NAIROBI-MAVOKO-KITENGELA WATER SUPPLY PROJECT - FEASIBILITY STUDY REPORT

THE GOVERNMENT OF KENYA

MINISTRY OF WATER AND IRRIGATION

TANATHI WATER SERVICES BOARD

NAIROBI-MAVOKO-KITENGELA WATER SUPPLY PROJECT

FEASIBILITY STUDY REPORT

SEPTEMBER 2015

NAIROBI CITY

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Nairobi-Mavoko-Kitengela Water Supply Project Feasibility Study Report

NAIROBI-MAVOKO-KITENGELA WATER SUPPLY PROJECT

FEASIBILITY STUDY REPORT

TABLE OF CONTENTS

1. INTRODUCTION AND OBJECTIVES ......................................................................................... 1

1.1 COUNTRY OVERVIEW ................................................................................................................... 1 1.1.1 Basic information ............................................................................................................... 1 1.1.2 Geographic Information .................................................................................................... 1 1.1.3 Political System and Government Structure ..................................................................... 2 1.1.4 Macroeconomic Introduction ............................................................................................ 4 1.1.5 National Development Strategy ........................................................................................ 6

1.2 STUDY CONTEXT ........................................................................................................................ 11 1.3 GENERAL OBJECTIVES ................................................................................................................. 11

2. SOCIO-ECONOMIC CONTEXT ............................................................................................... 11

2.1 INTRODUCTION ......................................................................................................................... 11 2.2 NAIROBI CITY ............................................................................................................................ 12

2.2.1 Study Area and Socio-Economic Context ......................................................................... 12 2.2.2 Topography and Climate .................................................................................................. 16 2.2.3 Water Supply Undertaking .............................................................................................. 16

2.3 MAVOKO-KITENGELA AREA ......................................................................................................... 16 2.3.1 Study Area and Socio-Economic Context ......................................................................... 16 2.3.2 Climate, Topography and Geology .................................................................................. 17 2.3.3 Water Supply Undertaking .............................................................................................. 17

3. PRESENT WATER SOURCES .................................................................................................. 19

3.1 NAIROBI CITY ............................................................................................................................ 19 3.1.1 Surface Water Sources..................................................................................................... 19 3.1.2 Groundwater.................................................................................................................... 21

3.2 MAVOKO-KITENGELA AREA ......................................................................................................... 21 3.2.1 Introduction ..................................................................................................................... 21 3.2.2 NCWSC Bulk Water Supply .............................................................................................. 22 3.2.3 Norturesh Bulk Water Supply .......................................................................................... 23 3.2.4 MAVWASCO Boreholes .................................................................................................... 23 3.2.5 Private Boreholes ............................................................................................................. 23 3.2.6 Other Sources .................................................................................................................. 23

4. WATER DEMAND ESTIMATION ............................................................................................ 24

4.1 INTRODUCTION ......................................................................................................................... 24 4.2 NAIROBI CITY WATER DEMAND ................................................................................................... 24 4.3 MAVOKO-KITENGELA WATER DEMAND ........................................................................................ 27 4.4 COMBINED TARGET AREA WATER DEMAND .................................................................................. 29

5. PLANNED WATER SUPPLY DEVELOPMENTS ......................................................................... 31

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5.1 INTRODUCTION ......................................................................................................................... 31 5.2 NAIROBI CITY PLANNED WATER SOURCES ..................................................................................... 31 5.3 MAVOKO-KITENGELA PLANNED WATER SOURCES .......................................................................... 34 5.4 DESCRIPTION OF PLANNED WATER SOURCES ................................................................................. 35

5.4.1 Stony Athi Dam ................................................................................................................ 35 5.4.2 Ndarugu 1 Dam ................................................................................................................ 40 5.4.3 Ndarugu 2 Dam ................................................................................................................ 47 5.4.4 Maragua 4 Dam and S. Mathioya Transfer Tunnel .......................................................... 52

6. GENERAL APPROACH TO THE DEVELOPMENT OF STRATEGIES .............................................. 58

6.1 INTRODUCTION ......................................................................................................................... 58 6.2 STRATEGIES ANALYSED ............................................................................................................... 58

7. ALTERNATIVE 1 – DEVELOPMENT STRATEGY FOR WATER SUPPLY TO MAVOKO-KITENGELA . 60

7.1 PRELIMINARY COMPARISON OF SCHEMES ...................................................................................... 60 7.1.1 Key Characteristics and Comparison ............................................................................... 60 7.1.2 Recommendations and Next Steps .................................................................................. 62

7.2 NDARUGU 1 DAM SCHEME COMPONENTS .................................................................................... 63 7.2.1 Introduction ..................................................................................................................... 63 7.2.2 Dam Characteristics ......................................................................................................... 64 7.2.3 Raw Water Transmission ................................................................................................. 66 7.2.4 Water Treatment ............................................................................................................. 66 7.2.5 Treated Water Transmission ........................................................................................... 67

7.3 NDARUGU 2 DAM SCHEME COMPONENTS .................................................................................... 70 7.3.1 Introduction ..................................................................................................................... 70 7.3.2 Dam Characteristics ......................................................................................................... 70 7.3.3 Raw Water Transmission ................................................................................................. 72 7.3.4 Water Treatment ............................................................................................................. 73 7.3.5 Treated Water Transmission ........................................................................................... 73

7.4 COST ESTIMATES AND ECONOMIC COMPARISON ............................................................................ 75 7.4.1 Introduction ..................................................................................................................... 75 7.4.2 Dam Construction ............................................................................................................ 75 7.4.3 Water Treatment Plant .................................................................................................... 76 7.4.4 Pumping Stations ............................................................................................................. 76 7.4.5 Main Water Transmission and Distribution Pipelines ..................................................... 76 7.4.6 Service Reservoirs ............................................................................................................ 77 7.4.7 Summary of Costs ............................................................................................................ 78 7.4.8 Economic Comparison of Schemes .................................................................................. 78 7.4.9 Land Acquisitions and Compensation .............................................................................. 79 7.4.10 Conclusions and Recommendations ................................................................................ 83

8. ALTERNATIVE 2 – DEVELOPMENT STRATEGY FOR WATER SUPPLY TO NAIROBI AND MAVOKO-KITENGELA (INTEGRATED PLAN) ................................................................................ 85

8.1 PRELIMINARY COMPARISON OF SCHEMES ...................................................................................... 85 8.1.1 Key Characteristics and Comparison ............................................................................... 85 8.1.2 Recommendations and Next Steps .................................................................................. 87

8.2 NDARUGU 1 DAM SCHEME ......................................................................................................... 87

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8.2.1 Introduction ..................................................................................................................... 87 8.2.2 Dam Characteristics ......................................................................................................... 88 8.2.3 Raw Water Transmission ................................................................................................. 89 8.2.4 Water Treatment ............................................................................................................. 90 8.2.5 Treated Water Transmission ........................................................................................... 90

8.3 MARAGUA 4 DAM AND SOUTH MATHIOYA TUNNEL SCHEME ........................................................... 95 8.3.1 Introduction ..................................................................................................................... 95 8.3.2 Dam Characteristics ......................................................................................................... 96 8.3.3 South Mathioya Raw Water Transfer Tunnel .................................................................. 96 8.3.4 Raw Water Transmission ................................................................................................. 98 8.3.5 Water Treatment ........................................................................................................... 100 8.3.6 Treated Water Transmission ......................................................................................... 101

8.4 COST ESTIMATES AND ECONOMIC COMPARISON OF SCHEMES ........................................................ 103 8.4.1 Introduction ................................................................................................................... 103 8.4.2 Dam Construction .......................................................................................................... 103 8.4.3 Raw Water Transmission Tunnel ................................................................................... 104 8.4.4 Water Treatment Works ................................................................................................ 104 8.4.5 Pumping Stations ........................................................................................................... 104 8.4.6 Main Water Transmission Pipelines .............................................................................. 105 8.4.7 Service Reservoirs .......................................................................................................... 106 8.4.8 Summary of Costs .......................................................................................................... 106 8.4.9 Economic Comparison of Schemes ................................................................................ 107 8.4.10 Land Acquisitions and Compensation ............................................................................ 108 8.4.11 Conclusions and Recommendations .............................................................................. 113

9. SELECTION OF THE ADVANTAGEOUS ALTERNATIVE FOR DEVELOPMENT ............................ 115

9.1 INTRODUCTION ....................................................................................................................... 115 9.2 WATER SUPPLY DEVELOPMENT ................................................................................................. 116 9.3 WATER SUPPLY OPERATIONS .................................................................................................... 117 9.4 CONCLUSIONS AND RECOMMENDATIONS .................................................................................... 118

10. ECONOMIC, FINANCIAL AND SOCIAL BENEFITS ANALYSIS................................................... 120

10.1 ECONOMIC ANALYSIS ............................................................................................................... 120 10.1.1 Description of Compilation of Investment Estimate ..................................................... 120 10.1.2 Description of Financial Appraisal ................................................................................. 123

10.2 FINANCING ASSESSMENT: ......................................................................................................... 125 10.2.1 Cash flow Analysis .......................................................................................................... 125 10.2.2 Cost and Revenue Analysis ............................................................................................ 125 10.2.3 Financial analysis conclusion of project ......................................................................... 126

10.3 SOCIAL BENEFIT AND IMPACT ..................................................................................................... 126 10.3.1 Employment ................................................................................................................... 126

10.4 ENVIRONMENT IMPACT ASSESSMENT ......................................................................................... 127 10.4.1 The Environment Impact Assessment Assignment ....................................................... 127 10.4.2 Procedural steps of EIA .................................................................................................. 127 10.4.3 The EIA Report ............................................................................................................... 128 10.4.4 Positive impacts ............................................................................................................. 128 10.4.5 Negative impacts ........................................................................................................... 129

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10.4.6 Conclusion of EIA report ................................................................................................ 129

11. REPAYMENT ANALYSIS ..................................................................................................... 130

11.1 REPAYMENT METHODS ............................................................................................................. 130 11.2 SOURCE OF REPAYMENT ........................................................................................................... 130 11.3 REPAYMENT PLAN .................................................................................................................... 130

12. RISK ANALYSIS AND MITIGATION PLAN ............................................................................. 130

12.1 PROJECT OWNER RISKS ............................................................................................................ 130 12.1.1 Risk Identification .......................................................................................................... 130 12.1.2 Risk Allocation ................................................................................................................ 132 12.1.3 Risk Description and Mitigation ..................................................................................... 132

12.2 PROJECT CONTRACTING RISK ..................................................................................................... 134 12.2.1 Political Risk ................................................................................................................... 134 12.2.2 Price Risk ........................................................................................................................ 134 12.2.3 Management Risk .......................................................................................................... 134 12.2.4 Construction Risk ........................................................................................................... 134 12.2.5 Risk Management Plan .................................................................................................. 135

12.3 MARKET RISK .......................................................................................................................... 135 12.4 LABOR UNION AND EMPLOYMENT .............................................................................................. 135 12.5 PRODUCT AND TECHNICAL RISK .................................................................................................. 136 12.6 IMPLEMENTATION / CONSTRUCTION RISK .................................................................................... 136 12.7 FINANCING AND REPAYMENT RISK .............................................................................................. 136 12.8 ECONOMIC CONTEXT AND FINANCIAL FRAMEWORK (MACRO-ECONOMIC PERFORMANCE AND STABILITY)136

13. CONCLUSION .................................................................................................................... 137

13.1 SIGNIFICANCE AND NECESSITY TO THE COUNTRY ............................................................................ 137 13.2 ECONOMIC AND SOCIAL BENEFITS ............................................................................................... 137 13.3 PROJECT PLAN AND PREPARATION .............................................................................................. 138 13.4 RISKS AND CONTROL ................................................................................................................ 138

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1. INTRODUCTION AND OBJECTIVES

1.1 Country Overview

1.1.1 Basic information

Capital (and largest city)

: Nairobi 1°16′S 36°48′E / 1.267°S 36.8°E

Official languages : Swahili, English Demonym : Kenyan Government : Presidential Republic

President : Uhuru Kenyatta Independence : from the United Kingdom

Date : December 12, 1963 Republic declared : December 12, 1964

Area

Total : 580,367 km2 (47th) 224,080 sq mi

Water (%) : 2.3 Population

2009 : 43,000,000 (36th) 8 February 2007 census 31,138,735

Density : 68.6/km2 (140th) 177.6/sq mi

GDP (PPP) : 2014 Total : $60.94 billion Per capita : $2,909.8

GDP (nominal) : 2014 estimate Total : $55,243 billion Per capita : $1,337

HDI (2013) : 0.535 (medium) (147th) Currency : Kenyan shilling (KES) Time zone : EAT (UTC+3) Summer (DST) : not observed (UTC+3) Drives on the : Left Internet TLD : .ke

Calling code : +254

1.1.2 Geographic Information The Republic of Kenya is a country in East Africa. Lying along the Indian Ocean, at the equator, Kenya is bordered by Ethiopia (north), Somalia (northeast), Tanzania (south), Uganda plus Lake Victoria (west), and Sudan (northwest). The capital city is Nairobi. Kenya spans an area about 85% the size of France or Texas. The population has grown rapidly in recent decades to nearly 38 million. Kenya has numerous wildlife reserves, containing thousands of animal species.

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Kenya comprises 47 Counties each headed by a Governor (duly elected by the people). The Counties (Kaunti in Swahili) are subdivided into 497 divisions (taarafa). The divisions are then subdivided into 2,427 locations (mtaa) and then 6,612 sublocations (mtaa mdogo). The City of Nairobi enjoys the status of a full County. Kenya is a unitary state with two levels of Governments; the Central Government and the 47 County Governments. The central Government is headed by the President and the County Governments by the Governors. The functions of the two levels of the Government are distinct but mutually interdependent. The Central Government is responsible for administration of functions like security, all Government policies among other functions in the Country while the County Governments are involved in the functions relating to Social-economic development of the Counties. The Counties are:

Kiambu, Murang’a, Nyeri, Nyandarua, Kirinyaga, Mombasa, Kilifi, Kwale,Tana River, Taita Taveta, Lamu, Meru, Tharaka Nithi, Embu, Machakos, Makueni, Kitui, Isiolo, Marsabit, Nairobi, Wajir, Mandera, Garissa, Kisii, Homa Bay, Siaya, Kisumu, Nyamira, Kajiado, Narok, Saburu, Lakipia, Nakuru, Bomet, Kericho, Uasin Gishu, Trans Nzoia, Pokot, Turkana, Elgeyo Marakwet, Baringo,Kakamega, Vihiga, Bungoma, Busia

Constituencies are an electoral subdivision. There are 290 Constituencies in Kenya. Each Constituency is represented by a Member of National Assembly elected by people in a General Election. Each Constituency is further divided into wards whose representatives are elected as Members of County Assembly in an election held alongside General Elections.

1.1.3 Political System and Government Structure On 28 February 2008, Kibaki and Odinga signed an agreement on the formation of a coalition government in which Odinga would become Kenya's second prime Minister. Under the deal, the president would also appoint cabinet ministers from both PNU and ODM camps depending on each party's strength in Parliament. The agreement stipulated that the cabinet would also include a vice-president and two deputy Prime Ministers. After being debated and passed by Parliament, the coalition would hold until the end of the 8th Parliament or if either of the parties withdrew from the deal before then. Under the presidency of Mwai Kibaki, the new ruling coalition promised to focus its efforts on generating economic growth, combating corruption, improving education, and transform Kenyans’ quality of life and to secure the future of generations to come. In 2007 the government issued a statement declaring that from 2008, secondary education would be heavily subsidised, with the government footing all tuition fees. The new office of the PM had power and authority to co-ordinate and to supervise the functions of the Government and was occupied by an elected MP who was also the leader of the party or coalition with majority members in Parliament.



In 2010 Kenya enacted a new constitution which has further entrenched democracy, individual freedom through the bill of right and devolutions as a mean of entrenching equitable development in all the 47 counties. This improved public freedoms contributed to generally credible democratic and open elections held in March 2013. Under this new constitution, Kenya is a presidential representative democratic republic, whereby there is both the head of state and head of government, and of a multi-party system. Executive power is exercised by the government. Legislative power is vested in both the Senate, the National Assembly and the 47 County Assemblies. The Judiciary is independent of the executive and the legislature. Kenya has maintained remarkable stability despite changes in its political system and crises in neighboring countries. In March 2013, Uhuru Kenyata was elected as the President and declared to the position on 9th April 2013. The 2013 elections marked an important turning point in Kenya's democratic evolution in that power was transferred peacefully from the Coalition Governments comprising the Party of National Unity (PNU) and Orange Democratic Movement(ODM), to Jubilee Coalition comprising The National Alliance(TNA) and United Republican Party(URP). The coalition's agenda for Kenya under Jubilee's leadership is to:

• Put food and clean water on every Kenyan table • Ensure that every child in Kenya gets quality education • Create wealth • Ensure that every Kenyan gets quality and affordable healthcare • Empower Kenyan women to take their rightful place in developing this country • Keep Kenya safe and secure both internally and externally • Develop a cogent foreign relations and trade policy for Kenya

The coalition Government set three central pillars that illustrate the shared Agenda for Kenya, which are:

• Unity (umoja) • Economy (uchumi) • Openness (uwazi)

The coalition created the right team, to not only make Kenya’s Vision 2030 a reality, but also to immediately deliver accelerated economic growth, higher living standards, better healthcare and more jobs from 2013 onwards. Most importantly, the Coalition has purposed to radically address the inexcusable poverty and inequality that exists in our country today. Under the 3rd pillar (openness), the coalition introduced some of the toughest anti- corruption legislation in the world. The coalition Government will:

• Give the Ethics and Anti-Corruption Commission (EACC) the power to prosecute corruption cases as happens in other African countries.



• Set up local anti-corruption boards at county level with the power to refer cases to the EACC or to the Director of Public Prosecutions.

• Ban anyone convicted on corruption charges from working in Government, in any public sector job.

• Enact the necessary legislation so that Kenyan companies found guilty of corrupt practices will be liable to have their assets frozen by the courts.

• Ban foreign companies found guilty of corrupt practices from operating in Kenya. • Introduce an automatic freeze on the assets of anyone indicted on corruption charges

(with appropriate judicial approval). • Introduce the automatic suspension of any official indicted on corruption charges. • Put an end to Parliamentary immunity from corruption charges.

1.1.4 Macroeconomic Introduction After independence, Kenya promoted rapid economic growth through public investment, encouragement of agricultural production, and incentives for private and foreign industrial investment. Gross domestic product (GDP) grew at an annual average of 6.6% from 1963 to 1973. Agricultural production grew by 4.7% annually during the same period, stimulated by redistributing estates, diffusing new crop strains, and opening new areas to cultivation. Between 1974 and 1993, however, Kenya's economic performance declined. Inappropriate agricultural policies, inadequate credit, and poor international terms of trade contributed to the decline in agriculture. In 1993, the Government of Kenya began a major programme of economic reform and liberalization. A new minister of finance and a new governor of the Central Bank of Kenya undertook a series of economic measures with the assistance of the World Bank and the International Monetary Fund (IMF). As part of this programme, the government eliminated price controls and import licensing, removed foreign exchange controls, privatised a range of publicly owned companies, reduced the number of civil servants, and introduced conservative fiscal and monetary policies. From 1994 to 1996, Kenya's real GDP growth rate averaged just over 4% a year. Between 1997 and 2000, however, the economy entered a period of slowing or stagnant growth, due in part to adverse weather conditions and reduced economic activity. In 2001, GDP growth improved slightly as rainfall returned closer to normal levels. Economic growth continued to improve slightly in 2002 and reached 1.4% in 2003. It was 4.3% in 2004 and 5.8% in 2005 and it has stabilized between 5-6% from 2005 to 2014. In July 1997, the Government of Kenya refused to meet commitments made earlier to the IMF on governance reforms. As a result, the IMF suspended lending for 3 years, and the World Bank also put a $90-million structural adjustment credit on hold. Although many economic reforms put in place in 1993-94 remained, conservative economists believe that Kenya needs further reforms, particularly in governance, in order to increase GDP growth.



The Government of Kenya took positive steps on reform, including the 1999 establishment of the Kenya Anti-Corruption Authority (KACA), and measures to improve the transparency of government procurements and reduce the government payroll. In July 2000, the IMF signed a $150 million Poverty Reduction and Growth Facility (PRGF), and the World Bank followed suit shortly after with a $157 million Economic and Public Sector Reform credit. The Anti-Corruption Authority was declared unconstitutional in December 2000, and other parts of the reform effort faltered in 2001. The IMF and World Bank again suspended their programmes. Various efforts to restart the programme through mid-2002 were unsuccessful. Under the leadership of President Kibaki, who took over on December 30, 2002, the Government of Kenya began an ambitious economic reform programme and has resumed its cooperation with the World Bank and the IMF. The new National Rainbow Coalition (NARC) government enacted the Anti-Corruption and Economic Crimes Act and Public Officers Ethics Act in May 2003 aimed at fighting graft in public offices. Other reforms especially in the judiciary, public procurement etc., have led to the unlocking of donor aid and a renewed hope at economic revival. In November 2003, following the adoption of key anti-corruption laws and other reforms by the new government, donors reengaged as the IMF approved a three-year $250 million Poverty Reduction and Growth Facility and donors committed $4.2 billion in support over 4 years. The renewal of donor involvement has provided a much-needed boost to investor confidence. The Privatisation Bill has been enacted although the setting up of a privatisation commission is yet to be finalized, civil service reform has been implemented and in 2007 the country won the UN Public Service reform award. [42] However a lot of work needs to be done to make the country catch up with the rest of economic giants especially the Far East. The main challenges include taking candid action on corruption, enacting anti-terrorism and money laundering laws, bridging budget deficits, rehabilitating and building infrastructure. This hopefully will help in maintaining sound macroeconomic policies, and speed up the rapidly accelerating economic growth. In 2007, the Kenyan government unveiled Vision 2030, which is a very ambitious economic blueprint and which, if implemented in its entirety, has the potential of putting the country in the same league as the Asian Economic Tigers. Nairobi continues to be the primary communication and financial hub of East Africa. It enjoys the region's best transportation linkages, communications infrastructure, and trained personnel. A wide range of foreign firms maintain regional branch or representative offices in the city. In March 1996, the Presidents of Kenya, Tanzania, and Uganda re-established the East African Community (EAC). The EAC's objectives include harmonizing tariffs and customs regimes, free movement of people, and improving regional infrastructures. In March 2004, the three East African countries signed a Customs Union Agreement. Real GDP in 2014 grew by 5.3 percent and amounted to $60.94 billion compared with 5.7 percent growth in 2013. The real GDP is estimated to have increased by 4.8 percent in the first quarter, 6.1 percent in the second quarter, 5.4 percent in the third quarter and 5.1 percent in the fourth quarter of 2014 compared with growth of 6.0 percent, 7.0 percent, 6.8 percent and 3.0 percent in comparable quarters of 2013. Growth in 2014 was largely supported by improved performance in



construction; transport and storage; education; financial and insurance activities; real estate; and information and communication activities.

1.1.5 National Development Strategy Kenya is ushering in a national vision that is bound to touch the lives of all citizens. For the first time, a long-term plan to transform the lives of Kenyans was launched. This is Kenya Vision 2030: Transforming National Development.

1.1.5.1 Historical Background of the Initiative

Kenya has in the past had two long-term policies and several 5-Year Development Plans that have guided planning and investment: The first was Sessional Paper No. 10 of 1965: African Socialism and its Application to Kenya, and the second was Sessional Paper No.1 1986: Economic Management for Renewed Growth. These plans attempted to confront the country’s most entrenched problems- by charting a vision of how development would tackle them. Whereas the country grew by an average of 6 per cent over 1964-1980 and 4.1 per cent over 1980-1990, the period 1990-2002 was a period of declining per capita income with GDP growth of 1.9 per cent against a population growth of 2.9 per cent. However, since 2003, we have made tremendous effort to get the economy back on track through the Economic Recovery Strategy (ERS) with the GDP growth rate shooting back to 5.8 per cent by 2005. But how do we consolidate and increase this in the long-term? As a minimum, we have to transform the Socio-economic Structure from a situation where Agriculture still accounts for 23 per cent of GDP & 56 per cent of employment while manufacturing accounts for barely 9.9 per cent of GDP and less than 2 per cent of employment. Services account for the bulk of economic activity at 51.6 per cent of GDP constituted mainly by informal sector activities. While Kenya fares well in social indicators when compared to Sub-Saharan Africa, it does poorly compared to the middle-income countries, and especially the second-generation Newly Industrialising Countries, such as Malaysia Indonesia and Thailand that 35 years ago were at the same stage of development as Kenya. To remain relevant and competitive regionally and globally, Kenya must plan for the future. It must chart a new road map - a road map that learns from our past failures, builds on our strengths and confronts the realities of poverty, unemployment and globalization. The need for a vision is, therefore, apparent. Kenya 2030 lays the foundation for an economic revolution for the present and future leadership. Kenya could chart a path involving radical transformation. Through maximum exploitation of science, technology and innovation, we can initiate focused interventions targeting the elimination



of absolute poverty; improvement of equity and access to social services; promotion of private sector development through a regulatory framework that reduces the cost of doing business; a sound legal system that protects property rights and effectively dispenses justice; all these underpinned by accountable leadership at all levels of government. This path constitutes the basis for the development of Kenya’s long-term vision for sustained economic and social development. Thus the launch of Kenya Vision 2030 process is an ideal starting point to focus attention on what should be done in concrete terms to realize a prosperous Kenya. What must we do in the face of dwindling resources like water, rising unemployment and problems of urbanization?

1.1.5.2 Major Gains under ERS

• Revenue Growth from about 100bn in 2001/02 to over 340 in 2005/06 • Tourism Growth by over 1.3 Million Visitors since Yr 2005. • Primary school enrolment 7.6 million –Yr 2005. • Health Facilities 4,557 –Year 2003 -4,912 –Yr 2005 • CDF & LATF • Percentage of Roads in poor state fell to 32% -Yr 2005.

1.1.5.3 Present Challenges

• Unemployment Especially In Youth- Most jobs in informal sector • Income Redistribution – Inequality • Rapid Urbanization – 6 % Annually • Low Saving Ratio (16%) Compared To Need • Composition of our Economy over time

1.1.5.4 A plan for prosperity

The vision will be anchored on three pillars namely:

• Economic Aspirations - Sustained economic growth of 10% per annum

• Social Aspirations - A just and cohesive society enjoying equitable social development in a clean and

secure environment

• Political Aspirations - Issue-based, people centered, results oriented and accountable democratic political

system

The Kenya Vision 2030 is a long term vision and should have broad based public support and ownership. The Vision will be developed in three phases: Phase I will be high Level Diagnostic and Benchmarking, Phase II, development of High Level Strategies and Phase III will involve development of a Master plan and Communication.



The Vision will be implemented in stages to deliver short-term, medium-term as well as long-term Economic and Social targets.

1.1.5.5 Pro-poor Interventions

NESC recognizes that the benefits of economic growth may still not reach all the people, particularly the most disadvantaged members of the population. Consistent with the Government’s goal of fighting poverty, the vision will cover some social sector interventions that are critical in addressing the problem of poverty. The pro-poor spending proposals particularly in health and education are important in reducing the state of inequality.

1.1.5.6 Global Lessons- The Role of National Vision

As noted earlier, Kenya’s economy started well in the 1960s, but began a downward spiral that has persisted since the mid- 1970s. It is now understood that economic and social development are exceedingly dependent on the implementation of good policies and building of strong and effective institutions. And this should begin with a long term country vision and supporting strategies and action plans. It is clear that a number of poor, predominantly agricultural countries have transformed into Newly Industrialized Nations in a space of a generation. Chile, Malaysia, Mauritius, Thailand and South Korea achieved spectacular economic and social progress over a very short period since the 1960s. These countries had a number of things in common, the most significant of which are the strategic visions they formulated and implemented. These visions defined their long and short-term agendas on development priorities. With the national visions, stakeholders were all mobilized and facilitated to own the vision and the required reforms. To do this, the countries developed institutional structures to implement short-term and medium term actions making it possible to reorder priorities to achieve the long term vision. For Kenya, this lesson is particularly important and urgent. There is therefore, need to get back to the drawing board and now plan for a great future of all our Children. The Council under the direction of H.E the President has set out to develop the vision for Kenya: “A globally competitive and prosperous nation with a high quality of life by 2030”

1.1.5.7 Water Situation in the Country

Water plays a key role in the Nation’s economy as a resource for urban and rural consumption, for energy generation, for agricultural development, for industrial growth, livestock and tourism development, fisheries, navigation, National Parks and the environment. According the National Water Master Plan (JICA 2013), Kenya has limited natural renewable water resources estimated at 42.1 BCM/year, which consists of 20.6 BCM/year of surface water and 21.5



BCM/year of groundwater recharge. The per capita renewable water resources (precipitation – evapotranspiration) is estimated at 1,093m3 per capita per year for the country’s population of 38.53 million in 2010. Subsequently, the available water resources is estimated at 22.6 BCM/year and the per capita available water resources is estimated at 586m3 per capita per year in 2010. The available water resources are the total of renewable surface water resources and sustainable yield of groundwater, which are theoretically available quantities. It is important to note that since water resources are distributed unevenly in the country in terms of time and space, the actual usable water resources are less than the available water resources. The country’s natural endowment of freshwater is therefore highly limited, with annual renewable freshwater supply significantly below the 1,000m3 per capita set as the marker for water scarcity by the United Nations. The situation is worsened by the current low level of development of water resources in Kenya. Only about 15% of the renewable fresh water resources (known as the safe yield) has been currently developed. This low level of development means that water supply storage per capita has declined dramatically from 11.4m3 in 1969 to about 4.3m3 in 1999 – simply because of population growth and under investment in water resources infrastructure. However, the country possesses sufficient water resource to meet demand. The National Water Master Plan (JICA 2013) has estimated the current aggregate water demand as 3,218Mm3/yr (2010) which will rise to 21,468Mm3/yr Mm3 by year 2030. This would still be within the country’s available water resource of 22,564Mm3/yr, although the cost of supplying each additional increment of water is likely to rise steeply as readily accessible sources are progressively tapped. The decline in water storage infrastructure implies that there has been inadequate water resources development and management in Kenya. Consequently, there have been insufficient funds to properly allocate water, police illegal water extractions, control discharge of wastes into lakes and rivers, stop illegal irrigation activities, protect catchments, and help prevent excessive erosion in headwaters. Water users have taken advantage of these conditions to use water illegally to the detriment of those further downstream. There is no contradiction in the country being simultaneously water-scarce and able to safely exploit many times in the current water usage. It simply means that not only does Kenya receive one of the world’s lowest per capita water replenishment rates each year, but that it has also not developed the limited amount of water available at a time when its population has rapidly grown. This, together with the long-term degradation of the existing water resources, makes the country very vulnerable to perturbations in water supply, particularly from the climate variability, catchment degradation, illegal abstractions, pollution and invasive weeds.

1.1.5.7.1 Key Legislation and Policies

Key legislation and policies for the water sector in Kenya include:

• The National Policy on Water Resources Management and Development, Sessional Paper No. 1 of 1999, and



• The Water Act, 2002, which was aimed at providing for a harmonized and streamlined

management of water resources, water supply and sewerage services. The institutional arrangements and authorities in charge are shown in Figure 1.1 and described in the sections below. Figure 1.1: Functions and Roles of Institutions set up under Water Act, 2002

1.1.5.7.2 Ministry of Water and Irrigation

The Ministry of Water and Irrigation (MWI) is the ministry in charge of the water sector and is therefore responsible for the overall management of water resources and general government policy on the water sector in the country with the goal of conserving, managing and protecting water resources for socio-economic development. Under the water sector reforms, the MWI transferred management of and operation of water services to the Water Services Regulatory Board (WASREB) from mid-2005. The Director of water was the person in charge of water services in the ministry but these powers and duties were transferred to the regional water service boards that are now licensed by the WASREB to provide water services in different regions across the country. The ministry and other state corporations that were involved in water supply such as the National Water Conservation and Pipeline Corporation also transferred their water supply facilities to these regional water service boards. NGOs, CBOs and any other community self-help groups are required to enter into agreements with the respective regional water service boards with regard to use of water supply facilities owned by the community organizations.



1.2 Study Context The Nairobi Metropolitan Area contributes over 50% of the National GDP. Nairobi is also an important regional centre for trade, commerce, and regional integration. The City has an estimated resident population of 3.5 million people and an estimated daytime population of around 6 million people. The current population of in the Nairobi Metropolitan is estimated to be 5 million people and it is projected to increase to 8 million by the year 2030. It is therefore imperative for a high political priority to be assigned to address the chronic water supply problems facing Nairobi and the Metropolitan Area. Investments in water supply infrastructure have lagged since 1994 with the completion of the Third Nairobi Water Supply Project and the demand in the Nairobi Metropolitan area now far outstrips supply. The Nairobi Eastlands and Movoko-Kitengela area have particularly experienced exponential growth in population and general development which has been unmatched by water supply expansion. These areas are largely served through Nairobi Water and Sewerage Company (NCWSC) water supply which over the years has been reduced due to the general water demand growth in Nairobi and the unmatched water supply development. The reduced water supply to these areas have been done due to prioritization of demands and therefore it will be important if independent water supplies are developed for these areas.

1.3 General Objectives

The primary objective of this study is to identify sufficient water source(s) to meet the medium term water demand for Nairobi and Mavoko-Kitengela areas. The focus for water supply development for Nairobi will be the Eastlands areas covering the areas of Ruai, Utawala, Mihongo, Njiru, Donholm, Savanna, Kayole, Dandora, Mwiki among other areas. The areas generally comprise of low to middle income areas.

The Mavoko-Kitengela area covers parts of Mavoko Municipality area in Machakos County and Kitengela town in Kajiado County. The area lies to the Southeast of the City of Nairobi with a common Boundary at Jomo Kenyatta International Airport and the Nairobi National Park. Mavoko hosts Athi River, Mlolongo and Syokimau Urban areas and neighbours Kitengela town which falls under Kajiado County.

2. SOCIO-ECONOMIC CONTEXT

2.1 Introduction

The Nairobi Metropolitan Region (NMR) covers Nairobi City, Parts of Kiambu County, Thika, Kajiado and Machakos. Nairobi is spread over 696 km2 which is about 2% of the NMR area; it accommodates 3.13 million people according to the 2009 National census figures.

The specific study area is Nairobi and Mavoko-Kitengela areas as defined in Chapter 1 of this report.



2.2 Nairobi City

2.2.1 Study Area and Socio-Economic Context

The City of Nairobi owes its birth and growth to the Kenya Uganda Railway (KUR). The railhead reached Nairobi in May 1899 “enroute” to the present day Kisumu and Uganda. The moving of the railway headquarters from Mombasa to Nairobi by its chief engineer, Sir George Whitehouse resulted in the subsequent growth of Nairobi as a commercial and business hub of the then British East Africa protectorate. By 1900, Nairobi had already become a large and flourishing place with the settlement consisting mainly of the railway buildings and separate areas for Europeans and Indians, the latter being mainly the labourers employed on the construction of the railway. There was practically no African Settlement.

In 1907, Nairobi became the capital of Kenya and in 1950, Nairobi became a city. The population density in Nairobi has shown an increasing trend as clearly shown on Table 1.1.

Table 1.1: Population of Nairobi City between 1906 and 1999 Year Area (Ha) Population % Increase in

Population Population

Density (Persons / Ha)

1906 1,813 11,512 - 6 1928 2,537 29,864 159% 12 1931 2,537 47,919 60% 19 1936 2,537 49,600 4% 20 1944 2,537 108,900 120% 43 1948 8,315 118,976 9% 14 1963 68,945 342,764 188% 5 1969 68,945 509,286 49% 7 1979 68,945 827,755 63% 12 1989 68,945 1,324,570 60% 19 1999 68,945 2,143,254 62% 31 2009 68,945 3,138,366 46% 46

Spatial Development of Nairobi

From its earliest times, emerging spatial patterns in Nairobi showed segregation between the Central Business District (CBD) and European, Asian and African residential areas. By 1909 much of the internal structure especially the road network was developed. The boundary of Nairobi was extended in 1927 to cover 30 square miles (77 Km2) as a result mainly of the rapid growth of the urban centre both in terms of population and infrastructure.

From 1928 to 1963, this boundary remained the same with only minor additions and excisions taking place. In 1963, the boundary of Nairobi was extended to cover an area of approximately 266 square miles (686 Km2). There have not been any boundary changes since then. From this early growth, the city’s functions have developed and expanded such that today it has achieved an overwhelming dominance in the political, social, cultural and economic life of the people of Kenya and the whole of the Eastern Africa region.



The Nairobi Municipal Committee Regulations of 1960 defined the initial boundaries for the then Nairobi town as: “The area within a radius of one and a half miles [about 2.25 km] from the offices of the sub-commissioner of the then Ukambani Province”.

Figure 2.1 illustrates the boundary changes that took place from 1900 until 1963 after which the boundary did not change. The population of the town has also changed significantly. Its main sources of growth have been immigration especially from Central parts of Kenya. The long distance sources have been mainly the Eastern, Nyanza and Western Provinces of Kenya.

By 1963, the Africans who formed a major part of the population lived in the eastern parts, while the Europeans and Asians lived in the western suburbs with access to better services. This position is reflected today not so much in terms of race, but rather in terms of incomes as well as population densities. The people living in the western suburbs are generally the more affluent while the lower and middle-income elements of society dominate the eastern suburbs. Nairobi displays a complex surface structure, making it difficult to decipher the distinct land uses of the city surface. Inevitably, there are wide variations in population density reflecting different land use patterns within what is seen as the six distinct and different land use divisions, namely; the Central Business District (CBD); Industrial Area; public and private open spaces; public land; residential areas; and undeveloped land. The spatially divided internal structure is based on land uses and income levels.

Figure 2.1 Boundary Changes for Nairobi



Demographics of Nairobi

Apart from both the CBD and industrial areas which contain low population densities and a low incidence of housing, below are five residential areas of varying population density and social mix:

• Upper Nairobi lying to the west and north of the CBD. This is an area of low density, high-income population (2-25 people per hectare in 1980) and comprises many of the former well-known expatriate residential areas such as Woodley, Kileleshwa, Kilimani, Lavington, Bernard, Thomson and Muthaiga.

• Parklands, Eastleigh and Nairobi South, an area of medium income, medium density population (30-40 people per hectare in 1980) and consists of mainly owner-occupier housing (many owned by Asians). Eastleigh has presently outgrown to upper low income areas.

• Karen and Langata, to the south and south-east, are also high income, low-density residential areas, typified by large housing, gardens and paddocks. These areas are in transitional phase in that several mid-income estates often owner-occupied by civil servants are growing to absorb the population spilling from the other areas.

• Eastlands in the marginalised urban fringe to the east of and away from the CBD, is a low-income densely populated area (50-300 people per hectare in 1980) with the core region of old NCC housing areas and new institutional housing estates (Race Course, Ngara, Shauri Moyo, Pumwani, Mathare Valley, Eastleigh, Kariobangi, Kaloleni, Bahati, Jericho, Mbotela, Dandora - bywords for urban deprivation and disadvantage) reaching densities of 200-300 people per hectare in 1980). The Eastlands area has presently expanded to include Buru Buru, Donholm, Umoja, Kayole, Njiru, Ruai etc. which largely low and lower-middle income areas.

• Mathare Valley to the east of the city and Kibera to the west form the most famous, largest uncontrolled urban settlements in the city, reaching staggering densities of 1,250 people per hectare in 1980. The populations of these (and other areas like Korogocho and Kawangware) grew by 220% between 1969 intercensal period. They are characterised by the uncontrolled, spontaneous mushrooming of squatter settlements created by low-income migrants fleeing from the rapidly rising costs of living in the city but fleeing into cardboard cities along valleys close to the CBD itself. Other newer low income areas (slums) include Mukuru, Kiambio, Obama, among others. Here there are rapid shifts and movements of the population, shortages of accommodation, high rents and overcrowding. Also to be observed is the starkest interrelationship between income structures and housing and schooling opportunities and the inadequate distribution of schooling and educational opportunities despite the high profile of social demand for education in the country as a whole. It is a sharp illustration of “subsistence urbanism”.

The Urban Economy of Nairobi

In Nairobi, 86.3 per cent of the people aged between 15 and 64, are economically active according to Government estimates. Since independence, there has been considerable growth in wage employment in the modern sector. Access to formal sector employment declined marginally by -



0.43 per cent between 1998 and 2001. In spite of this decline, Nairobi still dominates urban formal sector employment, contributing 29.3 per cent of the active population.

However, there has been a decline in wage employment in the public sector in Kenya owing to the restructuring and privatisation programme introduced in 1990. Wage employment in Nairobi includes the following: in 1998; 67,900 individuals in Nairobi’s labour force were in manufacturing industry; 39,700 in building and construction; 57,300 in trade, restaurants, and hotels; 42,200 in finance, insurance, real estate and business services; while community, social, and personal services employed 155,900 people.

The livelihood of most inhabitants of Nairobi comes from informal economic activities, and formal wage employment has been decreasing relative to population growth. The informal sector where most of the poor belong has been noted to generate more employment than the formal sector. Estimates of the size of the informal sector vary. The 2002 GoK Economic Survey shows that the contribution of informal sector employment has grown by 176 per cent compared to –0.43 per cent from the formal sector.

Those with relatively little capital can accede to informal income-generating activities as the unregulated and unprotected production of goods and provision of services. Earnings from many informal sector activities in Nairobi compare favourably with those from urban unskilled or rural agricultural wage employment. The formal and informal sectors are generally thought to be symbiotic, with the vitality of the informal sector depending upon the wages and demand generated by formal sector. The lack of employment opportunities in the city has led to informal trading manifested in the form of haphazardly distributed kiosks some of which are licensed by the City County but the majority of which trade without a valid license.

The most important way in which women generate income in the informal sector is through the marketing of farm and imported manufactured goods. The first category is comprised of women engaged in trade at either retail or wholesale level, mostly in the low-income zones. Some sell in large quantities and regulate the major supplies to urban areas. The majority engages in retail trade in small kiosks that sell consumables. Others are engaged in distributing sisal products such as ropes for making “kiondos,” a type of local basket. The second category comprises urban women who sell a variety of goods ranging from food and jewellery to imported new and old shoes and clothing. Such women live within low and medium-income zones in Nairobi.

The informal sector contributes significantly to Nairobi’s economy and has strong backward linkages with commercial and public enterprises. The creation of employment opportunities in this sector is not necessarily dependent upon direct public expenditure and commitment of public investment in advance. The other advantages of the informal sector are that it uses simple technology appropriate to the resource base of the communities and that it produces jobs at lower costs. Despite the growth of this sector, unemployment is particularly widespread among young urban dwellers and women.



2.2.2 Topography and Climate

Nairobi lies at the southern end of Kenya’s agricultural heartland, 1.19 degrees south of the Equator and 36.59 degrees east of meridian 70. Its altitude varies between 1,500 and 1,900 metres above sea level. The climate is generally a temperate tropical climate, with cool evenings and mornings becoming distinctly cold during the rainy seasons. There are long rainy periods between April and June, while the short rains come in November and early December. There is a constant of 12 hours of daylight. Average daily temperatures range from 29º C in the dry season to 24º C during the rest of the year.

2.2.3 Water Supply Undertaking

The responsibility for water supply and sewerage in Nairobi is shared between an asset holding company, Athi Water Services Board (AWSB), and an operating company, the Nairobi City Water and Sewer Company that operates under contract with the AWSB. 10 other Water Service Providers (WSPs) operate under the AWSB in localities near Nairobi that are located outside of Nairobi County. Service standards are set and monitored by a national water regulatory agency called the Water Services Regulatory Board (WASREB).

The Athi Water Services Board is a government institution under the authority of the Ministry of Water and Irrigation and covers its costs through a Regulatory Levy collected from the Water Service Providers. The Minister of Water and Irrigation, appoints the Board of AWSB.

Water and sewer services in Nairobi city are provided by the Nairobi City Water & Sewerage Company Ltd. The Company is owned by the Nairobi County Government and has a supervisory Board of 12 Directors from the private sector, professional associations, NGOs and the County Government.

2.3 Mavoko-Kitengela Area

2.3.1 Study Area and Socio-Economic Context

The water supply area covers parts of Mavoko Municipality area in Machakos County and Kitengela town in Kajiado County. The area lies to the Southeast of the City of Nairobi with a common Boundary at Jomo Kenyatta International Airport and the Nairobi National Park. Mavoko hosts Athi River, Mlolongo and Syokimau Urban areas and neighbours Kitengela town which falls under Kajiado County.

The industrial base within Mavoko area is located around Athi River and has continued to increase with new industries moving into the area. Major industries include 4No. cement factories, meat processing (KMC), leather tannery among many other industries. Kitengela is also the residential area for the Export Processing Zone (EPZ) which also hosts a number of industries. The town has the highest industrialization potential in the country courtesy to vast land currently under ranches which is gradually changing use from ranching to industrial and commercial. Currently there are approximately 150 light and heavy industries in the town and host several major factories.



The population has also increased tremendously due to the massive intrusion of the residential developments between the airport along Mombasa road, River Athi and in the Kitengela surroundings. The area has amongst the fastest growing urban centres in the country a consequence of ‘burst’ overflows of industrialization and human settlement in Nairobi city. The Town Centre is along the Nairobi-Mombasa Highway and at the junction of Namanga-Nairobi highway. The Town Centre also straddles the Nairobi-Mombasa Railway line. Recent proposals to locate an ICT centre in the area increases its significance as a major growth centre in the Nairobi Metropolitan Region.

2.3.2 Climate, Topography and Geology

The area is generally semi-arid and experience hot and dry weather for most of year with an average annual daily temperature is 240C indicating general hot climate for the area. The area is semi-arid and receives very little and erratic precipitation with long rains occurring in March to May and the short rains fall between October and December. The annual average rainfall varies from 300 – 700mm with a mean of 460mm. The rainfall is very unreliable and varies from year to year making it difficult to predict the annual rainfall.

The project area is mainly comprised of flat to undulating landscapes that vary in elevation from 1,400 masl along the Athi River to the high areas of Syokimau and Lukenya. The Lukenya Hills straddles the west side of the area and rises to above 1,800 masl. The area slopes are oriented from Ngong and Lukenya Hills to the northwest towards the Athi River.

The geological rock class found in the area is mainly igneous rock dissected unconsolidated rocks along the valleys. Lithologically, the rock groups are mainly intermediate igneous rocks, with pockets of Eolian and pyroclastic unconsolidated formations. Metamorphic rocks are the main geological rock class found on the eastern parts in Lukenya area.

The area soils and vegetation varies widely between the lower, plains and upper altitudes. The plains which are located in the southern parts are characterised by clayey sandy soils, open grasslands with scattered trees. The areas along the banks of Stony Athi River are dominated by exposed rocks with limited gravel soils interspersed with scattered trees. Along the Athi River banks the soils are mainly deep dense clay and black cotton soils with medium dense grass vegetation. The northern parts are characterised with deep clay sandy soils overlying rock formations and several stone quarries are located in the area. The eastern areas of Lukenya are dominated by clayey sandy soils with rock outcrops at the hills

2.3.3 Water Supply Undertaking

Mavoko Municipality and Kitengela town areas are presently served by Mavoko Water & Sewerage Company (MAVWASCO). The Company was established in 2006 within the Water Act 2002 sector reforms as a legal entity under the companies Act Cap. 486 (Laws of Kenya) with the mandate to provide water and sanitation services to the entire population within a defined service area in the former Mavoko Municipality and the neighbouring Kitengela town in Kajiado County. The total mandated area coverage is 860km2 with a total population of approximately 250,000 but the area presently being served is 70km2 with an approximate population of 80,000.



The area falls under the jurisdiction of Tanathi Water Services Board (TAWSB) which is one of the eight water services boards in Kenya created in 2008 to provide water and sanitation service in areas that were initially parts of the Athi and Tana Water Services Board. The Board’s area of jurisdiction covers the fifteen ASAL districts and covers a total area of 66,582 Km2 which is approximately 11.5% of the surface area of Kenya with a population of 5.5 million. Farming, livestock keeping, small scale business and industries are the economic mainstay of the region.

The project area has no independent water sources and relies on bulk supplies from NCWSC and Norturesh water system. The area has only one surface water production facility at Athi river which is dilapidated and in disuse. The current bulk supplies to the area are inadequate to meet the present and increasing water demands. In addition, due to increased demand from the two bulk systems, it is expected that in future the bulk supply to the area will be reduced or terminated. The existing water facilities also have limited capacity and coverage is low. There is therefore great and urgent need to identify and formulate feasible and sustainable water augmentation project to serve and improve services in the area.



3. PRESENT WATER SOURCES

3.1 Nairobi City

3.1.1 Surface Water Sources

The main source for water supply for Nairobi is the Eastern Aberdare Rivers within the Aberdare Conservation Area (ACA). The ACA includes the Aberdare National Park and the gazetted Forest Reserves that surround the National Park. These areas are all under Government protection through Kenya Wildlife Service (KWS) and Kenya Forest Service (KFS). These areas are not subject to much catchment degradation through settlement and forest clearance, as has been recorded in other national forests, notably the Mau Forest. It can reasonably be assumed that the “protected area” status will not only be maintained by the Government, but will be strengthened; hence the sustainability of the surface water sources arising from the ACA is assured under current Government policy, subject to control of permitted abstractions.

The Existing Water Sources forming the Nairobi Water Supply System and their capacities are given in Table 3.1 below. A layout plan showing the existing system is given in Figure 3.1.

Table 3.1: Capacity of Existing Nairobi Water Sources Source Capacity

m3/s m3/d Kikuyu Springs 0.06 4,800 Ruiru Dam 0.25 21,700 Sasumua Dam 0.65 56,200 Thika Dam + (Kiama-Kimakia-Chania River) 4.80 414,700

Total 5.76 497,400

Figure 2 shows the existing water sources and transmission lines for Nairobi City.



Figure 3.1: Existing Nairobi Water Sources and Supply System



3.1.2 Groundwater

Groundwater contributions to Nairobi Water Supply for both domestic, commercial or industrial purpose via public, private or individual boreholes and wells is estimated to be about 45,000 m3/day.

3.2 Mavoko-Kitengela Area

3.2.1 Introduction

The service area has very limited independent water sources and relies mainly on bulk supplies by other WSP. The area is currently supplied with water through two bulk water supplies and boreholes. The design capacities of the present supplies and current supply are given in Table 3.2.

Table 3.2: Design Capacity of Existing Sources and Present Average Supply Source Current Average

Supply (m3/d) Design Capacity

(m3/d) NCWSC 7,500 22,000 Nol Turesh System 970 4,000 MAVWASCO Boreholes 700 - Private Boreholes Unknown -

The Nairobi City Water & Sewerage Company (NCWSC) source is the present Nairobi City source and is supplied through the Export Processing Zone (EPZ) line.

The Nol Turesh water supply scheme (capacity 4,000 m3/d) was implemented in 1990 and consist of a 550 mm dia. steel pipe, taking water from the Nol Turesh springs in the foothills of Mt. Kilimanjaro to the towns of Sultan Hamud, Kajiado, Athi River and Machakos. The Nol Turesh source is very unreliable and highly rationed with water being supplied irregularly.

There are 6No. boreholes in the area which are operated by the Company. The borehole yields are also unreliable.

Thus the area is currently being supplied with 9,170m3/d of water which is inadequate to meet the area water demands. Figure 3.2 shows the existing water supplies serving Mavoko and Kitengela areas. Brief description of the present water sources is given in the following sections.



Figure 3.2: Layout Plan Showing the Existing Mavoko-Kitengela Water Supply System

3.2.2 NCWSC Bulk Water Supply

The Nairobi bulk supply was designed to supply 22,000 m3/d and was constructed in 1993 to provide water to EPZA in Athi River. NCWSC supplies water in bulk to EPZA through its infrastructure. EPZA in turn supply water in bulk to MAVWASCO and directly to customers in Mlolongo, Athi River and



Kitengela areas. It is reported that at present EPZA receives between 5,000 - 8,000m3/d from NCWSC. In turn EPZA supplies about 1,500m3/d to MAVWASCO.

Due to increased shortfall of water supply in Nairobi, the supply to EPZA is expected to be constrained or curtailed completely in the immediate future.

3.2.3 Norturesh Bulk Water Supply

The Norturesh bulk supply was completed in 1992 and was designed to supply 4,000 m3/d to Athi River town through Lukenya Reservoir. Due to increased water use along the transmission system, only about 1,000 m3/d of water is now delivered to Lukenya Hill tank for supply to Athi River town.

Due to increased demands and losses along the Norturesh pipeline, plans are underway to rehabilitate and augment the Norturesh system. However, these rehabilitation and augmentation plans are not expected to provide additional water to Mavoko as most of the water is meant to serve the areas along the main line route as well as towns of Machakos and Loitoktok.

3.2.4 MAVWASCO Boreholes

MAVWASCO has boreholes which are located in Athi River town, Utawala (Githunguri) and Syokimau. One of the old boreholes is inactive while the new borehole is yet to be commissioned. The existing operational boreholes produce about 400 m3/d.

3.2.5 Private Boreholes

Several industries and individuals have drilled their private boreholes in the area. Most of the owners also supply water to their neighbours through kiosks, tankers and handcarts.

3.2.6 Other Sources

The EAPACC and KMC industries have developed their individual water sources. EAPCC has a dam wall across the river at the confluence of Mbagathi and Kitengela River where they abstract water. KMC also have a mass concrete arch dam across the Stony Athi River from where they obtain water for their use.



4. WATER DEMAND ESTIMATION

4.1 Introduction

Water demand is defined as the volume of water different categories of consumers can afford to consume in a context of unrestricted supply. The water demand of a Municipality is dependent on the climate, economic considerations, sanitation facilities and industrial / institutional requirements.

The spatial distribution of the water demand within the Municipality / City is largely dependent on the land use, density and spread of the population. The water demand has been computed from estimates in the Feasibility Study and Master Plan for Developing New Water Sources for Nairobi and Satellite Towns by egis/MIBP JV, (2012).

4.2 Nairobi City Water Demand

In the Master Plan Study (egis/MIBP JV, 2012), the present Nairobi City water demand was estimated at 644,625m3/d (year 2015) and projected to grow to 873,418m3/d by year 2015 and 1,205,322m3/d by year 2035. This is for respective population of 3.7million (year 2015), 5.0million (year 2025) and 6.5million (year 2035). Table 4.1 gives the population projections and estimated water demands for Nairobi City. The same is shown graphically in Figures 4.1 and 4.2 respectively. Table 4.1: Population and Water Demand Projection

Year Year 2015 Year 2020 Year 2025 Year 2030 Year 2035 Population 3,796,818 4,403,791 5,007,274 5,693,457 6,444,969 Water Demand, m3/d 644,625 728,309 873,418 1,018,528 1,205,322

Figure 4.1: Nairobi City Population Projections

3,500,000

4,000,000

4,500,000

5,000,000

5,500,000

6,000,000

6,500,000

2015 2020 2025 2030 2035

Popu

latio

n

Year



Figure 4.2: Nairobi City Water Demand Estimate

Nairobi City is divided into 11 Hydraulic Pressure Zones. The zone boundaries are largely based on their elevations relative to the main service reservoirs for the City. Figure 4.3 shows the pressure zones and Table 4.2 gives a description of the zones and the present and future projected water demand for each zone.

The focused zones in this study for water supply are zones 10 and 11. Zone 10 is presently supplied via Ring Road Tank while zone 11 is supplied via Kasarani and Karura Tanks. The present total water demand for these zones is 113,296m3/d (2015) while the projected year 2035 water demand is 211,840m3/d.

3,500,000

4,000,000

4,500,000

5,000,000

5,500,000

6,000,000

6,500,000

2015 2020 2025 2030 2035

Wat

er D

eman

d, m

3 /d

Year



Figure 4.3: Nairobi City Hydraulic Water Distribution Pressure Zones Table 4.2: Distribution of Water Demand – Nairobi City

Pressure Zone

Service Reservoir Description

Water Demand, m3/d % of Total 2015 2025 2030 2035

PZ-1 Kikuyu Springs Tanks

Zone 1S - Supplied by Spring I Zone 1N - Supplied by Spring II 2% 9,790 13,265 15,469 18,306

PZ-2N

Dagoretti Reservoir

Supplied from Kabete via Dagoretti Reservoir

3% 22,547 30,549 35,625 42,158

PZ-2S 1% 6,299 8,534 9,952 11,778

PZ-3S 1% 9,563 12,957 15,109 17,880

PZ-3N Uthiru Reservoir

Supplied from Kabete via Uthiru Reservoir 11% 72,834 98,685 115,080 136,185

PZ-4 Loresho Reservoir

Zone 4 is fed by Sasumua line while zone 5 is supplied by pumping water from Kyuna to Loresho Reservoir

0.4% 2,825 3,828 4,463 5,282

PZ-5 Sasumua Line + Loresho 3% 20,924 28,350 33,060 39,123

PZ-6 Kabete Reservoir

Zone 6 is supplied directly from Kabete Reservoir while Zone 7 is supplied via Hill Tank by pumping from Kenyatta Ave. Pumping Station

12% 74,198 100,532 117,235 138,735

PZ-7 8% 48,543 65,772 76,699 90,766

PZ-8 Gigiri and Kiambu Reservoirs (Intermediate

These Zones are supplied from Ngethu Treatment Plant alone and the Distribution System is interconnected

15% 94,463 127,990 149,254 176,626

PZ-9 25% 163,370 221,354 258,129 305,469



Pressure Zone

Service Reservoir Description

Water Demand, m3/d % of Total 2015 2025 2030 2035

PZ-10 Reservoirs are Karura, Wilson, Kasarani and Ring Road)

2% 10,291 13,943 16,259 19,241

PZ-11 16% 103,005 139,564 162,751 192,599

Bomas Comprises mainly of Nairobi National Park 1% 5,976 8,097 9,442 11,174

Total Gross Water Demand 100% 644,625 873,418 1,018,528 1,205,322

4.3 Mavoko-Kitengela Water Demand

In the Master Plan Study (egis/MIBP JV, 2012), the present water demand within Mavoko Municipality and Kitengela town was estimated at 24,200m3/d (year 2015) and projected to grow to 80,200m3/d by year 2035. The water demand calculation was based on the existing water supply coverage with the coverage expected to grow towards the planning horizon. Table 4.3 gives the population projections while Table 4.4 gives the estimated water demands for Mavoko Municipality. The same is shown graphically in Figures 4.4 and 4.5 respectively.

Table 4.3: Population Projections Year 2015 2025 2030 2035 Total Population 203,072 416,520 522,319 638,005

Table 4.4: Water Demand Estimates

Town / Zone Water Demand, m3/d Year 2015 Year 2025 Year 2030 Year 2035

Syokimau / Mlolongo 10,890 22,343 28,980 36,090 Athi River 7,260 14,895 19,320 24,060 Kitengela 6,050 12,413 16,100 20,050 Total 24,200 49,650 64,400 80,200



Figure 4.4: Mavoko-Kitengela Population Projections

Figure 4.5: Mavoko-Kitengela Water Demand Estimation

100,000

200,000

300,000

400,000

500,000

600,000

700,000

2015 2020 2025 2030 2035

Popu

latio

n

Year

5,000

15,000

25,000

35,000

45,000

55,000

65,000

75,000

85,000

95,000

2015 2020 2025 2030 2035

Wat

er D

eman

d, m

3 /d

Year



A Feasibility Study and Preliminary Design Report for Athi River - Mavoko Water Supply by Connex Consultants (2010) estimated the water demand for Mavoko Municipality at 26,000m3/d (year 2015) growing to 68,000m3/d by year 2030.

The present water sources supply approximately 9,200m3/d which means that currently there is a water supply deficit of 13,400m3/d representing about 40% coverage. It is important to note that the present bulk supplies are unreliable and highly rationed.

4.4 Combined Target Area Water Demand

The aim of this study is to identify sufficient water sources to serve parts of the Nairobi Eastlands and Mavoko-Kitengela areas. The target areas have in the recent past experienced exponential growth in population and general development which has been unmatched by water supply expansion. These areas are presently mainly served by the Nairobi Water and Sewerage Company (NCWSC) which over the years has reduced the water supplies to these areas due to the general increase in water demand in Nairobi which has been unmatched by water supply development.

Figure 4.6 shows the target area of Nairobi Eastlands and Mavoko-Kitengela considered for water supply. Table 4.5 gives a summary of Population and Water Demand Projections.

Table 4.5: Summary of Population and Water Demand Projections Year 2015 2025 2030 2035

Nairobi Eastlands Population 683,427 901,309 1,024,822 1,160,094

Mavoko-Kitengela Population 203,072 416,520 522,319 638,005

Total Population 886,499 1,317,829 1,547,141 1,798,099

Nairobi Eastlands Water Demand, m3/d 116,033 157,215 183,335 216,958

Mavoko-Kitengela Water Demand, m3/d 24,200 49,650 64,400 80,200

Total Water Demand, m3/d 140,233 206,865 247,735 297,158



Figure 4.6: Target Area of Nairobi Eastlands and Mavoko-Kitengela



5. PLANNED WATER SUPPLY DEVELOPMENTS

5.1 Introduction

Presently, the total water demand for the study area (Nairobi Eastlands and Mavoko-Kitengela areas) is approximately 140,000m3/d as estimated in Section 4.4 of this report. The water demand is expected to increase to 248,000m3/d and 297,000m3/d by year 2030 and 2035 respectively. This means that presently there is a water supply deficit of approximately 110,000m3/d which is expected to rise to 218,000m3/d by year 2030 if additional water supplies are not mobilized for these areas.

Several alternative potential water sources to serve Nairobi and Mavoko / EPZA have been studied in that past under the following studies:

• The National Water Master Plan of December 2013 by the Japan International Cooperation Agency (JICA)

• Feasibility Study and Master Plan for developing New Water Sources for Nairobi and Satellite Towns (egis/MIBP JV, 2012)

• Athi River-Mavoko Water Supply and Sanitation Project Feasibility Study and Preliminary Design Report (Connex, 2010)

• Independent Water Supply Project, EPZA - 1998 by MIBP

• EPZA Water Supply and Sanitation Project, EPZA - 1994 by MIBP

• The National Water Master Plan of December 1991 by the Japan International Cooperation Agency (JICA)

• Third Nairobi Water Supply Project – Long Term Development Plan (Regional Studies) – Howard Humphreys, 1986

• Project of Preliminary Design Report for Athi River Town Water Supply, MOWD – 1984 by RKL

5.2 Nairobi City Planned Water Sources

The Feasibility Study and Master Plan for developing New Water Sources for Nairobi and Satellite Towns (egis/MIBP JV, 2012) proposed a number of water sources to augment the existing sources in order to meet the present and future water demand for Nairobi City. The water sources are shown graphically on Figure 5.1:



Figure 5.1: Proposed water sources for Nairobi City

A brief description of the water sources is given below:

1. Kiunyu Wellfield – 40,000m3/d yield: Proposed as a short term water source for Nairobi City with 2014 as the year of operation. Exploratory wells were later drilled which determined that the yield is not feasible for the wellfield to be developed

2. Ruiru Wellfield – 35,000m3/d yield: Proposed as a short term water source for Nairobi City with 2015 as the year of operation. Exploratory wells were later drilled which determined that the yield is not feasible for the wellfield to be developed

3. Northern Collector Tunnel Phase I diverting water from rivers North of Thika Dam (Ndakaini) (Irati, Gikigie and Maragua rivers) into the dam – 121,000m3/d yield: Proposed as a short term water source for Nairobi City with 2017 as the year of operation. Presently under implementation

4. Maragua Dam (33Mm3) together with the S. Mathioya River Transfer Tunnel – 132,000m3/d yield: Proposed as a medium term water source for Nairobi City with 2020 as the year of operation

5. Northern Collector Tunnel Phase II diverting water from rivers North of Thika Dam (Ndakaini) (Githugi, Hembe and N. Mathioya rivers) into the dam – 120,000m3/d yield: Proposed as a long term water source for Nairobi City with 2026 as the year of operation

6. Ndarugu Dam (300Mm3) at the confluence of Ndarugu and Komu rivers – 216,000m3/d yield: Proposed as a long term water source for Nairobi City with 2030 as the year of operation.

Either Ndarugu 1 Dam or Maragua 4 Dam has been considered as potential sources for development to supply Nairobi after the implementation of the Northern Collector Tunnel Phase I. Both scenarios



assume that the Wellfields will not be developed. The mobilization of the schemes will be as shown on the following figures. The development plan with Ndarugu 1 as the next source after NC Ph. 1 is given in Figure 5.2 while with Maragua 4 and S. Mathioya Tunnel as the next source is given in Figure 5.3. Both scenarios the Wellfields have been excluded.

Figure 5.2: Proposed water sources for Nairobi City – Ndarugu 1 Option

Figure 5.3: Proposed water sources for Nairobi City – Maragua 4 and S. Mathioya Option



5.3 Mavoko-Kitengela Planned Water Sources

Figure 5.4 shows the proposed future water sources for Mavoko Municipality area as documented in the Feasibility Study and Master Plan for developing New Water Sources for Nairobi and Satellite Towns (egis/MIBP JV, 2012) as the adopted scenario under the mixed water supply option.

Figure 5.4: Proposed water sources for Mavoko Municipality

A brief description of the water sources is given below:

1. Stony Athi Dam (21Mm3) – 60,480m3/d yield: Proposed as a short-medium term water source for Mavoko Municipality area with 2016 as the year of operation

2. NCWSC Bulk Water Supply – 12,000m3/d capacity: Proposed as a long term water source for Mavoko Municipality area with 2032 as the year of operation. Comprises of bulk water supply from Nairobi City. The implementation of this relies on Ndarugu 1 dam construction and to curtail the supply deficit at Nairobi City, it was proposed that the Chania-Komu Transfer Tunnel into Ndarugu 1 reservoir be constructed.

For the purposes of this study, it is proposed that Stony Athi Dam, Ndarugu 1 Dam and Ndarugu 2 Dam be considered as potential water sources for initial development to supply water independently to the Mavoko Municipality area. The mobilization of the schemes will be as shown on Figures 5.5.



Figure 5.5: Water Demand and Proposed Additional Mavoko Water Source

A brief description of the potential sources and criteria for consideration is given in the following sections.

5.4 Description of Planned Water Sources

5.4.1 Stony Athi Dam

The Stony Athi Dam has been considered as a potential water source for Mavoko-Kitengela area. The dam has been studied and recommended both in the Feasibility Study and Master Plan for developing New Water Sources for Nairobi and Satellite Towns by egis/MIBP JV, (2012) and in the Athi River-Mavoko Water Supply and Sanitation Project Feasibility Study and Preliminary Design by Connex, (2010) for water supply to Mavoko-Kitengela areas.

The proposed dam is located in Machakos County approximately 2km from Athi River Town. The dam at an optimal height of 22.5m is proposed to give a net reliable yield of 60,000m3/d based on the 96% Reliable Annual Run-off at a reservoir storage volume of 21.3 Million m3. The dam height is limited by the Nairobi-Mombasa railway line since if built above 1540masl elevation, the reservoir will impound the railway line. The railway line is proposed to be upgraded to the Standard Gauge Railway line thus it might be expensive to realign the railway line if need arises.

The dam embankment is proposed to be a zoned earth fill of volume of approximately 1.8 Million m3 at the optimal dam height. The dam Catchment area is 1,574Km2 and is generally semi-arid and experiences hot and dry weather for most of year with an average annual daily temperature is 24oC indicating general hot climate for the area. Figure 5.6 shows the dam catchment area. The catchment area is semi-arid and receives very little and erratic precipitation with long rains



occurring in March to May and the short rains fall between October and December. The annual average rainfall varies from 300 – 700mm with a mean of 460mm. The rainfall is very unreliable and varies from year to year making it difficult to predict the annual rainfall.

Land use within the catchment is particularly influenced by the large ranches within Kaputei plains and Kitengela conservancy area. About 76% of the catchment area is undifferentiated grazing or open grassland with few acacia shrubs and mainly used as livestock ranches. Part of the catchment is in Kitengela protected area covering about 240km2.

Urban areas only occupy about 2% of the catchment area. Parts of Kitengela town and urban areas between Isinya urban centre and Kitengela including Isinya Urban Centre fall within the dam catchment area. The main urban centres within the catchment area are Isinya, parts of Kitengela town and Konza town. The catchment area continues to experience rapid population growth and urbanization. The ranches within the catchment area are presently being subdivided for residential and commercial use.

Pollution risks in the catchment area are mainly due to increased erosion and urban waste discharge. Increased erosion may occur due to overgrazing in the ranches. The urban areas falling within the catchment largely do not have an urban sewerage system. The proposed Konza ICT City is also located within the Stony Athi Dam Catchment. There is also increased establishment of horticultural farms within the area which may discharge agricultural pesticides and fertilisers.



Figure 5.6: Stony Athi Dam Catchment Area



The key characteristic of the proposed dam and reservoir are as follows (Connex, 2010):

Location: • County – Machakos County • Sub-County - Athi River • Source - Stony Athi River • Catchment - Stony Athi Sub-Catchment

Catchment: • Catchment Area - 1,754 km2 • Mean Annual Rainfall - 702 mm • 96% Reliable Annual Run-off - 128.7 Mm3 • Maximum Flood Flow - 578 m3/s (1:10,000 return period)

Reservoir: • Design Capacity - 21.3 Mm3 • Full Supply Level - 1,540 masl • Impounded Area (FSL) - 351 ha • Design Yield - 60,000 m3/d • Design Storage Reliability - 5 Months

Embankment: • Type - Zoned Earth fill Embankment with clay core • Filter - Horizontal Drainage Blanket with Chimney Drain • Crest Level - 1,542.5 masl • Volume - 1.8 Mm3 • Height - 22.5 m • Crest Width - 6.0 m • Crest Length - 1,651 m • Upstream Slope - 1:3 • Downstream Slope - 1:2.5 • Gross Freeboard - 2.5m • Wave Protection - Rip-rap on gravel bed

Spillway: • Type - Concrete Chute Spillway • Capacity - 578 m3/s • Chute Width - 100m • Chute Length - 75m • Diversion and Intake Works: • Diversion Type - Reinforced Box Culvert • Capacity (1:100yrs) - 265 m3/s (5x4x100m) • Intake Water Tower Type - Open Dry Reinforced Tower • Tower Height - 25m • Draw-Off Pipe - 900mm • Scour Pipe - 600mm



The dam low water level intake will be at level 1,535 masl while the treatment works inlet top level is elevation 1,548 masl. Hence raw water abstracted from the dam must be pumped over a head difference of 13m over 1.6km distance.

The water transmission system comprises the treated water pump stations and transmission mains. The treated water is proposed to be pumped to storage reservoirs for four zones for distribution by gravity into the distribution network. A layout plan showing the proposed Stony Athi Dam Scheme is given in Figure 5.7.



Figure 5.7: Layout Plan Showing the Proposed Stony Athi Dam Water Supply Scheme

5.4.2 Ndarugu 1 Dam

The Ndarugu 1 Dam is proposed as a potential source to supply both Nairobi and Mavoko-Kitengela area. The Ndarugu 1 Dam is particularly proposed for development because of the need to have a robust and a high yielding dam for water supply to Nairobi City and Mavoko-Kitengela area. The dam



site has been subjected to previous studies including the Feasibility Study and Master Plan for developing New Water Sources for Nairobi and Satellite Towns by egis/MIBP JV, (2012) and the Third Nairobi Water Supply Project – Regional Studies by Howard Humphreys (1986).

The proposed Ndarugu 1 Dam is located before Ndarugu River joins Munyu and Athi Rivers at approximately at Survey of Kenya coordinates N9875699; E295698 and at an elevation of approximately 1420m amsl at the lowest supply level. The reservoir location on a Survey of Kenya topographical map is shown in Figure 5.8.

Figure 5.8: Ndarugu 1 Dam Location Plan (Reservoir Area at Maximum Dam Height of 35m)

The dam was adopted for development in the Long Term Development Plan (Regional Studies) by Howard Humphreys (1986) for water supply to Nairobi and surrounding areas. The site was again adopted in the Feasibility Study and Master Plan for developing New Water Sources for Nairobi and Satellite Towns by egis/MIBP JV, (2012) for water supply to Nairobi and the satellite towns.

Various proposals have been made with regard to the location of the dam in relation to the three rivers (Ndarugu River, Munyu River and Athi River). Damming the three rivers will give a substantially high yield for water supply to demand areas. However there are sewage discharges on Athi River from Nairobi City and Mavoko Area and Munyu River receives discharges from Thika town. In fact, damming of Munyu River will require relocation of Thika town sewage treatment works since they fall within the reservoir area. Nairobi City falls within the Athi River Catchment and about 80% of Thika Urban and Peri-urban areas fall within the Munyu River Catchment.



In order not to compromise the quality water for potable water supply, it has been found appropriate to construct the dam across the Ndarugu River valley. The Ndarugu River valley gives the highest storage out of the three rivers.

Ndarugu 1 Dam at a maximum height of 35m can give a net reliable yield of 198,720m3/d at a reservoir storage volume of 225 Million m3. The net reliable yield of the dam is based on 90% reliability based on annual occurrence of failures. This is the conventional method of reliability analysis for water supply reservoirs to large urban centres.

It is important that the dam is constructed to the full height in order to avoid future land acquisition issues. Presently there is ongoing rapid sub division and development of the land falling within the reservoir area. The need for the construction of Ndarugu 1 Dam cannot be understated because it’s a key future source for water supply to Nairobi and surrounding areas.

For the case of development to supply Mavoko-Kitengela area, the construction of Ndarugu 1 dam to maximum height can meet the ultimate future (year 2035) water demand for Mavoko-Kitengela area of 80,000m3/d. However, in order to avoid developing a large dam with low initial utilization, a 12.5m high dam can be constructed at the initial phase. The proposed dam height will give a reservoir storage volume of about 25Million m3 and a net reliable yield of 60,000m3/d. The reservoir location for a 12.5 high dam on a Survey of Kenya topographical map is shown in Figure 5.9.

Figure 5.9: Ndarugu 1 Dam Location Plan (Reservoir Area at a Dam Height of 12.5m)

The dam embankment is proposed to be a Roller Compacted Concrete Dam of volume of approximately 0.4 Million m3 for a 35m high dam and 0.12 Million m3 for a 12.5m high dam. The



spillway for either case will be an Overflow Type Spillway. The dam Catchment area is 190Km2 with the river originating from the Eastern Aberdares forest reserve. The forested catchment area is protected, as it lies within the National Park and Forest Reserve. Approximately 25% of the catchment area falls within the Forest Reserve. The importance of the forest to the catchment hydrology has long been recognised, and the Government is committed to the forest conservation. The indigenous forests clothing the mountains play an important role in maintaining dry season flow by stabilizing the soils, maintaining high infiltration rates and reducing surface water runoff in the wet season.

The dam Catchment area is approximately 190Km2 with the river originating from the Eastern Aberdares forest reserve. The forested catchment area is protected, as it lies within the National Park and Forest Reserve. The indigenous forests clothing the mountains play an important role in maintaining dry season flow by stabilizing the soils, maintaining high infiltration rates and reducing surface water runoff in the wet season.

Outside the Eastern Aberdares forest boundary, the upper zone comprises of smallholder tea plantations mainly developed in the 1950s to 70s and the lower zone comprises of subsistence farms, small scale coffee farms as well as large scale coffee farms. The dam catchment area is shown in Figure 5.10.

The main existing water abstraction points upstream of the proposed dam site is a run-of-river intake for Gatundu urban and rural water supply system located at the edge of Aberdare Forest and Juja town water supply run-of-river intake located about 5Km upstream of the proposed Ndarugu 1 Dam reservoir area. In addition, there are a number of other run-of-river intakes located upstream of the dam site for domestic water supply and irrigation.

Downstream of the proposed dam site, the river is joined by Munyu river approximately 1 Km downstream. The river then joins Athi river approximately 1.8 Km downstream.

The dam optimal maximum height is proposed to be 35m with a reservoir storage volume of approximately 225 Million m3. The dam height-storage relationship is given in Figure 5.11. The impoundment area at maximum dam height is approximately 14.5 Km2 (1450 Ha) and at 12.5m height is 0.45Km2 (450 Ha). The dam height-impoundment area relationship is given in Figure 5.12.

The net reliable yield based on 90% reliability based on annual occurrence of failures is 198,720m3/d (2.3m3/s) at maximum dam height and 60,000m3/d (0.73m3/s) at 12.5m dam height. This is according to a detailed yield assessment by Howard Humphreys (1986) which was confirmed in the Feasibility Study and Master Plan for Developing New Water Sources for Nairobi and Satellite Towns by egis/MIBP (2012). The storage-yield relationship is given in Table 5.1 and shown in Figure 5.13. The dam body is proposed to be a Roller Compacted Concrete dam of volume of approximately 0.4 Million m3 at maximum dam height. Figure 5.14 shows the river channel profile at the proposed dam site and the normal reservoir water supply level.



Table 5.1: Ndarugu 1 Dam Reservoir Yields Live Storage (S)

Mm3 S/MAI Yield (Y)

m3/s Y/MAI 350 3.14 2.6 0.75 305 2.75 2.5 0.71 250 2.23 2.4 0.67 200 1.80 2.2 0.63 150 1.34 2.1 0.58 100 0.90 1.8 0.51 50 0.45 1.2 0.35 25 0.23 0.7 0.20

Notes:- -Info Source: Howard Humphreys (1986) -Mean annual inflow (MAI) = 3.52m3/s (111 Mm3/year) -Yields are net of allowances for other water users and minimum compensation flows -MAI is net of releases for downstream users and upstream abstractions

Figure 5.10: Ndarugu 1 Dam Catchment Area



Figure 5.11: Ndarugu 1 Dam height-storage relationship

Figure 5.12: Ndarugu 1 Dam height-impoundment area relationship

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Figure 5.13: Ndarugu 1 Dam storage-yield relationship

Figure 5.14: Ndarugu River Channel Profile at the Proposed Dam Site

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5.4.3 Ndarugu 2 Dam

The Ndarugu 2 Dam has been considered as a potential water source for Mavoko-Kitengela area. The proposed dam site is located immediately downstream of Ndarugu and Githobokoni river confluence approximately at Survey of Kenya coordinates N9895164; E264258 and at an elevation of approximately 1770m amsl at the bottom level. The proposed dam site is located approximately 40Km upstream of Ndarugu 1 Dam.

The main advantage of Ndarugu 2 Dam over the Stony Athi and Ndarugu 1 dam sites is that the dam elevation has the potential to supply Mavoko area with water by gravity. The dam site is located approximately 60km from the Mavoko-Kitengela demand area and therefore the water transmission pipelines will be long in comparison with for Ndarugu 1. The dam location on a Survey of Kenya topographical map is shown in Figure 5.15.

Figure 5.15: Ndarugu 2 Dam Location Plan

The dam was first proposed for development in the Long Term Development Plan (Regional Studies) by Howard Humphreys (1986). The dam site though with a small storage compared with other dam sites then was considered worthy for assessment because of its close proximity to Nairobi City and demand centres to the North-East of the City. In order to augment the yield from the reservoir, yield assessments were also carried out with additional inflows provided by an 8m3/s capacity gravity diversion from Karimenu River which runs approximately 2km to the North. This option has however been taken over by the proposed implementation of Karimenu 2 Dam.

In the Feasibility Study and Master Plan for Developing New Water Sources for Nairobi and Satellite Towns carried out by egis/MIBP JV (2012), the development of Ndarugu 2 Dam was ruled out primarily because it would interfere with the yield at Ndarugu 1 Dam located at the confluence of



Ndarugu and Munyu rivers. Ndarugu 1 Dam was proposed for bulk water supply to Nairobi City and its environs.

Karimenu 2 dam site, a more feasible site was therefore proposed for development to supply the demands to the North-East of Nairobi City. Upstream of the Ndarugu 2 dam site at the edge of the forest, another potential dam site, Ndarugu 3 dam was identified for development. The supply area was not assigned to the dam site though it was thought that the dam could be used to regulate abstractions for the existing Gatundu run-of-river intake. If the dam site is developed, the greatest benefit will go Ndarugu 2 site since in addition to sustaining the flows for the Gatundu run-of-river intake the dam will also increase storage in the river system for use at Ndarugu 2 dam site.

The dam Catchment area is 67Km2 with the river originating from the Eastern Aberdares forest reserve. The dam catchment area is shown in Figure 5.16. The forested catchment area is protected, as it lies within the National Park and Forest Reserve. The importance of the forests to the catchment hydrology has long been recognised, and the Government is committed to the forest conservation. The indigenous forests clothing the mountains play an important role in maintaining dry season flow by stabilizing the soils, maintaining high infiltration rates and reducing surface water runoff in the wet season. Outside the Eastern Aberdares forest boundary comprises a zone of smallholder tea plantations on the slopes of the deeply incised valleys, mainly developed in the 1950s to 70s with further down comprising of coffee farms and subsistence crops.

Raw water from the dam will be gravitated to a treatment works approximately 3km downstream of the dam. After full treatment, treated water will be conveyed by gravity via a pipeline of approximate length 56km to a terminal reservoir at Syokimau. The terminal reservoir will be located close to the new Syokimau Railway Station at the Nairobi-Mavoko boundary and will need to be sited at an elevation above 1630masl. Water in the reservoir will be distributed by gravity to the demand centres at Syokimau/Mlolongo, Athi River and Kitengela.

The main existing water abstraction point upstream of the proposed dam site is a run-of-river intake for Gatundu urban and rural water supply system. Downstream there is a run-of-river intake for Juja town water supply. There are a number of other run-of-river intakes upstream and downstream of the dam site both for domestic water supply and irrigation. For the intakes located immediately downstream of the dam site, flows will be sustained by release of downstream compensation flows from the dam. For the intakes further downstream, the flows will be sustained by the intermediate catchment and spills from the dam.

Downstream of the proposed dam site, the river is joined by Mandune river approximately 5 Km downstream and Ruabura river approximately 10Km downstream. The Ndarugu river joins Athi river approximately 40 Km downstream at Munyu.

The dam optimal maximum height is proposed to be 45m with a reservoir storage volume of approximately 18 Million m3. The dam height-storage relationship is given in Figure 5.17. The impoundment area at maximum dam height is approximately 1.33Km2 (133Ha). The dam height-impoundment area relationship is given in Figure 5.18.



The net reliable yield based on 90% reliability based on annual occurrence of failures is 55,000m3/d (0.64m3/s). This is according to a detailed yield assessment by Howard Humphreys (1986). The yield assessment then has been held valid since no major changes in dam catchment have occurred since then. The storage-yield relationship is given in Table 5.2 and shown in Figure 5.19. The dam embankment is proposed to be a zoned earth fill of volume of approximately 0.97 Million m3 at maximum dam height. The dam height-embankment volume relationship is given in Figure 5.20 and the river channel profile at the proposed dam site is shown in Figure 5.21.

Table 5.2: Ndarugu 2 Dam Reservoir Yields Live Storage (S)

Mm3 S/MAI Yield (Y)

m3/s Y/MAI 45 1.15 0.90 0.72 33 0.84 0.82 0.66 28 0.71 0.76 0.61 23 0.59 0.70 0.57 15 0.38 0.59 0.47 10 0.26 0.48 0.39

Notes:- -Info Source: Howard Humphreys (1986) -Mean annual inflow (MAI) = 1.24m3/s (39.1 Mm3/year) -Yields are net of allowances for other water users and minimum compensation flows -MAI is net of releases for downstream users and upstream abstractions

Figure 5.16: Ndarugu 2 Dam Catchment Area



Figure 5.17: Ndarugu 2 Dam height-storage relationship

Figure 5.18: Ndarugu 2 Dam height-impoundment area relationship

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Figure 5.20: Ndarugu 2 Dam height-embankment volume relationship

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Figure 5.21: Ndarugu River Channel Profile at the Proposed Dam Site

5.4.4 Maragua 4 Dam and S. Mathioya Transfer Tunnel

The Maragua 4 Dam in combination with the South Mathioya Tunnel is proposed as a potential water source to supply both Nairobi and Mavoko-Kitengela area. The proposed source can supply water to the demand areas by gravity and is proposed as an alternative to Ndarugu 1 Dam which is a pumped scheme. The Maragua 4 dam site has been subjected to previous studies including the Feasibility Study and Master Plan for developing New Water Sources for Nairobi and Satellite Towns by egis/MIBP JV, (2012) and the Third Nairobi Water Supply Project – Regional Studies by Howard Humphreys (1986). The dam has previously been proposed for water supply to Nairobi only.

The proposed Maragua 1 Dam is located at the confluence of Maragua and Gikigie Rivers at approximately at Survey of Kenya coordinates N9875699; E295698 and at an elevation of approximately 1900m amsl at the lowest supply level. The dam site is located approximately 80km from the proposed demand area and therefore the water transmission pipelines will be long. The dam location on a Survey of Kenya topographical map is shown in Figure 5.22.

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Figure 5.22: Maragua 4 Dam and S. Mathioya Tunnel Location Plan

Upstream of the proposed dam site, the Northern Collector Tunnel (NCT) which is presently under construction will divert flows from Maragua and Gikigie Rivers into Thika Reservoir. The NCT will therefore significantly reduce the safe yield of the dam. It is on this regard that it was proposed that the South Mathioya Tunnel be constructed at the same time to increase the amount of inflows into the dam. The S. Mathioya Tunnel is proposed to divert flows from the S. Mathioya river into Thika Reservoir at Ndakaini with the extra flows being diverted into Maragua 4 dam. Thika Reservoir has the potential to serve the middle and high level areas of Nairobi City in comparison to the Maragua Reservoir which can only serve the low level areas. The construction of the NCT therefore significantly affects the viability of the Maragua 4 dam. The dam is however important in ensuring that storage in the system is increased to ensure supply security since the buffering capacity of Thika Reservoir will significantly be reduced by the NCT.

According to the Master Plan Study by egis/MIBP (2012), raw water from the dam will be conveyed by gravity to a treatment plant approximately 24km south of the dam at Ndunyu Chege. After full treatment, treated water will then be conveyed by gravity to Gigiri terminal reservoirs for distribution.

The dam direct catchment area is 72Km2 comprising of the Maragua and Gikigie River systems while the S. Mathioya Tunnel catchment area with an intake at S. Mathioya River is 31Km2. The catchment area for Maragua 4 dam and the S. Mathioya Tunnel abstraction point is shown on Figure 5.23. The river systems originate from the Eastern Aberdares forest reserve. The forested catchment area is protected, as it lies within the National Park and Forest Reserve. The importance of the forests to the catchment hydrology has long been recognised, and the Government is committed to the forest



conservation. The indigenous forests clothing the mountains play an important role in maintaining dry season flow by stabilizing the soils, maintaining high infiltration rates and reducing surface water runoff in the wet season. Outside the Eastern Aberdares forest boundary comprises a zone of smallholder tea plantations on the slopes of the deeply incised valleys, mainly developed in the 1950s to 70s with further down comprising of coffee farms and subsistence crops.

The dam embankment is proposed to be a zoned earth fill of volume of approximately 4.8 Million m3 at 75m height. The dam height can still be increased to have more reservoir storage volume, however increasing the dam height beyond 75m is believed not to be feasible. The dam height-storage relationship is given in Figure 5.24. The impoundment area at maximum dam height is approximately 1.17Km2 (117Ha). The dam height-impoundment area relationship is given in Figure 5.25.

The dam at an optimal height of 75m can give a net reliable yield of 80,000m3/d at a reservoir storage volume of 32 Million m3. The net reliable yield of the dam is based on 90% reliability and is net of the NCT transfers to the Thika Reservoir. The reservoir storage-yield relationship is given in Table 5.3 and is shown in Figure 5.26. The construction of the S. Mathioya Tunnel to Thika Dam is expected to give an additional yield of 52,000m3/d. Therefore the total yield from the construction of Maragua 4 Dam and the S. Mathioya Tunnel will be 132,000m3/d (egis/MIBP, 2012).

The dam embankment is proposed to be a zoned earth fill of volume of approximately 4.8 Million m3 at optimal dam height. The dam height-embankment volume relationship is given in Figure 5.27 and the river channel profile at the proposed dam site is shown in Figure 5.28.

Table 5.3: Maragua 4 Dam Reservoir Yields Live Storage (S)

Mm3 S/MAI Yield (Y)

m3/s Y/MAI 120 2.08 1.70 0.94 90 1.56 1.45 0.79 60 1.04 1.28 0.70 30 0.52 0.93 0.51

Notes:- -Info Source: egis/MIBP (2012) -Mean annual inflow (MAI) = 1.83m3/s (58 Mm3/year) -Yields are net of allowances for other water users and minimum compensation flows -MAI is net of releases for downstream users and upstream abstractions (Northern Collector Tunnel)



Figure 5.23: Maragua 4 Dam Catchment Area

Figure 5.24: Maragua 4 Dam height-storage relationship

0

10

20

30

40

50

60

70

80

- 5 10 15 20 25 30 35

Dam

Hei

ght,

m




Figure 5.25: Maragua 4 Dam height-impoundment area relationship

Figure 5.26: Maragua 4 Dam storage-yield relationship

0

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40

50

60

70

80

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Dam

Hei

ght,

m


y = 0.5334ln(x) - 0.898

0.8

0.9

1.0

1.1

1.2

1.3

1.4

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1.7

1.8

30 40 50 60 70 80 90 100 110 120

Rese

rvoi

r Yie

ld, m

3 /s




Figure 5.27: Maragua 4 Dam height-embankment volume relationship

Figure 5.28: Maragua River Channel Profile at the Proposed Dam Site

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ght,

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Embankment Volume, Mm3

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Spillway Level




6. GENERAL APPROACH TO THE DEVELOPMENT OF STRATEGIES

6.1 Introduction

The evaluation of potential water sources for Mavoko and Kitengela areas discovered the need for identifying a source to supply areas within Nairobi City which are currently underserved and which border the original target areas Mavoko and Kitengela. Both Mavoko-Kitengela and Nairobi Eastlands areas fall within a semi-arid region with no potential water sources for development and presently the areas are the most underserved with regard to water in the region. The areas also fall approximately within the same elevation (1600 – 1500m amsl) and therefore the convenience of considering both areas for water supply development.

In order to allow for flexibility in planning and implementation of the new water supply strategy for both areas, it has been found prudent to consider two strategies for development, namely:

• Alternative 1 – Mavoko-Kitengela Water Supply Strategy

• Alternative 2 – Nairobi and Mavoko-Kitengela Water Supply Strategy (Integrated Utilization)

The two alternatives are described further in the following section.

6.2 Strategies Analysed

Two alternatives for development of a new water source development for Nairobi and Mavoko have analysed:

• Alternative 1 – Mavoko Water Supply Strategy: The scope covers new water source development to meet the medium term water demand for Mavoko and Kitengela areas. The water supply undertaking will be by the Mavoko Water & Sewerage Company (MAVWASCO).

• Alternative 2 – Nairobi and Mavoko Water Supply Strategy (Integrated Plan): The scope covers new water source development to meet the medium term water demand for Nairobi with focus on the Eastlands areas, Mavoko and Kitengela areas. The water supply undertaking will be by the Nairobi City Water and Sewerage Company (NCWSC) as the water source operator and distributor to Nairobi City and also as a bulk water supplier to Mavoko Water & Sewerage Company (MAVWASCO) which will distribute water to Mavoko and Kitengela areas.

The basic philosophy used in the analysis of the two alternatives is as follows:

• Common new water source is considered

• The Northern Collector Tunnel Phase I which is under construction is assumed to be already in place with a net yield of 1.4m3/s (120,960m3/d) to Nairobi City

• The new water source to meet the medium term water demand for the areas



• The new water source to be in sync with the existing water supply master plans for the region

• All water supplies are to be treated to a common accepted standard for potable water supply

• The costing method for physical components to be the same

• Water distribution costs to demand areas to be considered to be essentially the same no matter the water source considered.



7. ALTERNATIVE 1 – DEVELOPMENT STRATEGY FOR WATER SUPPLY TO MAVOKO-KITENGELA

7.1 Preliminary Comparison of Schemes

7.1.1 Key Characteristics and Comparison

The scope of this Alternative involves identification of a new water source for development to meet the medium term water demand for Mavoko and Kitengela areas. The potential sources are Stony Athi, Ndarugu 1 (12.5m high Dam) and Ndarugu 2 dam sites and the key characteristics are given in Table 7.1. Table 7.2 lists the principle advantages and disadvantages associated with the water supply schemes based on the three dams.

Table 7.1: Key Characteristics of the Proposed Schemes Component Stony Athi Scheme Ndarugu 1 Scheme Ndarugu 2 Scheme Dam Location - Kiambu County Kiambu County Kiambu County

Catchment Area - 1,754 km2 190Km2 67Km2 Optimal Dam Height - 22.5m 12.5m (Phase I) 45m Optimal Reservoir

Capacity - 21.3Mm3 25Mm3 18Mm3

Impoundment Area (FSL) - 351Ha 450Ha 133Ha Reliable Yield - 60,000m3/d 60,000m3/d 55,000m3/d Full Supply Level - 1540masl 1455masl 1770masl Embankment Type & Vol.

at Optimal Height -

Zoned Earth fill with clay core (Vol=1.8Mm3)

Roller Compacted Concrete Vol=0.12Mm3)

Zoned Earth fill with clay core Vol=0.97Mm3)

Water Treatment

Type - Conventional Conventional Conventional Capacity - 55,000m3/d 55,000m3/d (Initial

Phase) 55,000m3/d

Water Transmission

Pumped / Gravity - Pumped Pumped Gravity Lengths - Approx. 15 Km Approx. 40 Km Approx. 70 Km



Table 7.2: Advantages and Disadvantages of Proposed Schemes Scheme Advantages Disadvantages

Stony Athi Dam • Close to the demand area

• No households and buildings to be

relocated

• High pumping costs for both raw water

and treated water

• Poor raw water quality

• Future pollution threats due to increased

urbanisation and industrial development

in the catchment area

• Likely to flood the Nairobi-Mombasa

railway line

• Poor raw water quality

• Poor security of supply from source

• Poor dam site with regard to dam

construction

Ndarugu 1 Dam • Potential for redevelopment to

increase storage and yield for supply

to other demand areas and for

multipurpose use

• Better raw water quality compared to

Stony Athi Dam

• Secure and reliable water source

• Good dam site with regard to dam

construction


and treated water

• Large area of land to be flooded when

compared to other schemes

• Far from demand area compared with

stony Athi Dam

• About 50 households to be relocated

Ndarugu 2 Dam • Gravity water supply

• Best raw water quality

• Minimal land acquisition

• Minimum maintenance and operation

costs

• Secure and reliable water source and

supply system


construction

• Far from demand area compared to

Ndarugu 1 and Stony Athi Dam Sites

• High potential agricultural land to be

flooded

• Households (about 20), school, coffee

factory and road to be relocated

Based on the above comparison, all schemes have unique advantages and disadvantages and therefore it is difficult to select the best scheme. However, if the advantages of the schemes were to be compared, Ndarugu 1 and 2 Schemes clearly outweigh the Stony Athi Scheme. Due to the difficulty in identification of the best scheme for adoption, a multicriteria comparison has been carried out to identify the scheme out of weighted criteria. Table 7.3 shows the multicriteria comparison and scores of the schemes.



Table 7.3: Multicriteria Comparison

Criteria Weighting Score (0 - Poor; 0.5 - Medium; 1 - Good) Ranking

Stony Athi Ndarugu 1 Ndarugu 2 Stony Athi Ndarugu 1 Ndarugu 2

1. Reliable Yield for abstraction

30% 0.5 0.8 0.5 15.0% 24.0% 15.0%

2. Security of Supply 20% 0.2 0.6 0.9 4.0% 12.0% 18.0%

3. Gravity Water Supply

15% 0.2 0.1 1 3.0% 1.5% 15.0%

4. Raw Water Quality 5% 0.2 0.9 1 1.0% 4.5% 5.0%

5. Site Suitability for Dam Construction

5% 0.1 0.9 0.8 0.5% 4.5% 4.0%

6. Distance from Water Demand Area

5% 1 0.7 0.3 5.0% 3.5% 1.5%

7. Resettlement and Land Losses

20% 0.8 0.1 0.5 16.0% 2.0% 10.0%

Total 100% 44.5% 52.0% 68.5%

Comparison of the three Schemes shows that Ndarugu 2 Scheme with 68.5% score is the best option for development to supply water to Mavoko and Kitengela areas. The second option is Ndarugu 1 Scheme at 52.0% while the Stony Athi Scheme takes the last position at 44.5%.

7.1.2 Recommendations and Next Steps

From the multicriteria analysis carried out, a scheme based on Ndarugu 2 Dam is the best option for development to supply water to Mavoko and Kitengela areas. The Scheme is followed by Ndarugu 1 Scheme. The comparison has been carried out at pre-feasibility level and therefore it cannot be confidently stated that Ndarugu 2 Scheme is the best option over Ndarugu 1 Scheme.

It is therefore recommended that the two schemes be subjected to additional studies and comparison in order to identify the most plausible scheme. The two schemes are studied further in the following sections in order to give an indication of the works and costs involved.

The sizing and cost basis for development of the schemes is a follows:

• The existing bulk supplies (NCWSC and Nolturesh) to Mavoko and Kitengela are to be discontinued and the new scheme will utilise the existing infrastructure where possible. The existing bulk supplies can be utilised as standby sources.

• The capacity for abstraction from either of the two schemes will be 55,000m3/d to meet the year 2027 water demand for Mavoko and Kitengela areas. Abstracting 55,000m3/d from Ndarugu 2 dam will mean abstracting the source capacity and therefore the scheme development will be in a single phase. Abstracting the same capacity from Ndarugu 1 Dam will mean abstracting about 28% of the total reservoir yield if the dam is constructed to full height. It is therefore proposed that the dam be constructed to 12.5m high dam in the initial phase which will meet the desired abstraction capacity of 55,000m3/d.

• The supply capacities to the demand centres of Syokimau / Mlolongo, Athi River and Kitengela to meet year 2027 water demand will be as follows.



Town / Zone Year 2027 Water Demand m3/d

Syokimau / Mlolongo - 23,400 Athi River - 25,300 Kitengela - 6,300 Total - 55,000

• Feasible water transmission routes have been established from the 1:50,000 topographical maps published by the Survey of Kenya. The water transmission will involve delivery of treated water to a common terminal reservoir at Syokimau. The terminal reservoir will be located close to the new Syokimau Railway Station at the Nairobi-Mavoko boundary and will need to be sited at an elevation above 1630masl.

• The selection of a location for the water treatment plant and the general alignment of the transmission mains have been evaluated based on the following criteria:

- Where possible, the source to utilise its elevation to convey water to the demand areas by gravity,

- Water Transmission pipelines to follow existing road reserves where possible,

- The treatment plant should be easily accessible for operational purposes particularly chemical deliveries,

• The Distribution System for the two schemes will be similar and will involve gravity distribution from the Syokimau terminal reservoir. The terminal reservoir location has the elevation to command the Syokimau/Mlolongo, Athi River and Kitengela demand centres by gravity.

7.2 Ndarugu 1 Dam Scheme Components

7.2.1 Introduction

The proposed Ndarugu 1 Water Supply Scheme involves raw water and treated water transmission through pumping. Raw water transmission will involve pumping of water from the dam to a proposed water treatment site located approximately 1km from the dam. The treated water transmission will involve pumping of water from the proposed treatment site to Syokimau terminal reservoir via a pipeline of 40Km approximate. Water in the Syokimau terminal reservoir will be distributed by gravity to the demand centres at Syokimau/Mlolongo, Athi River and Kitengela.

In brief, the proposed Ndarugu 1 Scheme will involve construction of the following works:

• Ndarugu 1 Dam (12.5m high Dam) on Ndarugu River approx. 1Km upstream of the confluence with Munyu River

• Raw Water Pumping Station at Ndarugu 1 Dam Outlet Works

• Raw Water Pumping Main of approximate length of 1Km from Ndarugu 1 Dam to a Proposed Water Treatment Site



• Water Treatment Plant

• Treated Water Pumping Station at the proposed Water Plant Site

• Treated Water Pumping Main of approximate length of 30Km from Water Treatment Plant to Syokimau Tanks

• Utawala Pumping Station

• Treated Water Pumping Main of approximate length of 14.5Km from the Utawala Pumping Station to Syokimau Tanks

• Utawala, Syokimau and Mavoko Tanks

• Distribution Mains from Syokimau Terminal Reservoir to Syokimau/Mlolongo, Athi River and Kitengela areas

A layout plan showing the proposed Ndarugu 1 Water Supply Scheme to Mavoko-Kitengela area and the existing water transmission systems is given in Figure 7.1.

7.2.2 Dam Characteristics

The dam is proposed to be 12.5m high Roller Compacted Concrete Dam with a reservoir storage volume of approximately 25 Million m3. The impoundment area at maximum dam height is approximately 4.5 Km2 (450 Ha).

The construction of the Ndarugu 1 Dam is expected to involve works given in Table 7.4 below. Table 7.4: Estimated Works for Ndarugu 1 Dam

Item Unit Quantity Soft Excavation m3 80,000 Roller Compacted Concrete m3 120,000 Curtain Grouting m 600 Draw-off works, River Diversion among to the works



Figure 7.1: Layout Plan – Ndarugu 1 Scheme



7.2.3 Raw Water Transmission

The raw water transmission from Ndarugu 1 Dam to the water treatment plant will comprise of Raw Water Pumping Station and a DN900 Pumping Main. The raw water pumping station will be sited at the dam outlet works at the foot of the dam. The pumping station will include 100% stand-by capacity and the pump characteristics will be as follows:

• Pumping rate - 2,292 m3/hr • Head on Pumps - 43.1 m • Power - 431 Kw

The hydraulics constraints of the raw water transmission system are summarised in Table 7.5 below.

Table 7.5: Raw Water Transmission – Hydraulic Constraints and Optimisation Parameters Ndarugu 1 Dam Water Treatment Plant

Approximate Ground Elevation - 1425 masl 1465 masl

Static Lift - 40 m

Approximate Distance - 1.0 Km

Design Capacity - 55,000 m3/d

Pipeline Diameter - 900 mm

Nominal Pressure Rating - 10 bar

7.2.4 Water Treatment

The Water Treatment Facilities will cater for a raw water flow of 55,000m3/d (0.64m3/s) in the initial phase. This will cater for year 2027 water demand for Mavoko-Kitengela area. The next phase for development will be carried out to cater for the water demand for Nairobi City as envisaged in the Nairobi Water Supply Master Plan (egis/MIBP, 2012).

The water treatment process and capacity will therefore be similar for both Ndarugu 1 and 2 schemes. Details of the water treatment process are given in Chapter 8 to avoid repetitive reporting.

Generally, the water treatment process will comprise of the following:

1. Cascade Aeration

2. Pre-chlorination

3. Dosing with Sodium Carbonate (Soda Ash), to adjust the pH

4. Dosing with aluminium sulphate (alum), as coagulant aid,

5. Dosing with Polyelectrolyte, as coagulant aid (when necessary)

6. Flocculation

7. Horizontal Flow Clarification

8. Rapid Gravity Filtration



9. Disinfection with Chlorine

10. Dosing with Sodium Carbonate (Soda Ash), to adjust the pH for corrosion control

11. Sludge Drying Beds – To receive Sludge from Clarifiers

12. Backwash Water Lagoons – Good Environmental Practice to recycle backwash water from the filters.

7.2.5 Treated Water Transmission

The treated water transmission will comprise of two-stage pumping. The first stage will be from Ndarugu 1 Treatment Plant to a Proposed Tank at Utawala. The second stage will be from the Proposed Utawala Tank to the Proposed Syokimau Tank. The two-stage pumping has been adopted primarily because of the following reasons:

• To reduce the head on pumps to optimal pumping heads

• To reduce the transient pressures on the pumping main so as to have a lower class of pipe in relation to pipeline pressure rating

• Part of the water from Ndarugu 1 Scheme can be supplied to Nairobi Eastern areas in the initial years since the Mavoko water demand will be less than the supply capacity during this period

• Matches well with the long term plan for water supply development for Nairobi and Mavoko areas which includes full development of the Ndarugu 1 Scheme to the maximum supply capacity of about 200,000m3/d

The proposed two pipeline sections for the treated water transmission are described below.

i) Treatment Plant to Utawala Tank The treated water transmission from the proposed water treatment plant to Utawala Tank will comprise of Treated Water Pumping Station and a DN900 Pumping Main of approximate length, 30Km. The treated water pumping station will be sited within the water treatment site and will include 100% stand-by capacity. The pumps characteristics will be as follows:

• Pumping rate - 2,292 m3/hr • Head on Pumps - 143 m • Power - 1,510 Kw

The hydraulics constraints of the raw water transmission system are summarised in Table 7.6 below. The raw water transmission route ground and hydraulic profile is given in Figure 7.2.



Table 7.6: Treated Water Transmission – Hydraulic Constraints and Optimisation Parameters Water Treatment Plant Utawala Tank


Static Lift - 100 m

Approximate Distance - 30 Km




A preliminary pipeline route has been identified for conceptual design purposes. The most convenient pipeline route will be determined at the detailed design stage to avoid disruption of private property and farmlands and also to avoid engineering difficulties. Generally, the proposed pipeline will traverse across developed areas of Ruai and Utawala.

The pipeline has been routed to cross Nairobi River after the confluence with Ruiru and Thiririka rivers. The pipeline will then run along the southern edge of Nairobi River close to Ruai sewage works before joining the Eastern Bypass road to Utawala.

Figure 7.2: Transmission Route Profile - Water Treatment Plant to Utawala Tank

ii) Utawala Tank to Syokimau Tank The treated water transmission from the proposed Utawala Tank to Syokimau Tank will comprise of Treated Water Pumping Station and a DN800 Pumping Main of approximate length, 14.5Km. The

1420

1440

1460

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1620

0 5 10 15 20 25 30

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atio

n m

asl

Distance, Km

Ground Profile

Hydraulic Gradient Line

Ndarugu Pumping Station

Nairobi River crossing

Utawala Reservoir



treated water pumping station will be sited within Utawala Tank site and will include 100% stand-by capacity. The pumps characteristics will be as follows:

• Pumping rate - 2,292 m3/hr • Head on Pumps - 91 m • Power - 958 Kw

The hydraulics constraints of the water transmission pipeline are summarised in Table 7.7 below. The water transmission route ground and hydraulic profile is given in Figure 7.4.

Table 7.7: Treated Water Transmission – Hydraulic Constraints and Optimisation Parameters Utawala Tank Syokimau Tank


Static Lift - 70 m





The pipeline is proposed to cut across Utawala after which it will run along the South-Eastern boundary of Jomo Kenyatta International Airport along Syokimau-Airport Road. The pipeline then follows the road up to Mombasa Road and to the proposed Syokimau Tank site.

Figure 7.3: Transmission Route Profile – Utawala Tank to Syokimau Tank

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1660

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Distance, Km

Ground Profile


Utawala Pumping Station

SyokimauReservoir



7.3 Ndarugu 2 Dam Scheme Components

7.3.1 Introduction

The proposed Ndarugu 2 Water Supply Scheme utilises the elevation of the source to transmit raw water and treated water by gravity. The raw water will be gravitated to a treatment plant approximately 3km downstream of the dam while treated water will be gravitated via approximately 56km long main to a terminal reservoir located at Syokimau. Water in the reservoir will be distributed by gravity to the demand centres at Syokimau/Mlolongo, Athi River and Kitengela.


• Ndarugu 2 Dam at the confluence of Ndarugu and Githobokoni rivers

• Raw Water Gravity Main of approximate length of 3Km from Ndarugu 2 Dam to a Proposed Water Treatment Plant

• Water Treatment Plant

• Treated Water Gravity Main of approximate length of 56Km from the Treatment Plant to Syokimau Tank

• Syokimau and Mavoko Tanks

• Distribution Mains from Syokimau Reservoir to Syokimau/Mlolongo, Athi River and Kitengela areas

A layout plan showing the proposed Ndarugu 2 water supply scheme to Mavoko-Kitengela area and the existing water transmission systems is given in Figure 7.3.

7.3.2 Dam Characteristics Ndarugu 2 Dam is proposed to be an earth embankment dam, 45m high with an impoundment area of 133ha at spillway level. The estimated quantities for the construction of Ndarugu 2 Dam are given in Table 7.8. Table 7.8: Estimated Quantities for Ndarugu 2 Dam

Item Unit Quantity Soft Excavation m3 100,000 Compacted Fill m3 970,000 Curtain Grouting m 800 Draw-off works, River diversion, Spillway among other works



Figure 7.4: Layout Plan Showing the Proposed Ndarugu 2 Water Supply Scheme




An assessment of the available options for water transmission has been carried out. The assessment has demonstrated that the most feasible option for raw water transmission will involve gravitating water from Ndarugu 2 Dam and treating the water approximately 3Km downstream of the dam close to Gatei Market. The scour level at the dam is estimated to be 1760masl with the lowest supply level taken as 1770masl. The raw water inlet level to the Treatment Plant has been taken to be 1755masl.

The hydraulics constraints of the raw water transmission system are summarised in Table 7.9 below. The raw water transmission route hydraulic profile is given in Figure 7.4.

Table 7.9: Raw Water Transmission – Hydraulic Constraints and Optimisation Parameters Ndarugu 2 Dam Water Treatment Plant


Approximate Hydraulic Elevation - 1770 masl (LSL) 1760 masl





The full length of raw water pipeline route follows Ndarugu river up to the Water Treatment Plant. The pipeline length follows vegetated riparian land, coffee farms and other subsistence farms.

Figure 7.5: Transmission Route Ground Profile - Ndarugu 2 Dam to Water Treatment Plant

1720

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1780

0.0 0.5 1.0 1.5 2.0 2.5 3.0

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asl

Distance, Km

Ground Profile

Hydraulic Gradient Line (HGL)

Ndarugu 2 Dam Offtake

Treatment Works Inlet




The Water Treatment Facilities will cater for a raw water flow of 55,000m3/d (0.64m3/s). This represents the yield of Ndarugu 2 Dam at the optimal dam height.

The water treatment process and capacity will be similar for both Ndarugu 1 and 2 schemes and therefore details of the water treatment process are given in Chapter 8 to avoid repetitive reporting.


1. Cascade Aeration

2. Pre-chlorination




6. Flocculation








The Treated Water Transmission will involve transfer of water from the Water Treatment Plant to a Main Reservoir at Syokimau in the Nairobi-Mavoko border close to the Syokimau Railway Station. The service reservoir location has the elevation to command the Syokimau/Mlolongo, Athi River and Kitengela demand centres by gravity. The Service Reservoir will need to be located at an elevation above 1630masl.

The treated water pipeline will exit the treatment plant along Ndarugu river and then exit the valley approximately 3Km downstream close to Wamwangi. The pipeline will then cross Ruabura and Thiririka rivers at the downstream side of Gatundu town, cross Kenyatta road close to Kimunyu then cut through a coffee estate to Mugutha road. A wayleave will need to be acquired for this section of approximately 14Km long.

The pipeline will then follow Mugutha road to Thika highway where it will follow the highway through Ruiru town to the Eastern Bypass road intersection. The pipeline will follow the Eastern Bypass all through to Utawala from where it will exit through the road serving Githunguri Estate at the border to the Airport Land where it will turn west to join the Syokimau-Airport Road to



Mombasa Road and to the Syokimau Reservoir. The pipeline for this section is approximately 42 Km long and will mainly follow existing road reserves and therefore minimal wayleave acquisition will be required. An option for this section exists to follow the Eastern Bypass to Airport North road then to Mombasa road and to Syokimau reservoir.

A preliminary transmission route has been identified for conceptual design purposes. The most convenient transmission route needs to be determined at the detailed design stage to avoid disruption of private property and farmlands and also to avoid engineering difficulties.

The hydraulic constraints on the water transmission route are given in Table 7.10 below. The transmission route hydraulic profile is given in Figure 7.6.

Table 7.10: Treated Water Transmission to Syokimau – Hydraulic Constraints and Optimisation

Parameter Water Treatment Plant Syokimau Reservoir


Approximate Hydraulic Minimum Elevation - 1740 masl 1640 masl





Figure 7.6: Transmission Route Profile - Water Treatment Plant to Syokimau Reservoir

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1700

1750

0 10 20 30 40 50 60

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atio

n, m

asl

Distance, Km

Ground Profile

Hydraulic Gradient Line (HGL)

Treatment Works

Syokimau Reservoir



7.4 Cost Estimates and Economic Comparison

7.4.1 Introduction The costing criteria and estimates for the various components in Ndarugu 1 and Ndarugu 2 schemes are given in the following sections. A summary of costs for the two schemes is given in section 10.8. Additional costs to cater for preliminaries and general costs (15%), engineering services (7%), and physical contingencies (10%) have been added in the summary. All costs are exclusive of duties and VAT taxes.

7.4.2 Dam Construction

i) Ndarugu 1 Dam Ndarugu 1 Dam is proposed to be a 35m high Roller Compacted Concrete Dam. The impoundment area is estimated to be 1450ha at spillway level. The estimated quantities and costs associated with the construction of Ndarugu 1 Dam are given in Table 7.11. Table 7.11: Estimated Quantities and Costs for Ndarugu 1 Dam Item Unit Quantity Rate

Kshs Amount

Kshs Soft Excavation m3 80,000 900 72,000,000 Roller Compacted Concrete m3 120,000 10,000 1,200,000,000 Curtain Grouting m 600 450,000 270,000,000 Draw-off works - sum - 300,000,000 River diversion - sum - 400,000,000 Other works - sum - 400,000,000

Total 3,858,000,000

ii) Ndarugu 2 Dam Ndarugu 2 Dam is proposed to be an earth embankment dam, 45m high with an impoundment area of 133ha at spillway level. The estimated quantities and costs associated with the construction of Ndarugu 2 Dam are given in Table 7.12. Table 7.12: Estimated Quantities and Costs for Ndarugu 2 Dam Item Unit Quantity Rate

Kshs Amount

Kshs Soft Excavation m3 100,000 900 90,000,000 Compacted Fill m3 970,000 1,950 1,891,500,000 Curtain Grouting m 800 450,000 360,000,000 Draw-off works - sum - 350,000,000 River diversion - sum - 650,000,000 Spillway - sum - 1,250,000,000 Other works - sum - 600,000,000

Total 5,191,500,000



7.4.3 Water Treatment Plant A relationship between capital cost and treatment plant design capacity has been derived from recent and ongoing water supply projects. The proposed water treatment plant of capacity 55,000m3/d has been estimated to cost approximately Kshs. 1,580,000,000.

7.4.4 Pumping Stations Ndarugu 1 Scheme involves raw and treated water pumping. Three pumping stations are required at Ndarugu Dam (Raw Water Pumping Station), Treatment Plant (Treated Water Pumping Station – Stage I) and Utawala Reservoir (Treated Water Pumping Station – Stage II). Ndarugu 2 scheme is purely a gravity scheme and therefore no pumping station is required. Pumping Stations have been sized to include 100% stand-by capacity. Costs for Electrical and Mechanical Plant have been build-up from budget quotations as well rates from similar ongoing and recently completed projects. The pump costs are assumed to include the cost of pipework and necessary electricity supply. The costs for Ndarugu 1 Pumping Stations are given below: Ndarugu 1 Scheme Pumping Stations: • Raw Water Pumping Station - Kshs. 70,000,000 • Treated Water Pumping Station – Stage I - Kshs. 80,000,000 • Treated Water Pumping Station – Stage II - Kshs. 80,000,000 • Total - Kshs. 230,000,000

Costs for pumping have been estimated based on the lift (static + friction) and the required pump discharge rate with the electricity requirement based on a pump efficiency of 70% and power factor of 85%. Annual power costs have been estimated using a rate of Kshs16/Kwh corresponding to the current industrial rate for electricity provided by Kenya Power Limited Company.

7.4.5 Main Water Transmission and Distribution Pipelines The costs for water transmission and distribution pipelines are based on current unit rates build up from local steel manufacturers quotations. All rates are inclusive of supply of pipes and fittings, transporting to site, excavation, laying, jointing, testing and backfilling. The rates are average rates taking into consideration of terrain, urban and sub-urban construction.

i) Ndarugu 1 Scheme Main Water Transmission Pipelines Table 7.13 gives a summary of pipe sizes, lengths and associated costs required for Ndarugu 1 scheme water transmission.

Table 7.13: Estimated Costs for Water Transmission Pipelines – Ndarugu 1 Scheme Nominal Diameter

(mm) Length

(m) Nominal

Pressure Rating Cost per meter

(Kshs) Amount (Kshs)

900 1,000 NP10 45,000 35,000,000



900 44,500 NP16 45,000 2,002,500,000 Total Cost 2,037,500,000

ii) Ndarugu 2 Scheme Main Water Transmission Pipelines Table 7.14 gives a summary of pipe sizes, lengths and associated costs required for Ndarugu 2 scheme water transmission. Table 7.14: Estimated Costs for Water Transmission Pipelines – Ndarugu 2 Scheme

Nominal Diameter (mm)

Length (m)

Nominal Pressure Rating

Cost per meter (Kshs)

Amount (Kshs)

900 2,800 NP10 35,000 98,000,000 900 56,000 NP25 52,000 2,912,000,000

Total Cost 3,010,000,000

iii) Ndarugu 1 and 2 Schemes Water Distribution Pipelines Water distribution is similar for both Ndarugu 1 and 2 Schemes. Table 7.15 gives a summary of pipe sizes, lengths required and associated costs for proposed water distribution pipelines. Table 7.15: Estimated Quantities and Costs for Water Distribution Pipelines


Length (m)



Amount (Kshs)

700 4,100 NP16 34,000 139,400,000 500 12,700 NP16 26,000 330,200,000 400 1,700 NP16 22,000 37,400,000

Total Cost 507,000,000

7.4.6 Service Reservoirs

i) Ndarugu 1 Scheme Storage Reservoirs For Ndarugu 1 Scheme, it is proposed that 5,000m3 storage be provided at Utawala Pumping Station. For supply to Mavoko and Kitengela, it is proposed that 20,000m3 of storage be provided at Syokimau and an additional 5,000m3 at the existing Mavoko tanks site. The storage tanks are assumed to be reinforced concrete tanks and to be partially buried. The costs for provision of storage in the two sites have been derived from recent and ongoing water supply projects. The associated costs for reservoir construction are given in Table 7.16. Table 7.16: Ndarugu 1 Service Reservoir Costs

Reservoir Site Proposed Capacity (m3) Amount (Kshs) Utawala 5,000 50,000,000 Syokimau 20,000 120,000,000 Mavoko 5,000 50,000,000 Total 25,000 220,000,000

ii) Ndarugu 2 Scheme Storage Reservoirs For Ndarugu 2 Scheme, it is proposed that 20,000m3 of storage be provided at Syokimau Reservoir site and an additional 5,000m3 at the existing Mavoko tanks site. The storage tanks are assumed to



be reinforced concrete tanks and to be partially buried. The costs for provision of storage in the two sites have been derived from recent and ongoing water supply projects. The associated costs for reservoir construction are given in Table 7.17. Table 7.17: Ndarugu 2 Service Reservoir Costs

Reservoir Site Proposed Capacity (m3) Amount (Kshs) Syokimau 20,000 120,000,000 Mavoko 5,000 50,000,000 Total 25,000 170,000,000

7.4.7 Summary of Costs A summary of costs for the proposed project components for the two schemes is given in Table 7.18. Preliminaries and general costs (15%), engineering services (7%), and physical contingencies (10%) have been added in the summary. Table 7.18: Summary of Costs

Item Amount (Kshs) Ndarugu 1 Scheme Ndarugu 2 Scheme

1. Dam Construction - 2,642,000,000 5,191,500,000

2. Water Treatment Plants - 1,580,000,000 1,580,000,000

3. Pumping Stations - 230,000,000 -

4. Main Water Transmission Pipelines - 2,037,500,000 3,010,000,000

5. Distribution Pipelines - 507,000,000 507,000,000

6. Service Reservoirs - 220,000,000 170,000,000

Sub Total 1 - 7,216,500,000 10,458,500,000

Preliminary and General Costs (15% of Sub Total 1) 1,082,475,000 1,568,775,000

Sub Total 2 - 8,298,975,000 12,027,275,000 Physical Contingencies (10% of Sub Total 2) 829,897,500 1,202,727,500

Sub Total 3 - 9,128,872,500 13,230,002,500 Engineering Costs (7% of Sub Total 1) 639,021,075 926,100,175

GRAND TOTAL COST - 9,767,893,575 14,156,102,675 * All costs are exclusive of duties and VAT taxes

7.4.8 Economic Comparison of Schemes The economic parameters and results derived from economic analysis are summarized in Tables 7.19, 7.20, 7.21, 7.22 and 7.23. To obtain Present Value costs, discounting has been carried out for 8%, 10% and 12% discount rates over a period of 30 years.



Table 7.19: Capital Costs

Component Ndarugu 1 Ndarugu 2

Civil Works 6,986,500,000 10,458,500,000 Pumps and Motors 230,000,000 -

Total Cost (Kshs.) 7,216,500,000 10,458,500,000 Table 7.20: Annual Operation and Maintenance Costs

Component Ndarugu 1 Ndarugu 2

Maintenance Costs* 81,365,000 104,585,000

Electricity Costs 414,251,328 -

Other Operational Costs** 139,730,000 209,170,000

Total Cost (Kshs.) 495,616,328 104,585,000 *Based on 1% of Civil Works and 5% of Pump and Motors Costs **Based on 2% of Civil Works Costs

Table 7.21: Cost per Unit Yield

Scheme Yield (m3/d) Capital Cost per Unit Yield

(Kshs/m3/d) O&M Costs Per Unit Yield*

(Kshs/m3/d)

Ndarugu 1 55,000 131,209 9,011

Ndarugu 2 55,000 190,155 1,902 *Operation and Maintenance Costs

Table7.22: Discounted Costs over a Period of 30 year – Present Value

Scheme

Discount Rate 8% 10% 12%

Ndarugu 1 Kshs. 14,522,261,331 Kshs. 13,310,407,233 Kshs. 12,424,262,184

Ndarugu 2 Kshs. 13,990,685,813 Kshs. 13,432,118,331 Kshs. 13,001,731,028

Table 7.23: Dynamic Prime Costs of Schemes

Scheme

Discount Rate 8% 10% 12%

Ndarugu 1 264,041 Kshs/m3/d 242,007 Kshs/m3/d 225,896 Kshs/m3/d

Ndarugu 2 254,376 Kshs/m3/d 244,220 Kshs/m3/d 236,395 Kshs/m3/d

7.4.9 Land Acquisitions and Compensation

i) Ndarugu 1 Dam Scheme The Ndarugu 1 Dam impoundment area is estimated to be 450ha at reservoir spillway level. It is estimated that about 500ha of land will need to be acquired. About 50 households will also be displaced since they fall within the reservoir area. The dam impoundment area is shown on google imagery in Figure 7.7.

A permanent wayleave will also be required for both raw water and treated water pipelines. It is assumed that the wayleave will be required for the full pipeline lengths since there are no well-defined roads to follow. A 7m wide permanent wayleave is proposed for a length of about 40Km.



The land acquisition and compensation budget costs associated with the construction of Ndarugu 1 water supply scheme are given in Table 7.24. Table 7.24: Land Acquisition and Compensation Costs

Item Unit Quantity Rate (Kshs)

Amount (Kshs)

1. Ndarugu 1 Dam Land acquisition

‐ Land only ha 500 5,000,000 2,500,000,000 ‐ Crops compensation ha 300 200,000 60,000,000 ‐ Households and infrastructure - sum - 150,000,000

Sub-Total 2,710,000,000 2. Main Water Transmission and Distribution Pipelines

‐ Land only ha 30 5,000,000 150,000,000 ‐ Crops compensation ha 10 200,000 1,000,000 ‐ Infrastructure - sum - 50,000,000

Sub-Total 201,000,000 3. Service Reservoirs

‐ Land only ha 0.8 - 40,000,000 Sub-Total 40,000,000

Total 2,951,000,000 The land acquisition and compensation costs for all the sites to be acquired under the proposed Ndarugu 1 water supply scheme are estimated to be Kshs. 2,951,000,000.



Figure 7.7: Ndarugu 1 Dam Impoundment Area



ii) Ndarugu 2 Dam Scheme The Ndarugu 2 Dam impoundment area is estimated to be 133ha at reservoir spillway level. It is assumed that about 150ha of land will need to be acquired. The dam impoundment area on a google imagery is shown in Figure 7.7. The following households and developments are likely to be displaced by the dam embankment and impoundment:

• Approximately 20No Households • Primary School • Coffee Factory • Kibauini-Hawatathi road and bridge among other tracks

A permanent wayleave will also be required for both raw water and treated water pipelines. It is assumed that the wayleave will be required for approximately 14Km length of pipeline. A 7m permanent wayleave is proposed to be acquired where the pipeline is not passing along road reserves.

The land acquisition and compensation budget costs associated with the construction of Ndarugu 2 water supply scheme are given in Table 7.25.




Table 7.25: Land Acquisition and Compensation Costs Item Unit Quantity Rate

(Kshs) Amount (Kshs)


‐ Land only ha 150 1,500,000 225,000,000 ‐ Crops compensation ha 120 200,000 24,000,000 ‐ Households and infrastructure - sum - 200,000,000

Sub-Total 449,000,000 5. Main Water Transmission and Distribution Pipelines ‐ Land only ha 20 2,000,000 40,000,000 ‐ Crops compensation ha 15 200,000 3,000,000 ‐ Infrastructure - sum - 20,000,000

Sub-Total 63,000,000 6. Service Reservoirs ‐ Land only ha 0.8 - 40,000,000

Sub-Total 40,000,000 Total 552,000,000

The land acquisition and compensation costs for all the sites to be acquired under the proposed Ndarugu 2 water supply scheme are estimated to be Kshs. 552,000,000.

7.4.10 Conclusions and Recommendations The proposed works under the Ndarugu 1 water supply scheme are estimated to cost Kshs. 7,216,500,000 excluding Preliminary and General Costs, Physical Contingencies Costs and Engineering Costs and Kshs. 9,767,893,575 including Preliminary and General Costs, Physical Contingencies Costs and Engineering Costs. The proposed works under the Ndarugu 2 water supply scheme are estimated to cost Kshs. 10,458,500,000 excluding Contingencies, Engineering and Supervision Costs and Kshs. 14,156,102,675 including Contingencies and Engineering and Supervision Costs. The Present Value and Dynamic Prime Costs for Ndarugu 1 scheme are lower at 10% and 12% Discount Rates and higher at 8% Discount Rate. Ndarugu 1 Scheme is therefore favored economically at higher Discount Rates where the effects of pumping costs are reduced. This is based on Capital Investment Cost and Discounted Operation and Maintenance Costs over a period of 30years. However, examination of the costs for the two schemes shows that there is little to choose between the options in economic terms. Realistically, the degree of confidence placed upon the cost estimates is wider than the range between the minimum and maximum costs and therefore it is suggested that the preferred option be selected on grounds other than purely economic criteria.



The principle advantages and disadvantages associated with the two schemes are as listed Table 7.26. Table 7.26: Principle Advantages and Disadvantages of Ndarugu 1 and 2 Schemes

Scheme Advantages Disadvantages

Ndarugu 1 Dam • Potential for the yield to be cheaply

increased by raising the dam height

thus lowering the cost per unit yield

of the scheme

• Potential to supply other demand

areas (Nairobi City) with about

150,000m3/d if dam height raised to

maximum level


construction


and treated water

• Large area of land to be flooded when

compared to Ndarugu 2 scheme

• About 50 households to be relocated

Ndarugu 2 Dam • Gravity water supply thus minimum

maintenance and operation costs

resulting to security of supply

• Good raw water quality


• Far from demand area


flooded

• Households (about 20), school, coffee

factory and road to be relocated

• Possible objection of the scheme by

downstream water users and local

residents

Based on the economic and non-economic factors considered, Ndarugu 1 Water Supply Scheme is recommended for development under Alternative 1 to serve Mavoko and Kitengela areas.



8. ALTERNATIVE 2 – DEVELOPMENT STRATEGY FOR WATER SUPPLY TO NAIROBI AND MAVOKO-KITENGELA (INTEGRATED PLAN)

8.1 Preliminary Comparison of Schemes

8.1.1 Key Characteristics and Comparison

The scope of this Alternative involves identification of a new water resource for development to meet the medium term water demand for Nairobi with focus on the Eastlands areas, Mavoko and Kitengela areas. The potential water sources are Ndarugu 1 dam and Maragua 4 dam together with the S. Mathioya Transfer Tunnel. The key characteristics of the two sources are given in Table 8.1. Table 8.2 lists the principle advantages and disadvantages associated with the water supply schemes based on the two dams.

Table 8.1: Key Characteristics of the Proposed Schemes Component Ndarugu 1 Scheme Maragua 4 Scheme Dam Location - Kiambu County Murang’a County

Catchment Area - 190Km2 72Km2 Optimal Dam Height - 35m 75m Optimal Reservoir Capacity - 225Mm3 32Mm3 Impoundment Area (FSL) - 1450Ha 117Ha Reliable Yield - 199,000m3/d 80,000m3/d incl. NCT & S.

Mathioya Tunnel Full Supply Level - 1455masl 1980masl Embankment Type & Vol. at

Optimal Height -

Roller Compacted Concrete Vol=0.4Mm3)

Zoned Earth fill with clay core Vol=4.82Mm3)

Tunnel Location - NA Murang’a County Tunnel Intake Catchment Area - NA 31Km2 Tunnel Length and Diameter - NA 3Km long, 3.0m diameter Reliable Yield - NA 52,000m3/d at Thika Dam

Water Treatment

Type - Conventional Conventional Capacity - 199,000m3/d 132,000m3/d

Water Transmission

Pumped / Gravity - Pumped Gravity Lengths - Approx. 30 Km Approx. 100 Km

NA – Not Applicable



Table 8.2: Advantages and Disadvantages of Proposed Schemes Scheme Advantages Disadvantages

Ndarugu 1 • Very high storage and yield with

potential to supply other demand

areas and for multipurpose use

• Better raw water quality compared to

Stony Athi Dam

• Secure and reliable water source


construction

• Closer to demand area compared to

Maragua 4

• Pumped supply for both raw water and

treated water

• Large area of land to be flooded

• Extensive land acquisition - Large

developed area of land to acquired

• Many households to be relocated (about

200)

• Rapid development in the reservoir area

Maragua 4 • Gravity water supply




costs

• Far from demand area

• Includes the construction of a Tunnel to

improve the viability of the Scheme

• Poor site for dam construction when

compared to Ndarugu 1


flooded

• About 20 No. households to be relocated

Based on the above comparison, all schemes have unique advantages and disadvantages and therefore it is difficult to select the best scheme. Due to the difficulty in identification of the best scheme for adoption, a multicriteria comparison has been carried out to identify the scheme out of weighted criteria. Table 8.3 shows the multicriteria comparison and scores of the schemes.

Table 8.3: Multicriteria Comparison

Criteria Weighting Score (0 - Poor; 0.5 - Medium; 1 - Good) Ranking

Ndarugu 1 Maragua 4 Ndarugu 1 Maragua 4 Reliable Yield for abstraction

30% 0.9 0.5 27.0% 15.0%

Security of Supply relating to Reservoir Capacity

20% 1 0.6 20.0% 12.0%

Gravity Water Supply

10% 0 1 0.0% 10.0%

Raw Water Quality 5% 0.8 1 4.0% 5.0%

Site Suitability for Dam Construction

5% 0.9 0.6 4.5% 3.0%

Distance from Water Demand Area

10% 0.8 0.1 8.0% 1.0%

Resettlement and Land Losses

20% 0.1 0.5 2.0% 10.0%

Total 100%

65.5% 56.0%



Comparison of the two Schemes shows that Ndarugu 1 Scheme with 65.5% score is the best option for development to supply water to Nairobi and Mavoko-Kitengela area. The Maragua 4 Scheme scores 56.0%.

8.1.2 Recommendations and Next Steps

From the multicriteria analysis carried out, a scheme based on Ndarugu 1 Dam is the best option for development to supply water to Nairobi Eastlands and Mavoko-Kitengela area. The comparison has been carried out at pre-feasibility level and therefore it cannot be confidently stated that Ndarugu 1 Scheme is the best option over Maragua 4 Scheme.

It is therefore recommended that the two schemes be subjected to additional studies and comparison in order to identify the most plausible scheme. The two schemes are studied further in the following sections in order to give an indication of the works and costs involved.

8.2 Ndarugu 1 Dam Scheme

8.2.1 Introduction

The proposed Ndarugu 1 Water Supply Scheme involves raw water and treated water transmission through pumping. Raw water transmission will involve pumping of water from the dam to a proposed water treatment site located approximately 1km from the dam. The treated water transmission will involve pumping of water from the proposed treatment site to Utawala reservoir via a pipeline of approximate length 30Km. About 50,000m3/d of water will be distributed to serve parts of Nairobi lower than 1550 which include Ruai among others while the rest will be boosted to existing Ring Road Tank (35,000m3/d), proposed Embakasi Tank (38,000m3/d) and proposed Syokimau Tank (50,000m3/d). Water distribution from the existing and proposed tanks will then be by gravity to the demand areas.


• Ndarugu 1 Dam on Ndarugu River approx. 1Km upstream of the confluence with Munyu River

• Raw Water Pumping Station at Ndarugu 1 Dam Outlet Works

• Raw Water Pumping Main of approximate length of 1Km from Ndarugu 1 Dam to a Proposed Water Treatment Site

• Water Treatment Works, capacity 173,000m3/d

• Treated Water Pumping Station at the proposed Water Treatment Site, capacity 173,000m3/d

• Treated Water Pumping Main of approximate length of 30Km from the Pumping Station to Utawala Tank, capacity 173,000m3/d

• Treated Water Pumping Main of approximate length of 13Km from Utawala Tank to Ring Road Tank, capacity 35,000m3/d



• Treated Water Pumping Main of approximate length of 6Km from Utawala Tank to Embakasi Tank, capacity 38,000m3/d

• Treated Water Pumping Main of approximate length of 14Km from Utawala Tank to Syokimau Tank, capacity 50,000m3/d

• Utawala, Embakasi, Syokimau and Mavoko Tanks


A layout plan showing the proposed Ndarugu 1 Water Supply Scheme to Nairobi and Mavoko-Kitengela area and the existing water transmission systems is given in Figure 8.1.

8.2.2 Dam Characteristics

The dam optimal maximum height is proposed to be 35m high Roller Compacted Concrete Dam with a reservoir storage volume of approximately 225 Million m3. The impoundment area at maximum dam height is approximately 14.5 Km2 (1450 Ha).

The construction of the Ndarugu 1 dam is expected to involve the works given in Table 8.4. Table 8.4: Estimated Works for Ndarugu 1 Dam

Item Unit Quantity Soft Excavation m3 150,000 Roller Compacted Concrete m3 400,000 Curtain Grouting m 1000 Draw-off works, River Diversion among to the works



Figure 8.1: Layout Plan – Ndarugu 1 Scheme


The raw water transmission from Ndarugu 1 Dam to the water treatment works will comprise of Raw Water Pumping Station and a DN1200 Pumping Main. The raw water pumping station will be sited at the dam outlet works at the foot of the dam. The pumping station will include 100% stand-by capacity and the pump characteristics will be as follows:

• Pumping rate - 7,200 m3/hr • Head on Pumps - 47.2 m • Power - 1,558 Kw

The hydraulics constraints of the raw water transmission system are summarised in Table 8.5 below.

Table 8.5: Raw Water Transmission – Hydraulic Constraints and Optimisation Parameters Ndarugu 1 Dam Water Treatment Works


Static Lift - 40 m








The Water Treatment Facilities will cater for a raw water flow of 173,000m3/d (2.3m3/s). This will cater for year 2025 water demand for Nairobi Eastlands and Mavoko-Kitengela area.


1. Cascade Aeration

2. Pre-chlorination




6. Flocculation








iii) Treatment Works to Utawala Tank The treated water transmission from the proposed water treatment works to Utawala Tank will comprise of Treated Water Pumping Station and a DN1200 Pumping Main of approximate length, 30Km. The treated water pumping station will be sited within the water treatment site and will include 100% stand-by capacity. The pumps characteristics will be as follows:

• Pumping rate - 7,200 m3/hr • Head on Pumps - 177 m • Power - 5,847 Kw

The hydraulics constraints of the raw water transmission system are summarised in Table 8.6 below. The raw water transmission route ground and hydraulic profile is given in Figure 8.2.

Table 8.6: Treated Water Transmission – Hydraulic Constraints and Optimisation Parameters Water Treatment Works Utawala Tank


Static Lift - 100 m




Parameters Water Treatment Works Utawala Tank




A preliminary pipeline route has been identified for conceptual design purposes. The most convenient pipeline route will be determined at the detailed design stage to avoid disruption of private property and farmlands and also to avoid engineering difficulties. Generally, the proposed pipeline will traverse across developed areas of Ruai and Utawala.

The pipeline has been routed to cross Nairobi river after the confluence with Ruiru and Thiririka rivers. The pipeline will then run along the southern edge of Nairobi river close to Ruai sewage works before joining the Eastern Bypass road to Utawala.

Figure 8.2: Transmission Route Profile - Water Treatment Works to Syokimau Reservoir

iv) Utawala Tank to Ring Road Tank The treated water transmission from the proposed Utawala Tank to Ring Road Tank will comprise of Treated Water Pumping Station and a DN700 Pumping Main of approximate length, 30Km. The treated water pumping station will be sited at Utawala Tank site and will include 100% stand-by capacity. The pumps characteristics will be as follows:


1400

1450

1500

1550

1600

1650

1700

0 5 10 15 20 25 30

Elev

atio

n m

asl

Distance, Km

Ground Profile


Ndarugu Pumping Station

Nairobi River crossing

Utawala Reservoir



The hydraulics constraints of the water transmission pipeline are summarised in Table 8.7 below. The raw water transmission route ground and hydraulic profile is given in Figure 8.3.

Table 8.7: Treated Water Transmission – Hydraulic Constraints and Optimisation Parameters Utawala Tank Ring Road Tank


Static Lift - 70 m





A preliminary pipeline route has been identified for conceptual design purposes. Generally, the proposed pipeline will traverse across developed areas of Utawala, Mihango, Njiru, Komarock, Kayole, Umoja and Donholm. The pipeline will run along Kangundo Road, Kayole spine Road Mananja Road and a short section of Outering Road. The exact pipeline alignment will be determined at the detailed design stage to minimise disruption of private property.

Figure 8.3: Transmission Route Profile – Utawala Tank to Ring Road Tank

v) Utawala Tank to Embakasi Tank The treated water transmission from the proposed Utawala Tank to Embakasi Tank will comprise of Treated Water Pumping Station and a DN700 Pumping Main of approximate length, 6Km. The

1500

1520

1540

1560

1580

1600

1620

1640

1660

1680

0 2 4 6 8 10 12 14

Elev

atio

n m

asl

Distance, Km

Ground Profile



Ring Road Reservoir



treated water pumping station will be sited within the water treatment site and will include 100% stand-by capacity. The pumps characteristics will be as follows:



Table 8.8: Treated Water Transmission – Hydraulic Constraints and Optimisation Parameters Utawala Tank Embakasi Tank


Static Lift - 60 m





The pipeline route is proposed to run along the Eastern Bypass Road.

Figure 8.4: Transmission Route Profile – Utawala Tank to Embakasi Tank

1550

1560

1570

1580

1590

1600

1610

1620

1630

1640

1650

0 1 2 3 4 5 6

Elev

atio

n m

asl

Distance, Km

Ground Profile



EmbakasiReservoir



vi) Utawala Tank to Syokimau Tank The treated water transmission from the proposed Utawala Tank to Syokimau Tank will comprise of Treated Water Pumping Station and a DN800 Pumping Main of approximate length, 14.5Km. The treated water pumping station will be sited within the water treatment site and will include 100% stand-by capacity. The pumps characteristics will be as follows:



Table 8.9: Treated Water Transmission – Hydraulic Constraints and Optimisation Parameters Utawala Tank Syokimau Tank


Static Lift - 70 m





The pipeline is proposed to cut across Utawala after which it will run along the South-Eastern boundary of Jomo Kenyatta International Airport along Syokimau-Airport Road. The pipeline then follows the road up to Mombasa Road and to the proposed Syokimau Tank site.



Figure 8.4: Transmission Route Profile – Utawala Tank to Syokimau Tank

8.3 Maragua 4 Dam and South Mathioya Tunnel Scheme

8.3.1 Introduction

The Maragua 4 Dam in combination with the South Mathioya Tunnel is proposed as a potential water source to supply both Nairobi and Mavoko-Kitengela area. The proposed source can supply water to the demand areas by gravity and is proposed as an alternative to Ndarugu 1 Dam which is a pumped scheme. The scheme was proposed in the Water Supply Master (egis/MIBP, 2012) as the next scheme for development after the Northern Collector Tunnel Phase I.

Raw water will be conveyed by gravity to a treatment works approximately 27km to the south of the dam at Ndunyu Chege. Another raw water pipeline of approximate length 13km will convey water by gravity from Thika Dam to the proposed treatment works site. Treated water will then be conveyed by gravity via approximately 61km long main to the proposed Syokimau Tank at the southern boundary of Nairobi City. Along the main pipeline there’ll be offtakes after 48km to Ring Road Tank and after 48km to the proposed Embakasi Tank. Water in the Service Tanks will then be distributed by gravity to the demand centres at Nairobi Eastlands and the Mavoko-Kitengela area.

In brief, the proposed Maragua 4 Scheme will involve construction of the following works:

• Maragua 4 Dam at the confluence of Maragua and Gikigie rivers

• South Mathioya Tunnel of approximate length 3km to transfer part of South Mathioya River flows into Maragua river

1550

1560

1570

1580

1590

1600

1610

1620

1630

1640

1650

0 2 4 6 8 10 12 14

Elev

atio

n m

asl

Distance, Km

Ground Profile



SyokimauReservoir



• Raw Water Gravity Main of approximate length of 27Km from Maragua 4 Dam to a Proposed Water Treatment Works at Ndunyu Chege, capacity 80,000m3/d

• Raw Water Gravity Main of approximate length of 13Km from Thika Dam to the Proposed Water Treatment Works at Ndunyu Chege, capacity 52,000m3/d

• Water Treatment Works at Ndunyu Chege of capacity 132,000m3/d

• Treated Water Gravity Main of approximate length of 61Km from the proposed Treatment Works to Ring Road, Embakasi and Syokimau Tank

• Embakasi, Syokimau and Mavoko Tanks


A layout plan showing the proposed Maragua 4 water supply scheme to Nairobi Eastlands and Mavoko-Kitengela area and the existing water transmission systems is given in Figure 8.5.

8.3.2 Dam Characteristics Maragua 4 Dam is proposed to be an earth embankment dam, 75m high with an impoundment area of 117ha at spillway level. The estimated quantities for the construction of Maragua 4 Dam are given in Table 8.10. Table 8.10: Estimated Quantities for Maragua 4 Dam Item Unit Quantity Soft Excavation m3 900,000 Compacted Fill m3 4,820,000 Curtain Grouting M 1400 Draw-off works, River diversion, Spillway among other works

8.3.3 South Mathioya Raw Water Transfer Tunnel

The S. Mathioya Transfer Tunnel is proposed to be a 3m diameter horseshoe shaped tunnel which will be fully lined with concrete. The construction of the transfer tunnel will also require the construction of a run-of-river intake at the South Mathioya river and an outfall structure at Maragua river.



Figure 8.5: Layout Plan Showing the Proposed Maragua 4 Water Supply Scheme




i) Maragua 4 Dam to Ndunyu Chege Treatment Works An assessment of the available options for water transmission has been carried out. The assessment has demonstrated that the most feasible option for raw water transmission will involve gravitating water from Maragua 4 Dam and treating the water approximately 27Km away from the dam at Ndunyu Chege as proposed in the Master Plan Study by egis/MIBP (2012). The scour level at the dam is estimated to be 1910masl with the lowest supply level taken as about 1920masl. The raw water inlet level to the Treatment Works has been taken to be 1835masl.


Table 8.11: Raw Water Transmission – Hydraulic Constraints and Optimisation Parameters Maragua 4 Dam Water Treatment Works







The pipeline is proposed to follow the Maragua river valley until the southern ridge is low enough for the pipeline to exit. After existing the Maragua river valley the pipeline will cut across farmlands comprising mainly of tea and coffee farms up to the proposed Ndunyu Chege Water Treatment Works. No convenient route i.e. roads exists for the pipeline to follow.



Figure 8.6: Transmission Route Profile – Maragua 4 Dam to Water Treatment Works

ii) Thika Dam to Ndunyu Chege Treatment Works The pipeline is proposed to draw additional yield at Thika Dam available with the construction of the South Mathioya Tunnel. The pipeline will follow the Thika river valley and then exit to follow the Ndakaini-Gatanga road up to the proposed Ndunyu Chege Water Treatment Works. The pipeline will be a 13km long pipeline of capacity 52,000m3/d.


Table 8.12: Raw Water Transmission – Hydraulic Constraints and Optimisation Parameters Thika Dam Water Treatment Works







1650

1700

1750

1800

1850

1900

1950

0 5 10 15 20 25 30

Elev

atio

n m

asl

Distance, Km

Ground ProfileHydraulic Gradient Line

Maragua 4 Dam Lowest Supply Level

Ndunyu Chege Water Treatment Plant



Figure 8.7: Transmission Route Profile – Thika Dam to Water Treatment Works


The Water Treatment Facilities will cater for a raw water flow of 132,000m3/d (1.53m3/s). This represents the yield of Maragua 4 Dam and South Mathioya Tunnel.


1. Cascade Aeration

2. Pre-chlorination




6. Flocculation






1820

1840

1860

1880

1900

1920

1940

1960

1980

2000

2020

0 2 4 6 8 10 12 14

Elev

atio

n m

asl

Distance, Km


Thika Dam Lowest Supply Level






The Treated Water Transmission will involve transfer of water from the proposed Water Treatment Works to Syokimau Tank with offtakes to the existing Ring Road Tank and to the proposed Embakasi Tank. The Syokimau Tank will be located at the Nairobi-Mavoko border close to the Syokimau Railway Station while the Embakasi Tank will be located close to the Jomo Kenyatta International Airport for water distribution to the lower Eastlands areas of Nairobi. The Syokimau Tank will have the elevation to command the Syokimau/Mlolongo, Athi River and Kitengela demand areas by gravity. The Service Reservoir will need to be located at an elevation above 1630masl.

The treated water pipeline is proposed to follow the route for the existing Ngethu-Gigiri pipelines up to Kiambu where it will follow existing road reserves up to Syokimau Tank.

A preliminary transmission route has been identified for conceptual design purposes. The most convenient transmission route needs to be determined at the detailed design stage to avoid disruption of private property and farmlands and also to avoid engineering difficulties.

The hydraulic constraints on the water transmission route are given in Table 8.13 below. The transmission route hydraulic profile is given in Figure 8.8.

Table 8.13: Treated Water Transmission to Syokimau – Hydraulic Constraints and Optimisation

Parameter Water Treatment Plant

Ring Road Tank

Emabaksi Tank

Syokimau Tank

Approximate Ground Elevation - 1830 masl 1630 masl 1620 masl 1630 masl

Approximate Hydraulic Elevation - 1830 masl 1670 masl 1650 masl 1645 masl



Pipeline Diameter - 1000 mm (48Km), 800 mm (13Km)




Figure 8.8: Transmission Route Profile - Water Treatment Works to Syokimau Tank

1550

1600

1650

1700

1750

1800

1850

0 10 20 30 40 50 60

Elev

atio

n m

asl

Distance, Km


Syokimau Tank


Embakasi Tank Offtake

Ring RoadTank Offtake



8.4 Cost Estimates and Economic Comparison of Schemes

8.4.1 Introduction The costing criteria and estimates for the various components in Ndarugu 1 and Maragua 4 schemes are given in the following sections. A summary of costs for the two schemes is given in section 10.8. Additional costs to cater for preliminaries and general costs (15%), engineering services (7%), and physical contingencies (10%) have been added in the summary. All costs are exclusive of duties and VAT taxes.

8.4.2 Dam Construction

i) Ndarugu 1 Dam Ndarugu 1 Dam is proposed to be a 35m high Roller Compacted Concrete Dam. The impoundment area is estimated to be 1450ha at spillway level. The estimated quantities and costs associated with the construction of Ndarugu 1 Dam are given in Table 8.14. Table 8.14: Estimated Quantities and Costs for Ndarugu 1 Dam Item Unit Quantity Rate

Kshs Amount

Kshs Soft Excavation m3 150,000 900 135,000,000 Roller Compacted Concrete m3 400,000 10,000 4,000,000,000 Curtain Grouting M 1000 450,000 450,000,000 Draw-off works - sum - 600,000,000 River diversion - sum - 900,000,000 Other works - sum - 800,000,000

Total 6,885,000,000

ii) Maragua 4 Dam Ndarugu 2 Dam is proposed to be an earth embankment dam, 75m high with an impoundment area of 117ha at spillway level. The estimated quantities and costs associated with the construction of Maragua 4 Dam are given in Table 8.15. Table 8.15: Estimated Quantities and Costs for Ndarugu 2 Dam

Item Unit Quantity Rate Kshs

Amount Kshs

Soft Excavation m3 900,000 900 90,000,000 Compacted Fill m3 4,820,000 1,950 1,891,500,000 Curtain Grouting M 1,600 450,000 360,000,000 Draw-off works - sum - 350,000,000 River diversion - sum - 650,000,000 Spillway - sum - 1,250,000,000 Other works - sum - 600,000,000

Total 5,191,500,000



8.4.3 Raw Water Transmission Tunnel The rates for the proposed South Mathioya Raw Water Transmission Tunnel have been obtained the ongoing Northern Collector Tunnel (NCT) Project. The tunnel is proposed to be a 3m diameter concrete lined tunnel similar to the NCT tunnel. A rate of Kshs.1,000,000 per meter length has been used. The associated costs are given Table 8.16 below: Table 8.16: Estimated Quantities and Costs for S. Mathioya Tunnel

Component Unit Quantity Rate (Kshs) Amount (Kshs) • Tunnel construction M 3000 1,000,000 3,000,000,000 • Intake Structure - Sum - 75,000,000 • Outfall Structure - Sum - 50,000,000

Total 3,125,000,000

8.4.4 Water Treatment Works A relationship between capital cost and treatment works design capacity has been derived from recent and ongoing water supply projects of similar capacity in Kenya. The construction costs for the proposed water treatment works are given below:

i) Ndarugu 1 Scheme The proposed water treatment works of capacity 172,800m3/d has been estimated to cost approximately Kshs. 5,530,000,000.

ii) Maragua 4 Scheme The proposed water treatment works of capacity 132,000m3/d has been estimated to cost approximately Kshs. 4,224,000,000.

8.4.5 Pumping Stations Ndarugu 1 Scheme involves raw pumping to the proposed treatment works and treated water pumping to Utawala Tank. In addition there is a boosting station at Utawala to pump water to Ring Road Tank, Embakasi Tank and Syokimau Tank. Therefore three pumping stations are required. Pumping Stations have been sized to include 100% stand-by capacity. Costs for Electrical and Mechanical Plant have been build-up from budget quotations as well rates from similar ongoing and recently completed projects. The pump costs are assumed to include the cost of pipework and necessary electricity supply. The costs for Ndarugu 1 Pumping Stations are given below: Ndarugu 1 Scheme Pumping Stations: • Raw Water Pumping Station - Kshs. 210,000,000 • Treated Water Pumping Station at

Treatment Works - Kshs. 400,000,000

• Treated Water Boosting Station at Utawala - Kshs. 300,000,000 • Total - Kshs. 910,000,000



Costs for pumping have been estimated based on the lift (static + friction) and the required pump discharge rate with the electricity requirement based on a pump efficiency of 70% and power factor of 85%. Annual power costs have been estimated using a rate of Kshs16/Kwh corresponding to the current industrial rate for electricity provided by Kenya Power Limited Company.

8.4.6 Main Water Transmission Pipelines The costs for water transmission and distribution pipelines are based on current unit rates build up from local steel manufacturers quotations. All rates are inclusive of supply of pipes and fittings of Nominal Pressure Rating NP25, transporting to site, excavation, laying, jointing, testing and backfilling. The rates are average rates taking into consideration of terrain, urban and sub-urban construction.

i) Ndarugu 1 Scheme Main Water Transmission Pipelines Table 8.17 gives a summary of pipe sizes, lengths and associated costs required for Ndarugu 1 scheme water transmission.

Table 8.17: Estimated Costs for Water Transmission Pipelines – Ndarugu 1 Scheme Pipeline Section Nominal

Diameter (mm)

Length (m)

Nominal Pressure

Rating


Amount (Kshs)

Ndarugu Dam – WTP 1200 1,000 NP16 75,000 75,000,000 WTP – Utawala 1200 30,000 NP25 100,000 3,000,000,000 Utawala – Ring Road 700 13,000 NP16 34,000 442,000,000 Utawala – Embakasi 700 6,000 NP16 34,000 204,000,000 Utawala - Syokimau 800 14,500 NP16 40,000 580,000,000

Total Cost 4,301,000,000

ii) Maragua 4 Scheme Main Water Transmission Pipelines Table 8.18 gives a summary of pipe sizes, lengths and associated costs required for Maragua 4 scheme water transmission. Table 8.18: Estimated Costs for Water Transmission Pipelines – Maragua 4 Scheme

Pipeline Section Nominal Diameter

(mm)

Length (m)

Nominal Pressure

Rating


Amount (Kshs)

Maragua 4 – Ndunyu Chege 900 27,000 NP25 52,000 1,404,000,000 Thika Dam – Ndunyu Chege 600 13,000 NP16 25,000 325,000,000 Ndunyu Chege – Ring Road 1000 48,000 NP25 80,000 3,840,000,000 Ring Road – Embakasi 800 9,000 NP25 48,000 432,000,000 Embakasi – Syokimau 500 4,000 NP25 29,000 116,000,000

Total Cost 6,117,000,000



iii) Ndarugu 1 and Maragua 4 Schemes Water Distribution Pipelines Water distribution is similar for both Ndarugu 1 and Maragua 4 Schemes. Table 8.19 gives a summary of pipe sizes, lengths required and associated costs for proposed water distribution pipelines. Table 8.19: Estimated Quantities and Costs for Water Distribution Pipelines


Length (m)



Amount (Kshs)

700 4,100 NP16 34,000 139,400,000 500 12,700 NP16 26,000 330,200,000 400 1,700 NP16 22,000 37,400,000

Total Cost 507,000,000

8.4.7 Service Reservoirs The sizing of Service Reservoirs is on the basis of half day storage. More storage capacity is required for Ndarugu 1 scheme because a higher yield is expected from the scheme. The storage tanks are assumed to be reinforced concrete tanks and to be partially buried. The costs for provision of storage in the two sites have been derived from recent and ongoing water supply projects. The associated costs for reservoir construction are given in Table 8.20 for Ndarugu 1 scheme and Table 8.21 for Maragua 4 scheme. Table 8.20: Service Reservoir Costs – Ndarugu 1

Reservoir Site Proposed Capacity (m3) Amount (Kshs)

Utawala 40,000 250,000,000 Ring Road 5,000 100,000,000 Embakasi 10,000 80,000,000 Syokimau 20,000 120,000,000 Mavoko 5,000 50,000,000 Total 80,000 600,000,000

Table 8.21: Service Reservoir Costs – Maragua 4

Reservoir Site Proposed Capacity (m3) Amount (Kshs)

Ring Road 5,000 100,000,000 Embakasi 30,000 200,000,000 Syokimau 20,000 120,000,000 Mavoko 5,000 50,000,000 Total 60,000 470,000,000

8.4.8 Summary of Costs A summary of costs for the proposed project components for the two schemes is given in Table 8.22. Preliminaries and general costs (15%), engineering services (7%), and physical contingencies (10%) have been added in the summary.



Table 8.22: Summary of Costs

Item Amount (Kshs) Ndarugu 1 Scheme Maragua 4 Scheme

1. Dam Construction - 6,885,000,000 16,739,000,000

3. Tunnel - - 2,675,000,000

2. Water Treatment Plants - 5,529,600,000 4,224,000,000

3. Pumping Stations - 910,000,000 -

4. Main Water Transmission Pipelines - 4,301,000,000 6,117,000,000

5. Distribution Pipelines - 507,000,000 507,000,000

6. Service Reservoirs - 600,000,000 470,000,000

Sub Total 1 - 18,732,600,000 30,732,000,000

Preliminary and General Costs (15% of Sub Total 1) 2,809,890,000 4,609,800,000

Sub Total 2 - 21,542,490,000 35,341,800,000 Physical Contingencies (10% of Sub Total 2) 2,154,249,000 3,534,180,000

Sub Total 3 - 23,696,739,000 38,875,980,000 Engineering Costs (7% of Sub Total 1) 1,658,771,730 2,721,318,600

GRAND TOTAL COST - 25,355,510,730 41,597,298,600 * All costs are exclusive of duties and VAT taxes

8.4.9 Economic Comparison of Schemes The economic parameters and results derived from economic analysis are summarized in Tables 8.23, 8.24, 8.25, 8.26 and 8.27. To obtain Present Value costs, discounting has been carried out for 8%, 10% and 12% discount rates over a period of 30years. Table 8.23: Capital Costs

Component Ndarugu 1 Maragua 4

Civil Works 17,822,600,000 30,732,000,000

Pumps and Motors 910,000,000 -

Total Cost (Kshs.) 18,732,600,000 30,732,000,000 Table 8.24: Annual Operation and Maintenance Costs

Component Ndarugu 1 Maragua 4

Maintenance Costs* 223,726,000 307,320,000

Electricity Costs 1,341,925,701 -

Other Operational Costs** 356,452,000 614,640,000

Total Cost (Kshs.) 1,922,103,701 921,960,000 *Based on 1% of Civil Works and 5% of Pump and Motors Costs **Based on 2% of Civil Works Costs



Table 8.25: Cost per Unit Yield

Scheme Yield (m3/d) Capital Cost per Unit Yield

(Kshs/m3/d) O&M Costs Per Unit Yield*

(Kshs/m3/d)

Ndarugu 1 173,000 108,281 11,110 Maragua 4 132,000 232,818 6,985

*Operation and Maintenance Costs

Table 8.26: Discounted Costs over a Period of 30 year – Present Value

Scheme

Discount Rate

8% 10% 12%

Ndarugu 1 Kshs.40,943,804,190 Kshs.37,265,768,413 Kshs.34,571,311,395

Maragua 4 Kshs.41,111,225,931 Kshs.39,486,054,897 Kshs.38,221,374,246

Table 8.27: Dynamic Prime Costs of Schemes

Scheme

Discount Rate

8% 10% 12%

Ndarugu 1 236,669 Kshs/m3/d 215,409 Kshs/m3/d 199,834 Kshs/m3/d Maragua 4 311,449 Kshs/m3/d 299,137 Kshs/m3/d 289,556 Kshs/m3/d

8.4.10 Land Acquisitions and Compensation

iii) Ndarugu 1 Dam Scheme The Ndarugu 1 Dam impoundment area is estimated to be 1ha at reservoir spillway level. It is estimated that about 1500ha of land will need to be acquired. About 200 households will also be displaced since they fall within the reservoir area. The dam impoundment area is shown on google imagery in Figure 8.9.

A permanent wayleave will also be required for both raw water and treated water pipelines. It is assumed that the wayleave will be required for the full pipeline lengths since there are no well-defined roads to follow. A 7m wide permanent wayleave is proposed for a length of about 40Km.



Amount (Kshs)


‐ Land only ha 1500 5,000,000 7,500,000,000 ‐ Crops compensation ha 500 200,000 100,000,000 ‐ Households and infrastructure - sum - 400,000,000

Sub-Total 8,000,000,000 2. Main Water Transmission and Distribution Pipelines

‐ Land only ha 30 5,000,000 150,000,000




Amount (Kshs)

‐ Crops compensation ha 10 200,000 1,000,000 ‐ Infrastructure - sum - 50,000,000

Sub-Total 201,000,000 3. Service Reservoirs

‐ Land only ha 0.8 - 40,000,000 Sub-Total 40,000,000

Total 8,241,000,000 The land acquisition and compensation costs for all the sites to be acquired under the proposed Ndarugu 1 water supply scheme are estimated to be Kshs. 8,241,000,000.






iv) Maragua 4 Dam Scheme The Maragua 4 Dam impoundment area is estimated to be 117ha at reservoir spillway level. It is assumed that about 130ha of land will need to be acquired. The dam impoundment area on a google imagery is shown in Figure 10.1. The following households and developments are likely to be displaced by the dam embankment and impoundment:

• Approximately 40No Households • Marrum roads / tracks

A permanent way leave will also be required for both raw water and treated water pipelines. It is assumed that the way leave will be required for 40Km length of Raw Water Pipelines and 40Km for the Treated Water Pipeline. A 7m permanent way leave is proposed to be acquired where the pipeline is not passing along road reserves.



Amount (Kshs)

1. Maragua 4 Dam Land acquisition

‐ Land only ha 130 1,500,000 195,000,000 ‐ Crops compensation ha 125 500,000 62,500,000 ‐ Households and infrastructure - sum - 80,000,000

Sub-Total 337,500,000 2. Main Water Transmission and Distribution Pipelines ‐ Land only ha 60 1,500,000 90,000,000 ‐ Crops compensation ha 50 300,000 15,000,000 ‐ Infrastructure - sum - 30,000,000

Sub-Total 135,000,000 3. Service Reservoirs ‐ Land only ha 0.8 - 40,000,000

Sub-Total 40,000,000 Total 512,500,000

The land acquisition and compensation costs for all the sites to be acquired under the proposed Ndarugu 2 water supply scheme are estimated to be Kshs. 512,500,000.



Figure 8.10: Maragua 4 Dam Impoundment Area



8.4.11 Conclusions and Recommendations The proposed works under the Ndarugu 1 water supply scheme are estimated to cost Kshs. 18,732,600,000 excluding Contingencies, Engineering and Supervision Costs and Kshs. 25,355,510,730 including Contingencies and Engineering and Supervision Costs. The proposed works under the Maragua 4 water supply scheme are estimated to cost Kshs. 30,732,000,000 excluding Contingencies, Engineering and Supervision Costs and Kshs. 41,597,298,600 including Contingencies and Engineering and Supervision Costs. The Present Value and Dynamic Prime Costs for Ndarugu 1 scheme are lower at 8%, 10% and 12% Discount Rates when compared to Ndarugu 1 Scheme. Ndarugu 1 Scheme is therefore cheaper than Ndarugu 1 Scheme based on capital investment cost and discounted costs over a period of 30 years. The difference in costs between the two schemes is mainly as a result of the dam construction costs Maragua 4 scheme. The land acquisition and compensation costs for Ndarugu 1 scheme are however high at Kshs.8,241,000 compared to Kshs.512,500,000 for Maragua 4 scheme. However, the two schemes should not be only compared on capital cost basis since there are other principle factors for consideration. It is important to note that Ndarugu 1 Dam at the proposed maximum height of 35m will give a net yield of 198,720m3/d (2.3m3/s) compared to a net yield of 132,000m3/d (1.53m3/s) for Maragua 4 Dam at an optimal height of 75m together and together with the South Mathioya Tunnel. The Ndarugu 1 Dam is a key source for water supply to Nairobi City and surrounding areas as proposed under the Nairobi and Satellite Towns Water Supply Master Plan (egis/MIBP, 2012). Delay in the construction of the dam may prove to be costly in future if the reservoir area land is not acquired at this stage. The reservoir area is close to Nairobi and based on the current development trends, developments will in the near future occupy a large extend of the reservoir. Already the large land parcels in the area are presently being subdivided for sale. The principle advantages and disadvantages associated with the two schemes are as listed Table 8.30. Table 8.30: Principle Advantages and Disadvantages of Ndarugu 1 and 2 Schemes


Ndarugu 1 • Cheaper scheme to construct

• Very high reservoir storage and yield


construction


and treated water

• Large area of land to be flooded

• Extensive land acquisition - Large

developed area of land to acquired

• Many households to be relocated (about

200)

• Poorer raw water quality

Maragua 4 • Gravity water supply • High Capital cost for investment







costs

• Far from demand areas


flooded

Based on the economic and non-economic factors considered for Alternative 2, Ndarugu 1 Water Supply Scheme is recommended for development to serve both Nairobi City and the Mavoko-Kitengela areas.



9. SELECTION OF THE ADVANTAGEOUS ALTERNATIVE FOR DEVELOPMENT

9.1 Introduction

The schemes recommended under the two alternatives are as follows:

Alternative Description Recommended Scheme

Alternative 1 - Development Strategy for Water Supply to Mavoko-Kitengela

- Ndarugu 1 Water Supply Scheme (12.5m High Dam)

Alternative 2 - Development Strategy for Water Supply to Nairobi and Mavoko-Kitengela (Integrated Plan)

- Ndarugu 1 Water Supply Scheme(35m High Dam)

In brief, the proposed Scheme under Alternative 1 will involve construction of the following works:

• Ndarugu 1 Dam (12.5m high Roller Compacted Concrete Dam) on Ndarugu River approx. 1Km upstream of the confluence with Munyu River and 2Km upstream of the confluence with Athi River

• Raw Water Pumping Station at Ndarugu 1 Dam Outlet Works of capacity 55,000m3/d

• DN900, NP10 Raw Water Pumping Main of approximate length of 1Km from Ndarugu 1 Dam to the Proposed Water Treatment Plant Site

• Water Treatment Plant of capacity 55,000m3/d

• Treated Water Pumping Station at the proposed Water Treatment Site of capacity 55,000m3/d

• DN900, NP16 Treated Water Pumping Main of approximate length of 30Km from the Water Treatment Plant to Utawala Tank

• Utawala Pumping Station of capacity 55,000m3/d

• DN900, NP16 Treated Water Pumping Main of approximate length of 14.5Km from Utawala Pumping Station to Syokimau Tank

• Storage Tanks at Utawala, Syokimau and Mavoko of total capacity 30,000m3

• DN400-DN700, NP16 Distribution Mains of total length of approximately 19Km from Syokimau Terminal Reservoir to Syokimau/Mlolongo, Athi River and Kitengela areas

The proposed Scheme under Alternative 2 will involve construction of the following works:

• Ndarugu 1 Dam (35m high Roller Compacted Concrete Dam) on Ndarugu River approx. 1Km upstream of the confluence with Munyu River and 2Km upstream of the confluence with Athi River

• Raw Water Pumping Station at Ndarugu 1 Dam Outlet Works of capacity 173,000m3/d



• DN1200, NP16 Raw Water Pumping Main of approximate length of 1Km from Ndarugu 1 Dam to the Proposed Water Treatment Site

• Water Treatment Plant of capacity 173,000m3/d

• Treated Water Pumping Station at the proposed Water Treatment Site of capacity 173,000m3/d

• DN1200, NP25 Treated Water Pumping Main of approximate length of 30Km from the Pumping Station to Utawala Tank, capacity 173,000m3/d

• DN700, NP16 Treated Water Pumping Main of approximate length of 13Km from Utawala Tank to Ring Road Tank, capacity 35,000m3/d

• DN700, NP16 Treated Water Pumping Main of approximate length of 6Km from Utawala Tank to Embakasi Tank, capacity 38,000m3/d

• DN800, NP16 Treated Water Pumping Main of approximate length of 14Km from Utawala Tank to Syokimau Tank, capacity 50,000m3/d

• Storage Tanks at Utawala, Embakasi, Syokimau and Mavoko of total capacity 80,000m3

• DN400-DN700, NP16 Distribution Mains from Syokimau Reservoir to Syokimau/Mlolongo, Athi River and Kitengela areas

The selection of the two schemes has been done on least cost basis for water supply to meet the medium term water demand projections. Consideration has also been given to other non-economic factors like technical capability, efficiency of supply, operation and maintenance and social factors among others.

To decide which alternative would be most advantageous to adopt, other factors must be taken into account. The other factors are essentially non-technical and are concerned with administrative aspects, management, operation, maintenance and finance.

9.2 Water Supply Development

The demand areas of Mavoko-Kitengela fall under the Tanathi Water Services Board (TAWSB) while Nairobi City falls under Athi Water Services Board (AWSB). The Water Services Boards have been established under Section 51(2) of the Water Act 2002 as part of the reforms in the water sector. The Boards operate under a license issued by Water Services Regulatory Board (WASREB). The direct provision of water services to end users is entrusted to Water Services Providers (WSPs) who are contracted agents of the Board.

The mandate of the Boards is to contract, monitor and enforce agreements between the Board and water service providers in accordance with regulations set by the Water Services Regulatory Board; ensure effective and economical provision of water services within its area of jurisdiction; monitor and acquire assets; plan, manage and develop water and sewerage services; and take custody of water services provision assets.

The water sources which have been recommended under the two alternatives fall under AWSB. The area falling within and around Mavoko-Kitengela area is semi-arid with no viable potential water



sources. Therefore water for the area has to be sourced from the neighbouring WSB area of jurisdiction. Presently, there is no proper coordination in the development of water resources between the two bordering WSBs of AWSB and TAWSB. There has been little effort to consider the need of other demand areas or the possibility of utilising one scheme to provide water to a number of Water Service Providers (WSPs) in the two WSBs. This is not acceptable especially for areas where water sources are limited.

AWSB or TAWSB can develop either of the two schemes proposed under the two alternatives as long as there is coordination between the Boards. The water supply operations are discussed in the following section.

9.3 Water Supply Operations

Under the Water Act 2002, water supply operations are undertaken by Water Service Providers (WSPs). The full functions of WSPs include direct provision of water and sanitation services and the development, rehabilitation and maintenance of water and sewerage facilities of the WSB. The Water Service Providers act as agents of the Water Service Boards. Under the Water Act, Water Service Providers are defined to include companies, NGOs, other persons or bodies. The Interpretation and General Provisions Act, Chapter 2 of the Laws of Kenya defines “person” as legal or natural person. The implications are that community groups to qualify as Water Service Providers must be formally registered under the Societies Act, Chapter 108 of the Laws of Kenya to gain legal personality.

The proposed service area under Alternative 1 falls under a single WSP which is Mavoko Water and Sewerage Company (MAVWASCO). The service area under Alternative 2 fall under two WSPs which is MAVWASCO and the Nairobi City Water and Sewerage Company (NCWSC).

Generally, water supply operations may be considered to consist of two components:

a) Water Treatment - This includes water abstraction, storage, water treatment and bulk water transmission to distribution system. The need to balance treatment works outputs with such factors as raw water availability, demands, service reservoir levels, bulk water transmission rates, etc. necessitates managerial control being exercised over total water abstraction, treatment, transmission and storage system.

b) Water Distribution - This includes control, design, installation, repair and maintenance of the pipelines and other systems used for local distribution of water to consumers. The management and operation of water distribution system necessitates officers concerned having not only very close involvement with local consumers but also detailed knowledge and experience of the actual distribution system and experience of the actual operation. It is always important to ensure that distribution systems are locally managed, controlled and operated



The scheme proposed under Alternative 1 will comprise of Ndarugu 1 Dam which is located 40Km away from the demand area. Both the Dam and the Water Treatment Plant fall within AWSB jurisdiction area. The water supply scheme will be a dedicated water source for MAVWASCO. The water transmission system will cross the water service jurisdiction area for Ruiru-Juja Water and Sanitation Company and NCWSC. There is therefore the possibility of the water being lost within the transmission system and MAVWASCO having little control of it. This scheme is therefore not favoured in terms of Water Supply Operations.

The scheme proposed under Alternative 2 is meant for water supply to Nairobi and Mavoko-Kitengela area. The scheme Water Treatment and Distribution component is not far from the demand area within Nairobi City. The scheme Water Treatment component is perfectly suited to be operated by NCWSC since the WSP has the requisite experience in operating large water supply schemes. The Water Distribution component falling under Nairobi City will be operated by NCWSC while the component under Mavoko-Kitengela are will be operated by MAVWASCO. Generally the Water Supply Operations under the two WSPs will need to be coordinated so that there is no prioritization of demands when it comes to water allocations. The fears of prioritization of demands can however be avoided by the formation of a Bulk Water Company to supply water in Bulk to the two WSPs.

9.4 Conclusions and Recommendations

In conclusion, the water supply scheme proposed under Alternative 2 is favoured for development. The scheme will supply water to Nairobi City Eastlands areas together with Mavoko-Kitengela area which are presently underserved and experiencing severe water shortages. The Ndarugu 1 scheme will serve an approximate population of 1.3million with potable water and will meet the medium term, year 2025 water demand. Figure 9.1 gives a graphical presentation of the Nairobi City and Mavoko-Kitengela Water Demand and Proposed Water Supply Development. A layout plan showing the proposed scheme is given in Figure 9.2.



Figure 9.1: Nairobi City and Mavoko-Kitengela Water Demand and Proposed Water Supply Development

Figure 9.2: Layout Plan showing Ndarugu 1 Water Supply Scheme



10. ECONOMIC, FINANCIAL AND SOCIAL BENEFITS ANALYSIS

10.1 Economic Analysis

10.1.1 Description of Compilation of Investment Estimate The investment estimate of Kenya Ndarugu I Dam Water Supply Project is compiled according to the project feasibility study documents mainly including:

• A reservoir (Dam) 35m high roller compacted concrete dam with a total storage capacity of 225 million m3;

• 1km DN1200 raw water transmission pipeline, 30km DN1200 treated water transmission pipeline from treatment works to Utawala tank, 13km DN700 treated water main from Utawala tank to Ring road tank, 6km DN700 from Utawala tank to Embakasi tank, 14.5km DN800 from Utawala tank to Syokimau tank, 4.1km DN700; 12.7km DN500; 1.7km DN400 distribution pipelines.

• Service Reservoirs; 40,000m3 at Utawala, 5,000m3 at outer Ring Road, 10,000m3 at Embakasi, 20,000m3 at Syokimau and 5,000m3 at Mavoko.

• Pump stations; raw water pumping stations, treated water pumping station at treatment works and treated water boosting stations at Utawala.

• A 172,800m3 water treatment works. The total estimated amount is US$ 261,973,400 and investment estimate of this Project is US$ 276,739,500 (inclusive of loans interest during construction period and initial working capital) as itemized in Table 10.1.



Table 10.1 Investment Estimate Sheet S/N Item name Cost (1*103US$) Remarks I Project cost 213,855.80 (I) Construction of Ndarugu I Dam 81,000.00

1 Soft excavation 1,588.00 2 Roller compacted concrete for dam wall 47,059.00 3 Curtain grouting 5,295.00 4 Draw-off works 7,059.00 5 Temporary works/river diversion 10,588.00 6 Management facility and levee safety

detection system 2,841.00

7 Electrical and mechanical equipment 3,070.00 8 Special requirement 3,500.00

(II) Pipeline works 50,037.00

1 Raw water pipeline from Ndarugu I Dam to Treatment waterworks

529.40

2 Clear water pipeline from treatment waterworks to Utawala

24,470.60

3 Clear water pipe from Utawala to Outer Ring Road Service reservoir

6,890.00

4 Clear water pipe from Utawala to Embakasi Service reservoir

3,180.00

5 Clear water pipeline from Utawala to Syokimau Service reservoir

9,120.50

6 Water distribution pipe from Syokimau reservoir to Mlolongo, Athi River and Kitengela areas

5,847.00

(III) Treatment Waterworks 65,054.00

1 Water taking works 1,112.70 2 Sedimentation tank 9,711.80 3 V-shaped filtration tank 11,331.60 4 Clear water tank 2,540.50 5 Dosing room 2,044.80 6 Backwash pump house and blower house 3,860.60 7 Chlorination room 1,214.10 8 Chemical storage room 745.50 9 Management building 3,940.50

10 Workshop and dormitory 852.00 11 Power distribution room 1,043.70 12 Backwash wastewater tank 1,094.60 13 Sludge drying yard 962.40



S/N Item name Cost (1*103US$) Remarks 14 Employee dormitory and auxiliary building 5,986.20 15 Landscaping ,drainage system, power

installation, street lighting , and access road

8,001.65

16 Electro-mechanical works 9,042.50 (IV) Pumping stations 10,705.90

1 Raw water pumping station 2,470.60 2 Treated water pumping station at WTP 4,705.90 3 Treated water boosting station at Utawala 3,529.40

(V) Service reservoirs 7,058.90

1 Utawala 40,000m3 2,941.20 2 Embakasi 10,000m3 941.20 3 Outer Ring Road 5,000m3 1,176.50 4 Syokimau 20,000m3 1,411.80 5 Mavoko 5,000m3 588.20

Sub-total 1 213,855.80 (VI) Preliminary and general cost (5% of sub-

total 1) 10,692.80

Sub-total 2 224,548.59 (VII) Physical contingencies (10% of sub-total 2) 22,454.90 Sub-total 3 247,003.50 (VIII) Engineering costs (7% of sub-total 1) 14,969.90 TOTAL COST 261,973.40 (IX) Initial working capital 3% 7,859.20 (X) Loan interest for construction period 6,906.90 GRAND TOTAL PROJECT COST 276,739.50 COST FOR IMPLEMENTATION OF ESIA

REPORT 88,900.00

TOTAL INVESTMENT COST 365,639.50



10.1.2 Description of Financial Appraisal

10.1.2.1 Calculation Principle

(a) Project calculation period Project calculation period takes 18 years, in which construction period is 3 years and production and operation period is 15 years.

(b) Basis for exchange rate The exchange rates for this Project adopt Kshs 87 VS US$1.

(c) Loan rate and repayment period (1) The total contract amount is USD 276,739.50 15% of the contract amount is prepared by the owner and the remaining 85% is raised with bank loans. (2) Loan conditions:

i) Before the first loan is released, the owner must pay 15% of the contract price, i.e. only 85% of contract price can be raised with loans;

ii) The loan term is 15 years, in which grace period is 3 years and repayment term is 12 years;

iii) According to normal experience, the average loan rate may adopt annual rate of 2% (6-month Libor rate for USD is ~0.33%).

(c) Determination of water rate According to the Feasibility Study and Master Plan for Developing New Water Sources for Nairobi and Satellite Towns (by EGIS in Association with Mangat, I.B.Patel & Partners in March 2012), the local water rate in Kenya is shown in table 9.1 as follows: Table 10.2 Tariff of Water

Customer Category Monthly

consumption Range (m3)

Tariff

Kshs/m3 US$/m3

Kiosk & Standpipe Flat rate 15.0 0.1716

Domestic/Residential, Commercial/Industrial, Governmental Institution and Schools

0 to 10 11 to 30 31 to 60

>60

18.71 28.07 42.89 53.8

0.2141 0.3212 0.4908 0.6156



The current water tariff of this Project is 0.52 US$/m3 though the rate will be increase to cater for the inflation at a rate of 5% p.a. to 1.03 US$/m3 by the 15th year of operation. The average tariff for financial analysis used for 15 year operation period is therefore 0.78 US$/m3

10.1.2.2 Cost Forecasts

Basic data of cost forecasts and expenses are given in the following table:

Table 10.3 Costs for Water Production & Operating S/N Item and expense name Basic data 1 Water supply volume (10kt/day) 17.2 2 Comprehensive change coefficient K2 1 3 Pump lift (m) 180 4 Water pump and motor efficiency 0.85 5 Power consumption of equipment, etc. (KWH/year) 56,502,000 6 Unit price of electricity (US$/KWH) 0.23 Regular treatment

A Poly aluminum chloride dosage (mg/L) 5.00 B Unit price of poly aluminum chloride (US$/t) 400.50 C Disinfectant (liquid chlorine) dosage (mg/L) 1.50 D Unit price of disinfectant (liquid chlorine) (US$/t) 1,945.28 E Soda dosage (mg/L) 15.00 F soda unit price (US$/t) 286.07 G RAM dosage (mg/L) 0.05 H RAM unit price (US$/t) 6,000

7 Fixed staff (person) 39.00 8 Per capita annual salary (US$) 11,409.18 9 Total construction project investment (1kUS$) 276,739.50 Wherein: fixed asset, engineering expenses and other investments

(1kUS$) 261,973.40

Initial working capital including purchase of O&M equipment (1kUS$) 7,859.20 Loan interest for construction period (1kUS$) 6,906.90 10 Comprehensive depreciation rate of fixed assets 2.40% 11 Major overhaul rate 0.50% 12 Other operating expense 2.00% Note: Unit price data of electricity, chemicals and average annual salary are obtained from local market or the Feasibility Study and Master Plan for Developing New Water Sources for Nairobi and Satellite Towns (by EGIS in Association with Mangat, I.B.Patel & Partners in March 2012). Table 10.4 Annual Operation Expenses and Unit Water Production Cost

S/N Annual operation expenses and unit water production cost Expenses (1KUS$) 1 Water resource expenses 0.00 2 Power cost 12,995.50 3 Reagent cost 597.20 4 Salary & benefit expenses 444.96



S/N Annual operation expenses and unit water production cost Expenses (1KUS$) 5 Comprehensive depreciation expenses of fixed assets 5,798.25 6 Major overhaul expenses 1,207.97 7 Management expenses, selling expenses and other expenses 780.28 8 Other Annual operating cost 3,496.90 Annual total cost 25,321.10 Wherein: variable cost 14,372.48 Fixed cost 10,948.52 Unit water production cost (US$/t) 0.40 Wherein: variable cost of unit water production (US$/tt) 0.23

Total costs & expenses are all the costs and expenses of the production and operation within one year after the project starts production and operation (including outsourced raw materials, power, salaries, major overhaul expenses, etc. The normal annual total cost of this Project: US$25,321.10; unit water production cost: US$0.40/m3 as shown in table 9.4.

Based on the relationship with output changes, production costs are divided into variable cost and fixed cost. The normal annual variable cost of this Project: US$14,372.48; fixed cost: US$10.948.52

10.2 Financing Assessment:

10.2.1 Cash flow Analysis

10.2.2 Cost and Revenue Analysis Financial receipts and expenditure based on basic calculation statement of financial analysis are summarized in Table 10.5 as below:

Table 10.5: Financial Summary

S/N Item name Amount (x1000)

I. Financial revenue

Water fee income within calculation period 15yrs * 788,202.80

II. Financial expenses

1 Construction investment 276,739.50

2 Operating costs including electricity costs for 15yrs 274,723.20

3 Taxes 84,349.30

4 Interest expenses 30,579.70

Total financial expenses 666,391.70

III. Financial benefits 121,811.10



10.2.3 Financial analysis conclusion of project Based on the water rate of US$0.78/m3 in financial analysis, the before-tax FIRR of project investment is 6.69% and investment recovery period is 14.20 years. In addition, the following four aspects can effectively improve the economic benefits of this Project:

1. This financial analysis is temporarily based on the local electricity rate of US$0.229/kwh. If a more preferential electricity rate is obtained, then water production cost can be lowered.

2. This Project is predicted to start production in 2018. This financial analysis temporarily does

not consider the water rate adjustment factor of local government. If water rate is raised in future, this will increase the economic benefits of this Project and decrease government subsidy.

3. It is shown in Table 6.5 (Water Supply Capacity and Water Supply Guarantee Rate) that the water supply guarantee rate for the raw water supply capacity of 172,800m3/d is 95%, .

IF head loss between the dam and water treatment works can be reutilized to generated power by mini hydropower station, the economic benefit will also be improved.

10.3 Social benefit and impact

10.3.1 Employment During construction, the project will supply many work opportunities to local people, not only labor, but also engineers and technicians. After the completion of the project, there are work opportunities of operation in the water treatment works and Dam management & operation office. With enough water supply for Nairobi and Satellite towns, the economic in this region will grow rapidly, which will create many work opportunities. Taxation revenue As shown in table 9.5, within project period the project will bring USD 84.35 million tax which will increase the income of the government. Local economic development The project will lead to the growth of local economic development as bellows:

• Supply adequate water to Eastern parts of Nairobi, EPZ, Mavoko and Kitengela will guarantee their economic development.

• Direct Economic growth of the urban centres envisaged to be supplied by water from the dam therefore a step towards realization of vision 2030.



• Increased value of land in the project area. The project will attract more investment to the region hence leading to accelerated business growth.

• The project will ease the current water deficit in Nairobi City and the environs consequently promoting the country’s economic growth.

• The proposed project presents an opportunity for tourism, training and skill acquisition. • The goods will be sourced from local suppliers thus creating a ready market leading to

general economic growth. • Improved infrastructural services within the project area opening it up for development

opportunities. Human resource During construction, the local works can gain skills and experience. The client’s engineers and technicians also can get training and skills by knowledge transferring program. Inflow investment As indicated above in Local Economic Development, the project will attract mote investment to the region, such as real estate, tourism, farming, industrials, etc.

10.4 Environment Impact Assessment The environment impact assessment will be finalized before the commencement of works.

10.4.1 The Environment Impact Assessment Assignment The Ministry has carried out Preliminary Environmental Impact Assessment. This preliminary EIA report has identified real environmental impacts that could arise as a result of the proposed construction of the Ndarugu 1 Dam, assessed them and suggested measures of intervention to minimize the negative impacts.

10.4.2 Procedural steps of EIA The procedural steps involved in this preliminary Environment Impact Assessment include the following:

a) Scoping and development of the TOR using a variety of methods and tools; b) Identification of key stakeholders; c) Baseline Studies; d) Construction sites/premises inspection; e) Public consultations and public disclosure; f) Impacts identification and analysis; g) Development of mitigation/enhancement measures; h) Analysis of project alternatives; i) Development of the environmental social management and monitoring plan; j) Development of environmental and social monitoring program; k) Development of environmental management and monitoring plan.



10.4.3 The EIA Report Existing literature was studied. To get of information about community concerns on the Dam project, the expert interviewed community leaders and the general public along the project. Standard questionnaires, observations and discussions were the main techniques used to gather the required information (Schnell, R; Hill, B et al 1999). Focus Group discussion with small discussion groups within centers along the project area was also another technique used by the consultants to involve the public. The experts held various public meetings along the project area as well as impromptu interviews and discussions. The participants were communities and individuals living in close proximity to the project area, relevant stakeholders (Relevant Ministries and lead agencies). Local elders (chiefs, sub-chiefs), vehicle drivers, business people youngsters, among others With due consideration to gender, meetings were held mainly within shopping centers along the project area as well as establishments close to project area (school, churches). To facilitate the identification, prediction of environmental impacts as well as to give an indication of the significance of the identified impacts, the checklists were mainly used. Previous feasibility studies, EIA reports of related works are key sources of secondary data including:

i) Master Plan Report for Supply of Water to Nairobi and Satellite Towns –Mangat IB Patel and BCEOM 2012

ii) Environmental Impact Assessment and Audit Regulation 2009 - NEMA iii) Hydrological Report on Ndarugu River January 2013

Minutes of initial meetings held in the project areas were reviewed. The Construction of the Ndarugu 1 Dam was found to have both positive and negative implications as briefly explained in this section and exhaustively discussed within the EIA report.

10.4.4 Positive impacts There are a number of positive impacts, which will benefit the local community and the nation in general. The benefits of the project in the proposed area are both social and economic and are outlined below:

(i) The dam will be effectively used to regulate river levels and flooding downstream of the dam by temporarily storing the flood volume and releasing it later ensuring a sustainable supply of water to various users.

(ii) Increased value of land in the project area. The project will attract more investment to the

region hence leading to accelerate business growth. (iii) The project will ease the current water deficit in Nairobi, EPZ, Mavoko and Kitengela and

other Satellite towns



(iv) Promoting the country’s economic growth. The proposed project presents an opportunity for tourism, training and skills acquisition

(v) Creation of market for goods and services. This will be significant especially during

construction period. The goods will be sourced from local suppliers thus creating a ready market leading to general economic growth.

(vi) Provision of employment opportunities during both construction and operation phases of

the project. Impoundment itself may however be favorable to some fish species.

(vii) Improved infrastructural services within the project area opening it up for development opportunities.

10.4.5 Negative impacts The negative impacts associated with the Project’s construction include: Water abstraction; workmen’s camp and sanitation / hygiene issues; soil erosion and depletion of vegetation cover; impacts related to raw material sites and borrow pits; dust pollution; social conflicts; pressure and local resources; social pollution; waste pollution; noise and vibrations; discharge of storm water; oil pollution; climate change impacts; accidents; crime. However, the negative impacts which come along with the expansion of the Project can be adequately mitigated through the various environmental management tools within the Proponent’s reach namely: Cleaner Production Assessment; Life Cycle Assessment; Capacity Building; Eco-design; Corporate Reporting; environmental Management Systems and Plans; Environmental Impact Assessment; Environmental Sound Technology; Environmental Technology Assessment, Environmental Policies and adherence with the laws/various regulations.

10.4.6 Conclusion of EIA report The Environmental Management and Monitoring Plan (EMP) as set out in the document seek to point out measures that can be followed to address concerns raised by the EIA Report. These include all the environmental areas of concern some of which are material handling and storage, water supply, energy use, wastewater containment channels, keeping required records of equipment maintenance and solid waste management. The Construction of this project needs to develop a corporate environmental policy stating commitment, intentions and principles of action with respect to the environment including compliance with relevant environmental regulations. This will form a basis upon which the management of the dam will set its environmental objectives, policies and targets as in the environmental management plan. It is hoped that the management will comprehensively implement the recommendation as given in the proposed Environmental Management Plan to improve on their level of compliance when the project commences its construction & operation phase. These mitigations will not only be of benefit to the facility managers/owners, but will also assist other stakeholders in understanding and managing the environmental and business risks of operating the facility.



Mitigation measures have been proposed for all identified impacts, and an environmental and social management plan has been prepared. Mitigation measures to be included in the Bill of Quantities are drainage, provision of sign boards, road marking, road studs, guardrails, curbstones, bumps, gabions, scour checks, miter and cut-off drains, re-profiling of side drains, de-silting culverts, planting of grass and trees, HIV/AIDS awareness campaign, rehabilitation of materials sites, compensation for acquisition of land and making good after construction. Other measures (e.g. protection of water sources, minimization of dust) shall be specified in the conditions of contract and the technical specifications.

11. REPAYMENT ANALYSIS

11.1 Repayment methods The financing will be through BANK soft Loan and the National Treasury of Kenya shall, acting on behalf of our government, borrow and repay the loan on the ground of stable increase of GDP, fiscal revenue and water tariff.

11.2 Source of repayment There are three sources as bellows:

(1) Government fiscal revenue; (2) Water tariff; (3) Depreciation of the facilities

11.3 Repayment plan The repayment plan will be discussed between the Kenya governmental and BANK

12. RISK ANALYSIS AND MITIGATION PLAN There are many risks in the project. The project owner and the contractor are main parties in the project, so risks related to them are descripted here, and other risks are descripted briefly.

12.1 Project Owner Risks

12.1.1 Risk Identification Project risk contains political risks, country commercial risks, country legal risks, project development risks, construction/completion risks and operating risks, etc.



Table12.1 Risk Identification Description Small Medium High Political risks

Political support risks X Taxation risks X Expropriation /nationalization risks X Forced buy-out risks X Import/export restrictions X Failure to obtain / renew permits X

Country commercial risks Currency inconvertibility risks X Foreign exchange risks X Devaluation risks X Inflation risks X Interest rate risk X

Legal and regulation risk Changes in laws and regulations X

Law enforcement risk X Delays in calculating compensation X

Project development risks Bidding risks X Design risks X Planning delay risks X Permits approval risks X Land acquisition risks X Connection point risk X

Construction/ completion risks Delay risk X Cost overrun risks X

Construction/ completion risks (To be continued)

Completion risk X

Force majeure risk X

Delay risk X

Cost overrun risks X

Completion risk X

Work loss or damage risks X

Liability risk X

Performance risk X

Operating risks

Technical risks / breakdowns X



Description Small Medium High

Off-take risk X

Tariff risks X

Hydrological/climatic risks X

Water abstraction risks X

Cost escalation risks X

Management risks X

Force majeure risks X

Loss or damage of project facilities X

Liability risk X

12.1.2 Risk Allocation Table 12.2 Risk Allocation

Description Project

Company Insurance Company

Other contractors

Host Government

Political risks X X X X

Country commercial risks X

Country legal risks X

Project development risks X X

Construction/Completion risk X X

Operating risks X X X

12.1.3 Risk Description and Mitigation As shown in Table 12.1, there are no particular high risks expected. The risks assumed as medium like foreign exchange risk, inflations risk, interest rate, taxation planning, construction and cost overrun are not particular for the Ndarugu 1 project, but for every infrastructure project. Nevertheless, by strict and efficient project management these project development and construction risks can be extensively limited. General country commercial risk can hardly be influenced by the project. Therefore in the contractual and financial setup of the project these issues should be focused particularly. In the following section, in addition to the above tables some risks are described more in detail and possible mitigation factors are noted.



(1) Construction risks By their nature dam projects have significant construction risks arising from delayed completion and commissioning, costs escalation during construction period, logistical challenges and other implementation agencies risks. While Tanathi Water Services Board intends to execute competitive contracts with implementation agencies that mitigate most of risks associated with construction, factors beyond the control of TANATHI WSB and the implementation agencies might result in cost overturns to the detriment of TANATHI WSB. Mitigation factors: The Government of Kenya through the Ministry of Water and irrigation shall minimize the risks by constituting a Project Implementation Unit (PIU) headed by the Director of Water responsible for the Infrastructure Development and having representation from TANATHI Water Services Board and ATHI Water Services Board, and entering into agreements with the EPC Contractor selected from qualified firms from Financier Country. The Ministry of Water and Irrigation should also ensure that adequate base studies are carried out before entering into construction projects so that potential issues are known in advance. (2) Climatic conditions Some of TANATHI and ATHI Water Services Board's water sources are significantly affected by weather conditions, for example, dry years significantly reduce the water levels thereby impacting on the amount of water available for abstraction and the revenues recorded by Water Services Boards. Mitigation factors: To mitigate this risk there is a proposal to create water action groups that will be involved in catchment protection and should also monitor illegal abstraction upstream of the dam. (3) Liquidity risks and default risk in respect compliance with service agreements TANATHI and ATHI Water Services Board relies heavily on the timely payment by its water service providers in order to meet its legal obligations under the various service provision agreements between Boards and the Water Services Providers. Any non-compliance will have a direct impact on WSBs’ liquidity and businesses. Mitigation factors: A bulk Water Company will be established for this project whose ownership shall be the Nairobi County, Kiambu County and Machakos County. It will sell water in bulk to already established Ruiru Juja Water and Sewerage Company (RUJWASCO), Nairobi City Water and Sewerage Company (NCWSC), and Mavoko Water and Sewerage Company (MAWASCO). The Bulk Water Company will have a tripartite Service Provision Agreement with the both TANATHI and ATHI Water Services Boards including requirements for establishment of the Escrow Account Managed Jointly to meet the Loan repayment and Operation and Maintenance Cost of the Project. In Addition the Bulk Water Company will enter into offtake agreement with each of the Water Services Providers (RUJWASCO, NCWSC, and MAWASCO).



The Bulk Water tripartite SPA between the two boards (WSBs) and the Bulk Water Company (BWC) should be a valid, legal and enforceable contract between the BWC and WSBs. Any future SPAs should also be valid, legal and enforceable. Similarly Bulk Water Purchase agreement (Offtake agreement), should also be valid, legal and enforceable contracts guaranteed by the County Governments under whose jurisdiction the companies operate and the other party should have the legal remedies that are available under the relevant agreements. With regard to any liquidity risk, WSBs should minimize the liquidity risk by entering into SPA with WSPs that penalize the delays in servicing the Company's invoices. (4) Regulation of the water sector Activities in the water industry are subject to extensive regulation and supervision by the Water services regulatory Board on the behalf of the Government of Kenya. Such activities include licensing, competition, tariff controls, ownership, and other arrangements pertaining to the overall structure of the Sector. Changes in law, regulations or Government policy, or the implementation thereof, could affect the business activities and the results of the operations of WSBs. In particular, decisions of the regulators include tariff controls could adversely affect WSBs business, financial condition and operations. Accordingly WSBs is exposed to the risk that the tariff rates paid by WSPs might not be adequate to compensate it for capital invested. Mitigation factors: WSB should minimize the risk by negotiating agreements with BWC and WSPs that pay an adequate return for capital invested.

12.2 Project Contracting Risk

12.2.1 Political Risk Political risk is the risk which the international, domestic political, economic and technological fluctuations (such as war, civil strife and so on) bring to the project construction.

12.2.2 Price Risk Price risk is the risk which the economic factors related with project construction (such as changes of price and exchange rate) bring to the project construction.

12.2.3 Management Risk Management risk is the risk changes in project construction management functions and management objects (such as management organization, leadership qualities, management of foreign workers, etc.) bring to the project construction.

12.2.4 Construction Risk 1) The risks caused by nature force majeure include storm and floods; 2) The accident caused by fire and explosion; 3) The accident caused by design defects, manufacturing processes, or defective materials 4) The accident caused by workers and technical personnel due to their mishandling during the

construction process;


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5) The risk that the third party injury and property damage in the vicinity of the construction site or neighborhood during the construction process.

12.2.5 Risk Management Plan It is necessary to have a reasonable risk control for the development of this project. (1) Risk avoidance scheme Generally, during the project preparation stage or in the middle of the construction part, without affecting the overall project, taking some method to avoid risks is called risk aversion. It is general to take evasive countermeasures to the catastrophic risk of potential large losses and probability. Risk aversion can be divided into passive and active avoidance. Risk aversion usually appears as a regime in project management. But it can only avoid certain risks. Avoiding risks may lose the benefit of the project, and may generate new risks. There are several common risk avoidance approaches:

• Reduce technical risk through a rigorous bidding process to choose the right subcontractors or material and equipment suppliers;

• Prevent the project subcontracted to poor quality strict control engineering subcontractor by strict control engineering subcontractor;

• Plan and remove according to the actual situation, in the condition of meeting the requirements of engineering design requirement, as far as possible avoiding complicated geological conditions, construction and demolition difficult area.

(2) Risk transfer scheme The transfer of risk is often used and effective in the risk management of construction, such as providing performance guarantees for the engineering contract by providing its protective provisions, as well as the Construction All Risks Insurance. Due to the low cost of the first two methods, it is easier to implement and already has been widely used. Engineering insurance risk transfer will become the mainstream way. With the growing number of insurance works, more and more risk management experience has proved the efficiency of engineering insurance is very high, and can also resolve a wide range of risks. It has now been effectively used in the building construction industry.

12.3 Market risk There is a mature market in Kenya. The civil construction materials are abundant, other materials like pipes fittings, electromechanical equipment and plant; spare parts and accessories and construction equipment will be supplied from Financier Country

12.4 Labor union and employment Kenyans work hard and local residents support the construction of this project. The contractor also will try to employ as many as possible local labor, and supply good work condition to them. So the risk from the labor union and employment will be very low.



12.5 Product and technical risk The design of each facility buildings and apparatus all subjects to the functions and usage requirement. In order to improve the standardization and universal level of products and reduce the maintaining difficulties of daily use, the spare parts of these equipment are basically adopted to universal parts. Based on its advanced technology and rich experience, a Design and Build (DB) Company shall improve the design and process specifications to ensure the quality and reliability of all products. The Quality Assurance system of the DB Company from the financier country as well as its ISO9001 quality control system shall be applied throughout the Project execution period. Overall, the product and technical risk of the Project is fairly low and controllable.

12.6 Implementation / construction risk For the detailed design, the Construction and Design Company needs time to collect basic technical data and prepare detailed design and construction drawings, some of the equipment will be procured from a third country as well, which in the end may influence the completion time. Overall, the implementation and construction risk of this Project is fairly low and controllable.

12.7 Financing and repayment risk The financing will be through Bank(s) and the guarantee of the Financier Country Government and the National Treasury of Kenya shall, acting on behalf of our government, repay the loan on the ground of stable increase of GDP and fiscal revenue.

12.8 Economic context and financial framework (Macro-economic performance and stability)

In 2003，the Government put in place an aggressive programme to restore macroeconomic stability and then use this as the platform for accelerated growth and poverty reduction. The Economic Recovery Strategy for Wealth and Employment Creation 2003-07 ERSWEC identifies policy actions seen by the Kenyan government as necessary to spur the recovery of the Kenyan economy. The program was based on four pillars and the following five cross cutting themes:

Economic growth and poverty reduction Investing in human capital Rehabilitation and expansion of physical infrastructure Good governance Performance audit

Performance audit merits special mention as it has particularly been applied in the areas of education and health. The focus included putting in place measures to achieve 100 percent net enrolment at primary level; meeting the health challenge through the establishment of a comprehensive National Social Health Insurance Fund (NSHIF) to all Kenyans; and continuing the battle against the HIV/AIDS pandemic.



The country's fiscal performance has similarly been broadly satisfactory. The core objective of the fiscal strategy revolving around increasing pro-poor expenditure has been supported by increased Development Partner concessional assistance and grant flows on the one hand and expenditure restructuring, while containing debt stock within a sustainable and prudent level on the other. The public financial management system aims to facilitate the provision of essential public services to the people of Kenya by efficiently mobilizing public resources through the revenue and tax systems and channeling them to the most needed areas. Through this and other complimentary measures, fiscal performance has been satisfactory. Expenditure management has substantially improved and enabled the reorientation of public expenditure towards spending in prioritized areas of service, particularly education, health, security and justice infrastructure particularly for roads, energy, communication and water. Overall, Kenya is rated as a good performer in its macroeconomic reform effort. The favorable fiscal environment and other factors have led the Nairobi satellite towns to grow rapidly, which led to an increased demand for more water supply. Kenya like any other developing country also needs external resources primarily to supplement the domestic resources from its economy. External debt has been significantly reduced and is now at a sustainable level – so has been the dependence on donor assistance. The assistance the country receives is used to address the capital gap that arises from its development needs and acts as catalyst in the implementation of the national development programs as well as playing a complimentary role in helping the government efforts in poverty eradication. The country has set the year 2030 as a target date to become a middle income rapidly industrializing economy providing a high quality of life to all its citizens in a safe healthy environment. For the vision to be realized there will have to be massive investment in systemic reforms, infrastructure, and human and institutional capacity building. In this regard, external resources will be crucial in closing the resource gap that will arise from the resource needs and the available resources in the implementation of national development programs.

13. CONCLUSION

13.1 Significance and necessity to the country In order to meet water supply demand for Nairobi and the Satellite towns, it is necessary to carry out this project to ease the current water supply deficit.

13.2 Economic and social benefits The project brings good economic and social benefits to Kenya. Its cash flow in project period (15years) is enough for the repayment of loan, even has profit gained. It will bring employment opportunities and accelerate local economic growth and development of industries.



13.3 Project plan and preparation The project construction period is estimated for 3 years. This feasibility study, project proposal have been done, and the EPC contractor has also been procured for the project. Financing and repayment The Project is proposed to be supported by Soft Loan with minimum grant element of 30%. The detailed project budgeting and financing plan will be determined after negotiation with BANK. The repayment period is temporarily considered as 15 years, including 3 years’ grace period. The final repayment period and other detailed repayment methods will be determined after negotiation with BANK and the National Treasury of Kenya will be responsible for repay the loan from the Government Budget. With the stable social system and fiscal revenue, continuous GDP increase and profit produced from the project Kenyan Government has strong confidence for in-time repayment for the Chinese Government Concessional Loan.

13.4 Risks and control The risks in this project are low. Mitigation plan and risks management plan will be adopted during construction and operation period to minimize the risk. Overall, this Ndarugu 1 Dam Water Supply Project is feasible and shall contribute to the goals of Vision 2030. Therefore, we recommend this Project be granted and supported by BANK and Financier Country government at a cost of US$366 MILLION or €322 MILLION


Government & Nonprofit

NAIROBI-MAVOKO-KITENGELA WATER SUPPLY PROJECT - FEASIBILITY STUDY REPORT