Integrated sanitation program for Antananarivo

The already densely populated urban community of Antananarivo is experiencing significant demographic growth. A large proportion of the population lives in very precarious conditions. Against this backdrop, the sanitation system is experiencing organizational and functional difficulties, mainly due to institutional disorganization and a lack of budgetary resources dedicated to this sector.

This project is part of a general program to improve the Antananarivo urban area and its urbanization. Its main objective is to help improve health and social conditions for current and future residents. To improve the sanitation service throughout the city by 2035, it aims to develop an urban planning tool and an intervention framework that will make it possible to:

• reduce the risk of flooding**, which regularly affects many of the city's poorest residents,
• improve wastewater and excreta management**.

As part of this project, BRL Ingénierie drew up a master plan for wastewater and stormwater treatment in the Antananarivo urban community. It covers technical, institutional and organizational aspects. To carry out this mission, our teams studied the hydraulic functioning of the flood plain and defined the development work to be carried out on the downstream watercourses.

A first phase of emergency work was carried out, for which we carried out all the technical studies and supervised the work. A second phase of priority work was studied. The assignment was divided into two stages, the first of which included :

• institutional aspects: identification and analysis of the modes of intervention of the various players present in the sector, areas of overlap and shortcomings, and resources deployed;
• analysis of the influence of the downstream hydrographic system: with a counter-assessment of previously established work programs and a study to improve downstream flow conditions beyond the Antananarivo plain;
• study of the main hydrographic system: construction of a model of floodplain functioning and identification of the works required to ensure an appropriate level of protection;
• definition of a first stage of works (emergency works costing 12 M€); The second stage involved a phase dedicated to the strategic programming of drainage works, and a project management phase (monitoring of urgent works and preparation of tender documents for priority works). This phase included
• master plan for stormwater, wastewater and excreta ;
• preparation and supervision of works;
• environmental and social studies for the works program.