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 UKUNDA 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 - UKUNDA “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 WASTEWATER MASTER PLAN REPORT– UKUNDA RECORDS FOR REVISION Version DATE: DESCRIPTION/PURPOSE OF ISSUE: PREPARED CHECKED APPROVED BY: BY: BY: FINAL WASTEWATER MASTER PLAN 01 17-03-2017 NJN/EOA TSM MSB REPORT– UKUNDA 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 - UKUNDA 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– UKUNDA 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 ................................................................................................ E3 E5 WASTEWATER FLOW PREDICTIONS ...................................................................................... E3 E6 ALTERNATIVE WASTEWATER MANAGEMENT STRATEGIES .................................................... E4 E7 MULTI-CRITERIA ANALYSIS AND REVIEW OF DEVELOPMENT STRATEGIES .............................. E6 E8 PROJECT COSTS ................................................................................................................... E6 E9 FINANCIAL AND ECONOMIC ANALYSIS OF THE SELECTED DEVELOPMENT STRATEGY .............. E8 E10 CONCLUSION OF THE MASTER PLAN ................................................................................... E10 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 ...................................................................... 2-4 2.6.1 Water Supply ............................................................................................................. 2-4 2.6.2 Sanitation System ...................................................................................................... 2-4 2.7 IMMEDIATE MEASURES FOR THE IMPROVEMENT OF SANITATION SYSTEMS ........................................... 2-5 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 UKUNDA .............................................................. 3-1 3.1.1 Previous Population Trend ......................................................................................... 3-1 3.1.2 Population Growth Scenarios ..................................................................................... 3-2 3.1.3 Projected Population for Ukunda ............................................................................... 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 - UKUNDA 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 ........................................................................................................... 6-6 6.2.2 Sewage Pumping Stations .......................................................................................... 6-6 6.2.3 Siting of Sewage Pumping Stations ............................................................................