Sample Wells in Addis Ababa ..................................38

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Figures and Tables

Figure 1Possible ground topography (extracted from 30 m Digital Elevation Model

(DEM)) .................................................................................................................................................................... 5
Figure 2Ground and waste profile across selected cross-section lines in Figures 1 and 36
Figure 3Reppi Waste topography .............................................................................................................. 6
Figure 4Geological and Geo-structural map of Addis Ababa City ................................................ 7
Figure 5Soil map around project area ...................................................................................................... 9
Figure 6Groundwater flow direction around Reppi area ..............................................................11
Figure 7Seismic Risk Map (left, EBCS-8-95) and Epicenters (Black Dotes in the right)
around Addis Ababa (Modified from Mammo, 2005) .....................................................................13
Figure 8Simulated wet season groundwater table ...........................................................................17
Figure 9 Three dimensional Factor of Safety distribution across the waste disposal site
(left: Active site; right: Extensive site) ...................................................................................................30
Figure 10Final waste accumulation (1V;2H) topography at Reppi (top: Active site;
bottom: Extensive site) .................................................................................................................................33
Figure 11Space (in m) above the current waste surface available for further storage (top:
Active site; bottom: Extensive site) .........................................................................................................34

Table 1Water quality parameters of Borehole located within Reppi Solid Waste site and
WHO Standards. All units are mg/l..........................................................................................................18
Table 2Statistical summaries of bulk unit weight data for fresh waste (Fassett et al., 1994)
.................................................................................................................................................................................23
Table 3Examples of measured shear solid waste strength parameters ..................................23
Table 4Summary of Factors of safety for the slope stability analysis results .......................27
Table 5Availabile space and duration of service by Reppi waste disposal site....................32

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Table of Abbreviations

BOD Biochemical Oxygen Demand

COD Chemical Oxygen Demand

DEM Digital Elevation Model

EBCS Ethiopian Building Codes and Standards

EC Electrical conductivity

GIS Geographic information system

MSW Municipal solid waste

RWEP Reppi waste to energy plant

SWM Solid waste management

TDS Total Dissolved Solids

TSS Total suspended solids

USGS Unites States Geological Survey

WHO World Health Organization

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

1. Introduction

The Reppi dumpsite has been officially designated as a landfill site. While an open
dumpsite is a random location that allows for the accumulation of waste, a sanitary
landfill is a carefully engineered system that prioritizes the preservation of water
resources and public health. Despite being established in 1964, the Reppi waste disposal
site exhibits all the characteristics of an open dumpsite rather than a landfill site. It has,
however, been occasionally compacted. An open dump refers to a land disposal site
where solid waste is disposed of in a manner that does not safeguard the environment, is
susceptible to open burning, and is exposed to the elements, vectors, and scavengers.
Considering this broad definition, the Reppi dumpsite is more closely associated with an
open dumpsite rather than a landfill site.

Throughout its history, the Reppi dumpsite has been under the management of the city
administration office in order to address the issue of solid waste disposal in Addis Ababa.
In 1964, due to its distant location from the commercial and residential areas of the city,
the dumpsite was considered safe as it minimized the risk of disease and unpleasant
odors. Additionally, the Reppi dumpsite provided a cost-effective solution for the city
administrators at that time. Even today, the Reppi dumpsite is acknowledged as a viable
option for solid waste disposal given the current circumstances.

The dumpsite is situated at coordinates 8°58' 57'' N and 38°41' 78'' E in the southwestern
part of Addis Ababa. It spans across both the Kolfe Keranio and Nifas-Silk Lafto sub-cities,
covering approximately 25 ha of land from Kolfe Keraniyo and 7 ha of land from Nifas-
silk Lafto sub-city. The total area of the dumpsite compound is currently around 32 ha,
with 18 ha actively receiving solid waste, 6 ha dedicated to infrastructure and
management complexes, and the remaining 8 ha closed off. Presently, efforts are being
made, the following are the features of the Reppi open dumpsite.

• The waste-to-energy plant currently has a design capacity of 1400 tons per day,
but its current uptake capacity is between 1000 and 1200 tons per day. The waste
supply to the plant has been ranging from 2500 to 3369 tons per day in recent
years.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

• The site is equipped with two weigh bridges to accurately measure the incoming
waste.
• The plant is located in an area surrounded by residences, business areas, and even
a school in the north and east directions.
• The waste received at the plant is unsorted and requires manual waste separation.
• Due to low security measures, scavenging activities occur at the site, attracting
vermin, dogs, birds, and other vectors.
• To address the issue of landfill gas, a collection system has been installed in the
closed section of the dumpsite. However, there is no provision for managing
combustible gases in most sections of the dumpsite.
• The waste disposal and management system at the plant is semi-aerobic, with
vertical gas pipes used for ventilation.
• During the dry season, the waste is compacted, while during the wet season, it is
spread out. This practice has been followed for the past 11 years.
• In the dry season, surficial fires are common, often caused by people who scavenge
at the site. Internal fires, on the other hand, occur due to the generation of
combustible gases within the waste. These fires can be identified by the smell and
mirage of gases exiting the waste surface.
• Currently, there is minimal or no application of soil cover in the active waste
disposal locations, except for forming access roads.
• The management of leachate is incomplete, although some trial biotreatment
practices exist. Leachate leakage points are identified through visual monitoring,
such as the presence of bleeding slopes or dead plants.
• The waste accumulation at the site follows a 1V:2H slope with terraces, and the
current maximum height is approximately 26 meters.
• To ensure safety, smell and tension crack detection and monitoring are conducted
to identify potential waste slide threats.

The environment is directly impacted by waste disposal practices, as they have a direct
effect on the pollution of surface and groundwater. The method of waste disposal is
closely linked to the need for protecting these water sources. Additionally, the cost of
disposal sites is determined by factors such as their drainage system, soils, and geology.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

The operation and management expenses of a dumpsite also depend on the level of
protection required for the natural environment. In order to address solid waste
management, the Addis Ababa city administration has implemented strategies and
procedures. However, there is a significant issue with waste sorting based on its
composition and constituents. Currently, only a small number of collectors in the city are
involved in minimal separation of plastic materials at the source.

The Reppi open dumpsite covers an area of approximately 32 hectares and has a
maximum waste depth of 26 meters. Each day, a substantial amount of solid waste,
ranging from 2400 to 3369 tons, is dumped at the site. Although there are a few heavy
machines available for waste compaction, the current disposal method involves crude
open dumping, where waste is hauled by trucks, spread and leveled by bulldozers, and
compacted by compactors or bulldozers. Initially, waste was simply dropped on the
ground surface without any compaction machines, but they have been introduced
recently at Reppi. The waste-to-energy plant at Reppi is designed to convert 1400 tons of
waste per day, but its current operational capacity is between 1000 and 1200 tons per
day.

On March 11, 2017, the Reppi open dumpsite experienced a failure, resulting in
significant consequences for the people residing at the base of the failed slope. Numerous
temporary houses were buried under the debris of waste. The city administration made
the decision to temporarily close the site due to its overfilled condition. However, public
outcry regarding the alternative landfill facility, Sandafa, led to its reopening. Currently,
the Reppi facility continues to receive an average of 2700 tons of trash daily. Clague
(2017) reported that at the time of the failure, the slope had an inclination of
approximately 48° to the horizontal. The debris from the failure reached a height of 20 m
and extended 100 m beyond the actual toe line of the waste slope, causing damage to
nearby houses. Presently, public access to the dumping site is somewhat restricted.
Nevertheless, scavenging for valuable items to use or sell remains common among
people, including children and women.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

The failure occurred when the landfill was reopened for disposal, with fresh waste being
dumped on top of decomposed and rain-saturated organic waste. Prior to the failure, the
maximum height of the dumpsite was 20 m. Local experts indicate that the front slope
facing the open valley had a slope angle ranging between 40 and 50°.

This study aims to provide an overview of the effects and evaluate the current state and
future possibilities concerning the disposal of municipal solid waste at the Reppi open
dumpsite. The primary environmental impacts of open dumping are related to public
health and safety. This study also identifies public safety concerns that extend beyond the
immediate vicinity of the dumpsite. Environmental issues such as groundwater
contamination, surface water pollution, and air pollution are examples of safety concerns
associated with open dumpsites that go beyond their location. Additionally, the structural
safety of the dumpsite becomes a significant concern in the surrounding area, particularly
regarding the potential for waste-slides. It is crucial to assess the geotechnical and
engineering factors that influence the stability of the accumulated waste and the
underlying soil or terrain throughout the dumpsite's lifespan. By understanding and
conservatively estimating these factors, local safety concerns can be determined.

The objective of this study is to examine the current state of the Reppi open dumpsite,
analyze its impact, and draw conclusions regarding its strengths and weaknesses.
Ultimately, the findings from this research will contribute to the development of a
comprehensive solid waste management masterplan for the city over the next 20 years.

2. Description of the Site

The subsequent sections provides an account of the Reppi waste disposal site, focusing
on the factors that are pertinent for assessing its susceptibility and the resultant
consequences on the environment.

2.1. Site Topography

The site is a small piece of land that is surrounded by the Jemo-Ayertena road on the west
side, a small stream on the east side, and public and residential areas on the north side.
There are also additional residences located near the stream and highway.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Currently, the true ground topography of the area is hidden due to the presence of waste.
However, a digital elevation model was used to estimate the possible ground profile of
the site, which ranges from approximately 2274 m above mean sea level (amsl) at the
northeast limit of Reppi to 2230 m amsl at the southeastern limit. The waste-to-energy
generation plant is situated in the northwestern part of the site and includes a service
and parking area for waste weighing, sorting, and stacking equipment. The benches in the
area are typically covered with dried annual grasses and weeds, with only a few shrub
trees. The river channel has a dense growth of grasses and shrubs. In the southern portion
of the site, there are areas that were previously used as dumpsites but are now covered
with soil materials, resulting in a smooth gradient terrain and areas of fill.

The waste topography was also obtained from Google Earth, and the topographic map of
the site is shown in Figure 3. Additionally, Figure 2 displays the waste and ground profiles
along the selected lines with high waste gradients. The natural landscape of the site
exhibits a surface slope of approximately 2-5%, with a steeper slope leading towards the
small stream on the eastern boundary.

Figure 1Possible ground topography (extracted from 30 m Digital Elevation Model (DEM))

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

SW-NE Section NW-SE Section

2320 2310
Elevation (m amsl)

2300
2300
2290
2280 2280
2260 2270
Natural Ground Current Waste 2260
2240 2250
0 200 400 600 0 500 1000
Distance from SW Distance from NW
Figure 2Ground and waste profile across selected cross-section lines in Figures 1 and 3

Figure 3Reppi Waste topography

2.2. Site Geology

The geology of Addis Ababa city is composed of layers of varying volcanic rocks, with
ignimbrite and basalt sharing the major proportion (Figure 4). The ignimbrite unit is
exposed in the central part of Addis Ababa at the banks of the big and small Akaki rivers
and small creeks. It forms a gentle slope and lower topography and is overlain by young
Quaternary basalt while overlaying the Reppi basalt in the northwest of Addis Ababa.

These lithological units are naturally stable and composed of hard rocks, but in place, they
are highly fractured and affected by geological structures that favor the percolation of
leachate from accumulated solid waste. However, the lithologic units are strongly

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

affected by Rift geological processes and are associated with geological structures, which
act as conduits for surface contaminants to enter the groundwater regime.

Reppi is composed of mainly lacustrine and alluvial deposits and clay and loam residual
soils with a fine to very fine-grained texture at the top. According to the Nile Basin Master
Plan study by the Ministry of Water and Energy (Phase 2, 1993), these lithological units
have a low infiltration coefficient below 0.005 and form an impermeable layer at the top
of the groundwater table. The accumulated solid wastes also underwent biodegradation
and decomposition, forming thick clay that locally forms an impervious layer for direct
vertical recharge from Reppi solid waste leachate. However, this doesn’t blackout the risk
of groundwater contamination by leachate from Reppi Solid Waste Disposal, as there are
many places with fractured and highly weathered volcanic rocks exposed to the ground
surface that favor the direct and fast migration of leachates far into aquifer zones,
particularly during the rainy seasons.

Figure 4Geological and Geo-structural map of Addis Ababa City

Addis Ababa city is located on the western shoulder of the Main Ethiopian Rift, which
exhibits several and multifaceted fault systems with a general trend of the rift system

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

(NE-SW) direction with the density of faults and lineaments increasing to southeast
towards the rift valley (Figure 4). A geophysical survey was conducted in 2012 under the
project entitled “Environmental Impact and Vulnerability of the Surface and Ground
Water System from Municipal Solid Waste Disposal Site: Reppi, Addis Ababa," covering
the Reppi solid waste area and mapping weak zones in the vertical survey and near-
vertical discontinuities in the Reppi area. This geophysical survey identified geological
structures in east and west that could facilitate leachate migration into the groundwater
environment.

The site's regional geology comprises the Nazret Group of Ignimbrites (Nn), which
exhibits varying permeability across different areas. This geological formation was
created during the Miocene-Pliocene era. A 103-meter borehole was drilled at
coordinates 0467900m Easting and 0991900m Northing, revealing a surface covered by
thick clay soil. Waste is disposed of as an overburden. Near the stream, where the surface
slopes are gentle, weathered rock is present. The area also contains exposures of
ignimbrite, basalt, and trachyte rocks. The western part of the area, as well as the adjacent
areas near the streams, are covered by thick soil overburdens. The Wechecha-Yerer-Furi
Ignimbrite and Wechecha-Yerer-Furi Trachyte volcanic rocks dominate the region. In a
few areas, Quaternary basalt overlays the trachyte rock. The borehole drilling results
provide detailed descriptions and analysis of lithology types within one-meter intervals,
as outlined in the table below.

Depth range Lithological Description Aquifer Characteristics

(m)
From To
0 2 Top clay soil No water at all
2 8 Highly volcanic materials
8 24 Weathered volcanic rich in boulders
24 30 Fractured Scoracious basalt Very small quantity of water streaked
30 39 Highly weathered pyroclastic
materials
39 60 Fractured Scoracious Basalt Good water bearing layer

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

60 82 Pyroclastic materials
82 91 Sand
91 96 Highly weathered trachyte
96 103 Hardly weathered trachyte Poor water Bearing Layer
2.3. Soil types

The subsurface infiltration condition of the Addis Ababa area is mainly governed by the
thickness and hydraulic conductivity of the unconsolidated sediments overlying the
weathered and fractured volcanic rocks that form the aquifer blowing tenths of meters
below ground surface. The weathered and fractured volcanic rocks form major geologic
units in the Reppi area. The top few tenths of meters of Reppi area are covered by alluvial
deposits, and the facies and thickness of these unconsolidated deposits vary within Addis
Ababa city depending on topography and geomorphological conditions. In central, north,
and northwest Addis Ababa, this unconsolidated layer is very thin within 5–10 m,
whereas it becomes thicker, more than 15-20 m, in the west, south, and east of the city.
There are three groups of soils identified in the Reppi area as alluvial, residual, and
lacustrine clay deposits.

Figure 5Soil map around project area

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

The lacustrine deposit is mainly composed of clay and loam and is found in the Reppi
solid waste disposal area and along rivers. These lacustrine and clay deposits are highly
plastic clays with a thickness range of 8 to 25 meters, with the thickness increasing
towards the Reppi Solid Waste Site (Figure 5). Below these lacustrine and clay deposits
is the volcanic formation of ignimbrite and basalt that forms the main aquifer in the Addis
Ababa region. These lithological units are highly fractured and affected by geological
structures. They form local and regional aquifers whose depth of groundwater circulation
is within ten to many hundred meters. A layer of plastic clay shields the lithologic unit at
the Reppi Solid waste site, serving as a protective geo-membrane. This clay layer allows
leachates to directly pass through to the groundwater. However, on the eastern and
western sides, the lithologic unit is exposed to the surface, creating a favorable pathway
for leachates to migrate deep into the aquifer.

2.4. Groundwater occurrence and movement

The aquifers of northern and central part of Addis Ababa city and in the mountain,
areas are largely weathered and fractured volcanic rock with minor sediments
deposited between different series of lava flows. The aquifers in Reppi area are mainly
young volcanic rocks of lava flow and tectonic fractures with alluviums and
colluviums covers as top.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Figure 6Groundwater flow direction around Reppi area

A large proportion of the central part of the city is under semi-confined condition with
groundwater depth varying from 0 to 40 meters. The depth of the groundwater generally
increases to south direction which creates flow direction to same direction (Figure 6).

The groundwater flow within the city is variable with a general direction north to south
with groundwater elevation decreases in the same direction. Groundwater around Reppi
waste disposal area is only 6-8 m deep from ground surface which is much vulnerable to
pollution from Reppi solid waste leachate. The groundwater flow concentrates towards
the south constrained by geological structures (Figure 6).

2.5. Site Seismicity

The evaluation of potential seismic effects on the stability of deposited waste slopes
required an assessment of local seismic sources and historic earthquakes. Deterministic
peak ground accelerations were obtained from regional seismic sources, and these data
are presented in the following sections.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

According to Temesgen (2018)1, data recorded from January 2016 to August 2017, using
four permanently installed stations around the city (AAE, FURI, ANKE, and WLRA)
revealed 81 natural earthquakes and 123 quarry explosions around Addis Ababa. The
research also found that natural earthquakes had a local magnitude ranging from 1.3 to
5.1 ML, while quarry explosions had a magnitude ranging from 1.2 to 3.0 ML during the
20-month period. The strongest earthquake in the past 10 years near Addis Ababa
occurred on January 27, 2017, at 19:29 local time. It had a magnitude of 5.3 and struck
151 kilometers south of Addis Ababa at a depth of 10 km2.

The region has experienced several destructive earthquakes in the past. Notable ones
within 200 km of Addis Ababa include earthquakes with magnitudes of 6.8 (in 1906), 6.7
(in 1961), and 6.3 (in 1961). The 6.8-magnitude earthquake occurred approximately 120
km south of Addis Ababa. Smaller-magnitude earthquakes have also occurred at closer
ranges, such as a 4.1 magnitude earthquake about 22 km southwest in 1979 and a 4.6
magnitude earthquake about 100 km northeast in 19743 (Gouin, 1979). Figure 7 shows a
map of recorded earthquake epicenters, which primarily consist of small and
intermediate-level seismic activity4 (Mammo, 2005).

According to the Ethiopian Building Codes and Standards (EBCS) of 1995, the country is
categorized into five zones, each with a similar level of seismic risk determined by
historical earthquake data. These zones include no-damaging zones (Zone 0), less-
damaging zones (Zones 1 and 2), and zones of significant damage (Zones 3 and 4), as
illustrated in Figure 7. Based on this figure, Addis Ababa is situated in a location classified
as a less damaging zone, with a ground acceleration coefficient of 0.05 for a reference
return period of 100 years.

1 Melese Temesgen (2018), Seismic Activity around Addis Ababa, Thesis, AAU, School of Earth Sciences
2 https://earthquakelist.org/ethiopia/addis-ababa/addis-ababa/
3 Gouin, P. (1979). Earthquake history of Ethiopia and the Horn of Africa. International Development

Research Centre (IDRC), Ottawa, Ontario, pp.258.

4 Mammo Tilahun, 2005. Site-specific ground motion simulation and seismic response analysis at the

proposed bridge sites within the city of Addis Ababa, Ethiopia. Engineering Geology 79(2005) 127-150

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Figure 7Seismic Risk Map (left, EBCS-8-95) and Epicenters (Black Dotes in the right) around Addis Ababa
(Modified from Mammo, 2005)

2.6. Resources and Equipment

Solid waste disposal necessitates the regular availability of heavy earthmoving,

compacting, and other equipment. The primary concern in any solid waste management
endeavor is acquiring suitable human and financial resources. Additionally, the
operational and maintenance requirements of machinery are crucial factors to consider.
The efficiency of collection services heavily relies on the availability of human resources
and vehicles. The Reppi solid waste disposal site began utilizing heavy equipment for
compacting approximately 11 years ago. However, these machines have limitations when
it comes to compacting solid waste during the wet season.

At the Reppi waste disposal site, there is a scarcity of analytical laboratory facilities
capable of conducting basic tests such as pH, electrical conductivity, available chlorine,
and a few metals. This limitation poses a challenge in evaluating the impact of leachate
on the environment.

3. Surface Water and Groundwater of the Site

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

It can be deduced from the current circumstances that the disposal of solid waste at Reppi
is causing significant health and environmental issues in the nearby regions. Numerous
environmental concerns linked to the dumping of solid waste encompass the
proliferation of flies and mosquitoes, problems with unpleasant odors, unattractive
visual appearance, and the pollution of the surrounding soil and groundwater due to
leachate seeping from the site, among others.

3.1. Surface Water Drainage

The Reppi dumpsite is surrounded by both artificial (urban) and natural surface water
drainage systems. The pollution caused by urban drainage in a specific neighborhood is
just one part of a larger pollution hierarchy that affects the overall surface water. The
city's drainage network, which consists of various drains, also contributes to the pollution
levels. These drains range from major canals and large sewers that collect water from
extensive areas of the city to small ditches and drainpipes along the roadside. At the
lowest level of this hierarchy is the Akaki River, where the drainage system discharges its
water. Eventually, the Akaki River merges with the main Awash River through the
Abasamuel Dam. The primary drainage system, which includes main drains or
interceptor drains, follows the main roads and often aligns with natural drainage
channels like rivers or streams.

Previous studies have indicated that natural streams within the city have high levels of
pollution. These streams are considered to be at a high risk of pollution. The runoff within
the dumpsite can flow in any direction due to the site's higher elevation. Most of the
runoff accumulates towards the northeastern boundary of the compound, where it meets
a small natural stream. The southwestern part, which includes the main highway, carries
a relatively smaller amount of runoff from the compound. Despite the presence of
leachate collection ponds, untreated leachate from the dumpsite directly flows into local
surface waters and groundwater. The combination of Reppi leachate and pollutants from
urban drainage poses a threat to the downstream streams' health. The continuous impact
of urban drains and leachate from the Reppi disposal site on natural surface water bodies
has been observed throughout the year. Due to the steep inclines of both natural and man-
made drains, the water level in the receiving drain is consistently lower. As a result, runoff
is able to transfer at a faster rate. This increased speed of runoff also leads to a quicker

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

migration of pollutants. However, the current socio-economic status of the city poses
challenges for treating drainage water. Given the larger volume of runoff and higher
pollution levels, implementing treatment measures would not be practical.

It is important to note that not all rainwater is directed into the drainage system. Some of
it infiltrates into the waste and seeps into the ground, while the rest accumulates in
puddles and depressions before eventually evaporating. The portion that runs off the
waste surface and needs to be carried through the drainage system is referred to as the
runoff coefficient. During rainfall, evaporation is unlikely, so the runoff coefficient used
to calculate the required drain size is based on the waste's infiltration capacity. This
capacity is primarily influenced by waste conditions and the slope of the terrain. Loose
waste allows water to seep more easily compared to compacted waste, which
necessitates immediate compaction even during wet seasons. Additionally, water flows
more swiftly down steep slopes, reducing the time available for infiltration compared to
flat areas. Consequently, the use of drain pipes or canals across the waste, particularly in
wet season, becomes necessary.

3.2. Groundwater

The Akaki catchment of the Awash River Basin is where the site is situated. Within the
Addis Ababa aquifer system, two distinct groundwater states are commonly found: the
unconfined (local groundwater) and the confined (typically regional groundwater). A
borehole, drilled to a depth of 103 meters near the waste disposal site, confirms the
separation of these two systems. The static water level in this borehole is reported to be
27.5 meters below the ground level, indicating that it is significantly lower than the
nearby surface water stream. Conversely, the leachate level at the waste disposal site is
1-2 meters below the ground level, indicating the presence of different types of water.
The physiochemical parameters observed in these two water sources (as detailed in
Annex A) further support the notion of distinct groundwater systems at the Reppi solid
waste disposal site.

The unconfined groundwater elevation in the subsurface mirrors the surface topography,
resulting in a relatively consistent water depth along the river axis passing by the waste
disposal site. During the wet season, the groundwater level within the waste (leachate

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

level) is found to be higher (Figure 8). In certain areas, leachate is observed to emerge
from the side slope of the accumulated waste. The compaction that occurs during the dry
season may create a less permeable layer, hindering the downward flow of leachate.
Additionally, liquefied waste has been observed in the middle of the accumulated waste,
which is caused by the excessive rainfall accumulation during the wet season. Based on
these observations, it can be inferred that during the wet season, the groundwater levels
in the leachate have the potential to exceed the natural ground level and the waste top
level at some locations.

The groundwater table throughout the site is simulated as a two-layer geological

medium. The purpose of the simulation is to depict the leachate level during the wet
season in the waste area. The site is conceptualized as a two-layer unconfined aquifer
system, with a river boundary condition at its north-west boundary and uniform recharge
across its surface. The upper layer represents the disposed solid waste, while the bottom
layer is considered to be natural soil with a thickness of approximately 10 meters. During
the field visit in July and August of 2023, the observed water table values were used for
calibration, taking into account the slopes where bleeding occurred. The calibration
process involves adjusting the rainfall recharge during the wet season, as well as the
hydraulic conductivities of the natural soil and the disposed solid waste. It is important
to note that the modelling paradigm does not consider the fractured/weathered rock
system. The outcome of the modelling is illustrated in Figure 8.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Figure 8Simulated wet season groundwater table

The dumpsite generates leachate that contains a variety of pollutants, such as heavy
metals, trace elements, and organic compounds. These pollutants combine with the
surrounding groundwater or soil, resulting in contamination. The chemical composition
of the samples taken from the two wells within the Reppi compound is reasonably similar
to those obtained from other locations in Addis Ababa (refer to Annex A). The values
observed in these wells comply with the standards set by the environmental protection
authority and the Effluent and Solid Waste Disposal Regulations SI65 (EMA, 2007).
However, when comparing the chemical composition of the leachate with the standards
and other wells drilled for water supply in Addis Ababa, it becomes evident that the
leachate is highly contaminated and poses a threat to the unconfined (water table)
aquifer. Therefore, it is crucial to implement proper leachate management practices
throughout the waste disposal site. Natural treatment of the leachate will not alleviate
the threat, hence the necessity for effective leachate collection and disposal at Reppi.

5EMA. (2007). Environmental Management (Effluent and Solid Waste Disposal) Regulations, 2007. In
Environmental Management Agency (pp. 1–54)

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

The leachate produced by waste disposal sites contains many substances that are likely
to contaminate groundwater. The impact of such sites on groundwater can be judged by
monitoring the concentration of potential contaminants in the groundwater. In this
regard, water quality data around Reppi Waste disposal sites has been collected to assess
the potential impact of Reppi Solid Waste on groundwater quality. The assessment is
focused on the presence of common chemical effluents originated from solid waste
leachates and includes electrical conductivity (EC), Total Dissolved Solids (TDS), nitrate
(NO3), sulfate (SO4), ammonia (NH3), chloride (Cl), phosphate (PO4), chemical oxygen
demand (COD), and biochemical oxygen demand (BOD). The results have been compared
with WHO standards (Table 1).

Table 1Water quality parameters of Borehole located within Reppi Solid Waste site and WHO Standards. All
units are mg/l

Description TDS pH TSS Alk N03 SO4 NH4 Cl PO4 NH3 BOD COD
Reppi Well 473 8.3 47 206 7.5 15 0.4 1.8 0.97 0.37 5.3 246
WHO 500 6- 45 200 10 100 1.5 500 1.0 - 6.0 10.0
Standard 9
As shown in the table 1, groundwater in Reppi waste disposal sites has a uniquely high
COD load above the WHO standard. High levels of COD indicate concentrations of organics
that can deplete dissolved oxygen in groundwater, leading to negative environmental and
health consequences. The presence of average total suspended solids (TSS) in
groundwater is about 47 mg/l, which is also slightly higher than the 45 mg/l WHO
standard. The total alkalinity in groundwater is 206 mg/l, which is close to the 200 mg/l
WHO standard, but this value in rivers is highly inflated to 301 mg/l.

The high load of COD in groundwater around the Reppi solid waste site could be a result
of the accumulation of solid waste containing decayed organic matter, antifreeze, residual
food waste, and any other organic materials that undergo decomposition by bacteria.
Increased COD in groundwater could also be due to the oxidation of inorganic
compounds, which are commonly found in Reppi solid wastes.

As shown in Table 1, except COD, groundwater in the Reppi Solid Waste area has water
quality parameters within the WHO standard. This means that groundwater can be used

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

by reducing the COD by allowing bacteria to break down organic compounds in

groundwater through aeration processes.

It should be noted that the low concentration of other chemical parameters in the
groundwater of the Reppi area does not eliminate the risk of groundwater contamination
by leachate from Reppi solid waste. These chemicals from leachate may be attenuated in
the soil layers before reaching groundwater or the aquifer. However, this natural
attenuation capacity of the soil layer could become limited or deteriorate over time,
leading leachate to overpass the attenuation capacity of the underlying soil and
ultimately enter the aquifer, significantly contaminating groundwater quality beyond a
repairable level.

The leachate produced by waste disposal sites contains many substances that are likely
to contaminate groundwater. The full impact of Reppi solid waste on groundwater
resources can be judged by monitoring the concentration of potential contaminants at
several selected monitoring points on a regular basis.

The concentration levels of leachate chemicals in the study area have exceeded the
permissible limits according to both international and Ethiopian standards. As a result,
the groundwater from the unconfined aquifer in this area is not safe for drinking,
commercial use, irrigation, or industrial purposes. Therefore, this study highlights the
urgent need to improve the current practices of solid waste handling and management at
the Reppi waste disposal site. However, the chemical analysis of samples from two wells
within the Reppi compound indicates that the groundwater from the deep (confined)
aquifer system has good water quality. This makes it safe for various purposes other than
drinking. Nevertheless, it is important to take precautionary measures to prevent
leachate contamination in order to maintain the quality of this deep groundwater and
avoid pollution.

4. Physical (Slope) Stability

The stability of a waste disposal site is a significant geotechnical concern. Various factors
such as waste age, compaction, composition, climate, groundwater, and operation
conditions influence the stability of the site. The objective of this investigation was to
assess the geotechnical conditions at the Reppi site and conduct slope stability analysis

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

to identify potential failures in the accumulated waste. Slope failures in landfills can occur
due to various reasons, including inadequate site management and operation. In addition
to geotechnical factors, triggering factors such as excessive waste disposal, rainfall
without proper drainage, improper operation and construction activities, earthquakes,
and the absence of leachate collection and methane disposal systems can also affect the
slope stability of a waste disposal site. The upcoming sections will delve into the
important aspects of Reppi waste mechanics and stability analysis.

4.1. Waste Mechanics

The conventional approach to soil mechanics cannot be directly applied to analyze the
stability of solid waste due to its distinct mechanical behavior compared to soil. Municipal
solid waste (MSW) is a composite material that can exhibit both unusual stability and
weakness, regardless of its shape, type, or geometry. The shear strength of MSW is
generated by a combination of tensile (reinforcement) and friction forces. Tensile forces
arise from the presence of foils, clothes, plastics, and fibers within the MSW. The shear
strength of MSW is derived from cohesion, friction (associated with granular
components), and fiber cohesion (related to anisotropic and non-linear reinforcement
materials).

The anisotropy of fiber cohesion renders the commonly used Mohr-Coulomb failure
criterion inapplicable. Research indicates that MSW samples do not fail under tri-axial
load due to the effect of fiber cohesion (Dixon et al., 2005)6. Consequently, the evaluation
of the tri-axial compression test does not yield an accurate Mohr envelope. However, tri-
axial compression tests can provide data on the stress-strain behavior of MSW, and even
determine the shear strength parameter (φ, c) for specific deformations (Dixon et al.,
2005).

Considering the limited financial resources available to obtain the necessary geotechnical
parameters of waste, it is reasonable to prioritize efforts based on the risk of failure and
potential damage. Small and low landfills in arid regions face significantly lower risks of

6Dixon Neil, D. Russell and V. Jones (2005) Engineering properties of municipal solid waste, Elsevier
Geotextiles and Geomembranes 23 pp. 205–233

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

slope failure compared to large landfills in tropical countries. However, when selecting
an analysis method, the potential damages and casualties resulting from a landfill failure
should also be taken into account. Landfills situated in sensitive areas, such as near
residential zones, may require more comprehensive analysis.

Large deformations in the stability analysis of MSW can result in incompatibilities with
the deformations in the subsoil. This is especially true when the sliding surface intersects
both the waste and the subsoil. In such cases, the mobilized shear strength of MSW
depends on the smaller limiting strain of the subsoil.

Safety factors play a crucial role in stability analysis. They account for uncertainties in the
modeling and calculation methods, as well as the desired level of safety in relation to
potential failure consequences. In waste mechanics, the safety concepts of soil mechanics
(overall safety or partial safety) can be applied based on common experiences. In two-
dimensional analysis, higher reserve forces (such as 3-dimensional forces and large
deformations) that are not considered in modeling and calculation can help balance out
larger uncertainties in material parameters caused by testing and sampling issues.
Alternatively, higher partial safety factors can also be employed to mitigate modeling
uncertainties.

4.2. Geotechnical Characters of the Site:

The geotechnical evaluation of soil and dumped waste requires the determination of
various characteristics such as soil and waste strength, as well as the intensity of
earthquakes in terms of peak acceleration. Additionally, other factors like the degree of
compaction, type, and saturation of the dumped waste are considered due to their
potential impact on site stability. However, it is important to note that these values are
approached conservatively, providing an average characterization of the Reppi solid
waste dumpsite.

In the field of MSW engineering properties, there is a growing body of literature.

However, the lack of a universally agreed-upon classification system and test standards
makes it challenging to interpret published results. Often, the details regarding the nature
of the waste being tested and the specific test conditions are not adequately described.
Consequently, it becomes difficult to integrate the findings into a cohesive framework or

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

apply them to other sites. This review primarily focuses on the crucial parameters of unit
weight and shear strength.

4.2.1. Unit Weight

Knowledge of unit weight is essential for stability analysis and slope design in various
aspects. The unit weight of soils, for instance, is influenced by factors such as compaction
effort, layer thickness, overburden stress (depth of burial), and moisture content. In the
case of clay soil, which forms the top ground surface, the natural unit weight ranges from
16–22 kN/m3 under saturated conditions and 14 –21 kN/m3 under dry conditions.
Considering the higher moisture content of clay soil, an average unit weight of 17.5
kN/m3 is utilized for stability analysis.

On the other hand, the unit weight of solid waste exhibits significant variations due to
factors like waste constituents (size and density), decomposition state, and control
measures during placement (e.g., thickness of daily cover). At the Reppi dumpsite, it has
been observed that the waste consolidates over time, leading to a reduction in compacted
waste height. Initially, the unit weight of waste is primarily influenced by waste
composition, daily cover, and compaction during placement. However, as the waste ages,
the unit weight becomes more dependent on factors such as burial depth, decomposition
degree, and climatic conditions. Although there may be considerable variations in unit
weight over short distances, this is generally not a major concern in design. Average unit
weight values are typically used to calculate vertical and horizontal stresses. For instance,
average vertical stress values acting on a basal geo-membrane are employed in the design
of geotextile protection layers. Table 2 provides statistical summaries of bulk unit weight
data for fresh waste. At the Reppi dumpsite, the solid waste primarily consists of organic
and plastic waste (mainly thin film), indicating a lower density profile. In this study, the
average value of moderately compacted solid waste unit weight (7 kN/m3) was utilized.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Table 2Statistical summaries of bulk unit weight data for fresh waste (Fassett et al., 1994) 7

Poor Moderate Good

compaction compaction compaction
Range (kN/m )3 3.0–9.0 5.0–7.8 8.8–10.5
Average (kN/m )3 5.3 7.0 9.6
Standard deviation 2.5 0.5 0.8
(kN/m3)
Coefficient of variation 48 8 8
(%)
4.2.2. Shear Strength

Currently, there is limited knowledge regarding the shear behavior of municipal solid
waste (MSW) in its original location. The shear strength of MSW is typically determined
using the Coulomb failure criterion. Assessing the engineering properties and
consequently, the behavior of MSW is a complex task due to the diverse range of materials
present. In laboratory tests, the inability to induce shear failure has resulted in shear
strength being associated with different levels of strain. For each strain level, distinct
shear strength parameters are provided. While Table 3 presents a summary of waste
shear strength parameters compiled by Jones et al. (1997)8, it should be noted that this
summary is not exhaustive. Its purpose is to illustrate the significant variation in values
that can be obtained. Considering the wide array of potential waste compositions and the
challenges associated with measuring shear strength, the presence of a large scatter in
the data is not unexpected.

Table 3Examples of measured shear solid waste strength parameters

Shear strength parameters Method/Reference

c' (kPa) φ (o)
7 38 Not stated (Jessberger, 1994)
10 15 Back analysis (Jessberger, 1994)
10 17 Back analysis (Jessberger, 1994)
0 30 Estimate From field observations (Jessberger, 1994)
0 40 Estimate From field observations (Jessberger, 1994)
7 42 Simple shear (Jessberger, 1994). Nine month old MSW
28 26.5 Simple shear Fresh MSW. (Jessberger, 1994)
10 23 Suggested values (Fassett et al. 1994)

7 Fassett, J.B., Leonardo, G.A., Repetto, P.C., 1994. Geotechnical properties of municipal solid waste and their
use in landfill design. Waste Tech ’94, Landfill Technology Technical Proceedings, Charleston, SC (USA),
January 13–14
8 Jones, D.R.V., Taylor, D.P., Dixon, N., 1997. Shear strength of waste and its use in landfill stability analysis.

In: Yong, R.N., Thomas, H.R. (Eds.), Proceedings Geo-environmental Engineering Conference. Thomas
Telford, pp. 343–350

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

15 15 Suggested values (Kolsch, 1995)

18 22 Suggested values (Kolsch, 1995)
10 25 Back analysis Deep trench cut in waste. Suggested values (Cowland et al. 1993)
15.7 21 Direct shear Tests on baled waste Lower density bales (Del Greco and Oggeri,
1993)
23.5 22 Direct shear Tests on baled waste Higher density bales (Del Greco and Oggeri,
1993)
19 42 Direct shear Old refuse (Landva and Clark, 1986)
16 38 Direct shear Old refuse (Landva and Clark, 1986)
16 33 Direct shear Old refuse+1 year (Landva and Clark, 1986)
23 24 Direct shear Fresh, shredded refuse (Landva and Clark, 1986)
10 33.6 Direct shear Wood waste/refuse mixture (Landva and Clark, 1986)
0 41 Direct shear Project specific testing (Golder Associates, 1993)
Further investigation is required to gain a deeper understanding of the mechanical
behavior and shear strength of both fresh waste and degraded waste. This entails
conducting additional case history analysis as well as laboratory and field testing. In the
meantime, it is recommended to utilize a bilinear shear strength envelope based on the
findings of Stark et al. (2008)9. According to this recommendation, for effective normal
stresses below 200 kPa, the values for the shear strength parameters are c' = 6 kPa and
φ' = 35º degrees. On the other hand, for effective normal stresses exceeding 200 kPa, the
values are c' = 30 kPa and φ' = 30º degrees.

Considering the clay soil beneath the waste as a partially saturated material, the shear
strength parameters can vary. The cohesion can range between 10 and 20 kPa, while the
angle of shearing resistance can vary between 18 and 28 degrees. However, for a
conservative slope failure analysis, it is recommended to adopt values of 15 kPa for
cohesion and 23 degrees for the angle of shearing resistance.

4.3. Physical Stability of the Site:

Various methods have been documented in the literature to analyze the stability of slopes
in solid waste disposal sites. While there are strict recommendations for conducting
thorough geotechnical assessments, there is a minimum requirement that allows the
establishment of a landfill without detailed geotechnical considerations in certain cases.
However, recent instances of landfill failures worldwide have demonstrated the crucial
importance of geotechnical aspects, which should not be disregarded.

9Stark, T.D., N. Huvaj-Sarihan, and G. Li (2008] “Shear Strength of Municipal Solid Waste for Stability
Analyses”, Environmental Geology

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

The Bishop Method of Slices is commonly employed for slope stability calculations,
utilizing parameters such as the angles of shearing resistance (φ) and cohesion (c) to
describe the material. This method divides the slipping mass above the failure plane into
slices and applies force equilibrium conditions to each slice, generating an equation for
the factor of safety. However, it is important to note that these parameters do not
accurately reflect the bearing behavior of municipal solid waste (MSW), as discussed
earlier. Nonetheless, conducting an analysis using the Bishop Method can provide an
indication of slope stability. Each slice is subjected to force equilibrium conditions,
resulting in the generation of an equation for the factor of safety. By considering
mechanical equilibrium, the forces acting on each slice are determined. The interactions
between slices are disregarded as the resultant forces are parallel to the base of each slice.

For critical landfill site conditions, three dimensional (3D) methods are strongly
recommended. Those critical site conditions are:

• Extraordinary landfill height (> 30 m)

• Steep slopes (steeper than 33%)
• Inclined subsurface (> 5%)
• Soft subsoils (silk or softer)
• High water table (more than 20% of total height, “bleeding” slopes)
• Sensitive location (e.g., distance to a residential area <300m)
• Extraordinary loadings (e.g., earthquake)

In this report, the term "landslide" refers to deep-seated slope failures that involve
disposed solid waste features, which have the potential to compromise the long-term
stability of accumulated waste at Reppi. On the other hand, surficial failures pertain to
shallow failures occurring within approximately 1.2 m of the surface, which may lead to
localized raveling of waste material.

The susceptibility of a geological unit to sliding depends on several factors. These factors
include the presence and orientation of weak structures like fractures, faults, or clay beds,
as well as the degree of cementation of the material. Additionally, the height and
steepness of the slope, the presence and quantity of groundwater, and the occurrence of

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

strong seismic shaking also play a significant role in determining the susceptibility to
landslides.

The analysis of slope stability, taking into account the reinforcement effect of fiber
cohesion, is based on modifying well-known geotechnical stability analysis models such
as the Bishop's slip circle method or ordinary (Fellenius) method. To conduct the slope
stability analysis, Unites States Geological Survey (USGS) Scoops3D software was utilized.
Scoops3D is a computer program that evaluates the stability of slopes in a digital
landscape using a digital elevation model (DEM). It employs a three-dimensional (3D)
approach to assess the stability of numerous potential landslides within a user-defined
size range. For each potential landslide, Scoops3D analyzes the stability of a rotational,
spherical slip surface that encompasses multiple DEM cells. This analysis is conducted
using a 3D version of either Bishop's simplified method or the Ordinary (Fellenius)
method of limit-equilibrium analysis. In the Bishop method, a key distinction lies in the
assumption that the normal interaction forces between neighboring and adjacent slices
are collinear, while the final inter-slice shear force is regarded as zero. Scoops3D offers
various options for users to systematically and efficiently search the entire DEM, taking
into account the effects of complex surface topography. During a comprehensive search,
each DEM cell is considered in multiple potential failures, and Scoops3D records the
lowest stability (factor of safety) for each cell, along with the associated size (volume or
area) of the potential landslides. Additionally, it identifies the least-stable potential
failure for the entire DEM. Users have the flexibility to build a 3D domain using different
options, such as layers or full 3D distributions of strength and pore-water pressures,
simplistic earthquake loading, and unsaturated suction conditions. The results obtained
from Scoops3D can be easily integrated into a geographic information system (GIS) or
other visualization software for further analysis and interpretation. By employing the
Limit Equilibrium Method, Scoops3D can analyze both simple and complex models,
including profiles with additional fiber cohesion achieved through the use of geo-
synthetics, soil nails, and ground anchors.

The global stability of waste slopes was analyzed using different methods, including
Bishop's simplified method and the Ordinary (Fellenius) methods. These analyses were
conducted under both static and seismic conditions in both dry and wet season,

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

considering rotational and composite failure surfaces. The Scoops3D computer program,
version 1.3.01, developed by USGS in 2015 (Reid et al., 2015)10, was used for these
analyses. The material strengths of the accumulated solid waste and native clay units
were determined by selecting average values from the literature. A representative slope,
based on the ground and accumulated waste topography of the site, was modeled for the
analysis as follows:

The primary influences on the stability are the slope geometry and the material strengths
of the native soil and waste fill units. To calculate the stability, the material strength
properties were modeled using the Mohr-Coulomb criteria. The maximum waste height
at Reppi geometries was considered for the stability calculations.

• 3D slope stability for a material volume between 500 and 10000 m3 was
conducted.
• The seismic stability calculations were performed using a lateral pseudo static
coefficient of 0.05, based on a very conservative interpretation of regional seismic
conditions.
• Wet season groundwater situation of the site was modeled and the piezometric
surface was obtained as shown in Figure 8. The piezometer is verified by the
presence bleeding slope in the waste disposal site
• Rock units were not included in the model as these units, under global stability
conditions, would exhibit infinite strength relative to waste and clay units at the
site.

Table 4Summary of Factors of safety for the slope stability analysis results

Dry-season (FS) Wet-Season (groundwater)

Static (SSFS) Seismic (SSEQ) Static (SSGW) Seismic (SSGWEQ)
Minimum 0.8 0.75 < 0.5 < 0.5
Remark Figure 9a Figure 9b Figure 9c Figure 9d

10 Reid, M.E., Christian, S.B., Brien, D.L., and Henderson, S.T., 2015, Scoops3D—Software to analyze 3D slope

stability throughout a digital landscape: U.S. Geological Survey Techniques and Methods, book 14, chap. A1,
218 p., http://dx.doi.org/10.3133/tm14A1.

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 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Two distinct methods, Fellenius and Bishop, have been employed to calculate the three-
dimensional factor of safety. The final stability result is determined by selecting the
method that yields the lowest factor of safety. Table 4 displays the outcomes obtained
from both methods. The results clearly demonstrate the potential for slope failure,
especially when the safety factor falls below 1.5 (Figure 9). This risk is further
exacerbated during the wet season, as the groundwater level rises and signs of seepage
become evident on the slopes of the waste disposal site.

Based on the data presented in Figure 9, it is clear that the accumulation of waste at a
slope ratio of 1V:2H up to a height of 30 meters is more stable during the dryer season
compared to the wet season. Both dry and wet seasons are susceptible to seismic
activities, which can pose a risk to stable waste slopes. However, the main threat to
stability comes from the higher groundwater levels (leachate) observed during the wet
season (Figures 9c and d). Therefore, it is crucial to promptly implement leachate level
monitoring within the waste area to ensure its stability.

The provision of leachate drainage systems over landfill sites encompasses several key
aspects. Firstly, drainage pipes are utilized to collect and direct leachate to collection
sumps. These pipes, which can be made from materials such as HDPE, PVC, and
geotextiles, are perforated and laid on top of the collection layer. Secondly, sump stations
serve as collection points for the leachate, from where it can be transferred to treatment
facilities or storage tanks. Lastly, treatment facilities are responsible for treating the
leachate before it is discharged or reused.

In the case of Reppi landfill, appropriate types of leachate drainage systems may involve
a combination of horizontal and vertical systems. Horizontally laid pipes across the
landfill base collect the leachate and direct it to the sumps, while vertically installed pipes
throughout the waste mass enhance leachate extraction. Furthermore, it is important to
consider integrating the existing gas collection systems with the leachate drainage
systems at Reppi landfill. This integration can optimize space and improve the efficiency
of leachate collection. It is crucial to note that leachate drainage systems should remain
operational even after landfill closure, ensuring long-term environmental protection.

28
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

It is essential to emphasize that the design and implementation of leachate drainage

systems at Reppi landfill should be carried out by qualified environmental engineers.
Adhering to relevant regulations is vital to ensure the effectiveness and sustainability of
leachate management.

The study has additionally indicated that the regions in the northwest and northeast are
the most vulnerable areas for potential failure (Figures 9c and d). Consequently, it is
imperative to ensure the appropriate isolation of properties and residences from these
specific locations. Although the current state of property existence may not be adversely
impacted by the waste slide, it is crucial to impose restrictions on future activities in these
two sections of the site.

(a) For static dry season

(b) For Seismic dry season

29
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

(c) For static wet season

(d) For seismic wet season

Figure 9 Three dimensional Factor of Safety distribution across the waste disposal site (left: Active site;
right: Extensive site)

5. Future Use of Reppi

The city's cleansing agency has implemented numerous initiatives to enhance solid waste
management (SWM) and mitigate its impacts. One notable initiative is the conversion of
the open dumping site into a semi-aerobic disposal system, also known as the Fukuoka
system. Another significant milestone is the installation of a weighbridge at the landfill
site, which provides valuable data on the amount of solid waste collected. Recent data
from the Reppi weighbridge reveals that the solid waste disposal site receives 2500 to
3369 tons of solid waste daily, averaging to 2700 tons. The data from the weighing bridge
offer many opportunities for accurate forecasting in SWM planning. By utilizing this
historical data, we can optimize the operation of the landfill site, estimate its future
lifespan, and explore alternative disposal methods such as composting, waste-to-energy,

30
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

and incineration. These measures not only improve efficiency but also help conserve
urban land area.

A spatial analysis was carried out to assess the current available space for waste disposal
in Reppi. The analysis utilized data collected through a GPS survey and current air survey
of Addis Ababa, with a specific focus on the current waste topography and the safe slope
for waste accumulation.

Two possible situations were assessed to determine the amount of space available within
the Reppi waste disposal site compound. Specifically, one scenario involved considering
only the current active waste disposal area, while the other scenario took into account
both the current active and already capped waste disposal locations. The findings from
the slope stability analysis, specifically the section on physical stability, revealed that
waste accumulation can be safely conducted on a slope with a ratio of 1 vertical unit to 2
horizontal units. However, this is contingent upon the implementation of appropriate
measures for leachate drainage. The analysis was conducted based on a maximum height
above the ground level near the main gate, which is approximately 30 meters. Taking into
account these parameters, the future site for waste disposal in Reppi was reconstructed,
as shown in Figure 10.

The final fill topography was analyzed for the waste, which is disposed of at a maximum
elevation of 2307 meters with a side slope of 1V:2H. This design allows for better
drainage control. This final fill scenario was chosen to determine the optimal space
available for waste dumping, considering a globally stable slope with improved drainage
control (steeper slope of 1:2), as depicted in Figure 10.

The determination of the available space for waste disposal at Reppi can be achieved by
comparing the current waste topography (Figure 3) with the final waste topography
(Figure 10). A visual representation of the available space for both scenarios is provided
in Figure 11. Based on the volumetric analysis, there is a capacity of 1,842,641 m3 and
2,955,721 m3 for waste disposal in the sole active site utilization and active site plus
already capped site utilization scenarios, respectively. Taking into account an average
compacted density of 7 KN/m3, the site has the capability to accommodate 1,314,831 and
2,109,077 tons of waste for the two scenarios, respectively.

31
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Based on an average daily waste generation of 2,700 tons, it is estimated that the site will
reach its full capacity within ~16 months. It is important to note that the consumption of
waste by the Reppi waste to energy plant (RWEP) is not taken into account in these
calculations. Table 5 summarizes the waste disposal site space availability and period of
service the Reppi solid waste disposal site can provide. These assessments rely on data
collected on the present surface topography of the waste. If an actual assessment of the
waste surface topography were carried out, the outcome's reliability would be
substantial.

Table 5Availabile space and duration of service by Reppi waste disposal site

Space Waste W/O With 5R (worst-

(m3) (ton) RWEP RWEP(3) scenario)
Current 1,842,641 1,314,831 10-16 17-23 14-20 months
Active WDS(1) months months
Active and 2,955,721 2,109,077 20-26 31-37 26-32 months
capped months months
WDS(2)
(1) Using the current active waste disposal area within the Reppi compound.
(2) Using both active and an already-filled section of the compound (the southeastern
parts)
(3) 800 ton/day net waste reduction by RWEP
(4) Waste reduction as per the 5R approach and active management (2176.7 ton/day
for 2023)11
From the table, it is evident that the second scenario offers a larger space and a longer
service duration for the Reppi waste disposal site. However, it is important to consider
the potential safety risks associated with utilizing an already-capped site for fresh waste
disposal. These risks include slope instability, which can lead to landslides and structural
failure, as well as an increased risk of fires due to the dumping of fresh waste.

11 Integrated solid waste management in compassing the 5Rs (Refuse, Reduce, Reuse, Recycle and Recover)

and opportunities for public private partnerships in ISWM in the City

32
Solid Waste Disposal at Reppi (issues, and concerns for planning)

Figure 10Final waste accumulation (1V;2H) topography at Reppi (top: Active site; bottom: Extensive site)

33
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Figure 11Space (in m) above the current waste surface available for further storage (top: Active site;
bottom: Extensive site)

5.1. Expansion of Reppi Solid Waste Site

The current landfill site, located within 50 meters of the highway and less than 100
meters from the residential area, does not meet internationally recommended standards.
Therefore, based on the findings of the study, it is not advisable to expand this site beyond

34
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

its current boundaries due to the surrounding socio-economic activities. Additionally, the
Reppi Solid Waste site has a thick plastic clay layer that acts as a geo-membrane,
preventing solid waste leachate from directly reaching the groundwater. However,
outside of this site, towards the northeast and southwest, the geo-membrane unit thins
out, exposing the underlying lithologic unit. Moreover, the area surrounding the Reppi
Solid Waste Site is heavily influenced by geological structures aligned in the N-S direction.
These ground conditions facilitate the direct infiltration and movement of leachate deep
into the groundwater, posing a risk of contaminating a larger portion of the aquifer.
Therefore, expanding the Reppi Solid Waste disposal site laterally could worsen
groundwater contamination on a significant scale.

6. Conclusion

It can be inferred from the present situation that the disposal of solid waste at Reppi is
giving rise to considerable health and environmental problems in the neighboring areas.
Various environmental issues associated with the dumping of solid waste include the
increase in flies and mosquitoes, unpleasant odors, unsightly visual impact, and the
contamination of the surrounding soil and groundwater caused by the leakage of leachate
from the site, among other concerns.

The garbage being placed in Reppi Solid Waste Disposal comprises biodegradable solids
such as vegetables, paper, and metal, inert solids such as glass and plastics, and other
unclassified materials that pose a great threat to the quality of underground water. The
effects of dumping solid waste on open ground appeared most clearly as high COD in
groundwater. Groundwater has quality parameters within WHO standards except COD,
which is much higher than the WHO standard. However, those parameters within the
WHO standard do not necessarily reflect the absence of a risk of groundwater
contamination by leachate but indicate the current attenuation capacity of the soil layer
underlying the Reppi Solid Waste Site. This attenuation capacity of the soil layer could
diminish gradually as additional excessive leachates are released into the soil, leading to
contamination of the deep groundwater zone.

The stability of the waste slope is crucial in determining whether additional waste can be
disposed of. The potential for slope failure at the site was thus also evaluated.

35
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Unfortunately, the stability analysis has indicated a potential risk of slope failure at the
site. The analysis of slope stability was conducted for both wet and dry season situations.
The analysis has revealed that there is a possibility of slope failure due to factors such as
natural occurrences like rising groundwater levels and seismic activities. This issue poses
an even greater threat to overall stability if these loads coincide.

The results of the slope stability analysis reflect groundwater level configurations during
wet season is found to dictate the stability than seismic activities expected around the
site. This risk becomes more significant during the wet season, necessitating regular
monitoring of tension crack development along the top of the accumulated waste.
Monitoring the leachate level will also contribute to enhancing stability. Appropriate
drainage methods should be implemented to control the leachate level within the waste
complex, as natural causes of instability such as seismic activities are difficult to manage.

The historical information on accumulated waste disposed in Reppi demonstrates a

decrease in height over time due to waste decomposition, which in turn leads to an
increase in waste density. This decrease in height and increase in waste density
contribute to the stability of the waste slopes. On contrary, the current machinery and
trucks used for waste disposal could further destabilize the slope stability. The existing
bulldozer, in particular, creates a larger live load that can hinder the slope's stability. To
mitigate this, lightweight machines for waste spreading may be necessary.

The existing landfill site, situated less than 50 meters away from the highway and less
than 100 meters away from the residential area, does not comply with internationally
recommended standards. The waste management practices currently implemented at
Reppi are likely to incur hidden costs associated with pollution and the contamination of
surface and groundwater. Due to the diminishing attenuation capacity of the soil layer
and clay, as well as the exposure of rocks on the ground surface towards the east of the
Reppi Solid Waste Disposal Site, it is not advisable to expand the site in this direction.
Such expansion could lead to unprecedented effect on the overall socio-environmental
situation.

According to the analysis conducted on the active waste disposal area in the Reppi
compound, it is estimated that the site will reach its maximum capacity within a

36
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

timeframe of 10 to 16 months if the current management practice is continued solely over

the active waste disposal site. However, if the current management practice is extended
to include the active and already capped waste disposal site, the site's capacity will be
reached within a period of 20 to 26 months. Nevertheless, if proper waste management
is implemented and the waste-to-energy plant operates effectively, the duration could be
extended up to 31 months.

The available equipment and resources for solid waste management will determine the
most viable approach for waste collection and disposal. The allocation of budget,
personnel, machinery, and services will determine the availability of resources and
equipment. It is crucial for the staff responsible for solid waste management to possess
the appropriate qualifications. Providing training to personnel on various aspects of solid
waste management, including proper landfilling procedures and the identification and
handling of special waste, is a significant consideration.

Regular monitoring of groundwater quality at selected sites within and around Reppi
solid waste sites is required to fully explore the fate of Reppi solid waste disposal on
groundwater. To ensure proper monitoring of leachate quality at the Reppi waste
disposal site, it is essential to have an analytical laboratory with the recommended
minimum capacity. This laboratory should be able to measure various parameters,
including pH, electrical conductivity, chloride ion, ammonia nitrogen, nitrate nitrogen,
total phosphorus, zinc, BOD5 (five day biochemical oxygen demand), and heavy metals
such as cadmium, chromium, copper, mercury, lead, iron, magnesium, manganese, and
nickel.

37
 Solid Waste Disposal at Reppi (issues, and concerns for planning)

Annex A: Groundwater Quality Data for Sample Wells in Addis Ababa

Parameter Leachat Batu Kore Well Well Jemo Ayer Ghand Effluent & Solid Waste Disposal Regulations AEP Standard
e (2022) 1 1 2 1 Tena i SI6 (EMA, 2007) (AEP, n.d.)12
Safe Low Medium High Min Max
EC (μs/cm ) 27600 0.39 0.6 0.58 0.07 0.38 0.29 1612 ≤ 200 ≤ 1000 ≤ 2000 ≤ 3000 ≤ 3500 5800 52000
PH 8.3 8.69 8.61 8.61 8.62 8.68 7.55 7.88 6–7.5 6–9 5–6; 4–5; 10– 0–4; 5.12 7.8
9–10 12 12–14
TDS 15085 255.2 283.75 334.9 334.6 207.1 155.1 1034 ≤ 100 ≤ 500 ≤ 1500 ≤ 2000 ≤ 3000
DO (%) 0.21 0.045 0.12 0.11 0.115 0.06 0.000 > 75 > 60 > 50 > 30 > 15
Potassium 2739.73 5.99 5.32 24.89 24.61 10.51 4.91 7.57 ≤ 3500 350 3,100
Sodium 1430.8 19.36 19.19 50.79 50.67 23.87 16.69 410.75 ≤ 200 ≤ 200 ≤ 300 ≤ 500 ≤ 1000 474 2400
Iron 10.25 0.29 0.6 <0.07 0.54 0.39 0.27 0.39 ≤ 0.3 ≤1 ≤2 ≤5 ≤8 48.3 2300
Manganese 0.67 0.02 0.03 0.004 0.02 0.02 0.013 0.01 ≤ 0.1 ≤ 0.1 ≤ 0.3 ≤ 0.4 ≤ 0.5 1.4 164
Chromium 1.51 0.03 0.07 0.06 0.08 0.05 0.007 ≤ 1.0 ≤ 1.0 ≤ 1.2 ≤ 1.6 ≤2 0.03 0.3
Lead 0.44 0.13 0.18 0.15 0.15 0.1 0.061 ≤ 0.05 ≤ 0.05 ≤ 0.10 ≤ 0.20 ≤ 0.50 < 0.65
0.04
Mercury 0.04 0.02 0.03 0.03 0.03 0.03 <0.01 ≤ 0.01 ≤ 0.01 ≤ 0.02 ≤ 0.03 ≤ 0.05 0.000 0.001
1 5
Zinc 0.57 0.61 0.16 <0.01 0.07 0.07 1.109 ≤ 0.3 ≤ 0.5 ≤ 4.0 ≤ 5.0 ≤ 15 0.09 140
Nickel 0.45 0.03 0.08 0.03 0.03 0.03 <0.02 ≤ 0.3 ≤ 0.3 ≤ 0.6 ≤ 0.9 ≤ 1.5 < 1.87
0.03
Copper 0.65 0.06 0.07 0.001 0.08 0.08 0.036 ≤ 1.0 ≤ 1.0 ≤ 2.0 ≤ 3.0 ≤ 5.0 0.02 1.1

12 AEP (n.d.). An Ghníomhaireacht um Chaomhnú Comhshaoil LANDFILL MANUALS LANDFILL

38
Solid Waste Disposal at Reppi (issues, and concerns for planning)

Parameter Leachat Batu Kore Well Well Jemo Ayer Ghand Effluent & Solid Waste Disposal Regulations AEP Standard
e (2022) 1 1 2 1 Tena i SI6 (EMA, 2007) (AEP, n.d.)12
Safe Low Medium High Min Max
Chloride 4260 8.50 43.05 19.02 18.52 0.5 1.5 47.57 ≤ 200 ≤ 250 ≤ 300 ≤ 400 ≤ 500 659 4,670
Ammonia 1054.8 <0.01 0.001 <0.01 <0.01 <0.01 0.3 ≤ 0.5 ≤ 0.5 ≤ 1.0 ≤ 1.5 ≤ 2.0 194 3,610
Nitrate 2774.6 18.52 47.65 47.79 48.87 11.18 17.45 0.35 * * * * * < 0.2 18
Sulfate 243.28 5.15 3.56 6.19 6.32 4.55 1.09 39.43 ≤ 100 ≤ 250 ≤ 300 ≤ 400 ≤ 500 <5 1,560
Cadmium 0.02 0.01 0.01 0.01 0.01 0.01 0.002 ≤ 0.01 ≤ 0.01 ≤ 0.05 ≤ 0.1 ≤ 0.3 < 0.1
0.01
Calcium 157.15 61.48 73.62 68.40 69.07 46.58 37.53 4.00 270 6240
Magnesium 108.92 15.15 17.79 15.1 14.95 10.69 9.14 0.01 1.4 164
Bicarbonates 9108.9 4.54 4.29 6.39 6.28 4.04 2.93 976
Boron 2.03 0.08 0.22 0.02 0.08 0.07 0.02 0.19 ≤ 0.50 ≤ 0.50 ≤ 1.00 ≤ 1.50 ≤ 2.00
Arsenic 0.16 0.05 0.06 0.06 0.06 0.04 <0.01 ≤ 0.05 ≤ 0.05 ≤ 0.1 ≤ 0.15 ≤ 0.30 < 0.148
0.001
Selenium 0.08 0.03 0.03 0.02 0.02 0.02 <0.03 ≤ 0.05 ≤ 0.05 ≤ 0.10 ≤ 1.50 ≤ 3.00
Salinity (%) 16.4 0.2 0.3 0.35 0.3 0.2 0.1
Phosphorus 7.67 0.28 0.29 0.63 0.65 0.29 0.29
Molybdenum 0.06 0.002 0.002 0.01 0.01 0.001 0.01
Cobalt 0.18 0.02 0.03 0.02 0.03 0.02 <0.01 ≤ 0.20
Silicon 9.35 38.84 34.28 49.59 49.46 47.01 35.97

39
 Draft Report

Potential Landfill Sites in Addis Ababa:

evaluation and prioritization

Addis Ababa City Administration

Addis Ababa City Cleansing
Management Agency
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

School of chemical Engineering, Addis Ababa Institute of Technology

&
Center for Environmental Engineering, Collage of Natural and
Computational Science
Addis Ababa University

Draft Report
Potential Landfill Sites in Addis Ababa:
evaluation and prioritization

Addis Ababa City Administration Office of the City Manager/ Addis

Ababa City Cleansing Management Agency

January, 2024
Addis Ababa
Potential Landfill Sites in Addis Ababa: evaluation and prioritization

STUDY TEAM MEMBERS

Project Core Management Team
Name Institute Address
Prof. Seyoum Leta, CES, CNCS seyoum.leta@aau.edu.et
Dr. Shimelis Kebede SCBE, AAiT Shimelis.kebede@aait.edu.et
Prof. Zebene Kiflie SCBE, AAiT zebene.kifile@aau.edu.et
Dr. Berhanu Assefa SCBE, AAiT berhanu.assefa@aait.edu.et
Dr. Ahmed Hussen CES, CNCS ahmed.hussen29@aau.edu.et

Study team
Dr. Ing Mebruk Mohammed SCES, AAiT mebruk.mohammed@aau.edu.et
Dr. Wangari Furi CES, CNCS amenwako2010@gmail.com
Dr. Sileshi Degefa ES, ECSU sileshi.degefa@gmail.com
i Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Executive Summary

The city of Addis Ababa has grown at a faster rate in recent years, which has resulted in
an increase in the generation of solid waste. With the current solid waste disposal site
working closer to its capacity, finding alternative site is indispensable. This study
attempts to suggest landfill sites under Addis Ababa context. The intention in this study
is to find site that will (a) not create considerable negative impact on the environment
and health of the dwellers, (b) have less costly engineering solution and easily
manageable. To identify alternative landfill sites, a methodological framework that
integrates GIS and Multi-criteria decision-making methods (MCDM) was developed. Eight
scientific criteria (viz. surface slope, proximity to surface water bodies, proximity to
groundwater table, proximity to residential area, proximity to public institutions,
proximity to road network, soil and geology) important in deciding alternate land fill site
in Addis Ababa was prepared.

Figure. Landfill site Suitability class distribution across Addis Ababa

Taking into account all eight criteria, probable landfill sites were identified and
prioritized as suitable within the premises of Addis Ababa (Figure above and Table
i
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

below). The suitability map disclosed that there are no potential suitable sites (highly
suitable landfill sites). However, there are suitable areas in the city’s eastern,
southeastern and northern parts. There are also small suitable patches of areas in the
western parts of the city. The northern suitable sites are in a steep surface slope, and are
the main groundwater recharge location for water supply wells drilled in the city. Putting
landfill sites at these locations may bring polluted groundwater supply. The cost of land
preparation in such high slope area could also be enormous as such the north patches of
land deemed suitable shall be excluded.

Three potential applications of waste management practices, which include refuse, reuse,
recycle, composting, and anaerobic digestion, were envisioned. Practice A, also known as
Business as Usual, is considered the least effective among the three practices as it does
not demonstrate any progress. Practice B, referred to as the Fair Scenario, takes into
account the existing waste management strategies of households, institutions, and
commercial establishments, as well as the formal and informal sectors. It also considers
the experiences of benchmark countries and regions. Practice C, known as the Planning
Scenario, goes beyond Practice B by incorporating waste minimization at the source and
the thermochemical conversion (pyrolysis) of organic and plastic wastes. By
implementing these three practices, the amount of waste deposited in the landfill site is
projected to reach 29.52 million tons for practice A, 22.05 million tons for practice B, and
17.58 million tons for practice C by the year 2043.

The available space for landfills has been compared to the landfill size requirements for
each year of service, revealing that the top priority site will only be operational until 2034
(for Practice A) – 2037 (for Practice C). The site designated for waste treatment and
management in the city development plan (priority 2 in table below) will continue to
serve its purpose until 2029 (for Practice A) – 2030 (for Practice C). However, if the first
two prioritized sites are consecutively used for waste disposal and management, they
have the potential to operate until 2043, if management practice C is adopted. The three
most suitable sites have a combined area of 154 hectares and are capable of effectively
managing the waste generated in management Practice B.
ii
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Table: features of identified landfill sites

Priority Sub City UTM N UTME Area Current Land Planned Distance (BI
(Ha) cover Development Airport, Km)
1 Lemi 992394 485860 79.67 Crop Land, High and Low Density 6.186
Kura Quarry Mixed Residence
2 Lemi 989023 486036 36.79 Shrub and Grass Solid Waste 7.346
Kura Land treatment and
Management Site
3 Akaki 987286 476343 38.22 Crop Land, Manufacturing and 4.565
Kality Quarry Storage
4 Bole 989119 479736 22.13 Crop Land, Environmental 3.748
Quarry Protection Lake
5 Kolfe 991511 467204 14.84 Shrub and Grass Environmental 9.123
Keranyo Land Protection Forest
6 Kolfe 994188 466572 8.35 Shrub and Grass Low density mixed 9.875
Keranyo Land residence and forest
7 Yeka 1001650 481818 40.31 Crop Land, Environmental 10.142
Quarry Protection Forest
8 Kolfe 996121 466998 1.99 Shrub Land Environmental 8.987
Keranyo Protection Park
The eastern and southeastern patches of land are the most suitable sites for further
investigation regarding their suitability. However, according to the city’s development
master plan, all sites except for the city waste treatment and management site have
already been designated for other developments (table). The potential landfill sites that
have been identified consist of a combination of mixed residences and an area dedicated
to environmental protection. This discovery highlights a conflict of interest that requires
careful examination by city administration officials.

According to the advisory circular (No. ECAA-AC-AGA009) issued by the Ethiopian Civil
Aviation Authority, landfill sites must be located at least 13 km away from the airport. As
a result, all potential landfill sites are confined to this restricted area. Despite this
limitation, the sites remain viable as they align with the recommendations outlined in the
solid waste management manual developed by the Ministry of Urban Development and
Construction. According to the manual, a buffer zone of 3 km should be maintained. For
cities like Addis Ababa that have limited open spaces, it is necessary to reconsider this 13
km buffer distance. It is recommended to initiate discussions with the aviation authority
to explore alternative solutions. It is important to recognize that if the aviation zone
prohibits the establishment of any solid waste disposal site within a 13-kilometer radius
of the current airport in Addis Ababa, it becomes essential to pursue alternative viable
iii
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

options that extend beyond technical solutions. This approach would allow the aviation
authority to potentially contribute to finding a suitable resolution.

Sanitary landfills, in addition to the waste, comprise of daily to weekly soil covering, a
liner system, leachate, and a gas collection system. The quantities of daily covering, liner
system, and top covering can be adjusted based on the shape of the landfill. Furthermore,
the volume will depend on whether the materials for these systems are excavated from
within the landfill site. By taking into account these revised quantities, more precise
assessments of landfill capacity, height, and area can be determined. It is important to
note that landfill capacity values may undergo revisions during landfill operations if the
amount of waste delivered to the site differs from the estimated generation rates prior to
the commencement of operations.

Concerns of wind speed and direction are important in selecting landfill site. These
concerns and additional field level detailed studies on sites prioritized as suitable (see
Figure above) can help narrow the specific locations of the best landfill sites. It was found
that, if proper waste separation, selection, landfill design, construction, operation and
maintenance are made, the marginally suitable sites could potentially be used for landfill
site. The landfill site selection is thus requiring sound scientific approach on its operation
and management. Concerns related to socio-political issues however, need to be
thoroughly evaluated before finalizing the appropriate landfill site.

iv
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Contents
Executive Summary ............................................................................................................................................i

Tables of Figures and Tables ....................................................................................................................... vi

Table of Abbreviations .................................................................................................................................. vii

1. Introduction ................................................................................................................................................ 1

2. Method .......................................................................................................................................................... 2

2.1. Study Area........................................................................................................................................... 2

2.2. General Approach ............................................................................................................................ 2

2.3. AHP ........................................................................................................................................................ 4

3. Criteria for Landfill Site Selection ..................................................................................................... 6

3.1. General ................................................................................................................................................. 6

3.2. Landfill Sites Selection Criteria ................................................................................................. 7

3.2.1. Natural Surface Slope............................................................................................................ 7

3.2.2. Proximity to Surface Waterbody ..................................................................................... 9

3.2.3. Proximity to Main Road .....................................................................................................10

3.2.4. Proximity to Public Institutions .....................................................................................12

3.2.5. Proximity to Residential Area .........................................................................................14

3.2.6. Soil Properties ........................................................................................................................16

3.2.7. Groundwater Table Depth ................................................................................................18

3.2.8. Geologic Setting .....................................................................................................................20

4. Results and Discussion .........................................................................................................................21

4.1. Waste Generation in Addis Ababa ..........................................................................................22

4.2. Estimates of Required Landfill Area......................................................................................24

4.3. Potential landfill sites ..................................................................................................................26

5. Conclusion and recommendation....................................................................................................31

5.1. Conclusion ........................................................................................................................................31

v
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

5.1. Recommendation...........................................................................................................................35

Tables of Figures and Tables

Figure 1Surface slope distribution across Addis Ababa city .......................................................... 8

Figure 2Buffer zone classes for proximity to major surface waterbodies of across Addis
Ababa ....................................................................................................................................................................10
Figure 3Buffer zone classes for proximity to planned road network across Addis Ababa
.................................................................................................................................................................................12
Figure 4Buffer zone classes for proximity to public institutions across Addis Ababa ......13
Figure 5Land use Land Cover class values across Addis Ababa for landfill site selection
.................................................................................................................................................................................16
Figure 6Soil suitability class distribution across Addis Ababa....................................................18
Figure 7Groundwater table depth suitability map of Addis Ababa ...........................................20
Figure 8Geologic suitability class distribution across Addis Ababa..........................................21
Figure 9Projected total solid waste production by type via Practice A, B and C .................23
Figure 10Criteria weights as obtained from AHP .............................................................................27
Figure 11Landfill site Suitability class distribution across Addis Ababa city .......................28
Figure 12Suitable sites for further detailed feasibility study ......................................................29

Table 1Surface slope suitability classes for landfill site selection ............................................... 8
Table 2proximity to water bodies class for landfill site selection..............................................10
Table 3proximity to road network class for landfill site selection ............................................12
Table 4proximity to public institution class for landfill site selection .....................................13
Table 5Land Use Land Cover class for landfill site selection ........................................................15
Table 6Soils suitability classes for landfill site selection ...............................................................18
Table 7proximity to groundwater table class for landfill site selection ..................................19
Table 8Geologic setting classes for land fill site selection .............................................................21
Table 9average per capita per day waste generation rate over the next two decades .....23
vi

Table 10Total landfill size requirements via Practices A, B and C .............................................25

 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Table 11Landfill site suitability class % coverage ............................................................................27

Table 12 Features of identified landfill sites .......................................................................................29

Table of Abbreviations

AHP Analytical hierarchy process

BAU Business as Usual

C&D Construction and demolition

CI Consistency Index

CR Consistency ratio

FDRE Federal democratic republic of Ethiopia

GWT Groundwater Table

LULC Land use and land cover

MCDM Multi-criteria decision-making methods

MSW Municipal Solid Waste

RI Random index

WDS Waste disposal site vii

 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

1. Introduction

Solid waste disposal plays a crucial role in the waste management system. In addition to
preventing environmental pollution and health issues, it necessitates intricate socio-
economic analysis and interpretation. The waste management challenges faced in Addis
Ababa are a consequence of unscientific waste disposal methods, which stem from
inadequate planning and implementation. Unsafe practices like open dumping, burning, and
burying of solid waste are prevalent among the residents of Addis Ababa. This approach has
raised concerns among city dwellers due to the severe environmental pollution and health
problems it causes, as well as the contamination of surface and groundwater, waste slide
failures, and the negative impact on tourism and other businesses. As the current solid waste
disposal site is operating at its almost full capacity, the identification of suitable locations
within the city for solid waste disposal is a crucial step towards establishing sustainable
waste management in the city.

The Ministry of Urban and Construction Strategy (MUDC, 2013)1 advocates for the
development of landfill site plans that take into account socio-economic factors within the
city. When selecting a site, various factors such as wind direction, waterways, aviation zones,
and the potential for site reuse after closure should be considered. The city administrators
have been greatly concerned about the high population and urban system growth of the city,
as well as the ineffective and unscientific methods of solid waste collection, separation,
sorting, dumping, and treatment. It is crucial to address the waste management issues of
Addis Ababa in a well-planned and organized manner, taking into account the diverse and
complex situation of the city. One of the most difficult challenges in Addis Ababa is selecting
a suitable landfill site for engineered solid waste disposal, as there is a scarcity of affordable
and unused land in the city. The chosen landfill site must prioritize public health and
environmental pollution concerns. To achieve this, criteria for selecting landfill sites need to
be developed based on the current and projected characteristics of solid waste and the city's
1

1 MUDC (2013) የከተማ ልማትና ኮንስትራክሽን ሚኒስቴር የከተሞች የተቀናጀ የመሠረተ ልማት አቅርቦት ስትራቴጂና ስልት, አዲስ አበባ

ጥር 2004 ዓ.ም.
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

economic and social factors. This study aims to describe the criteria used to identify landfill
sites in Addis Ababa and utilizes multi criteria decision-making (MCDM) methods to
integrate these criteria-based factors into a single landfill site suitability class within the GIS
environment.

2. Method

2.1. Study Area

Addis Ababa, the capital city of federal democratic republic of Ethiopia (FDRE), is renowned
for its diverse population, languages, and cosmopolitan atmosphere. The study area roughly
encompasses from 38º 38′ E to 38° 55′ E longitude and 8°50ʹ to 9°06′ N latitude, with an
undulating topography and an average elevation of 2405 meters above sea level. The city
benefits from its strategic location, being well-connected to the rest of the country.
Additionally, Addis Ababa serves as the residence for numerous diplomats, including those
from the African Union.

For years, Addis Ababa has faced challenges due to the significant amount of waste generated
by its residents. The current solid waste management system has proven ineffective due to
limited disposal space and an unscientific approach. Furthermore, the city's living conditions
make it difficult to separate, sort, collect, and transport waste. It is common to find a mix of
slums and modern buildings in close proximity, reflecting the cohabitation of different
income groups.

During the wet and dry season, the characterization of waste production in Addis Ababa
reveals significant variations among households with different income levels. Household
waste constitutes a substantial portion of the city's overall waste generation, surpassing that
of commercial, institutional, industrial, street, and public sources. The daily waste generation
in Addis Ababa ranges from 2400 to 3369 tons, depending on the level of engagement from
the city's residents.

2.2. General Approach

A methodological framework that integrates GIS and MCDM was developed to identify
2

alternative landfill sites for solid waste disposal. In order to determine an alternate landfill
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

site in Addis Ababa, eight scientific criteria were established. The criteria weights were
assigned using the analytical hierarchy process (AHP) weighting method. These eight
criteria include proximity to a surface water body, proximity to a planned road network,
proximity to public institutions, proximity to residential areas, natural land surface slope,
groundwater table depth, soil composition, and geology. The 30 m digital elevation model
was obtained from the United States Geological Survey Earth Explorer website
(https://earthexplorer.usgs.gov). To verify the layers of the city, including residential areas,
water bodies, public institutions, present dumping grounds, and agricultural land, a
combination of Google Earth imagery and the city base map was utilized. Groundwater table
data were derived from an unconfined aquifer groundwater modeling analysis of the city,
while soil data were downloaded from the FAO soil data portal2. Geomorphic data,
specifically rock types, were obtained from geological survey of Ethiopia. The analysis was
performed using Arc-GIS 10.8 software. All criteria were first geo-referenced, converted into
a raster format, and then reclassified. The weights of each criteria were determined based
on environmental guidelines, country regulations, and expert opinions. Expert opinions
were collected through the development of questionnaires, which were distributed to
individuals involved in solid waste management such as engineers, health officials of the
municipality, and academicians who have previously worked on the solid waste issue in the
city. The questionnaires consisted of pairwise comparison matrices to gather opinions on
the degree of superiority of each criterion over the others. The AHP method was employed
to combine the weights of all criteria resulting from the questionnaire. These weights were
then linearly combined to generate a final site suitability map.

The preferences for each criterion were further categorized into a universal scale that
ranged from 1 (least preferred) to 5 (most preferred). In order to integrate the results from
each criterion, the criteria maps were standardized into a standard categorical unit
3

2 https://www.fao.org/soils-portal/
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

(Eastman, 20033; Al-Ansari, 20134; Alanbari et al., 20145). This standardization process was
carried out using the reclassifying tool in ArcGIS 10.8 software. The criteria maps were
transformed into integers between 1 and 5, where 1 represented "Not Suitable," 2
represented "Marginally Suitable," 3 represented " Moderately Suitable," 4 represented "
Suitable," and 5 represented "Highly Suitable."

2.3. AHP

AHP, which was introduced by Saaty (1980)6, has proven to be an effective tool for decision-
making. It has gained widespread usage in the selection of landfill sites. This method utilizes
a computational matrix to compare criteria in pairs and prioritize them (Vargas, 2010)7. To
determine the weights of each criterion for decision-making, normalization is performed for
each criterion. This ensures that the accuracy of the decision can be evaluated, making the
approach more reliable. The steps of AHP are outlined below.

To begin, experts provide their opinions on the criteria, which are then used to create a
pairwise comparison matrix. This matrix reflects the experts' judgments on the relative
importance of each criterion in the final decision. The pairwise comparison matrix is
represented as follows:

𝐶11 𝐶12 𝐶13

𝐶𝑜𝑚𝑝𝑎𝑟𝑖𝑠𝑜𝑛 𝑀𝑎𝑡𝑟𝑖𝑥 = |𝐶21 𝐶22 𝐶23 |
𝐶31 𝐶32 𝐶33

Where Cij denotes the relative importance of ith row (ith criteria) and jth column (jth criteria)
in this comparison matrix
4

3 Eastman, J.R., 2003. In: IDRISI Kilimanjaro tutorial, 269. Clark University, Clark Labs, Worcester, MA, USA, pp.
61–123
4 Al-Ansari, N.A., 2013. Locating landfills in arid environment. J. Earth Sci. Geotechn. Eng. 3 (3), 11–24.

https://www.diva-portal.org/
5 Alanbari, M.Ali., Al-Ansari, N., Jasim, H.K., 2014. GIS and multicriteria decision analysis for landfill site selection

in Al-Hashimyah Qadaa. Nat. Sci. (Irvine) 6 (5), 282–304. doi: 10.4236/ns.2014.65032

6 Saaty, T.L., 1980. The Analytic Hierarchy Process: Planning, Priority Setting, Resources Allocation. Mcgraw-

Hill, New York doi: 10.1080/01966324.1982.10737095

7 Vargas, R.V., 2010. Using the analytic hierarchy process (AHP) to select and prioritize projects in a portfolio.

Paper Presented at PMI®Global Congress 2010—North America, Washington, DC.

 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

The matrix was used to individually sum up the column values, and then each comparison
matrix was divided by this sum to create a normalized pairwise comparison matrix (equation
below):

𝑋11 𝑋12 𝑋13 𝑛

𝐶𝑖𝑗
𝑁𝑜𝑟𝑚𝑎𝑙𝑖𝑠𝑒𝑑 𝑐𝑜𝑚𝑝𝑎𝑟𝑖𝑠𝑜𝑛 𝑚𝑎𝑡𝑟𝑖𝑥 = = |𝑋21 𝑋22 𝑋23 | , 𝑤ℎ𝑒𝑟𝑒 𝐶𝑇𝑗 = ∑ 𝐶𝑖𝑗
𝐶𝑇𝑗 𝑋31 𝑋32 𝑋33 𝑖=1

The weight for each criteria is determined using the following equation

∑𝑛𝑗=1 𝑋𝑖𝑗 𝑊1
𝑊𝑖 = = |𝑊2 |
𝑛 𝑊3

In order to ensure the credibility of these weights, the consistency ratio (CR) is calculated.
This ratio is then compared to standard CR values that depend on the number of criteria. For
a larger number of criteria, it is recommended to have a CR value of 0.1 (10%) or less, as
suggested by Saaty (1980). To calculate this ratio, the largest Eigenvalue (𝜆max) of the
pairwise comparison matrix needs to be derived by taking the average value of all
consistency vectors, as stated by Tripathi et al. (2017)8. According to Han and Tsay (1998)9,
this largest Eigenvalue is crucial for computing the Consistency Index (CI), which measures
the extent to which a matrix deviates from consistency.

𝜆𝑚𝑎𝑥 −𝑛
𝐶𝐼 = , Where n was the number of criteria, and 𝜆max is the largest Eigenvalue (Han and
𝑛−1

Tsay, 1998; Leake, 199910).

Table: RI values, as suggested by Saaty (2006)

n 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
RI 0 0 0.52 0.89 1.11 1.25 1.35 1.4 1.45 1.49 1.51 1.54 1.56 1.57 1.58
5

8 Tripathi, G., Kanga, S., Singh, S.K., 2017. Forest fire hazards vulnerability and risk as- sessment in Bhajji forest
range of Himachal Pradesh (India): a geospatial approach. Project: For. Fire Vulner. Risk Assess. 8 (1).
9 Han, W.J, Tsay, W.D., 1998. Formulation of quality strategy using analytic hierarchy pro- cess. In: Twenty-

Seven Annual Meeting of the Western Decision Science Institute. University of Northern Colorado, USA, pp.
580–583
10 Leake, C., 1999. Jacek Malczewski GIS and multi-criteria decision analysis. J. Oper. Res. Soc. 51 (2), 247. doi:

10.2307/254268
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

The CR is determined by using the random index (RI) in conjunction with the CI comparison,
as suggested by Saaty (2006)11. The RI, which is dependent on the number of criteria (n)
being compared, is used to calculate the CR. The CR reflects the level of consistency in the
pairwise comparisons. If the CR is 0.10 or less, it indicates that the weights are acceptable
and decisions can be made based on these weights. However, if the CR is greater than 0.10,
it signifies that the weights are inconsistent and need to be revised.

3. Criteria for Landfill Site Selection

3.1. General

Several valuable lessons have been learned from the previous trial of identifying landfill
sites. It is crucial to consider the constraints that have significant socio-economic impacts.
The first step is to acknowledge and exclude sites that cannot be developed or are not
permitted due to their potential social, environmental, and political consequences. However,
this report also acknowledges the technical factors that govern the selection of landfill sites
in the context of Addis Ababa. In Addis Ababa, areas such as public institutions, residential
complexes, and water bodies are deemed unsuitable for landfill sites. To identify these
constraint areas, buffer analysis and proximity analysis were conducted in the GIS
environment, which helped identify specific exclusion features. Each landfill development
criterion was assigned a value of zero for unsuitable areas and a value of five for highly
suitable areas, resulting in a constraint map for each criterion. These criteria were derived
from expert opinions and a thorough literature review (Eastman, 2003). To generate an
overall constraint map of landfill sites in Addis Ababa, a linear combination of weights for
the eight criteria was used, as described in the equation below (Chou and Chang, 200812;
Hasan et al., 200913).
6

11 T.L. Saaty (2006) There is no mathematical validity for using fuzzy number crunching in the analytic
hierarchy process journal of systems science and systems engineering, volume 15, Issue 4,:457–464.
http://dx.doi.org/ 10.1007/s11518-006-5021-7
12 Chou, S-Y., Chang, Y.H., 2008. A decision support system for supplier selection based on a strategy-aligned

fuzzy SMART approach. Expert Syst. Appl. 34 (4), 2241–2253. doi: 10.1016/j.eswa.2007.03.001
13 Hasan, M.R., Tetsuo, K., Islam, S., 2009. Landfill demand and allocation for municipal solid waste disposal in

Dhaka city an assessment in a GIS environment ‖. J. Civil Eng. (IEB) 37, 133–149
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

𝑆𝑐 = ∑𝑛𝑖=1 𝑊𝑖 𝑋𝑖 Where, 𝑺𝒄 represent suitability constraint map for a landfill site, 𝑾𝒊 represent
the weight of criteria i, 𝑿𝒊 represent attribute score of criteria i
3.2. Landfill Sites Selection Criteria

Eight criteria were utilized to select an alternative landfill site, based on the opinions of
experts, available literature, and data in the study area. Each criterion was assigned a
suitability score ranging from 1 to 5. For criteria related to proximity, the scoring was
determined by establishing buffer zones. For other criteria, the score was based on
parameters crucial for pollution control. All these criteria maps were then reclassified within
the GIS environment. The descriptions and basis for the score value of each criterion are
provided below:

3.2.1. Natural Surface Slope

Environmental attributes such as excavation, area filling, and surface slope play a significant
role in controlling the migration of pollutants over the surface. A slope above 2% is inversely
correlated with landfill suitability, meaning that the higher the slope, the Marginally Suitable
the land is for being selected as a landfill site (Kontos et al., 2005)14. Areas with higher slopes
are unsuitable for dumping sites due to increased costs of land leveling and fill work, higher
risks of slope failure, increased pollution risks, and leachate movement. On the other hand,
lower slopes facilitate easier land leveling and fill work, enhancing the stability of waste
(Gbanie et al., 201315; Ebistu and Minale, 201316). However, the slope should still provide a
sufficient gradient for the collection of leachate flow. A very flat slope (<2%) is not suitable
for a landfill site as it allows ample time for leachate to percolate into the ground, thereby
polluting the groundwater. Once pollution occurs at such a flat gradient, the cost of treatment
becomes prohibitively expensive.
7

14 Kontos, T.D., Komilis, D.P., Halvadakis, C.P., 2005.

Siting MSW landfills with a spatial multiple criteria analysis
methodology. Waste Manage. (Oxford) 25 (8), 818–832. doi: 10.1016/j.wasman.2005.04.002
15 Gbanie, S.P., Tengbe, P.B., Momoh, J.S., Medo, J., Kabba, V.T.S., 2013. Modelling land- fill location using

geographic information systems (GIS) and multicriteria decision analysis (MCDA): case study Bo, southern
Sierra Leone. Appl. Geogr. 36, 3–12. doi: 10.1016/j.apgeog.2012.06.013
16 Ebistu, T.A., Minale, AS, 2013. Solid waste dumping site suitability analysis using geo- graphic information

system (GIS) and remote sensing for Bahirdar town, northwestern Ethiopia. Afr. J. Environ. Sci. Technol. 7 (11),
976–989
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Table 1Surface slope suitability classes for landfill site selection

Slope (%) Class Rank % coverage

0-2 Marginally Suitable 2 10.9
2-8 Highly Suitable 5 61.8
8-15 Suitable 4 21.1
15-30 Moderately Suitable 3 6.0
> 30 Not Suitable 1 0.2
The slope map was created using a 30-meter-resolution DEM. After generating the slope map
for the city (Figure 1), the resulting slope was categorized into five classes, as indicated in
Table 1. Based on the table, it is evident that lower-slope land is more suitable for landfill
sites compared to higher-slope land. From Figure 1, it can be concluded that, considering
slope as the sole criterion, over 82% of the land in Addis Ababa is classified as suitable.

Figure 1Surface slope distribution across Addis Ababa city

8
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

3.2.2. Proximity to Surface Waterbody

The city is traversed by several streams that extend beyond its boundaries to the
neighboring Shagar city and eventually join the Awash River through the Aba Samuel
Reservoir. Therefore, the interconnected ecological and environmental systems rely on
these surface water bodies. Due to the increased risk of leachate contamination, it is not
advisable to locate a landfill site near surface water bodies such as rivers and streams
(Gbanie et al., 2013; J. Olusina and Shyllon, 201417). According to the MUDC (2012)18 manual,
it is recommended that landfill sites should not be located in floodplains that are prone to
10-year floods. Additionally, if these sites are situated in areas susceptible to 100-year
floods, they must be designed in an economically feasible manner to prevent any possibility
of washout. Several researchers have recommended maintaining a safe distance (100 to 300
m) from water sources when selecting landfill sites to protect water bodies from
contamination (Chang, 199619; Gorsevski et al., 201220; Gemitzi et al., 200621; Akbari et al.,
200822; Jaybhaye et al., 201423). In this study, a buffer distance of 200 meters was delineated
around water bodies and classified as unsuitable for landfill sites, with higher weights
assigned to areas with buffer distances exceeding 1500 m (Table 2; Figure 2). More than 34%
of the land in Addis Ababa has been classified as suitable based on its proximity to surface
waterbodies.

17 Olusina, J., Shyllon, D.O., 2014a. Suitability analysis in determining optimal landfill location using multicriteria

evaluation (MCE), gis & remote sensing. Int. J. Comput. Eng. Res. 4 (6), 7–20
9
18 MUDC (2012) Solid Waste Management Manual: With Respect to Urban Plans, Sanitary Landfill Sites and

Solid Waste Management Planning

19 Chang, D.Y., 1996. Applications of the extent analysis method on fuzzy AHP. Eur. J. Oper. Res. 95 (3), 649–

655.
20 Gorsevski, P.V., Donevska, K.R., Mitrovski, C.D., Frizado, J.P., 2012. Integrating multi- criteria evaluation

techniques with GIS for landfill site selection: a case study using ordered weighted average. Waste Manage.
(Oxford) 32 (2), 287–296.
21 Gemitzi, A., Tsihrintzis, V.A., Voudrias, E., Petalas, C., Stravodimos, G., 2006. Combining geographic

information system, multicriteria evaluation techniques and fuzzy logic in siting MSW landfills. Environ. Geo
51, 797–811. doi: 10.1007/s00254-006-0359-1
22 Akbari, V., Rajabi, M.A., Chavoshi, S.H., Shams, R., 2008. Landfill site selection by com- bining GIS and fuzzy

multicriteria decision analysis, case study: bandar Abbas, Iran. World Appl. Sci. J. 3 (1), 39–47
23 Jaybhaye, R., Mundhe, N., Dorik, B., 2014. Site suitability for urban solid waste disposal using geoinformatics:

a case study of pune municipal corpora- tion, Maharashtra, India. Int. J. Adv. Rem. Sens. GIS 3 (1), 769–783.
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Table 2proximity to water bodies class for landfill site selection

Buffer Class Rank % Buffer (m) Class Rank %

(m) coverage coverage
< 200 Not Suitable 1 17.5 1000- Suitable 4 15.1
1500
200-500 Marginally Suitable 2 22.2 > 1500 Highly Suitable 5 19.3
500-1000 Moderately 3 25.7
Suitable

Figure 2Buffer zone classes for proximity to major surface waterbodies of across Addis Ababa

3.2.3. Proximity to Main Road

Due to the expenses associated with waste collection and transportation, it is preferable to
locate landfill sites closer to the main road networks. However, this proximity can lead to
health issues for individuals using the road network. Various studies have proposed different
buffer distances for landfill sites from main road networks. For instance, some researchers
10
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

suggest a buffer distance of 75 m (Chang et al., 200824), while others recommend a buffer
zone of 100 m (Kumar and Shaikh, 2013)25. The importance of close proximity to road
networks is emphasized in certain studies (e.g., Wang et al., 200926; Gorsevski et al., 2012;
Das and Bhattacharyya, 201527; Güler and Yomralo ğlu, 201728), while others (e.g.,
Bhambulkar, 201129; Rafiee et al., 201130; Jaybhaye et al., 2014) assign a lower rank to this
factor. On the other hand, some researchers (e.g., Lin and Kao, 1999)31 argue that an optimal
distance from existing roads should be considered, taking into account both transportation
costs and environmental impact.

As per the MUDC (2012) guidelines, it is essential for landfill sites to have convenient access
via a well-built public road that can handle the increased truck traffic without causing any
major disruptions to the flow of vehicles. Additionally, the manual recommends that the
access road leading from the public road to the site should be less than 10 km in length,
particularly in metropolitan cities such as Addis Ababa.

Based on economic and environmental considerations, areas within a 50-meter buffer

distance from the road were deemed unsuitable, while areas beyond a 500-meter buffer
distance were considered Marginally Suitable. The most suitable areas for landfill sites were

11
found to lie between these two ranges. The findings (Table 3; Figure 3) indicate that over

24 Chang, N-B, Parvathinathan, G, Breeden, JB, 2008. Combining GIS with fuzzy multicriteria decision-making
for landfill siting in a fast-growing urban region. J. Environ. Manage. 87 (1), 139–153. doi:
10.1016/j.jenvman.2007.01.011
25 Kumar, M., Shaikh, V.R., 2013. Site suitability analysis for urban development using GIS- based multicriteria

evaluation technique. J. Indian Soc. Rem. Sens. 41 (2), 417–424. doi: 10.1007/s12524-012-0221-8
26 Wang, G., Qin, L., Li, G., Chen, L., 2009. Landfill site selection using spatial information techno logies and AHP:

a case study in Bejing, China. J. Environ. Manage. 90 (8), 2414–2421. doi: 10.1016/j.jenvman.2008.12.008
27 Das, S., Bhattacharyya, B.Kr., 2015. Optimization of municipal solid waste collection and transportation route.

Waste Manag. 43, 9–18. doi: 10.1016/j.wasman.2015.06.033

28 Güler, D., Yomral ı o ğlu, T., 2017. Alternative suitable landfill site selection using analytic hierarchy process

and geographic information systems: a case study in Istanbul. Env- iron. Earth Sci. 76 (20), 678. doi:
10.1007/s12665-017-7039-1
29 Bhambulkar, A.V., 2011. Municipal solid waste collection routes optimized with ArcGIS network analyst. Int.

J. Adv. Eng. Sci. Tech. 11 (1), 202–207. http://esribulgaria.com/

30 Rafiee, R., Syed, E., Mahiny, A.R.S., Darvishsefat, A.A., Danekar, A., Khorasani, N., Hasan, S.E., 2011. Siting

transfer stations for Municipal solid waste using a spatial multi-criteria analysis. Environ. Eng. Geo-Sci. 17 (2),
143–154. doi: 10.2113/gsee- geosci.17.2.143
31 Lin, H-Y., Kao, J., 1999. Enhanced spatial model for landfills siting analysis. J. Environ. Eng. 125, 845–851. doi:

10.1061/(ASCE)0733-9372(1999)125:9(845)
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

19% of the Addis Ababa area is suitable for landfill sites when proximity to roads is taken
into account.

Table 3proximity to road network class for landfill site selection

Buffer (m) Class Rank % Buffer Class Ran %

coverage (m) k coverage
< 50 Not Suitable 1 29.2 350-500 Suitable 4 5.6
50-200 Moderately Suitable 3 40.8 > 500 Marginally 2 10.1
200-350 Highly Suitable 5 14.3 Suitable

Figure 3Buffer zone classes for proximity to planned road network across Addis Ababa

3.2.4. Proximity to Public Institutions

Public institutions play a crucial role in society. As previously mentioned, Addis Ababa City
has established numerous public institutions of national significance. These institutions
encompass various entities such as schools, hospitals, government offices, mosques,
12

churches, stadiums, bus stations, train stations, and more, serving as important platforms
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

for public engagement. They hold significant cultural, economic, and social value for the
community. Both residents of Addis Ababa and individuals from other regions rely on these
institutions. Therefore, any health concerns arising within these establishments can
potentially impact the entire country. According to MUDC (2012), it is recommended that
the landfill site be located at a distance of more than 1 km from socio-politically sensitive
areas where public acceptance may be doubtful. In this particular study, a 250-meter buffer
zone was designated around public institutions, deeming it unsuitable for landfill sites.
Moreover, areas with buffer distances exceeding 1500 meters were given the highest
priority (Table 4; Figure 4). The findings indicate that over 15% of the land area is
appropriate for a landfill site, provided that the sole criterion for selection is the proximity
to public institutions.

Figure 4Buffer zone classes for proximity to public institutions across Addis Ababa

Table 4proximity to public institution class for landfill site selection

13

Buffer (m) Class Rank % Buffer (m) Class Ran %

coverage k coverage
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

0-250 Not Suitable 1 53.8 1000-1500 Suitable 4 7.1

250-500 Marginally 2 16.0 > 1500 Highly 5 8.7
Suitable Suitable
500-1000 Moderately 3 14.4
Suitable
3.2.5. Proximity to Residential Area

The residential area of the city is determined by analyzing the land use situation. The land
use and land cover (LULC) data for the city were obtained from official city documents and
satellite images from 2021. Factors such as environmental concerns (such as air pollution),
aesthetic value (Tagaris et al., 2003)32, land value (Zeiss and Lefsrud, 1996)33, residents'
health (Giusti, 2009)34, fire risks, and public opposition (Lober, 199535; Mahini and
Gholamalifard, 200636; Kamdara et al., 201937) play a role in determining suitable landfill
sites. It is recommended by some researchers (Babalola and Busu, 201138; Donevska et al.,
201139; Gorsevski et al., 2012) that solid waste should not be disposed of in densely
populated areas. According to MUDC (2012), it is recommended that there should be no
residential buildings located directly next to the boundary of the landfill site. The manual
specifies that the design should include landscaping and protective berms to reduce the
visibility of the landfill's activities in residential areas.

One important consideration is to avoid locating landfill sites near agricultural land due to

14
the potential threat of leachate. Leachate can contaminate agricultural fields, negatively

32 Tagaris, E., Sotiropoulou, R.E.P., Pilinis, C., Halvadakis, C.P., 2003. A methodology to estimate odors around
landfill sites: the use of methane as an odor index and its utility in landfill siting. J. Air Waste Manage. Assoc. 53
(5), 629–634. doi: 10.1080/10473289.2003.10466198
33 Zeiss, C., Lefsrud, L., 1996. 1996 Making or breaking waste facility siting successes with a siting framework.

Environ. Manage. 20 (1), 53–64. doi: 10.1007/PL00006702

34 Giusti, L, 2009. A review of waste management practices and their impact on human health. Waste Manage.

(Oxford) 29 (8), 2227–2239. doi: 10.1016/j.wasman.2009.03.028

35 Lober, D.J., 1995. Resolving the siting impasse: modeling social and environmental lo- cational criteria with

a geographic information system. J. Am. Plann. Assoc. 61 (4), 482–495. doi: 10.1080/01944369508975659
36 Mahini, A.S., Gholamalifard, M., 2006. Siting MSW landfills with a weighted linear com- bination methodology

in a GIS environment. Int. J. Environ. Sci. Technol. 3 (4), 435–445. doi: 10.1007/BF03325953
37 Kamdara, I., Ali, S., Bennui, A., Techato, K., Jutidamrongphan, W., 2019. Mu- nicipal solid waste landfill siting

using an integrated GIS-AHP approach: a case study from Songkla, Thailand. Resour. Conserv. Recycl. 149 (2),
220–235. doi: 10.1016/j.resconrec.2019.05.027
38 Babalola, A., Busu, I., 2011. Selection of landfill sites for solid waste treatment in Damaturu town-using GIS

techniques. J. Environ. Prot. (Irvine, Calif) 2 (1), 1–10. doi: 10.4236/jep.2011.21001

39 Donevska, K.R., Gorsevski, P.V., Jovanovski, M., PeshevskiI, G., 2011. Re- gional non-hazardous landfill site

selection by integrating fuzzy logic, AHP and geographic information systems. Environ. Earth Sci. 67 (1), 121–
131. doi: 10.1007/s12665-011-1485-y
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

impacting crops, soil quality, and fertility for an extended period of time. The presence of
heavy metals like mercury, lead, cadmium, and arsenic in the leachate can also pose health
risks. Therefore, it is crucial to maintain a distance between landfill sites and agricultural
fields to prevent these issues (Jaybhaye et al., 2014). On the other hand, barren land, shrubs,
and grasslands are more suitable options for landfill sites. The LULC data is divided into nine
categories, with five suitability classes indicated in Table 5 and Figure 5.

Table 5Land Use Land Cover class for landfill site selection

Land use land cover Class Rank %

coverage
Residential and Public Not Suitable 1 47.3
institutions
Vegetation, Trees and Marginally Suitable 2 6.4
Irrigated
Agricultural Moderately Suitable 3 35.1
Grass and Shrub land Suitable 4 11.2
Barren land Highly Suitable 5 0.0
Upon examining the distribution of land use and land cover (LULC), it was found that there
were no areas that were highly suitable for landfills. In terms of relative proportions,
approximately 11% of the land in Addis Ababa, which is covered by shrubs, is considered
suitable. Similarly, agricultural land, accounting for 35% of the total area, has the potential
to be utilized for landfills. However, it is crucial to conduct further investigation into this land
to assess any potential socio-political implications that may arise during the implementation
process.
15
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Figure 5Land use Land Cover class values across Addis Ababa for landfill site selection

3.2.6. Soil Properties

Soil permeability, soil porosity, and soil clay content are significant factors that determine
the likelihood of groundwater contamination. Clay soils have the ability to retain and absorb
harmful substances found in landfill leachates. Soils with low permeability and high clay
content are particularly suitable because the high clay content reduces permeability, thereby
minimizing the entry of anionic pollutants into the ground (Kabite et al., 201240; Sharifi et al.,
200941). As per the MUCD (2012) report, it is anticipated that soils situated above the
16

40 Kabite, G., Suryabhagavan, KV., Argaw, M., Sulaiman, H., 2012. GIS-based solid waste landfill site selection in
Addis Ababa, Ethiopia. Int. J. Ecol. Environ. Sci. 38 (2–3), 59–72
41 Sharifi, M., Hadidi, M., Vessali, E., Mosstafakhani, P., Taheri, K., Shahoie, S., Khodamorad- pour, M., 2009.

Integrating multi-criteria decision analysis for a GIS-based hazardous waste landfill sitting in Kurdistan
Province, western Iran. Waste Manag. 29 (10), 2740–2758. doi: 10.1016/j.wasman.2009.04.010
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

groundwater table will possess a relatively low permeability, ideally less than 104 cm/s,
when undisturbed.

Soil maps were obtained from the FAO data portal. Three types of soil were identified in the
Addis Ababa area: Pellic Veritsols (Vp), Nitosol (Ne10-3b), and Nitosol (Ne13-3b). Pellic
Vertisols, after the upper 20 cm are mixed, contain 30% or more clay in all horizons up to a
depth of at least 50 cm from the surface. These Vertisols often develop cracks at least 1 cm
wide at a depth of 50 cm, unless they are irrigated. The moist chromas of these Vertisols are
predominantly less than 1.5 throughout the upper 30 cm of soil. Due to their low
permeability, watering Vertisol soils may lead to waterlogging and buildup. Nitosols, on the
other hand, have an argillic B-horizon with a clay distribution that does not decrease by more
than 20 percent within 150 cm of the surface. Nitosols are well-drained soils with higher
permeability, allowing them to be tilled within 24 hours of wetting without compromising
their soil structure. In this study, Vertisols were classified as having better suitability than
Nitosols (Table 6). From the discussion, it is clear that while more expensive engineering
solutions may be required to construct landfill sites on Nitosols compared to Vertisols, both
types of soils can be considered suitable for landfill sites.

17
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Figure 6Soil suitability class distribution across Addis Ababa

Table 6Soils suitability classes for landfill site selection

Soil Type Class Rank % coverage

Pellic Vertisols Highly Suitable 5 41.8
Nitosol (Ne13-3b) Moderately Suitable 3 58.2
Nitosol (Ne10-3b) Moderately Suitable
3.2.7. Groundwater Table Depth

Groundwater contamination from landfill sites is a significant concern, particularly when

these sites are located in areas with shallow groundwater depths. To prevent pollution of the
subsurface, it is crucial to ensure that landfills are situated at a reasonable distance above
the groundwater table (GWT). Various studies have proposed different distances for this
purpose. Effata and Hegazy (2012)42 suggest a distance of 6 m, Delgado et al. (2008)43 18

42 Effata, H.A., Hegazy, M.N., 2012. Mapping potential landfill sites for North Sinai cities using spatial
multicriteria evaluation. Egypt. J. Rem. Sens. Space Sci. 15 (2), 125–133. doi: 10.1016/j.ejrs.2012.09.00
43 Delgado, O.B., Mendoza, M., Granados, E.L., Geneletti, D, 2008. Analysis of land suitability for the siting of

inter-municipal landfills in the Cuitzeo Lake Basin, Mexico. Waste Manag. 28 (7), 1137–1146. doi:
10.1016/j.wasman.2007.07.002
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

propose 10 m, Moeinaddini et al. (2010)44 recommend 15 m, and Sadek et al. (2001)45

advocate for a distance of 30 m. According to MUDC (2012), it is recommended that the
excavation level of the landfill should be higher than the groundwater table that occurs once
every 10 years. Additionally, the manual advises against siting landfills in the 10-year
groundwater recharge area, especially if there are plans for existing or future water supply
development.

In the case of Addis Ababa city, the groundwater depth was modeled to classify suitable areas
into five distinct zones. The classification takes into account the depth of the water table,
with areas having a deeper water table considered the most suitable. Conversely, areas with
the shallowest depth are deemed the least suitable. This classification is presented in Table
7 and Figure 7.

Table 7proximity to groundwater table class for landfill site selection

GWT (m) Class Rank % GWT (m) Class Rank %

coverage coverage
< 10 Not Suitable 1 8.8 30-50 Suitable 4 14.0
10-20 Marginally Suitable 2 4.8 > 50 Highly 5 66.4
20-30 Moderately Suitable 3 6.0 Suitable

19

44 Moeinaddini, M., Khorasani, N., Danehkar, A., Darvishsefat, A.A., Zienalyan, M., 2010. Siting MSW landfill using

weighted linear combination and analytical hierarchy pro- cess (AHP) methodology in GIS environment (case
study: karaj). Waste Manage. 30 (5), 912–920. doi: 10.1016/j.wasman.2010.01.015
45 Sadek, S., El-Fadel, M., El-Hougeiri, N., 2001. Optimizing landfill siting through GIS ap- plication. In:

Seventeenth International Conference on Solid Waste Technology and Management, The Journal of Solid Waste
Technology and Management, Philadelphia, USA, p. 2124
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Figure 7Groundwater table depth suitability map of Addis Ababa

3.2.8. Geologic Setting

As per the MUDC (2012) manual, it is anticipated that there are no underlying limestone,
carbonate, or any other permeable rock formations that would hinder the effectiveness of
acting as barriers against leachate and gas migration. This condition applies to formations
that exceed a thickness of 1.5 m and are situated as the uppermost geological unit.
Additionally, the manual advises against the presence of fault lines or extensively fractured
geological structures within a 0.5 km radius of the proposed landfill cell development, as
they may lead to unpredictable movement of gas or leachate.

The Geological Survey of Ethiopia provided the regional geologic map for the study area. In
the process of selecting landfill sites, the lithology, or rock character, was considered as one
of the factors. Within Addis Ababa city, five volcanic rock types were identified: Ntb, Nc,
NQtb, Nn, and PNa. Sedimentary rocks are typically effective in containing leachate naturally,
20

while fractured volcanic rocks may facilitate leachate movement, resulting in faster travel to
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

the groundwater. In cases where the medium is largely fractured, engineering solutions such
as grouting and lining may be necessary. The geologic and hydrogeological settings of Addis
Ababa, described in Table 8 and Figure 8, play a crucial role in determining the selection of
landfill sites.

Table 8Geologic setting classes for land fill site selection

Symbol Geology Aquifer Class Rank % coverage

Nc Pliocene ignimbrite trachyte, Moderately Moderately 3 7.5
rhyolite and basalt productive Suitable
Nn Miocene ignimbrite, tuff and Minor Suitable 4 61.2
rhyolite
Ntb Middle Miocene Addis Ababa Productive Marginally 2 7.2
Basalt Suitable
PNa Oligocene rhyolite, tuff, trachyte Poor Highly 5 16.3
and agglomerate Suitable
NQtb Quaternary Scoria, scoraceaous Major Not Suitable 1 7.8
and vesicular basalts Productivity

Figure 8Geologic suitability class distribution across Addis Ababa

4. Results and Discussion

As a result of the growing population and urban expansion, the amount of solid waste is on
the rise, posing a challenge for city administrators due to the lack of suitable disposal sites.
The situation is further exacerbated by the use of unscientific waste management methods.
21

This study aims to address this issue by identifying potential landfill sites within the
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

premises of Addis Ababa. The study emphasizes the application of a scientific waste
management system, ensuring that the identified landfill sites (i) do not harm the
environment, (ii) are cost-effective, and (iii) improve the efficiency of the city's waste
management system. To achieve this, GIS techniques and the MCDM system were utilized.

4.1. Waste Generation in Addis Ababa

Authorized primary collection service providers carry out the collection of Municipal Solid
Waste (MSW) in Addis Ababa City. These providers collect the waste through door-to-door
collection and transport it to mini transfer stations or large container carrier locations
nearby. The average per capita waste generation rate over the next two decades is as shown
in table 9 (see theme one report46 for the details). The projected total household waste
generation rates for Addis Ababa city over the same 20-year period, is depicted in Figure 9
(refer to the theme three report47 for detailed information). According to the analysis of this
report, three potential applications of refuse, reuse, recycle, composting, and anaerobic
digestion management practices were envisioned.

• Practice A (Business as Usual, BAU): The quantities of waste being reused, recycled,
composted, subjected to anaerobic digestion, sent to landfill, and incinerated are all
increased at a rate similar to the rate at which waste is generated. This practice is
considered the worst among the 5R practices as it does not show any progress.
• Practice B (Fair Scenario): The rate at which municipal solid waste (MSW) is generated
is projected in a similar manner as in Practice A. The waste management strategies,
including reuse, recycling, composting, and anaerobic digestion, are projected by taking
into account the existing practices of households, institutions, and commercial
establishments, as well as the formal and informal sectors. Additionally, the experiences
of benchmark countries and regions are considered.
22

46 Addis Ababa City Municipality Solid Waste Generation Rate, Composition and PhysIco-Chemical
Characteristics Study Report
47 Integrated solid waste management in compassing the 5Rs (Refuse, Reduce, Reuse, Recycle and Recover)

and opportunities for public private partnerships in ISWM in the City

 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

• Practice C (Planning Scenario): In addition to Practice B, this scenario also includes waste
minimization at the source and the thermochemical conversion (pyrolysis) of organic
and plastic wastes. It is expected that the pyrolysis of organic and plastic wastes will be
implemented in 2043, with the aim of producing useful materials such as biochar and
bio-oil, as well as recovering energy from the MSW of the city.

Figure 9 illustrates the total waste generation over the next 20 years for the three
aforementioned practices. The results are based on the projected population provided by the
United Nations. By 2043, the estimated daily household waste disposed at landfill for the
respective management practices will reach 6594 tons, 4860 tons, and 2632 tons per day
from the current 2177 tons per day.

2500000

2000000
Practice A Practice B Practice C
WASTE (TON)

1500000

1000000

500000

0
2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043
YEAR

Figure 9Projected total solid waste production by type via Practice A, B and C

Table 9average per capita per day waste generation rate over the next two decades

Year 2023 2024 2025 2026 2027 2028 2029

Per capita per day Generation (Kg) 0.54 0.5448 0.555 0.5652 0.5754 0.5856 0.5958
Year 2030 2031 2032 2033 2034 2035 2036
23

Per capita per day Generation (Kg) 0.606 0.6162 0.6264 0.6366 0.6468 0.657 0.6672
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Year 2037 2038 2039 2040 2041 2042 2043

Per capita per day Generation (Kg) 0.6774 0.6876 0.6978 0.708 0.7182 0.7284 0.7386
4.2. Estimates of Required Landfill Area

A waste disposal site (WDS) serves as the ultimate stage in waste management. There are
two methods proposed for final waste disposal: controlled landfill and sanitary landfill.
Controlled landfill is an improvement over open dumping, as it involves periodically
covering the buried waste with soil to mitigate environmental disturbances. Additionally,
garbage leveling and compaction are carried out to optimize land use efficiency and stabilize
the surface of the WDS. Sanitary landfill, on the other hand, is the internationally accepted
method where waste is covered with soil daily to minimize potential disruptions. This
method is recommended for implementation in large cities and metropolitan areas and is
particularly suitable for large cities like Addis Ababa. To meet the standards of sanitary
landfill, the quality of the landfill must be improved gradually over time, starting with a
controlled landfill and progressively advancing according to the strategic plan of the city
government. The government must allocate significant funds and attention to secure enough
land and soil for waste processing. Therefore, a calculation is necessary to determine the
land requirements.

To address the need for facilities and infrastructure for WDS, it is crucial to estimate the
required land for the landfill site. It is essential for a landfill to have the capacity to
accommodate waste disposal for a minimum of 10 years of operation. The following
assumptions have been made for estimating the landfill area, height, and volume of waste for
the next 20 years of planning:

• The new landfill site will be commissioned by 2025.

• Assumed waste density: 0.714 ton/m3.
• A soil cover of 15 cm on top and sides, resulting in a lift height of 1.5 to 2 m.
• The maximum height above the ground for filling is set at 30 meters.
• The side slope of the waste accumulation is 1V:2H.
• 15% of the active waste accumulation area is required for infrastructural facilities.
24

• A liner system with a thickness of 5m (including leachate collection layer) and a cover
system with a thickness of 1.0 m (including gas collection layer).
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

• It is estimated that 10% of the waste will settle or biodegrade within 20 years,
resulting in available volume.

Table 10 presents the landfill capacity and overall space requirement for sanitary landfills,
based on the aforementioned assumptions. The table depicts the land size requirements by
years of service. The data clearly demonstrates that a larger area (115 – 190 ha) is necessary
by the end of 2043.

Table 10Total landfill size requirements via Practices A, B and C

Waste (Millions Ton) Volume (million m3) Area (ha)

Year Practic Practic Practic Practic Practic Practic Practic Practic Practic
eA eB eC eA eB eC eA eB eC
2023 0 0 0 0 0 0 0 0 0
2024 0 0 0 0 0 0 0 0 0
2025 0.89 0.80 0.79 1.35 1.22 1.20 10 2 2
2026 1.84 1.62 1.59 2.78 2.46 2.41 26 18 14
2027 2.84 2.46 2.41 4.30 3.73 3.64 23 20 20
2028 3.91 3.33 3.23 5.92 5.04 4.90 30 34 27
2029 5.04 4.22 4.08 7.64 6.39 6.17 37 31 31
2030 6.25 5.14 4.95 9.45 7.78 7.48 45 38 36
2031 7.52 6.10 5.83 11.38 9.23 8.83 55 44 42
2032 8.86 7.10 6.75 13.41 10.74 10.22 61 50 47
2033 10.28 8.14 7.69 15.56 12.32 11.64 70 57 54
2034 11.78 9.23 8.67 17.83 13.96 13.12 79 63 60
2035 13.36 10.36 9.68 20.22 15.69 14.65 90 71 66
2036 15.03 11.56 10.73 22.75 17.50 16.24 108 80 73
2037 16.79 12.82 11.82 25.41 19.40 17.89 110 87 80
2038 18.65 14.15 12.86 28.22 21.41 19.47 122 98 87
2039 20.60 15.55 13.86 31.18 23.53 20.97 135 103 92
2040 22.66 17.03 14.81 34.30 25.78 22.42 146 114 98
2041 24.83 18.61 15.73 37.58 28.16 23.81 160 125 104
2042 27.12 20.28 16.62 41.04 30.69 25.15 174 134 112
2043 29.52 22.05 17.58 44.68 33.37 26.61 190 144 115
The values, in table 10, serve as an initial estimate solely for planning purposes. The
quantities of daily cover, liner system, and top cover system can be adjusted based on the
shape of the landfill. Additionally, the volume will depend on whether materials for these
systems are excavated from within the landfill site. By considering these revised quantities,
more accurate estimates of landfill capacity, height, and area can be determined. The final
25

and precise estimates will be established after the topographical survey (with a contour
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

interval of 0.30 m) results become available. It should be noted that landfill capacity values
may undergo revisions during landfill operations if the amount of waste delivered to the site
differs from the estimated generation rates prior to the start of operations.

4.3. Potential landfill sites

A diverse set of professionals, including environmental specialists, scientists, academicians,

government officials, law experts, and ordinary city residents, were involved in assessing the
various aspects of site selection for a landfill within the city premises. This comprehensive
evaluation process aimed to determine the most advantageous location for the landfill. The
study identified and analyzed eight key factors that significantly influenced the selection of
the landfill site. These factors were then standardized, assigned weights, and combined to
create a suitable map indicating the ideal dumping site. The AHP weights for these eight
criteria were calculated based on the feedback received from the participants, as illustrated
in Figure 10.

In the AHP method, CR is used to determine the consistency of the relative weights. In this
study, the largest Eigenvalue (𝜆max) for AHP was found to be 8.735, resulting in a CI of 0.105.
According to Saaty (2006), the RI value for eight criteria is 1.4. The ratio of CI to RI is then
calculated to be 0.075, which falls within the acceptable range (<0.1) as suggested by Saaty
(1980). Therefore, the weights presented in Figure 10 are considered acceptable, and further
decisions can be made based on these criteria.

26
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

25.6% 26.8%

17.0%

11.1%
7.9%
5.3%
2.8% 3.4%

Figure 10Criteria weights as obtained from AHP

The assigned weights for each criterion indicate the relative influence of each factor. The
eight factors mentioned have varying degrees of impact on the suitability of landfill sites.
Figure 10 clearly shows that experts are opposed to landfill sites being located near
residential areas and public institutions. The respondents also emphasize the importance of
proximity to groundwater and surface water as a high-level concern for siting landfills in
Addis Ababa. On the other hand, lithology, road access, soil, and surface slope are considered
low-level concerns, in that order, for siting landfill sites.

To determine the final suitability of landfill sites in Addis Ababa, a weighted linear
combination method was employed. The resulting suitability map is divided into five classes:
highly suitable, suitable, moderately suitable, marginally suitable, and unsuitable areas. The
final outcome of the suitability classes can be observed in Figure 11 and Table 11.

Table 11Landfill site suitability class % coverage

Class Rank %
coverage
Not Suitable 1 0.4
Marginally 2 38.6
Suitable
Moderately 3 43.1
27

Suitable
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Suitable 4 17.9
Highly Suitable 5 0

Figure 11Landfill site Suitability class distribution across Addis Ababa city

A map of constraints was created to identify unsuitable locations for landfill sites, excluding
sensitive areas such as residential areas, public institutions, and surface and ground water
bodies. This was done by referring to Table 11, which excludes classes as 1, 2 and 3. The
exclusion of these sensitive areas is crucial in the process of determining suitable locations
for landfill sites.

Figure 12 showcases potential locations that satisfy the required conditions, as determined
by analyzing aerial photographs and satellite imagery. The prioritization of the identified
sites was determined based on the eight landfill site selection criteria values outlined in
section 3. The resulting priority is presented in Table 12. In cases where two sites possess
28

equal value, their spatial size is taken into consideration to establish a more favorable
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

priority value. Table 12 also provides an overview of the characteristics of these potential
sites, as depicted in Figure 12. These characteristics encompass both the existing and
planned developments, as outlined in the Addis Ababa city development master plan. Upon
examining the table, it becomes apparent that, with the exception of the second-prioritized
site, all other sites have already been designated for alternative developments. This finding
suggests the presence of a potential conflict of interest that warrants investigation by the
city administration officials.

Figure 12Suitable sites for further detailed feasibility study

Table 12 Features of identified landfill sites

Priority Sub City UTM N UTME Area Current Land Planned Distance
(Ha) cover Development (Bole Airport,
Km)
1 Lemi 992394 485860 79.67 Crop Land, High and Low Density 6.186
Kura Quarry Mixed Residence
2 Lemi 989023 486036 36.79 Shrub and Grass Solid Waste 7.346
Kura Land treatment and
Management Site
3 Akaki 987286 476343 38.22 Crop Land, Manufacturing and 4.565
29

Kality Quarry Storage

4 Bole 989119 479736 22.13 Crop Land, Environmental 3.748
Quarry Protection Lake
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

5 Kolfe 991511 467204 14.84 Shrub and Grass Environmental 9.123

Keranyo Land Protection Forest
6 Kolfe 994188 466572 8.35 Shrub and Grass Low density mixed 9.875
Keranyo Land residence and forest
7 Yeka 1001650 481818 40.31 Crop Land, Environmental 10.142
Quarry Protection Forest
8 Kolfe 996121 466998 1.99 Shrub Land Environmental 8.987
Keranyo Protection Park
Upon comparing Table 12, which indicates the available space for landfills, with Table 10,
which outlines the landfill size requirements for each year of service, it becomes apparent
that the initial priority site will only remain operational until 2034–2037. This timeframe is
contingent upon the implementation of specific management practices (A, B and C) at the
site. It is worth noting that the site (priority 2) already designated for waste treatment and
management in the city development plan will continue to serve its purpose until 2029–
2030. However, if the first two prioritized sites are consecutively utilized for waste disposal
and management, they have the potential to operate until 2043, provided that management
practice C is adopted. The three most appropriate sites encompass a combined area of 154
hectares, capable of effectively managing the waste generated in management practice B.

Figure 12 also showcases the designated aviation zone, which outlines the specifications for
building heights. Landfills have a tendency to attract a significant number of wildlife,
particularly birds. The Ethiopian Civil Aviation Authority Proclamation 616/2009 addresses
the management of wildlife hazards. Additionally, the authority has developed an advisory
circular (No. ECAA-AC-AGA009) that provides guidance on managing hazardous land use
practices around airports that attract wildlife. Table 12 displays the distances between the
chosen potential sites and the Bole International Airport runway. As per the guidelines
provided in the advisory circular, landfill sites should be situated at a minimum distance of
13 km from the airport. Consequently, all these potential sites fall within the restricted area.
However, for cities like Addis Ababa, which have limited open spaces, it becomes imperative
to reconsider this distance requirement. It is recommended to commence discussions with
the aviation authority in order to explore alternative solutions. It is crucial to acknowledge
that if the aviation zone prohibits the establishment of any solid waste disposal site within a
13-kilometer radius of the current airport in Addis Ababa, it becomes necessary to initiate
30

alternative viable options that go beyond technical solutions. This will enable the aviation
authority to potentially contribute to finding a suitable resolution. Despite this limitation,
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

the sites remain viable as they align with the recommendations outlined in the solid waste
management manual developed by the Ministry of Urban Development and Construction.
According to the manual, a buffer zone of 3 km should be maintained.

International standards, such as those in the Netherlands (6 km) and Canada, (8 km, (BC,
2016)48), suggest different minimum distances. Some researchers (Nadhir, 2013)49, the State
of Hawaii50, and the Queensland government of Australia (QG, 2021)51 recommend a
minimum distance of 3 km from the airport runway. Conversely, the solid waste
management manual (MUDC, 2012) provides distance guidelines based on the type of
aircraft engine. For turbojet airports, it is not recommended to have a landfill site within 3
km, while for piston engine aircraft airports, the recommended distance is 1.6 km. The
manual provides additional details stating that if the landfill site is situated within a distance
of 3 km to 8 km from the nearest turbojet airport (or within a distance of 1.6 km to 8 km
from the nearest piston engine aircraft airport), no attention should be given unless written
authorization from the aviation authority is acquired. This authorization should confirm that
the site's location does not present any risks to air safety.

5. Conclusion and recommendation

5.1. Conclusion

This study attempts to suggest a scientific method of landfill selection under Addis Ababa
context. The intention in this study is to find site that will (a) not create considerable negative
impact on the environment, and health of the dwellers, (b) have less costly engineering
solution and easily manageable. The MCDM method together with the GIS tools were used to
identify appropriate sites. The study has concluded that the landfill site should be located:
31
• at a reasonable slope that would reduce design and operation costs;

48 BC Ministry of Environment, 2016 Landfill Criteria for Municipal Solid Waste, Second Edition, British
Columbia
49 Nadhir Al-Ansari 2013 Locating Landfills in Arid Environment, Journal of Earth Sciences and Geotechnical

Engineering, vol. 3, no. 3, 2013, 11-24, 1792-9660 (online) Scienpress Ltd, 2013
50 https://www.honolulu.gov/opala/newlandfill.html, accessed Dec. 2023
51 QG Department of Environment and Science, 2021, Guideline: Landfill siting, design, operation and

rehabilitation, ESR/2015/1627, Version 5.00, Queensland Government, Australia

 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

• in less permeable soil and geologic settings to decrease potential groundwater

pollution;
• at reasonable distance from groundwater table, rivers, residential areas and public
institution to reduce effect on environmental pollution and societal health;
• at a reasonable distance from main road network to decrease transportation and
collection costs without creating health problems on the high way users.

Proximity of a landfill site to residential and public institutions is recognized as the upper
most essential criteria to consider while selecting landfill sites. This is manifested in higher
weight given to these two criteria of selecting landfill sites. This is also true for the case of
the existing open dumpsite. Reppi open dumpsite has been concern for the people living
around it because of its release of harmful gases, such as methane, carbon dioxide, ammonia,
and hydrogen sulfide. Besides uncontrolled fire (due to the combustible gases created during
decomposition of old solid wastes) has been common in Reppi. Due to the health risks from
landfill pose to the users of public institutions, landfill sites should be kept as far away from
these institutions as possible.

Proximity to road network, less permeable geologic setting and flatter surface slope are
recognized as desirable from engineering cost estimates. However, these criteria were given
less weight because of lack of knowledge on potential cost these criteria may incur during
construction, operation and maintenance. In general, this study reveals that local human
health concerns get the largest attention in selecting landfill sites. Next in the hierarchy is
environmental pollution, which is manifested in middle level weights given to proximity to
groundwater table and surface water bodies.

While considering LULC, soil and geologic (rock) properties, this study identified less
permeable, bare or vacant land without vegetation cover as the best option for solid waste
dumpsites. Because there is potential large scale pollutant spreading beyond the city
premise, proximity of the landfill to surface water source is taken into consideration. Landfill
site near the water source always increases the chance of contamination; thus, a 200-meter
buffer distance is drawn for each water body and is considered unsuitable.
32
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

Groundwater depth is one of the most crucial elements that depend on rock type,
permeability of the soil, and other climatic properties. This city’s groundwater depth ranges
from 0 m (springs and marshlands closer to perennial rivers) to more than 50 m, which
needs further classification as to which depth is more suitable for landfill siting. Shallow
groundwater areas are not preferred because of the risk of groundwater pollution and the
cost associated with its remedial measures.

The city of Addis Ababa has grown at a faster rate in recent years, which has resulted in an
increase in residential areas and the generation of more solid waste. Taking into account all
of the criteria as well as the exclusionary area, probable landfill sites were selected as
suitable areas on the suitability map. The overall suitability (Figure 11 and Table 11) shows,
with their percent coverage, the five suitability classes: not suitable, marginally suitable,
moderately suitable, suitable, and highly suitable. The suitability map disclosed that there
are no potential suitable sites (highly suitable landfill sites). However, there are large
suitable areas in the city’s eastern, southeastern and northern parts. There are also small
suitable patches of areas in the western parts of the city. The northern suitable sites are in a
steep surface slope, where the weight as given by the experts put it, as one of the less
significant factor for site selection. Besides as the main groundwater recharge location for
water supply boreholes in the city, putting landfill sites at these locations may bring polluted
groundwater supply. The cost of land preparation in such high slope area could be enormous
as such the north patches of land deemed suitable shall be excluded.

The eastern and southeastern patches of land are the most suitable sites for further
investigation regarding their suitability. However, it is important to note that these sites fall
within the exclusion area of the civil aviation authority advisory circular, which has a buffer
radius of 13 km from Bole International Airport. Despite this limitation, the sites remain
viable as they align with the recommendations outlined in the solid waste management
manual developed by the Ministry of Urban Development and Construction. According to the
manual, a buffer zone of 3 km should be maintained.

The waste production in the next twenty years will be immense; implementing a sanitary
33

landfill would necessitate a land area of up to 190 hectares. Sanitary landfills, in addition to
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

the waste, comprise of daily to weekly soil covering, a liner system, leachate, and a gas
collection system. The quantities of daily covering, liner system, and top covering can be
adjusted based on the shape of the landfill. Furthermore, the volume will depend on whether
the materials for these systems are excavated from within the landfill site. By taking into
account these revised quantities, more precise assessments of landfill capacity, height, and
area can be determined. It is important to note that landfill capacity values may undergo
revisions during landfill operations if the amount of waste delivered to the site differs from
the estimated generation rates prior to the commencement of operations.

Landfill sites need to see also the average wind direction. Landfill sites in a windy area,
pollutant migration into nearby public spaces is inevitable. Concerns of wind speed and
direction are important in selecting landfill site. These concerns and additional field level
detailed studies on sites prioritized as suitable (see Figure 12) can help narrow the specific
locations of the best landfill sites.

Three potential applications of waste management practices, including refuse, reuse, recycle,
composting, and anaerobic digestion, were envisioned. Practice A, known as Business as
Usual (BAU), is considered the least effective among the three practices as it does not show
any progress. Practice B, referred to as the Fair Scenario, takes into account the existing
waste management strategies of households, institutions, and commercial establishments,
as well as the formal and informal sectors. It also considers the experiences of benchmark
countries and regions. Practice C, known as the Planning Scenario, goes beyond Practice B
by incorporating waste minimization at the source and the thermochemical conversion
(pyrolysis) of organic and plastic wastes. The available space for landfills has been compared
to the landfill size requirements for each year of service, revealing that the top priority site
will only be operational until 2034–2037. This timeframe is dependent on the
implementation of specific management practices at the site. It is important to mention that
the site designated for waste treatment and management in the city development plan will
continue to serve its purpose until 2029 (Practice A) – 2030 (practice C). However, if the first
two prioritized sites are consecutively used for waste disposal and management, they have
34

the potential to operate until 2043, provided that management practice C is adopted. The
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

three most suitable sites have a combined area of 154 hectares and are capable of effectively
managing the waste generated in management practice B.

5.1. Recommendation

It was found that, if proper waste separation, selection, landfill design, construction,
operation and maintenance are made, the identified sites could potentially be used for
landfill site. The landfill site selection is thus more on the scientific approach of its
management. Concerns related to socio-political issues however, need to be thoroughly
evaluated before finalizing the appropriate landfill site.

The analysis of aerial photos and satellite images has identified potential sites that meet the
necessary criteria. However, apart from the city waste treatment and management site, all
other sites have already been planned for other developments. The identified potential
landfill sites encompass a combination of mixed residences and an area dedicated to
environmental protection. This finding highlights a potential conflict of interest that requires
careful examination by the city administration officials.

In accordance with the advisory circular (No. ECAA-AC-AGA009) issued by the Ethiopian
Civil Aviation Authority, landfill sites must be situated at a minimum distance of 13 km from
the airport. This requirement effectively confines all potential landfill sites within this
restricted area. However, for cities like Addis Ababa, which face a scarcity of open spaces, it
becomes imperative to reassess this distance. It is recommended to commence discussions
with the aviation authority in order to explore alternative solutions. It is crucial to
acknowledge that if the aviation zone prohibits the establishment of any solid waste disposal
site within a 13-kilometer radius of the current airport in Addis Ababa, it becomes necessary
to initiate alternative viable options that go beyond technical solutions. This approach would
enable the aviation authority to potentially contribute to finding a suitable resolution.

In the United States, landfill management practices involve categorizing landfills into three
main types: municipal solid waste landfills (MSWLFs), industrial waste landfills, and
35
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

hazardous waste landfills52. Similar classifications can be found in Australia and Europe. In
Australia, waste and landfill types are classified into putrescible (compostable) waste, non-
putrescible (non-compostable) waste, inert waste, and hazardous waste landfills (WCS,
2010)53. On the other hand, the European approach classifies landfills based on the level of
waste hazard: hazardous waste landfills, non-hazardous waste landfills, and inert waste
landfills54. Each category of landfill accepts specific types of waste and follows different
design, construction and management practices to minimize its environmental impact.

MSWLFs are specifically designed for the disposal of household waste and other
nonhazardous waste. These landfills facilitate the rapid transformation and degradation of
organic waste. The composition of these waste include food, yard and ashes and other fine
wastes that can be compostable.

Industrial waste landfills, on the other hand, are designated for the collection of recyclable
commercial and institutional waste and construction and demolition wastes (C&D). C&D
materials, primarily include debris from buildings, roads, bridges, and other structures.
Common items found in industrial waste landfills include woods, plastics, papers, concrete,
lumber, asphalt, gypsum, metal, bricks, clay, and various building components such as doors,
countertops, and cabinets. Unlike regular landfills, industrial waste landfills often function
as material recovery facilities rather than simply serving as repositories for construction
debris.

Hazardous waste landfills are specialized facilities that focus on the disposal of hazardous
waste. Unlike MSWLFs, which handle solid waste, hazardous waste landfills deal with
materials that are potentially dangerous or destructive. These landfills are subject to strict
regulations and have a well-structured design. Their primary purpose is to securely contain
hazardous waste, minimizing the risk of any release into the environment. Furthermore,
36

52 https://www.epa.gov/landfills/basic-information-about-landfills
53 WCS (wright corporate strategy) PTY limited (2010) landfill performance study: review of the application of
landfill standards, Australia
54 https://environment.ec.europa.eu/topics/waste-and-recycling/landfill-waste_eu
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

hazardous waste landfills undergo frequent inspections throughout the year to ensure the
safety of the facility and its impact on the environment.

In the context of Addis Ababa, the lack of space for larger landfill sites poses a significant
challenge. This situation is further complicated by the fact that all waste in Addis Ababa is
considered municipal waste, necessitating the need for a single landfill type. However, it has
been established through this study that the generation of different types of solid waste,
including compostable, non-compostable, inert, and hazardous waste, is inevitable. This
presents an opportunity to utilize various landfill sites and types for the disposal of different
waste categories.

To effectively manage solid waste disposal in Addis Ababa, a waste categorization system
has been proposed. This system includes MSWLFs for compostable waste, which constitutes
a significant portion of the total waste. These landfill sites will be designed with waste-to-
energy conversion possibilities in mind. Industrial landfills can also contribute to job
creation opportunities. In this process, waste items are dumped into a pile and then sorted
by landfill workers to identify reusable materials. These materials are either donated or sold
to local resale stores or businesses specializing in reclaimed materials. Additionally, the
material recovery facility may repurpose certain materials on-site, such as converting
lumber into mulch. Landfills that handle hazardous waste should adhere to stricter
standards in order to safeguard the environment from its detrimental impacts.

In general considering the type and amount of waste landfill contain, the hazard level and
the study and design quality required, landfills need to be classified. According to Ethiopian
Integrated city infrastructure development strategy (MUDC, 2013), landfill sites need to be
created based on the type of solid wastes they are handling. The Addis Ababa city structural
plan (AACPPO, n.d.)55 also proposes the implementation of waste segregation at its origin,
with three distinct categories of waste: recyclable, biodegradable, and hazardous. This
37

approach necessitates the establishment of dedicated landfill sites for each waste class. The

55 Addis Ababa City Plan and Development Commission (AACPDC) (n.d.) Addis Ababa City Structure Plan 2017–

2027
 Potential Landfill Sites in Addis Ababa: evaluation and prioritization

strategy promotes creating situations that would enable recycling the solid wastes, where
small industry enterprises involvement is justified.

It is crucial to classify landfills based on the type and quantity of waste they contain, as well
as the level of hazard they pose. Additionally, careful consideration must be given to the
study and design process involved in establishing these landfills. The Ethiopian Integrated
Urban Infrastructure Development Strategy (MUDC, 2013) emphasizes the importance of
selecting landfill sites based on the specific type of solid waste they handle. This strategy also
encourages the creation of conditions that facilitate the recycling of solid waste, with the
involvement of small industry enterprises.

38
 Draft Report

Technologies for Handling and Disposing of

Dead Animal Bodies

Addis Ababa City Administration

Addis Ababa City Cleansing
Management Agency
 Technologies for Handling and Disposing of Dead Animal Bodies

School of chemical Engineering, Addis Ababa Institute of Technology

&
Center for Environmental Engineering, Collage of Natural and
Computational Science
Addis Ababa University

Draft Report
Technologies for Handling and Disposing of
Dead Animal Bodies

Addis Ababa City Administration Office of the City Manager/ Addis

Ababa City Cleansing Management Agency

January, 2024
Addis Ababa
Technologies for Handling and Disposing of Dead Animal Bodies

STUDY TEAM MEMBERS

Project Core Management Team
Name Institute Address
Prof. Seyoum Leta, CES, CNCS seyoum.leta@aau.edu.et
Dr. Shimelis Kebede SCBE, AAiT Shimelis.kebede@aait.edu.et
Prof. Zebene Kiflie SCBE, AAiT zebene.kifile@aau.edu.et
Dr. Berhanu Assefa SCBE, AAiT berhanu.assefa@aait.edu.et
Dr. Ahmed Hussen CES, CNCS ahmed.hussen29@aau.edu.et

Study team
Dr. Ing Mebruk Mohammed SCES, AAiT mebruk.mohammed@aau.edu.et
Dr. Wangari Furi CES, CNCS amenwako2010@gmail.com
Dr. Sileshi Degefa CES, CNCS sileshi.degefa@gmail.com
 Technologies for Handling and Disposing of Dead Animal Bodies

Executive summary

Animals in urban areas perish due to mishandling, diseases, accidents, inter-animal

competition, or natural aging. These deceased animals are typically disposed of using
traditional methods, such as mixing them with other solid waste in Addis Ababa, regardless
of the cause of their demise. Furthermore, there are instances where dead animals are buried
or burned without the knowledge or approval of the city administration. These deceased
animals are then transported to nearby waste collection centers. While it is the responsibility
of the owners to transport carcasses from their homes to the waste collection centers, the
city's Cleansing Agency is responsible for transporting the deceased animals to the landfill.
However, it is not uncommon to observe a significant number of carcasses on the sides of
roads or in the middle of the road for several days. Apart from posing a threat to human
health, the failure to promptly remove these deceased animals is seen as an uncivilized
occurrence, indicating a lack of proper follow-up and efficient communication systems from
the relevant authorities.

The mishandling and improper disposal of dead animals in the city of Addis Ababa pose
numerous problems. Instead of being handled in a proper manner, these deceased animals
are often left on roadsides, riversides, and public areas, either for scavengers to feed on or to
decompose naturally. This practice not only creates various types of nuisances but also poses
significant environmental risks.

The objective of this section of the study is to propose viable alternative methods for
disposing of animals' remains and to provide the Addis Ababa City Administration Solid
Waste Cleansing Agency with a comprehensive set of approaches for managing such
carcasses in order to prevent the transmission of zoonotic diseases and infections. This will
enable the Solid Waste Cleansing Agency to act promptly. The selection of disposal methods
takes into account the well-being of humans, animals, and the ecosystem, with the aim of
identifying a safe, practical, cost-effective, and environmentally sustainable approach.

Various techniques and technologies are utilized for the disposal of dead animal bodies, but
there is no universally effective solution. Different countries employ methods such as burial,
incineration, rendering, or landfilling, each with its own advantages and disadvantages. For
i
 Technologies for Handling and Disposing of Dead Animal Bodies

instance, rendering and composting have gained popularity in many nations due to the
usefulness of their end-products. During disease outbreaks, burning and incineration are
preferred, although the cost of fuel and operational requirements can make incineration
expensive. Alkaline hydrolysis, while having the potential to destroy infectious agents
through solubilization and digestion, is not widely used due to its high initial and operational
costs. Therefore, carcasses can be managed using one or more methods, including
composting, burial, incineration, rendering, or landfilling.

Contents
Executive summary .................................................................................................................................................. i

1. Introduction ....................................................................................................................................................... 1

2. Characteristics of the dead animals......................................................................................................... 3

3. Disposal mechanisms and technologies ................................................................................................ 4

4. Procedure for Decision Making to Selecting Appropriate Disposal Technologies ........... 10

5. Conclusion ....................................................................................................................................................... 16

List of Figures and Tables

Figure 1Causes and nature of mortality ......................................................................................................... 4

Figure 2Decision Making approach to Selecting Appropriate DAB Disposal Technologies . 10

Table 1Advantage and disadvantages of the disposal options and technologies ...................... 11
ii
 Technologies for Handling and Disposing of Dead Animal Bodies

Table of Abbreviations

BOD Biochemical Oxygen Demand

COD Chemical Oxygen Demand

DAB Dead Animal Bodies

HH House hold
iii
 Technologies for Handling and Disposing of Dead Animal Bodies

1. Introduction

The animal population in Addis Ababa is large, particularly in the per urban areas. Some city
residents still practice urban agriculture, where animals are an integral component of
farming life. The city residents own livestock, pack animals, poultry, pets, etc. Pack animals
provide transportation services for the city, as the traditional means of transportation is not
yet obsolete. The transport to markets is mostly by pack animals or animal-drawn carts. In
addition, companion animals are also common across households in Addis Ababa, and they
are considered family members. There is also a population of free-roaming and uncontrolled
dogs and cats in the city. Despite the presumably large number of dogs and cats, research on
their population, ownership, and living conditions is absent (Gebremedhin et al., 2020)1. The
non-owned pets survive by scavenging from the refuse thrown out of businesses and homes.
A study estimated the dog population to be 250,000, of which 120,000 may be stray dogs
(Abraham et al., 2010)2.

Animals in the city die due to mishandling, disease, accidents, inter-animal competition, or
natural death due to aging. These dead animal bodies (DAB) are usually disposed of by
traditional methods by mixing with other solid wastes in Addis Ababa, regardless of the
causes of their deaths. There are also practices of burying and burning dead animals without
the knowledge of the city administration. The dead animals are transported to the nearby
waste collection centers. While the responsibility of taking carcasses from home to the waste
collection center is the responsibility of the owners, it is the responsibility of the city’s Solid
Waste Cleansing Agency to transport DAB to the landfill. But it is not uncommon to notice
large numbers of carcasses on roadsides and in the middle of the road for days. In addition
to having an adverse effect on human health, failing to pick up DAB in a timely manner is
1

1 Gebremedhin, E. Z., Sarba, E. J., Getaneh, A. M., Tola, G. K., Endale, S. S., & Marami, L. M. (2020). Demography
and determinants of dog and cat ownership in three towns of West Shoa zone, Oromia Region, Ethiopia. BMC
veterinary research, 16, 1-12
2 Abraham, A., Fasil, M., Kedir, H., Garoma, G., Asefa, D., Yimer, E., & Kassahun, T. (2010). Overview of rabies in

and around Addis Ababa, in animals examined in EHNRI Zoonoses Laboratory between, 2003 and
2009. Ethiopian Veterinary Journal, 14(2), 91-101
 Technologies for Handling and Disposing of Dead Animal Bodies

viewed as an uncivilized phenomenon and shows a lack of proper follow-up and rapid
communication systems from the responsible authorities.

The existing traditional way of disposing of dead animals in Addis Ababa has many flaws.
Dead animals are usually thrown to the roads, riverside, and public places for scavengers or
to decay, thus creating different types of menaces and environmental hazards. Dead animals
are potentially dangerous because their deaths may be caused by infection with contagious
diseases, like the bacteria that live on the flesh and wool of dead animals. These microbes
can resist the harsh external environmental conditions for several days and may spread via
air, which means increasing the scope of contamination. There was no awareness of the
healthy procedures that aim at removing DAB in the way they secure the health and safety
of solid waste collectors.

In order to determine the fate of DAB in Addis Ababa, semi-structured interviews were
conducted, particularly with those supposed to have different animals, regarding their past
and current carcass disposal practices, their relationships with the Addis Ababa City Solid
Waste Cleansing Agency, and their perceptions of suitable methods of carcass disposal.

The house hold (HH) survey conducted to assess the views of the community shows that
54.57% of the respondents felt that the current DAB management in the city was poor, while
about 35.39%, 9.59%, and 0.46% of the respondents felt that the current DAB management
was good, very good, and excellent, respectively. According to the respondents, The most
encountered DAB were that of dogs (57.68%), followed by that of cats (27.32%) and horses
(6.74%), hens (4.31%), mice (2.7%), donkeys (0.54%), and sheep, goats, and cattle (0.27%).
The community or HH members also asked if they traced the sources of the DAB, and they
replied that 69.67% were from the private HH and 23.39% were from unknown sources. The
survey result also indicated that although they constitute a small percentage, they said they
encounter DAB daily.

The objective of this report is to propose viable alternative methods of disposing of animals'
remains and to provide the Addis Ababa City Administration Solid Waste Cleansing Agency
with a comprehensive set of skills and knowledge in managing animal carcasses in order to
2

prevent the transmission of zoonotic diseases and infections. This will enable the Solid Waste
 Technologies for Handling and Disposing of Dead Animal Bodies

Cleansing Agency to act promptly and minimize the strain on the Reppi waste disposal site.
The selection of disposal techniques considers human, animal, and ecosystem health, and the
ideal disposal technique is safe, practical, economical, and environmentally sustainable.

2. Characteristics of the dead animals

The disposal technologies or disposal alternatives depend on the characteristics of DAB, the
causes of mortality, and the volume of DAB. There are some environmental, biosecurity,
social, and economic issues associated with these methods. Environmental constraints
associated with these disposal methods include contamination of air, soil, and water,
particularly due to the persistence of some infections. Social concerns are odor, fly menace,
and contamination of drinking water. Similarly, economic constraints are associated with
costs, availability of land, and transportation of mortalities to the site of disposal. Except for
the occasional and sporadic deaths of animals, there have been no strategies for
emergency/catastrophic and large-scale cases such as animal disease outbreaks, disasters
(flood, fire, drought), accidents (traffic accidents), or planned killing by chemicals. The
technology selection should take the following into consideration:
3
 Technologies for Handling and Disposing of Dead Animal Bodies

• When the cause • When it is not

due to non- mass disposal
infectious agent
or due to aging or
by accident
Routine
Normal
Carcass
Mortality
Disposal

Catastrophic
Abnormal /Emergency
Mortality Carcass
Disposal
• Mortality by infectious •Mass disposal of
by pathogens or by carcasses
chemicals

Figure 1Causes and nature of mortality

3. Disposal mechanisms and technologies

Dead animals can be disposed of by rendering, incineration, burial, composting, etc. Each
option has a set of advantages and disadvantages that must be considered during planning
for and prior to mortality disposal.

i. Incineration

Incineration is the thermal destruction of carcasses by auxiliary fuels such as propane, diesel,
or natural gas. Modern incinerators reduce carcasses to ash and are generally bio-secure.
Incineration requires a great deal of energy, compared with other disposal methods, and is
not considered a viable economic disposal option due to cost and labor. Incineration is a
preferred method for managing small carcasses (for example, poultry and swine), but often
large carcasses and/or a large number of mortalities. Incineration is often impractical for
privately owned animals due to the shortage of suitable facilities.

Incineration is the process where animal carcasses or by-products are turned into inorganic
ash by being burned at high temperatures (>850 °C), which kills the pathogens in the animal
4

carcass. The production of gaseous emissions from the burning of wood or fossil fuels is the
 Technologies for Handling and Disposing of Dead Animal Bodies

principal concern. Metal concentrations in the flue gas have also been found to be higher in
animal carcass incinerators than in medical incinerators. Other health issues arising from
incineration include the release of dioxins and furans from flue gas and fly ash; these can
enter the food chain through grazing animals and can also be ingested by humans through
the consumption of contaminated crops. In addition to having negative impacts on air quality
and composition, incineration can also be relatively expensive.

ii. Open air burning

Open-air burning involves the burning of carcasses in an open setting (outdoors), using
combustible materials as a primary fuel source. This category includes pyre burning, below-
ground air-curtain incineration (pit burning), above-ground air-curtain incineration
(fireboxes), and the use of small mobile incinerators (gas-fired).

This open system of burning dead animals is a well-established procedure that can be
conducted on site with no requirement for the transportation of animal material. However,
it takes an extended period of time and has no way of verifying the inactivation of pathogenic
agents, and there may be particulate dissemination from incomplete combustion. Further,
because the process is open to public view, there may be a lack of acceptance by the public.

iii. Burial

Burial (graves, trenches, or open-bottom containers) is a common method of carcass

disposal, but it poses a groundwater contamination risk if the burial site is not selected and
managed properly. Therefore, the selection and maintenance of a burial site are very
important. For example, areas with sandy or gravelly soil and a shallow groundwater table
must not be used as burial sites. Also, the disposal site should be away from any residence,
drinking water well, shallow aquifers, or areas that may be flooded. Prompt burial will
prevent nuisance problems such as odors, flies, and scavengers. Concerns stem from the fact
that burial, unlike some other DAB disposal methods such as incineration or rendering,
serves only as a means of disposing of carcass material but does not necessarily eliminate
disease agents that may be present.
5
 Technologies for Handling and Disposing of Dead Animal Bodies

Benefits include low cost, convenience, availability of necessary equipment, simple logistics,
and low technical requirements. Furthermore, the method is time-efficient considering daily
mortalities. Despite logistical and economic advantages, concerns about potential effects on
public health and the environment have resulted in a less favorable perception of this
method. This disposal method has been banned in many locations, including within the
European Union, since infectious diseases may inadvertently affect other organisms in the
food chain and can contribute to environmental hazards (Vithanage, 2021) 3.

iv. Rendering

Rendering is the process of converting animal carcasses into pathogen-free, useful

byproducts such as feed proteins. In the process of rendering, the carcasses are exposed to
high temperatures of about 130 oC using pressurized steam to ensure the destruction of most
pathogens. However, rendering poses biosecurity concerns due to the transportation of
livestock mortalities to multiple locations along the route to the rendering plant (Fonstad et
al., 2003)4. In Addis Ababa, there are no rendering facilities.

Rendering of animal carcasses involves their conversion into three end products using
mechanical processes (e.g., grinding, mixing, pressing, decanting, and separating), thermal
processes (e.g., cooking, evaporating, and drying), and sometimes chemical processes (e.g.,
solvent extraction). The end products are carcass meal (proteinaceous solids), melted fat or
6

3 Vithanage, M., Mayakaduwage, S. S., Gunarathne, V., Rajapaksha, A. U., Ahmad, M., Abduljabbar, A.,... & Ok, Y. S.
(2021). Animal carcass burial management: implications for sustainable biochar use. Applied Biological
Chemistry, 64(1), 1-20
4 Fonstad Terry, Meier D. E., Ingram L. J., Leonard J., 2003, Evaluation and demonstration of composting as an

option for dead animal management in Saskatchewan, Canadian Biosystems Engineering 45

 Technologies for Handling and Disposing of Dead Animal Bodies

tallow, and water. The benefits of rendering are that it provides a source of proteins for use
in animal feed formulations and provides a hygienic means of disposing of fallen and
condemned animals. However, a shortcoming of the technique includes the need for animal
carcasses to be transported from the farm to a rendering plant. Because the carcasses will be
removed from the infected premises, there are significant biosecurity risks, with the adverse
effects being the by-product wastewater production. Large amounts of energy are consumed
to generate the required high temperatures and pressure. This also necessitates the use of
specialized equipment and personnel.

v. Composting

Composting is a naturally occurring process in which the dead animal is broken down into
basic elements (organic matter) by microorganisms, bacteria, and fungi. Composting has
advantages over other methods of carcass disposal, including lower costs, easy-to-prepare
piles and windrows created with available machinery, and a lower risk of air and water
pollution when done properly. However, the selection of a proper composting site is
important to prevent surface water runoff to the compost site and runoff of leachate from
the compost site, as well as leaching of raw or finished compost nutrients to groundwater.
With composting, some viruses and spore-forming bacteria, such as Bacillus anthracis, and
other pathogenic agents, such as Mycobacterium tuberculosis, may survive.

Composting of animal carcasses has advantages including the production of valuable by-
products, versatility, ease of handling, and the destruction of pathogens by heat during the
production process. But major disadvantages of carcass composting methods include the
7

long processing time before the compost is mature, the production of nuisance odors and
 Technologies for Handling and Disposing of Dead Animal Bodies

greenhouse gases such as CO2, and the possibility that insects such as flies may invade the
composting area.

vi. Alkaline hydrolysis

This method uses sodium hydroxide or potassium hydroxide to catalyze the hydrolysis of
biological material into a sterile aqueous solution consisting of small peptides, amino acids,
sugars, and soaps. Heat is applied (150°C) to accelerate the process. The only solid by-
products are the mineral constituents of bones and teeth. This residue (2% of the original
weight of the animal) is sterile and easily crushed into a powder. The temperature and alkali
conditions of the process destroy the protein coats of viruses and the peptide bonds of
prions. Both lipids and nucleic acids are degraded. The process is carried out in an insulated,
steam-jacketed, stainless steel pressure vessel.

Alkaline hydrolysis uses sodium hydroxide or potassium hydroxide under heat and pressure
to catalyze the hydrolysis of biological material. This process is carried out in a tissue
digester consisting of an insulated, steam-jacketed, stainless-steel pressure vessel with a lid
that is manually or automatically clamped. The advantages of this technique of carcass
disposal include simultaneous sterilization and digestion of the carcass, as well as the
destruction of pathogens, including prions. It further reduces waste by weight and volume
by up to 97%, and radioactive contaminants are eliminated. However, alkaline hydrolysis is
practiced offsite and presents biosecurity problems arising from the transport of infected
animal carcasses from one area to a processing plant. A shortcoming of the process is the
generation of large volumes of water as a by-product resulting from the use of alkali, high
temperatures, and pressure to catalyze the hydrolysis of biological materials.

vii. Anaerobic digestion

Anaerobic digestion, sometimes referred to as biomethanization or biodigestion, is one

method for the disposal of carcasses. It can eliminate carcasses and produce energy at the
same time, but in some cases, it is necessary to reduce the size of the carcasses and sterilize
them on-site before proceeding with anaerobic digestion. These preliminary measures
prevent the risk of spreading pathogens during transportation to a digester and reduce the
8
 Technologies for Handling and Disposing of Dead Animal Bodies

need for new digesters. If the quantity of carcasses is large, it may be necessary to distribute
carcasses between several digesters and transport them to different locations.

viii. Disposal in landfill

Carcasses may be disposed of in a properly engineered, highly regulated landfill, typically

designed with sophisticated byproduct (methane and leachate) management systems to
protect the environment.

ix. Natural disposal

The act of naturally disposing of a deceased animal involves disposing of it in a way that
permits scavenging. If the animal in question is not known or suspected to have had an
infectious or contagious disease, if it was not euthanized using drugs or other chemical
substances, if the total weight of the animals being disposed of at a single location does not
exceed 1000 kg, and if the disposal takes place on the owner's property, then natural disposal
can be employed.

x. Bio-refining

Bio refining is a process of high-pressure, high-temperature thermal hydrolysis conducted

in a sealed, pressurized chamber. The waste material is treated with high-pressure saturated
steam at 180 oC under a minimum of 10 bar pressure and continuous disruption by
mechanical stirring for a period of 40 minutes. The whole procedure, from the loading of the
chamber until the discharge from the chamber, occupies approximately 120 minutes. All
microbiological agents are inactivated, and the infectivity of the infectious agents causing
transmissible spongiform encephalopathies is destroyed.

xi. Refeeding non-susceptible species

Refeeding is the use of whole or cut-up carcasses to feed other species. E.g., for feeding zoo
collections and farmed reptiles (crocodiles). This method would require the collection and
transport of carcasses under biosecure means to the feeding point, the storage of carcasses
at the feeding point, and the decontamination of transports. Some form of preprocessing of
carcasses (grinding, breaking down) may be required.
9
 Technologies for Handling and Disposing of Dead Animal Bodies

4. Procedure for Decision Making to Selecting Appropriate Disposal Technologies

The management of dead bodies involves a series of activities that begin with identifying
whether the mortality is normal or not. If the mortality is not normal, it requires the
involvement of animal health professionals to identify if the dead body is infected or not. The
infected body needs to be handled with due care because of the transmutability of the
infectious agents. In addition to the biosafety aspects, the volume of the dead animal body
should be taken into consideration to identify the right disposal mechanisms.

Dead Animal
Body

Normal Mortality

Yes No

Catastrophic Catastrophic

Yes No No Yes

Disinfected
Alkaline
Rendering Refeeding Yes No
hydrolysis
Composting Burial
Anaerobic Natural disposal
digestion
Bio-refining Refeeding
Incineration
Burial
Alkaline
Natural disposal hydrolysis
Bio-refining

Figure 2Decision Making approach to Selecting Appropriate DAB Disposal Technologies

10
 Technologies for Handling and Disposing of Dead Animal Bodies

Table 1Advantage and disadvantages of the disposal options and technologies

Disposal Advantage Disadvantage Remarks

Economi
m health
Ecosyste

feasibilit

feasibilit
Technic
Human
Mechanisms

health

al
y

y
c
Incineration ▪ Complete reduction ▪ Major capital investment +Ve +Ve -Ve +Ve Dioxins and
(commercial of volume along with expensive fuel furans are
incineration) ▪ Rapid oxidation to costs carcinogens and
carbon and water ▪ Must be maintained can negatively
▪ Environmentally safe (burners wear out and affect human
(may require an air soot must be scrubbed out reproduction,
permit) to prevent stack fires) development
▪ Can dispose of ▪ Ash has no fertilizer and immune
mortalities as they potential and there may be systems
are generated, a trace of heavy metals
therefore no from micronutrients fed to
temporary storage the animals
required ▪ Safety hazards associated
▪ Residue from with high temperature
properly incinerated incinerators
carcasses will not ▪ Smell and air quality
attract insects or problems
rodents ▪ Smoke/ash
▪ System can be mobile ▪ Heavy metals (Cd, Pb)
and could be ▪ Emission of dioxins from
purchased an incomplete carcass
incinerator to be combustion
shared between
neighborhoods
Open-air burning ▪ Can accommodate all ▪ Effects on air quality +Ve -Ve -Ve +Ve
11

(pyre burning, air- classes of animals

curtain
 Technologies for Handling and Disposing of Dead Animal Bodies

incineration, ▪ Requires only short- ▪ Significant rainfall events

above-ground air- term site monitoring can limit combustion
curtain efficiency
incineration ▪ Costs of f solid, liquid or
(fireboxes) and gas fuels
use of small mobile
incinerators (gas
fired)
Burial (Trench • Inexpensive or ▪ Public health and -Ve -Ve +Ve +Ve Less favorable
burial, Landfill) low cost Biosecurity risks due to possible
• Convenient or fast ▪ Can cause groundwater effects on the
to implement pollution. environment and
▪ Some infectious material public health.
such as anthrax spores can Only preferable
reside within the soil after if the DAB is not
carcass decomposition infected. E.g.
▪ Lack of burial sites in the Animals killed by
nearest car accidents.
▪ Can be found by Preferable for
scavengers the causal death
but not for mass
burial
Rendering ▪ Convenient, ▪ Timely pick up is the +Ve +Ve +Ve ± Discouraged for
(crushing ▪ Clean and waste-free biggest challenge infected carcass
carcasses into solution ▪ High cost of collecting because of the
small size, heating ▪ Production of safe small volumes of carcasses persistency of
the particles and and valuable end ▪ Costs of onsite infection during
extracting fat, products preservations the heat
protein and water ▪ Increased storage ▪ Gas and odor emissions treatment of the
to make useful time due to heat ▪ Bio-secure Concerns in carcass.
products like meat treatments Transport
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and bone meals Inappropriate for Poultry

and tallow.
 Technologies for Handling and Disposing of Dead Animal Bodies

▪ Job opportunity for ▪ Require wastewater

rendering treatment
enterprises
Composting ▪ Safe ▪ Long time to complete of - -Ve - +Ve ▪ should be
(aerated windrow, ▪ Sustainable the composting Ve Ve undertaken on
static pile and in- ▪ Easy to implement ▪ Contaminate of soil due to an impervious
vessel) the loss of leachate base
▪ Odor is a concern ▪ prevent entry
▪ Expensive of rain water
▪ Cause nuisance if located into the
on windward from compost piles
residential areas
▪ Degrade ground or surface
water
▪ Opportunistic pathogens
may colonize the compost
pile
Alkaline ▪ Can occur in fixed or ▪ Alkaline effluents with +Ve +Ve -Ve +Ve large scale
hydrolysis mobile facilities, high pH and high organic alkaline
(converting animal ▪ Nutrient rich effluent compound hydrolysis use
carcasses to a and bone residue cab ▪ large initial investment may only be
sterile aqueous be used as soil cost, feasible for
solution of amino amendments ▪ expensive maintenance, relatively small
acids, sugars, and ▪ Inactivates and carcass sizes
soaps) pathogens ▪ limited capacity for (birds instead of
large volume carcasses cattle).
Anaerobic ▪ Couples the ▪ Cost of construction is +Ve -Ve +Ve +Ve
digestion treatment of waste expensive
and production of ▪ Sludge disposal is a
energy problem in some locations
▪ Reduction of odors ▪ Larger than other
13

▪ Suited for large-scale installations such as lactic

operations acid fermentation
 Technologies for Handling and Disposing of Dead Animal Bodies

▪ Methane is used in ▪ Difficulty of storage of gas

place of fossil fuels (corrosive)
▪ Reduces pollution by ▪ Significant consumption of
GHGs by combusting water
methane ▪ Storage of fertilizer is
▪ Recycle effluent in difficult
fertilizer ▪ Problem of management
▪ Reduces COD and of the sludge
BOD, total solids and ▪ Does not destroy all
volatile solids of the pathogens:
carcass
▪ Destroys, or reduces
to acceptable levels,
coliform bacteria,
pathogens, insect
eggs and internal
parasites
Disposal in ▪ On-site facilities ▪ Sites may not have -Ve -Ve -Ve +Ve
landfill (power, water, capacity for burial of large
machinery, volumes of animal
personnel, security, carcasses and other
decontamination materials
facilities) are already
in place
▪ Many facilities are on
government-owned
land
Natural Disposal ▪ Technically easy ▪ Health problem -Ve -Ve +Ve +Ve
▪ Inexpensive ▪ Environmental Problem
▪ Public acceptance
problem
14
 Technologies for Handling and Disposing of Dead Animal Bodies

Bio-refining ▪ All microbiological ▪ Economically expensive +Ve +Ve -Ve -Ve

agents are ▪ Infeasible of mass
inactivated mortality
▪ the infectivity of the
infectious agents
destroyed.
Refeeding (to non- ▪ Biosecurity concerns ▪ Risk of diseases jumping +Ve -Ve +Ve +Ve
susceptible should be minimal if between species
species) refeeding is limited ▪ Potential for pathogens
to mortalities from present in carcasses fed to
natural disasters or others
noninfectious ▪ Difficulty in timely
diseases. processing of large scale
mortality events
15
 Technologies for Handling and Disposing of Dead Animal Bodies

5. Conclusion

There is no one-size-fits-all solution for disposing of dead animal bodies. Various

technologies and methods, such as burial, incineration, rendering, or landfilling, are utilized
in many countries. However, each of these methods has its own advantages and
disadvantages. For instance, rendering and composting have become popular in many
countries due to the usefulness of their end products. During disease outbreaks, burning and
incineration are preferred, although incineration can be expensive due to fuel and
operational requirements. Alkaline hydrolysis, while having the potential to destroy
infectious agents through solubilization and digestion, is not widely used due to high initial
and operational costs. As a result, for Addis Ababa, carcasses can be managed using one or
more methods, including composting, burial, incineration, rendering, or landfilling.
16