REPUBLIC OF KENYA COAST WATER SERVICES BOARD WATER AND SANITATION SERVICE IMPROVEMENT PROJECT – ADDITIONAL FINANCING (WaSSIP - AF) Consulting Services for Wastewater Master Plan for Mombasa and Selected Towns within the Coast Region Contract No. CWSB/WaSSIP-AF/C/10/2012 FINAL WASTEWATER MASTER PLAN REPORT FOR LAMU ISLAND VOLUME 1: MASTER PLAN MAIN REPORT In Association with: MARCH 2017 Water and Sanitation Service Improvement Project – Additional Financing (WaSSIP - AF) FINAL MASTER PLAN REPORT Wastewater Master Plan for Mombasa and Selected Towns within the Coast Region - LAMU ISLAND “DOCUMENT CONTROL” WATER AND SANITATION SERVICE IMPROVEMENT PROJECT – ADDITIONAL FINANCING (WaSSIP – AF) Wastewater Master Plan for Mombasa and Selected Towns within the Coast Region EMPLOYER: Coast Water Services Board (CWSB) DOCUMENT TITLE: FINAL MASTER PLAN REPORT– LAMU ISLAND RECORDS FOR REVISION Version DATE: DESCRIPTION/PURPOSE OF ISSUE: PREPARED CHECKED APPROVED BY: BY: BY: FINAL MASTER PLAN REPORT– LAMU 01 31-03-2017 JMO/NJN TSM MSB ISLAND MIBP/ CES/ BOSCH Water and Sanitation Service Improvement Project – Additional Financing (WaSSIP - AF) FINAL MASTER PLAN REPORT Wastewater Master Plan for Mombasa and Selected Towns within the Coast Region - LAMU ISLAND WATER AND SANITATION SERVICE IMPROVEMENT PROJECT – ADDITIONAL FINANCING (WaSSIP – AF) Wastewater Master Plan for Mombasa and Selected Towns within the Coast Region FINAL MASTER PLAN REPORT– LAMU TABLE OF CONTENTS EXECUTIVE SUMMARY E1 GOALS AND OBJECTIVES OF THIS STUDY ............................................................................... E1 E2 OBJECTIVES OF THIS REPORT ................................................................................................ E1 E3 STUDY AREA AND DEMOGRAPHY ......................................................................................... E1 E4 WATER DEMAND FORECAST ................................................................................................ E2 E5 WASTEWATER FLOW PREDICTIONS ...................................................................................... E3 E6 WASTEWATER MANAGEMENT STRATEGIES .......................................................................... E4 E7 MULTI-CRITERIA ANALYSIS AND REVIEW OF DEVELOPMENT STRATEGIES .............................. E5 E8 PROJECT COSTS ................................................................................................................... E6 E9 FINANCIAL AND ECONOMIC ANALYSIS OF THE SELECTED DEVELOPMENT STRATEGY .............. E7 E10 CONCLUSION OF THE MASTER PLAN ..................................................................................... E9 MAIN REPORT ................................................................................................................................ 1-1 1.0 PROJECT BACKGROUND ..................................................................................................... 1-1 1.1 GOALS AND OBJECTIVES OF THIS STUDY ....................................................................................... 1-3 1.2 EXECUTION OF THE STUDY ........................................................................................................ 1-3 1.3 OBJECTIVES OF THIS REPORT ..................................................................................................... 1-3 2.0 PROJECT AREA DESCRIPTION .............................................................................................. 2-1 2.1 LOCATION AND ADMINISTRATION .............................................................................................. 2-1 2.2 STUDY AREA ......................................................................................................................... 2-1 2.3 CLIMATE .............................................................................................................................. 2-3 2.4 TOPOGRAPHY, GEOLOGY AND SOILS ........................................................................................... 2-3 2.5 ECONOMIC ACTIVITIES ............................................................................................................. 2-3 2.6 EXISTING WATER SUPPLY AND SANITATION SYSTEMS ...................................................................... 2-3 2.6.1 Water Supply ....................................................................................................................... 2-3 2.6.2 Sanitation System ................................................................................................................ 2-4 2.7 IMMEDIATE MEASURES FOR THE IMPROVEMENT OF SANITATION SYSTEMS ........................................... 2-4 2.7.1 Ablution Blocks .................................................................................................................... 2-5 2.7.2 Sludge Handling Facility ...................................................................................................... 2-8 2.7.3 Implementation Cost for Immediate Measures ................................................................ 2-12 3.0 DEMOGRAPHY, LAND USE AND URBAN DEVELOPMENT ...................................................... 3-1 3.1 DEMOGRAPHY AND POPULATION DYNAMICS FOR LAMU ISLAND ........................................................ 3-1 3.1.1 Previous Population Trend .................................................................................................. 3-1 3.1.2 Population Growth Scenarios.............................................................................................. 3-2 3.1.3 Projected Population for Lamu Island ................................................................................. 3-3 3.2 LAND USE AND URBAN DEVELOPMENT ........................................................................................ 3-4 3.2.1 Introduction ........................................................................................................................ 3-4 3.2.2 Existing Land Use ................................................................................................................. 3-4 3.2.3 Land Use Planning and Policy .............................................................................................. 3-6 MIBP/ CES/ BOSCH i Water and Sanitation Service Improvement Project – Additional Financing (WaSSIP - AF) FINAL MASTER PLAN REPORT Wastewater Master Plan for Mombasa and Selected Towns within the Coast Region - LAMU ISLAND 3.2.4 Land Use Requirement per Land Use Zone ......................................................................... 3-7 4.0 WATER DEMAND FORECAST ............................................................................................... 4-1 4.1 ANALYSIS OF WATER CONSUMPTION RATES ................................................................................. 4-1 4.2 WATER DEMAND PROJECTIONS ................................................................................................. 4-4 5.0 WASTEWATER FLOW PREDICTIONS .................................................................................... 5-1 5.1 DESIGN CRITERIA ................................................................................................................... 5-1 5.1.1 Principal References ............................................................................................................ 5-1 5.1.2 Sewerage Collection System ............................................................................................... 5-1 5.1.3 Sewage Generation ............................................................................................................. 5-1 5.1.4 Peak Flow Factor and Sewer Capacity ................................................................................. 5-3 5.2 PROJECTED WASTEWATER FLOWS .............................................................................................. 5-4 6.0 DESIGN CRITERIA FOR SEWERAGE SYSTEM AND WASTEWATER TREATMENT PLANTS ........... 6-1 6.1 DESIGN OF SEWERS ................................................................................................................. 6-1 6.1.1 Minimum Size of Sewer....................................................................................................... 6-1 6.1.2 Hydraulic Design Criteria ..................................................................................................... 6-1 6.1.3 Self-Cleansing Gradients and Velocities .............................................................................. 6-2 6.1.4 Sulphide Generation ........................................................................................................... 6-2 6.1.5 Ventilation of Sewers .......................................................................................................... 6-3 6.1.6 Depth of Sewers .................................................................................................................. 6-3 6.1.7 Manhole Spacing and Sizes ................................................................................................. 6-4 6.1.8 Pipe Materials ..................................................................................................................... 6-4 6.1.9 Property Connections .......................................................................................................... 6-6 6.2 DESIGN OF SEWAGE PUMPING STATIONS ..................................................................................... 6-6 6.2.1 Sewage Pumps ...................................................................................................................