The Gambian Agency for the Management Preliminary and Detailed Engineering Design
of Public Works (GAMWORKS) Study for Bakoteh Dump Site
E1152
POVERTY ALLEVIATION AND CAPACITY BUILDING PROJECT (PACABP)The Gambian Agency for the Management of Public Works (GAMWORKS)
Preliminary and
Detailed Engineering Design Study of The Bakoteh
Dump Site
FINAL REPORT
VOLUME 1
Main Report
August 2004
Charchi Githinji & Partners
P.O. Box 60424 - 00200
Nairobi
Kenya
Email: / Cityscape Associates
61, Kairaba Avenue, Fajara
The Gambia
Email:
Charchi Githinji & Partners
iii
in association with
Cityscape Associates Final Report
The Gambian Agency for the Management Preliminary and Detailed Engineering Design
of Public Works (GAMWORKS) Study for Bakoteh Dump Site
Preliminary and
Detailed Engineering Design Study of The Bakoteh
Dump Site
FINAL REPORT
TABLE OF CONTENTS
CHAPTER 1 INTRODUCTION 1
1.1 Study Background 1
1.2 Objectives of the Study 2
1.3 Terms of Reference 2
1.4 Study Schedule 2
CHAPTER 2 SOLID WASTE MANAGEMENT IN KMC – SITUATION ANALYSIS 3
2.1 Introduction 3
2.2 Institutional Framework 3
2.2.1 International Agreements 3
2.2.2 The National Framework for Solid Waste Management 4
2.2.3 The Local Government Framework for Solid Waste Management 4
2.2.4 The Cleansing Services Unit 5
2.2.5 Landfill Management Capacity 8
2.3 Solid Waste Generation and Composition 9
2.4 Solid Waste Collection and Transportation 10
2.5 Solid Waste Disposal 14
2.5.1 Bakoteh Dump site 14
2.5.1.1 General 14
2.5.1.2 Environmental and Socio-economic impacts 15
CHAPTER 3 SOLID WASTE MANAGEMENT SYSTEM FOR THE BAKOTEH DUMP SITE 18
3.1 Introduction 18
3.2 Solid Waste Amount 19
3.3 Dump site topography 21
3.3.1 Topographic Surveys 21
3.3.2 Geo-technical and Hydro-geological considerations 22
3.3.3 Landfill Area within Bakoteh Dump Site 22
3.4 Sanitary landfill 26
3.4.1 Levels of operation 26
3.4.2 Method of Landfilling 29
3.5 Recommendations 31
CHAPTER 4 ENVIRONMENTAL IMPACT ASSESSMENT 32
4.1 General 32
4.2 Objectives of Impact Assessment. 32
4.3 Method of Impact Assessment 32
4.4 Identification and description of impacts 33
4.4.1 Impact of Landfill Location 33
4.4.2 Impact on Land Use 34
4.4.3 Visual Impacts 35
4.4.4 Impact on Air Quality 36
4.4.5 Impact on Flora and Fauna 37
4.4.6 Impacts on water resources 37
4.4.7 Impact on Human Beings and the Human-made Environment. 41
4.4.8 Community Stability 42
4.4.9 Potential negative impacts 42
4.4.10 Impact Assessment Statement 44
CHAPTER 5 DETAILED DESIGN OF PROPOSED SOLID WASTE MANAGEMENT SYSTEM 47
5.1 Introduction 47
5.2 Design considerations and Solid Waste Management 47
Components 47
5.2.1 General 47
5.2.2 Type of waste 47
5.2.3 Landfill area and capacity 47
5.2.4 Access roads 50
5.2.5 Enclosure Dike 50
5.2.6 Leachate management facilities 51
5.2.7 Leachate collection and treatment structures 51
5.2.8 Landfill Liner 51
5.2.9 Selection of gas control facilities 52
5.2.10 Selection of landfill cover configuration 52
5.2.11 Surface water drainage facilities 54
5.2.12 Environmental monitoring facilities 54
5.2.13 Aesthetic design considerations 55
5.2.14 Equipment Requirements 56
5.3 Landfill operation 56
5.4 Estimated cost of proposed Landfill components 58
CHAPTER 6 LANDFILL CLOSURE AND POST-CLOSURE CARE 61
6.1 Introduction 61
6.2 Routine Inspections 62
6.3 Infrastructure Maintenance 62
6.3.1 Grading and Landscaping. 62
6.3.2 Drainage Control Systems. 63
6.3.3 Gas Management Systems. 63
6.3.4 Leachate Collection and Treatment. 63
6.4 Environmental Monitoring Systems. 63
CHAPTER 7 Operation and Maintenance Manual of Sanitary Landfill 64
7.1 Landfill Control Facilities 64
7.1.1 Structure of control facilities 64
7.1.1.1 Management of sanitary landfill system 64
7.1.1.2 Control facilities Components 64
7.1.2 Safety Measures 71
7.2 Related Facilities 72
7.3 Landfill Works 75
7.3.1 Landfill Works 75
7.3.2 Landfill Method 75
7.3.2.1 Landfill Method 76
7.3.2.2 Cell Construction 77
7.3.2.3 Order of Landfill 77
7.3.2.4 Landfill Equipment 79
7.3.2.5 Cover Soil 79
ANNEXE 1 Landfill Leachate Evaluation 83
ANNEXE 2 Soil Investigation Results 91
ANNEXE 3 Workshop Report 97
Charchi Githinji & Partners
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in association with
Cityscape Associates Final Report
The Gambian Agency for the Management Preliminary and Detailed Engineering Design
of Public Works (GAMWORKS) Study for Bakoteh Dump Site
LIST OF TABLES
Table 2.1 Projected Household Waste Generation for Kanifing Municipality 9
Table 2.2 Composition of Household Wastes by Weight 10
Table 2.3 Solid Waste Collection zones and blocks 11
Table 2.4 Solid Waste Collection Vehicles for Cleansing Services Unit 12
Table 2.5 Skips and Trailers for Solid Waste Collection 13
Table 3.1 The Amount of Waste Expected at the Dump Site 20
Table 3.2 Capacity requirements of the disposal Site 20
Table 3.3 Area occupied by Bakoteh Dump Site 25
Table 3.4 Nominal volume of zone 3 25
Table 3.5 Volume of cover material on site and waste outside zone 3 25
Table 3.6 Components of a Sanitary Landfill 27
Table 3.7 Classification of sanitary level of landfill system 28
Table 4.1 Water Sampling Results of the Dump site Pond 38
Table 4.2 Impact pathways and mitigation measures 46
Table 5.1 Factors considered in the design of the landfill 48
Table 5.2 Estimated useful life of landfill 50
Table 5.3 Performance Characteristics of Landfill equipment 56
Table 5.4 Factors considered in the operation of the landfill. 57
Table 5.5 Estimated cost of proposed Landfill components 58
Table 5.5 Estimated cost of proposed Landfill components (continued) 59
Table 6.1 Typical elements of a landfill postclosure plan 61
Table 6.2 Closed landfill inspection items, frequency of inspection, and potential problems to be observed 62
Table 7.1 Check of sanitary landfill system 64
Table 7.2 Classification of control facilities 65
Table 7.3 Typical Input Information 66
Table 7.4 Typical Information for Management of Sanitary Landfill 67
Table 7.5 Typical Monitoring Scheme (Leachate) 68
Table 7.6 Proposed Monitoring Scheme 69
Table 7.7 Monitoring Scheme of Gas 69
Table 7.8 Landfill Works 75
Table 7.9 Performance Characteristics of Landfill equipment 79
Table A Landfill Leachate Evaluation 84
Table B Rainfall Data 89
Table C Evaporation Data 90
Table D Summary of soil investigation laboratory test results 92
Charchi Githinji & Partners
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in association with
Cityscape Associates Final Report
The Gambian Agency for the Management Preliminary and Detailed Engineering Design
of Public Works (GAMWORKS) Study for Bakoteh Dump Site
LIST OF FIGURES
Figure 2.1 Cleansing unit organisation chart 6
Figure 2.2 KMC organisation chart 7
Figure 3.1 Bakoteh Dump Site zoning 21
Figure 3.2 Landfill Method 29
Figure 3.3 Landfill Process by Cell Method 30
Figure 5.1 Landfill Liner System Design 52
Figure 5.2 Gas Exhaust Equipment 53
Figure 5.3 Typical cover system 54
Figure 5.4 Monitoring Well 55
Figure 7.1 Monitoring Well 70
Figure 7.2 Typical Notice Boards 74
Figure 7.3 Area Method 76
Figure 7.4 Cell Method 77
Figure 7.6 Spreading/Compaction Method 78
Figure 7.7 Pushing up and compacting the waste simultaneously 78
ABBREVIATIONS AND ACRONYMS
KMC Kanifing Municipal Council
KMA Kanifing Municipal Area
NEA National Environment Agency
GDP Gross Domestic Product
GBA Greater Banjul Area
NEMA National Environment Management Act
GEAP Gambia Environmental Action Plan
GSWMSR Gambia Solid Waste Management Strategy Report
EDPR Environmental Discharge Permit Regulation
DOH Director of Health
PHA Public Health Act
PHD Public Health Department
NAWEC National Water and Electricity Company
BOD Biochemical Oxygen Demand
COD Chemical Oxygen Demand
CBOs Community Based organizations
LGA Local Government Act
SWM Solid Waste Management
TDA Tourism Development Area
FC Faecal Coliform
TC Total Coliform
GMD Gambian Dalasi
BDSWMS – 2002 Bakoteh Dumpsite Solid Waste Management Study
MDD Maximum Dry Density
Exchange Rate: 1 USD = 30 GMD
Charchi Githinji & Partners
vi
in association with
Cityscape Associates Final Report
The Gambian Agency for the Management Preliminary and Detailed Engineering Design
of Public Works (GAMWORKS) Study for Bakoteh Dump Site
CHAPTER 1 INTRODUCTION
1.1 Study Background
Banjul and Kanifing Municipality and part of Western Division together referred to as the Greater Banjul Area, and Brikama Municipality, form the largest urban population representing over 40% of the total population of The Gambia.
According to 2001 population projection based on 1993 population census, Banjul, the capital of The Gambia has an estimated population of 40,056 (2004), while Kanifing Municipality with a population of 456,560 (2004) has the highest urban population followed by Brikama with an estimated population of 295,696 (2004).
Solid Waste for the City of Banjul is disposed at the Mile 2 dump site while that of the Kanifing and Brikama municipalities is disposed at Bakoteh and Tambana dump sites respectively.
The Government of The Gambia (GOTG) initiated, in 2001, a Solid Waste Management Study for The Greater Banjul Area and Brikama whose terms of reference included development of waste management system and a comprehensive study on waste management for the Greater Banjul Area and Brikama. This study identified a new landfill site in Tambana.
In 2002, a feasibility study, Support for the Bakoteh Dump Site Waste Management Study, was carried out for the effective management of Bakoteh Dump Site, as an interim short-term measure while the new landfill at Tambana was being developed. The study was completed in October 2002. The study, while disqualifying the site as a landfill site, identified a storage capacity in dump site for a period of 3-5 years.
The Bakoteh Dump Site, on the site of an old quarry is surrounded by human settlement and occupies an area of about 17.8 hectares. The Bakoteh dump site is the only official dump site serving the Kanifing Municipality, most populated municipality in The Gambia with an estimated population growth rate[1] of 6% per annum (2001). The generation of Solid Waste is estimated to be 219 tons/day (2002).
In spite of the above initiatives, the condition at the Bakoteh dump site continues to create hygienic, environmental, as well as aesthetic problems in and around the dump site.
1.2 Objectives of the Study
The objective of this study is to prepare preliminary and detailed engineering design of an effective and environmentally safe waste Management system for the Bakoteh Dump Site for a period of 3-5 years while the new landfill site at Tambana and the waste management system for the greater Banjul area is developed. The objective also includes the preparation for the ultimate closure of the Bakoteh Dump Site.
1.3 Terms of Reference
This study is based on the feasibility study and the framework developed for the effective waste management of the Bakoteh Dump Site Waste Management Study (BDSWMS) by the international consultant Jackson M. Nzainga of October 2002.
In order to meet the objectives of the study, the Terms of Reference cover the following:-
· Carry out the preliminary and detailed engineering design studies, including preparation of bidding documents, and the ultimate closure of the Bakoteh Dump Site in 3-5 years.
· Specifically the study will: -
· Identify and locate important features of the dump site and locate proposed facilities through topographic survey.
· Identify and prepare comprehensive action plan on safe operations of the landfill site, including closure and post-closure procedures of the existing landfill site.
· Determine by Geo-technical surveys the potential for excavation within the landfill and the landfill’s potential to provide cover material.
· Determine and mitigate (negative) environmental impacts of the existing and proposed solid waste management system.
1.4 Study Schedule
The contract for Consultants’ services was signed on 23rd February 2004 and the total duration of the study is six months. Four kinds of reports are to be prepared and submitted; i.e. Inception report, Interim report, Draft final report and Final report.
Charchi Githinji & Partners
2
in association with
Cityscape Associates Final Report
The Gambian Agency for the Management Preliminary and Detailed Engineering Design
of Public Works (GAMWORKS) Study for Bakoteh Dump Site
CHAPTER 2 SOLID WASTE MANAGEMENT IN KMC – SITUATION ANALYSIS
2.1 Introduction
The efficiency and effectiveness of the collection, transportation, disposal of solid waste in an environmentally sound manner depends on the efficacy of the institutional arrangements, management structures and resources available for waste management. Waste managers are increasingly challenged to come up with integrated waste management plans which deal with waste generated in a holistic manner.
In formulating successful and workable plans, procedures and policies, basic information covering the quantity of solid waste generated and the population covered by the collection services is essential. The availability of reliable data on solid waste generation, composition etc is important for the first stage of planning and designing Solid Waste Management (SWM) facilities.
The generation of solid waste varies significantly from one household to another within an area and within a municipality. The volume and composition of waste generated by a household further differs even within a household on different days of a week and months of a year. Thus, it is difficult to assess the per capita generation rate of solid waste. On the other hand calculating the accurate generation rate is very important for planning and designing of an effective solid waste collection and disposal system.
The three principal urban areas in The Gambia are Banjul City, Kanifing Municipality and Brikama. Presently the solid waste from these areas are disposed of in Mile 2, Bakoteh and Tambana Dump Sites respectively. The local councils in each of these municipalities is responsible for solid waste management in their jurisdiction.
The focus of this Study is the Bakoteh Dump Site, which is the official waste disposal facility within Kanifing Municipality.
The waste management strategy and engineering design options available for the Bakoteh Dump Site depend on the conditions and characteristics of the site, the volume and composition of waste generated, transported and disposed at the Site. The institutional arrangements for Solid Waste Management at the National and local level are important in these considerations.
2.2 Institutional Framework
2.2.1 International Agreements
The Gambia is party to a number of international agreements covering the environment which are meant to promote international cooperation in environmental protection. However for the purpose of this study, reference is made to the following:
§ The Basel Convention for the control of trans-boundary movements and disposal of hazardous waste adopted in 1989 and ratified in 1997 provided obligations to its parties to ensure that waste that is hazardous to people and the environment are managed and disposed of in an environmentally sound manner.