gpa_east_africa_case.. - GRID Africa GeoPortal - UNEP

Up-stream runoff• Hoti-hoti river basincatchmentKibarani dumping site(industrial wastes)Coastal and marineecosystemsShip wastes• Kilindini PortNote: Author's summary based on information from the National Report2. Estimated Cost of Proposed ActionsMombasa District Sewerage SystemResponses to wastewater pollution problems in Mombasa have long been delayed and majorinfrastructure projects planned for implementation in the past have not been constructed.According to information provided in the National Report, construction of the MombasaDistrict Sewerage System is now proposed for the coming 5-10 year period. The first stage inthe construction of the system is the Changamwe Sewage Treatment Plant to serve theMombasa Municipal Council Area. The Master Plan study for the treatment plant wassponsored by the City Council, carried out between 1974-1976. The reliminary designsprovided also for the construction of the main sewerage system, as part of the whole ofMombasa District, in three phases, 1976-96, to rehabilitation of the existing but inoperativeprimary wastewater collection system for a population of 77,000 in Chaani UpgradingScheme, Changamwe Estate and Mikindani Site and Service Scheme, and extending thenetwork to connect an additional residential population of 27,000 in the West Mainland andthe industrial area of Changamwe.As the project has not been implemented, and is included as part of the proposed MombasaDistrict Sewerage Syetem, technical information and details about its cost and phasing arescattered and unreliable, for the purposes of this Cost-benefit Study, the proposed project isconsidered as a single overall project. It is hoped that some of the conclusions of this Studymay illustrate useful approaches to defining priorities, alternative solutions and relatedfinancial and socio-economic costs and benefits considerations.The total capital cost of the Mombasa Sewerage Project was estimated 26 years ago atabout $10.0 million. The Changamwe Division section was then estimated at KSh. 111.0million ($1.4 million). However, the most recent cost estimate for the Changamwe Divisionsection is for $10.0 million (KSh. 730.0 million), that is a cost adjustment ratio of 7.14.Applying this ratio to the whole project for the other Divisions, it would follow that theestimated cost of the whole project is now roughly about $71.0 million: Phase I costestimatedat $10.0 million, Phase II at $15.5 million and Phase III at $45.5 million. Likewise,the annual operating cost for the Changamwe Division Project is estimated at $510,000,representing about 5% of the present estimated capital cost. However, an updated costestimate obtained from Mombasa City Council for the construction of the overall Districtsystem raises the capital cost to $120.0 million.According to existing information the proposed District Sewerage System will cover thefollowing areas and components:• Mombasa Island. Extension of the existing sewerage system to cover the entire island toprovide for pre-treatment of sewage before disposal at deep sea outside the reef at Nyali.It is planned to serve the Central Business District, Majengo, the area of the CoastGeneral Hospital and Kilindini Port.• North Mainland. Collection of sewage from the entire mainland to a treatment plantlocated at Bamburi and disposal of pretreated sewage to the deep sea outside the reef,extension of the collection network to Port Tudor and the enlargement of the treatmentplant and extensions to the Bamburi works and an additional out-fall pipe.• West Mainland. Construction of the collection network from Mazeras, Miritini andChangamwe and connection to the existing treatment plant at Changamwe for a sea out-Final Draft Report – Cost Benefit Case StudiesGPA Strategic Action Plan on Sewage, October, 200019