Difference between revisions of "DCOM Volume I"

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[[Image:DCOM_Volume_I_2020-03-11.png|540px|link=Preface]]
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[[Image:DCOM_Volume_I_Book_PrintReady.png|540px|link=Preface]]
<h4>Volume I: Design of Water Supply Projects </h4> [[Preface|Readmore...]]or Download  [[:File:DCOM_Volume_I_2020-03-10.pdf| Volume I PDF]]
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<h4>Volume I: Design of Water Supply Projects </h4> [[Preface|Readmore...]]or Download  [[:File:DCOM_VOLUME_I_Book_PrintReady.pdf| Volume I PDF]]
  
 
TABLE OF CONTENTS
 
TABLE OF CONTENTS
 
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{| class="wikitable"
LIST OF SPECIAL COMMITTEE MEMBERS v
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CHAPTER ONE 1
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! # !! Title !! Page
INTRODUCTION 1
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1.1 Global Considerations on Water Supply and Sanitation 1
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| 1 || [[Preface VOL.1|Preface]] || i
1.1.1 Sustainable Development Goals (SDGs) 1
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1.1.2 Climate Change and Resilience to Climate Change 2
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| 2 || [[Acknowledgements VOL.1|Acknowledgements]] || ii
1.1.3 Public Private Partnership in Water Supply and Sanitation Projects in Developing Countries 3
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1.1.4 International Water Law 4
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| 3 || [[List_of_Special_Committee_Members VOL.1|List of Special Committee Members VOL.1]] || iii
1.2 Development Agenda and Water and Sanitation Sector in Tanzania 5
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1.2.1 National Water Policy 7
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| 4 || [[List_of_Abbreviations I|List of Abbreviations I]] || iv
1.2.2 Legal and Institutional Framework for Water Supply and Sanitation Services 8
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1.2.3 Coverage and Access to Water Supply Services 9
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| 5 || [[Chapter_One:Introduction VOL1|Chapter One: Introduction]] || 1
1.2.4 Policy Environment for Water and Sanitation Services in Tanzania 9
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1.2.5 Major Stakeholders in  Water Supply and Sanitation Projects 10
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| 6 || [[Chapter Two: Project Planning|Chapter Two: Project Planning]] || 17
1.2.6 Water Supply and Sanitation Public Private Partnership in Tanzania 11
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1.3 Rationale for Preparation of the Fourth Edition DCOM Manual 12
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| 7 || [[Chapter Three: Water Sources Analysis|Chapter Three: Water Sources Analysis]] || 35
1.4 About the Fourth Edition of the DCOM Manual 13
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1.5 Organisation of the 4th edition of the DCOM Manual 14
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| 8 || [[Chapter Four: Water Demand Assessment|Chapter Four: Water Demand Assessment]] || 56
1.6 Purpose of this Volume 14
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1.7 References 15
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| 9 || [[Chapter Five: Pipelines Design|Chapter Five: Pipelines Design]] || 76
CHAPTER TWO 17
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PROJECT PLANNING 17
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| 10 || [[Chapter Six: Pumping Systems|Chapter Six: Pumping Systems]] || 91
2.1 Planning Considerations for Water Supply Projects 17
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2.2 Project Planning Steps 18
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| 11 || [[Chapter Seven: Water Treatment|Chapter Seven: Water Treatment]] || 96
2.3 Pump Protection 18
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2.3.1 Initiation 18
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| 12 || [[Chapter Eight: Treatment of Waters With Special Contaminants|Chapter Eight: Treatment of Waters With Special Contaminants]] || 148
2.3.1.1 Community Assessment Steps 20
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2.3.1.2 Methods of conducting community assessment 20
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| 13 || [[Chapter Nine: Design of Water Structures|Chapter Nine: Design of Water Structures]] || 159
2.3.1.2.1 Comprehensive community assessment 20
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2.3.1.2.2 Strategic community assessment 20
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| 14 || [[Chapter Ten: Application Software|Chapter Ten: Application Software]] || 203
2.3.2 Pre-feasibility Study 21
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2.3.3 Feasibility Study 21
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| 15 || [[Chapter Eleven: Metering|Chapter Eleven: Metering]] || 208
2.3.3.1 Water Supply Projects Ranking and Technology Selection Criteria 22
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2.3.3.1.1 Ranking of Projects 22
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| 16 || [[Chapter Twelve: Design Standards and Specifications|Chapter Twelve: Design Standards and Specifications]] || 217
2.3.3.1.2 Choice of Technology 23
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2.3.4 Preliminary and Detailed Design 23
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| 17 || [[Chapter Thirteen: Role of Stakeholders in Design of Water Supply Projects|Chapter Thirteen: Role of Stakeholders in Design of Water Supply Projects]] || 228
2.3.4.1 Detailed Engineering Drawings 24
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2.3.4.2 Detailed estimates of capital costs 24
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| 18 || Apendices: Appendices
2.3.4.3 Detailed estimates of recurrent costs 24
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* [[DCOM Volume I Appendix A|Appendix A: Climate Change and Resilience to Climate Change ]]
2.3.4.4 Anticipated revenue 25
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* [[DCOM Volume I Appendix B|Appendix B: Minimum Water Flow Requirement for Fire Fighting ]]
2.3.4.5 Detailed design report 25
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* [[DCOM Volume I Appendix C|Appendix C: Example: Estimating The Capacity Of Tank ]]
2.3.4.6 Project write-up to be submitted to potential financiers 25
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* [[DCOM Volume I Appendix D|Appendix D: Structural Design of Concrete ]]
2.3.5 Project Phasing 25
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* [[DCOM Volume I Appendix E|Appendix E: Supply Pumping Systems ]]
2.3.6 Procurement 26
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* [[DCOM Volume I Appendix F|Appendix F: Source of Pumping Power ]]
2.3.6.1 2.2.6.1 Preparation of Tender Documents 26
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* [[DCOM Volume I Appendix G|Appendix G: Additional Details of Various Unit Oprations ]]
2.3.6.2 Tendering process 27
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* [[DCOM Volume I Appendix H|Appendix H: Methods for Disinfecting Water ]]
2.3.7 Implementation/Construction Stage 27
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* [[DCOM Volume I Appendix I|Appendix I: Measurements of Water Hardness ]]
2.3.7.1 Contract Management 27
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* [[DCOM Volume I Appendix J|Appendix J: Basic Statistics Used in Estimation of Design of Flood Events ]]
2.3.7.2 Contract supervision and administration 27
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* [[DCOM Volume I Appendix K|Appendix K: Dams Detail Design ]]
2.3.8 Operation and Maintenance Stage 28
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* [[DCOM Volume I Appendix L|Appendix L: Standard Drawings ]]
2.3.9 Performance Monitoring 28
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* [[DCOM Volume I Appendix M|Appendix M: Selected Intake Designs ]]
2.4 Consulting the Integrated Water Resources Management and Development (IWRMD) Plans 28
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* [[DCOM Specification|Appendix O: Standard Specifications ]]
2.4.1 Status of Development and Implementation of IWRMD Plans 29
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|| 231
2.4.2 Components of IWRMD Plans 30
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2.5 Consult Guidelines for Preparation of Water Safety Plans - Resilient to Climate Change 30
 
2.6 Environmental and Social Impact Assessment Compliance 30
 
2.6.1 Procedures for Conducting ESIA in Tanzania 31
 
2.6.2 Strategic Environmental and Social Assessment (SESA) Compliance 31
 
2.7 Potential Impacts of Climate Change on Water Supply Projects 32
 
2.8 Participation of Community Based Water Supply Organizations (CBWSO) in Various Planning Stages 32
 
2.9 References 32
 
CHAPTER THREE 35
 
WATER SOURCES ANALYSIS 35
 
3.1 Availability of Water Resources in Tanzania Mainland 35
 
3.2 Water Sources Available in Tanzania Mainland 38
 
3.2.1 Rainwater and fog harvesting 39
 
3.2.2 Surface Water 39
 
3.2.2.1 Rivers or streams 39
 
3.2.2.2 Impoundments 39
 
3.2.2.3 Springs 39
 
3.2.2.4 Lakes 39
 
3.2.2.5 Dams 40
 
3.2.3 Groundwater 40
 
3.2.3.1 Infiltration galleries/wells 40
 
3.2.3.2 Well 40
 
3.2.3.3 Classification of wells based on the aquifer tapped 41
 
3.2.3.3.1 Shallow wells 41
 
3.2.3.3.2 Deep wells 41
 
3.2.3.3.3 Artesian wells 41
 
3.3 Quality Suitability of Water Sources for Water Supply Projects 42
 
3.4 Pilot Testing of Water Sources for Establishment of Appropriate Treatment 42
 
3.5 General Considerations for Selection of Water Sources 42
 
3.5.1 Adequacy and reliability 42
 
3.5.2 Quality of water sources 43
 
3.5.3 Technical Requirements 43
 
3.5.4 Cost implications to develop a water source 43
 
3.5.5 Protection of water sources 43
 
3.5.6 Legal and management requirements 44
 
3.5.7 Distance of water supply source 44
 
3.5.8 Topography of the project area and its surroundings 44
 
3.5.9 Elevation of a source of water supply 44
 
3.6 Determination of water source yield 44
 
3.6.1 Rainwater and fog harvesting 45
 
3.6.1.1 Rainwater harvesting 45
 
3.6.1.1.1 Types of rainwater harvesting 45
 
3.6.1.1.2 Components of rainwater harvesting system 46
 
3.6.1.1.3 Estimation of the yield 47
 
3.6.2 Hydrological Analysis of Surface Waters 47
 
3.7 Other considerations for various water sources 55
 
3.7.1 Water permits Considerations 55
 
3.7.2 Conservation of water sources 55
 
3.8 References 55
 
CHAPTER FOUR 56
 
WATER DEMAND ASSESSMENT 56
 
4.1 Water Demand Assessment 56
 
4.2 General Factors Affecting Water Demand Assessment 57
 
4.3 Determination of Water Demand for Different Uses 58
 
Step 7. Establish Net Water Demand 67
 
Step 9: Establish Operational water consumption 67
 
Step 10: Establish System water losses 68
 
Step 11 Establish Non-Revenue Water 69
 
4.4 Variations in Water Consumption 70
 
4.4.1 Definitions 70
 
4.4.2 Variation in the Rate of Consumption 71
 
4.4.2.1 Diurnal variation in demand 71
 
4.4.3 Peak Factors 72
 
4.4.4 Predicting Demand 74
 
4.4.5 Design Demand 75
 
4.5 References 75
 
CHAPTER FIVE 76
 
PIPELINES DESIGN 76
 
5.1 Design Requirements of pipelines 76
 
5.2 Types of pipelines 76
 
5.3 Security considerations for pipelines 76
 
5.3.1 Methods of water transmission and distribution 76
 
5.3.2 Gravity flow 77
 
5.3.3 Pumping with storage 77
 
5.3.4 Direct pumping to the distribution system 77
 
5.4 Pipeline Hydraulics Assessment 77
 
5.4.1 Pressure 77
 
5.4.2 Determination of Head Losses 77
 
5.5 Water supply transmission system 79
 
5.5.1 Determination of Transmission Pipe Size 79
 
5.5.2 Maximum Pressure 79
 
5.6 Distribution system 80
 
5.6.1 Branched System 80
 
5.6.2 Looped System 81
 
5.7 Pipe network analysis 82
 
5.7.1 Network analysis by Conventional method (Hardy Cross) 82
 
5.7.2 Network Analysis by Computer Software 82
 
5.7.2.1 EPANET Software 82
 
5.7.3 Pipeline design criteria 85
 
5.8 Pipeline materials selection 86
 
5.8.1 Considerations in Selecting Pipeline Materials 86
 
5.8.1.1 Flow Characteristics 86
 
5.8.1.2 Pipe Strength 86
 
5.8.1.3 Durability 87
 
5.8.1.4 Type of Soil 87
 
5.8.1.5 Availability 87
 
5.8.1.6 Cost of Pipes 87
 
5.8.2 Types of Pipe Materials Available 87
 
5.8.2.1 Galvanized Iron (GI) Pipes 87
 
5.8.2.2 Plastic Pipes 87
 
5.9 Appurtenances for transmission and distribution mains 88
 
5.9.1 Valves 89
 
5.9.1.1 Isolation Valves 89
 
5.9.1.2 Check Valves 89
 
5.9.1.3 Float Valves 89
 
5.9.1.4 Air Release Valves 89
 
5.9.1.5 Pressure Reducing Valves 89
 
5.9.1.6 Washout valves 89
 
5.9.2 Fittings 89
 
5.10 References 90
 
CHAPTER SIX 91
 
PUMPING SYSTEMS 91
 
6.1 Introduction 91
 
6.2 Rationale 91
 
6.3 Common Types of Pumps used in water supply 91
 
6.4 Pumping System Setup 91
 
6.5 Source of Pumping Power 92
 
6.6 Pumping system design pump selection 92
 
6.7 Pump Protection 95
 
6.8 References 95
 
CHAPTER SEVEN 96
 
WATER TREATMENT 96
 
7.1 Introduction 96
 
7.1.1 Classification of the qualities of water sources found in Tanzania according to the complexity of its treatment 96
 
7.1.2 Classification of Unit Operations to achieve water treatment levels 99
 
7.2 Recommended overall design approach for treatment plant components 99
 
7.3 Documents and websites consulted and those which are hyper-linked to the DCOM Manual 100
 
7.4 Water treatment design considerations 100
 
7.5 Water treatment levels and units 101
 
7.5.1 Pre-treatment 101
 
7.5.1.1 Scum and Floating Materials Skimmer 101
 
7.5.1.2 Screening or straining 101
 
7.5.1.3 Grit Removal 103
 
7.5.1.3.1 Design criteria 103
 
7.5.1.4 Sand Traps 105
 
7.5.1.5 Pre-chlorination 107
 
7.5.1.6 Water pre-conditioning (pH adjustment) 108
 
7.5.2 Primary Treatment 108
 
7.5.2.1 Sedimentation 108
 
7.5.2.2 Primary Filtration 114
 
7.5.2.2.1 Slow Sand Filtration 114
 
7.5.2.2.2 Rapid Gravity Sand Filtration 117
 
7.5.2.2.3 Comparison between Slow Sand Filters and Rapid Sand Filters 118
 
7.5.2.2.4 Other Types of Filters 119
 
7.5.2.3 Floatation 124
 
7.5.2.3.1 Dissolved-Air Floatation 124
 
7.5.2.3.2 Electrolytic Floatation 125
 
7.5.2.3.3 Dispersed-Air Floatation 125
 
7.5.2.4 Aeration 125
 
7.5.2.4.1 Falling Water Aerators 126
 
7.5.2.4.2 Spray Aerators 127
 
7.5.3 Secondary Treatment 130
 
7.5.3.1 Clarification 130
 
7.5.3.2 Coagulation 130
 
7.5.3.3 Flocculation 131
 
7.5.3.4 Filtration 131
 
7.5.4 Tertiary Treatment 132
 
7.5.4.1 Disinfection 132
 
7.5.4.1.1 Disinfection Methods 132
 
7.5.4.1.2 Chlorinators 132
 
7.5.4.1.3 Design considerations for chlorinators 133
 
7.5.4.2 Ozonation 133
 
7.5.4.3 Water softening 134
 
7.5.4.3.1 Methods of Softening 135
 
7.5.4.4 Defluoridation of Water 139
 
7.5.4.4.1 Fluorides 139
 
7.5.4.4.2 Defluoridation 139
 
7.5.4.5 Water Conditioning 141
 
7.5.5 Management of Water Treatment Sludge 141
 
7.5.5.1 Treatment of Water Treatment Sludge 141
 
7.5.5.1.1 Sludge Thickening 141
 
7.5.5.1.2 Sludge Dewatering 143
 
7.5.5.1.3 Sludge Drying Beds 144
 
7.5.5.1.4 Sludge Lagoons 144
 
7.5.5.1.5 Mechanical Sludge Dewatering 145
 
7.5.5.1.6 Backwash Water Recovery 145
 
7.5.5.1.7 Waste from Slow Sand Filters 146
 
7.5.5.2 Disposal of sludge 147
 
7.6 References 147
 
CHAPTER EIGHT 148
 
TREATMENT OF WATERS WITH SPECIAL CONTAMINANTS 148
 
8.1 Natural Organic Matter 148
 
8.2 Arsenic 149
 
8.3 Radioactive 149
 
8.4 Fluoride removal from drinking water 149
 
8.5 Toxic Cyanobacteria in Drinking Water 150
 
8.6 Available methods for removal of special water contaminants 152
 
8.7 Desalination 152
 
8.7.1 Additive method 152
 
8.7.2 Adsorption methods 153
 
8.7.3 Capacitive deionization (CDI) 153
 
8.7.4 Membrane Filtration 154
 
8.7.5 Reverse Osmosis 156
 
8.8 References 158
 
CHAPTER NINE 159
 
DESIGN OF WATER STRUCTURES 159
 
9.1 Sizing and Locating Water Structures 159
 
9.1.1 Tanks 159
 
9.1.1.1 Storage tanks 159
 
9.1.1.2 Sedimentation/Settling Tanks 160
 
9.1.1.3 Break Pressure Tanks 161
 
9.1.2 Water Intakes 162
 
9.1.3 Dams 164
 
9.1.3.1 Engineering Classification of Dams 164
 
9.1.3.2 Size classification of dams 164
 
9.1.3.3 Feasibility and geotechnical investigations 166
 
9.1.3.4 Hydrological analysis of the catchment 167
 
9.1.4 Geotechnical Investigation 169
 
9.1.4.1 Design of dams 170
 
9.1.5 Boreholes 173
 
9.1.5.1 Groundwater prospecting 179
 
9.1.5.2 Drilling 182
 
9.1.5.3 Siting of Well/Borehole 182
 
9.1.5.4 Well design 183
 
9.1.5.5 Pumping Tests 183
 
9.1.5.6 Groundwater quality 187
 
9.1.6 Water points and Service connections 190
 
9.1.7 Common Types of Water Points 191
 
9.1.8 Minimum Technical Requirements of Water Points 191
 
9.1.9 Criteria  for Design of Water Point/Kiosks 191
 
9.1.10 Location Considerations for Water Points 192
 
9.1.11 Technical Tips to Improve Water Points 193
 
9.1.11.1 Rainwater harvesting 196
 
9.1.11.2 Fog harvesting 200
 
9.2 Structural Design of Concrete 201
 
9.2.1 Structural requirements 201
 
9.2.2 Methods 201
 
9.2.2.1 Working Stress Method 201
 
9.2.2.2 Ultimate Load Method 201
 
9.2.2.3 Limit State Method 201
 
9.3 References 201
 
CHAPTER TEN 203
 
APPLICATION SOFTWARE 203
 
10.1 Application Software Contexts 203
 
10.2 Recommended Application Software 203
 
10.2.1 Distribution Network Design Software 203
 
10.2.1.1 Epanet 203
 
10.2.1.2 AutoCAD 204
 
10.2.1.3 WaterCAD 204
 
10.2.1.4 WaterGEMS 204
 
10.2.1.5 KY PIPES 204
 
10.2.1.6 GeoNode 204
 
10.2.1.7 AutoStudio 204
 
10.2.1.8 InfoWater 205
 
10.2.1.9 GIS Software 205
 
10.2.1.10 MS Project 205
 
10.2.2 Operation and Maintenance Software 205
 
10.2.2.1 MS Project 205
 
10.2.2.2 Excel 205
 
10.2.2.3 EDAMS 206
 
10.2.3 Water Quality 206
 
10.2.3.1 WaterCAD 206
 
10.3 Supervisory, Control and Data Acquisition (SCADA) Systems 206
 
10.4 References 207
 
CHAPTER ELEVEN 208
 
METERING 208
 
11.1 Introduction 208
 
11.2 Types of Water Meters 208
 
11.3 Prepaid Meters 208
 
11.4 Types of Prepaid water models commonly used in Tanzania 209
 
11.5 Importance of Prepaid Water Metering 210
 
11.6 Design Considerations for Prepaid Water Meters 210
 
11.7 Design considerations for prepaid public standpipes 211
 
11.8 Design consideration for individual domestic customer 212
 
11.9 Design consideration for Commercial and Institutional Customers 212
 
11.10 Importance of integrating Prepaid with Post paid revenue management 212
 
11.11 Selection Criteria for Prepaid water meters 212
 
11.12 References 214
 
11.13 Internet Links: 216
 
CHAPTER TWELVE 217
 
DESIGN STANDARDS AND SPECIFICATIONS 217
 
12.1 Design Standards 217
 
12.2 Specifications 218
 
12.3 Materials 218
 
12.3.1 Building Materials 218
 
12.3.2 Materials Testing 219
 
12.3.2.1 Aggregates 219
 
12.3.2.2 Water 221
 
12.3.2.3 Cement 221
 
12.3.2.4 Concrete Works 221
 
12.3.2.5 Steel 222
 
12.4 Soil Test 222
 
12.4.1 Methodology of conducting Soil Investigation for borehole and test pit 222
 
12.4.2 Soil Investigation for dams 223
 
12.4.3 Suitability of soil materials for dam construction 223
 
12.4.4 Determination of In-Situ Bearing Capacity of the Soil 224
 
12.5 References: 227
 
CHAPTER THIRTEEN 228
 
ROLE OF STAKEHOLDERS IN DESIGN OF WATER SUPPLY PROJECTS 228
 
13.1 Types of Stakeholders 228
 
13.2 Roles of stakeholders 228
 
13.3 References 230
 
APPENDIX A: CLIMATE CHANGE AND RESILIENCE TO CLIMATE CHANGE 232
 
APPENDIX B: MINIMUM WATER FLOW REQUIREMENT FOR FIRE FIGHTING 237
 
APPENDIX C: EXAMPLE: ESTIMATING THE CAPACITY OF TANK 239
 
APPENDIX D: STRUCTURAL DESIGN OF CONCRETE 241
 
APPENDIX E: SUPPLY PUMPING SYSTEMS 251
 
APPENDIX F: SOURCE OF PUMPING POWER 263
 
APPENDIX G: ADDITIONAL DETAILS OF VARIOUS UNIT OPRATIONS 275
 
APPENDIX H: METHODS FOR DISINFECTING WATER 281
 
APPENDIX I: MEASUREMENTS OF WATER HARDNESS 287
 
APPENDIX J: BASIC STATISTICS USED IN ESTIMATION OF DESIGN OF FLOOD EVENTS 289
 
APPENDIX K: DAMS DETAIL DESIGN 294
 
APPENDIX L: STANDARD DRAWINGS 306
 
APPENDIX M: SELECTED INTAKE DESIGNS. 307
 
SUBJECT INDEX 309
 

Latest revision as of 10:36, 21 July 2022