Athi Water Services Board (AWSB) is a state corporation established under the Water Act 2002. It is one of the eight Water Services Boards (WSBs) established under the Water Sector Reforms Programme through the Water Act (2002).The AWSB’s major functions include the planning, development, rehabilitation and expansion of water and sanitation services infrastructure, as well as asset ownership and the holding of water and sanitation assets within the area of jurisdiction.

Athi Water Services Board (AWSB) is a state corporation established under the Water Act 2002. It is one of the eight Water Services Boards (WSBs) established under the Water Sector Reforms Programme through the Water Act (2002).The AWSB’s major functions include the planning, development, rehabilitation and expansion of water and sanitation services infrastructure, as well as asset ownership and the holding of water and sanitation assets within the area of jurisdiction.

Reviewing the Nairobi City Master Plan
AWSB has commenced work to update the 1998 Master Plan for Sewers, Wastewater Treatment, and Sanitation that was carried out for the City of Nairobi. AWSB also seeks to expand the scope of the master plan to include selected satellite towns.The main goal of the updated master plan is to identify a sound and rational strategy for the development of sewerage services in Nairobi and the selected satellite towns over the next twenty-five years. This is being done to improve the quality of rivers and groundwater and to safeguard the health of the city’s residents.
The key objectives of the proposed master plan are:

a)    To prepare an investment programme of immediate, urgent works for the rehabilitation of existing sewers and sewage treatment plants in Nairobi and in selected satellite towns.
b)    To prepare a phased investment programme for the construction of new trunk sewers and secondary sewer networks over a twenty-five year planning period.
c)    To prepare a phased investment programme for providing new wastewater treatment facilities, and for increasing the capacity of existing facilities over a twenty-five year planning period.
d)    To carry out industrial effluent surveys in Nairobi and the satellite towns and to review the current pollution control strategies for industrial discharges.
e)    To review the feasibility study report prepared by AWSB and recommend a treated effluent and sludge disposal/reuse strategy for the effluent from DandoraWastewater Treatment Plant (WWTP) in Nairobi.

Nairobi Rivers Basin Rehabilitation and Restoration Programme Sewerage Improvement Project (NaRSIP)

The Project on Nairobi Sewerage Improvement is part of the larger Nairobi Rivers Basin Rehabilitation and Restoration Programme, which aims at enhanced, sustainable management of Nairobi’s rivers. The project also supports natural ecosystems regeneration, socio-economic activities and improved livelihoods.The African Development Bank (AfDB) funds the project.

Target areas
The improvement in sewerage network will target the following areas;
River Basins    Target Areas
Nairobi River Basin    Kawangware, Riruta satellite, Kangemi, Uthiru, Waithaka, Dagoretti, Kariakor, Kamukunji, Majengo, Gikomba, ShauriMoyo, Muthurwa, Ziwani.
Ngong River Basin    Upper Hill, Kenyatta area, Nairobi West, Madaraka Estate, Langata, and Nairobi Dam Area.
Mathare River Basin    City Park area, Muthaiga, National Youth Service area, Mathare 4A, Utalii, Mathare North, MathareMabatini, MlangoKubwa.
Kiu River Basin    Githurai 44, Githurai 45, GithuraiKimbo, Kahawa West, KahawaWendani, Mukia

Works components
The total works component of the NaRSIP project is approximately KES 4.5 billion, with progress currently at various stages of implementation. The works are divided into five works components, which are being implemented simultaneously.
The current various works components are as shown below:-

a)    Lot I – Construction of Kiu and Dandora Estate Trunk Sewer and Expansion of Dandora Wastewater Treatment Plant Construction Contract
The works included as part ofLot I are located inRuai and along the Eastern Bypass up to KahawaWest Thika Road and are as follows:

River Basin    Description    Length (m)    Areas Served
Nairobi & Kiu River Basins    11 No. Anaerobic Ponds of size 63 m x 93 m, Construction of 1 No. Sewage Pumping Station & 2.0 km DN 825 mm steel pipe   
n/a    Nairobi, Ngong, Kiu, &Mathare River Basins
Nairobi River Basin    Dandora Estate Box Culvert Sewer 2850 mm x 1700 mm    2,890    Nairobi, Kiu, Mathare, Ngong Rivers
Kiu River Basin    Riara River Trunk Sewer (2.7 km DN 600 mm GRP pipe and 1.5 km DN 675 mm)    4,200    Githurai 44, Githurai 45, GithuraiKimbo, Kahawa West, KahawaWendani, Mukia
    Kiu River Trunk Sewer (3.3 km DN 675 mm & 3 km DN 900 mm)    6,300   
    Kiu River Outfall Trunk Sewer (3.0 km DN 1050 mm and 4.6 km DN 1350 mm)    6,600   
Reticulation Sewers ranging between DN 300 & DN 450 mm    10,000    Nairobi &Kiu River Basins

b)    Lot II – Construction of Mathare, Nairobi and Ngong Rivers Trunk Sewers
The works under the ‘Construction of Mathare, Nairobi, and Ngong Rivers Trunk Sewers (Lot II)’ are located in Kawangware, Riruta Satellite, Dagoretti, Nairobi Central Business District and Mathare areas and are as follows:Construction of 22 km of DN 1200 / 375 mm Trunk Sewers; and Construction of 32.5 km of DN 450 / 300 mm Reticulation Sewers.
Detailed breakdown of the works is presented in the table below.

River Basin    Description    Length (m)    Areas Served
Nairobi River Basin    Nairobi River (Dagoretti) Trunk Sewer Extension DN 450 / 375    6,842    Kawangware, Riruta Satellite, Kangemi, Uthiru, Waithaka, Dagoretti, Kariakor, Kamukunji, Majengo, Gikomba, ShauriMoyo, Muthurwa, Ziwani.
Kangemi Reticulation Sewers DN 450 / 300    5,750   
KawangwareWaithaka Reticulation Sewers DN 450 / 300    7,850   
Uthiru Reticulation Sewers. DN 450 / 300    2,450   
Dagoretti Reticulation Sewers. DN 450 / 300    1,650   
Nairobi River Basin    Riruta North Trunk Sewer Extension DN 450    1,781    Kawangware, Riruta Satellite, Kangemi, Uthiru, Waithaka, Dagoretti, Kariakor, Kamukunji, Majengo, Gikomba, ShauriMoyo, Muthurwa, Ziwani.
Riruta Satellite Reticulation Sewers DN 450 / 300    3,050   
River Basin    Description    Length (m)    Areas Served
Nairobi River Trunk Sewer Duplication DN 1200    4,343   
Ngong River Basin    Rehabilitation of South Nairobi Dam Trunk Sewer DN 450 / 375    1,025    Langata, South Nairobi Dam, Kibera
Kiu River Basin    Githurai 44 Reticulation Sewers DN 450 / 300    2,400    Githurai 44, Githurai 45, GithuraiKimbo, Kahawa West, KahawaWendani, Mukia
KahawaSukari Reticulation Sewers DN 450 / 300    5,200   
River Basin    Description    Length (m)    Areas Served
KahawaWendani Reticulation Sewers DN 450 / 300    850   
Mathare River Basin    Mathare 4B Reticulation Sewers. DN 450 / 300    3,300    City Park area, Muthaiga, National Youth Service area, Mathare 4A, Utalii, Mathare North, MathareMabatini, MlangoKubwa.
Reconstruction of Mathare River Trunk Sewer    6,714   
Duplication of Getathuru Trunk Sewer DN 600 / 525    1,133 

c)    Lot III – Construction of Dandora, Kangundo Road, Kibera, Upper Hill and KirichwaDogo Trunk Sewers
The works under Lot III are located in Dandora, Kibera, Upper Hill, Kangundo Road and KirichwaDogo and are as follows:
River Basin    Description    Length (m)    Areas Served
Ngong River Basin    Construction of Kangundo Road Trunk Sewers, DN 600mm    4,300    Saika, Kagundo Road, Njiru
    Duplication of Kibera Trunk Sewer, DN 750 to 1050mm    4,700    Otiende, Langata, Kibera, Highrise, Mbagathi, T-Mall, Madaraka Estate, Nairobi West, Industrial South B, Mater Hospital Area
    Duplication of Upper Hill Trunk Sewer, DN 750mm
    2,000    Kenyatta National Hospital, Upper Hill, Madaraka, Bunyala, Nyayo Stadium, Nairobi West
Nairobi River Basin    Construction of KirichwaDogo Trunk Sewer, DN 300 to 600mm    4,700    KirichwaDogo, Lavington Area
    Duplication of Dandora Estate Box Culvert, 2850 mm x 1700 mm    1,800    Nairobi, Kiu, Mathare, Ngong Rivers
Reticulation Sewers, DN 300 mm    1,000    Nairobi &Ngong River Basins

d)    Lot IV – Rehabilitation of Kariobangi Wastewater Treatment Plant
Lot IV works aim at rehabilitating the Kariobangi conventional wastewater treatment plant to its original operating capacity.
The Kariobangi works are of conventional design, with an inlet works comprising screening, grit removal and flow measurement, followed by primary sedimentation, biological filtration and final settlement in humus tanks.  Combined settled, primary and humus sludge from the primary sedimentation tanks is treated in primary and secondary digestion tanks before being dewatered on sludge drying beds. 

The design capacity of this plant is 32,000 m³/day, but it was constructed in the early 1960s and it is now entirely non-functional due to mechanical and electrical breakdowns.  The fabric of the building works is also seriously defective.  The current wastewater flow that passes through the plant has been estimated as 12,000 m³/day.

e)    Lot V – Construction of Ablution Blocks in Nairobi Informal Settlements
Here, the objective is to construct 100 ablution blocks in areas targeted for sewers improvements under the Nairobi River Basin Rehabilitation and Restoration Program: Sewerage Improvement Project.

The most recent strategic plan for wastewater facilities in the city, entitled Nairobi Master Plan for Sewers, Sanitation, and Drainage, was undertaken between 1994 and 1998 under the Third Nairobi Water Supply Project.  The consultants comprised a consortium of local engineering consultants in association with SWECO.  The twenty-five year planning period for the study was 1995-2020. 

The study reconfirmed the Dandora Estate site at Ruai as the principal wastewater treatment site for the city and that waste stabilisation ponds should continue to be the preferred treatment technology for future extensions to the treatment facilities. Plans were proposed to increase the sewerage coverage by extending the sewerage network to include the newer developed areas of the city.

Unfortunately these plans were not implemented until 2008 when Athi Water Services Board initiated their revival with the implementation of the World Bank-funded Gatharaini Trunk Sewer Projects. This acted as the pilot to the current NaRSIP project currently under implementation.

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