Stereau, the engineering subsidiary of the Saur group, has been present on Reunion Island for over 15 years, applying its expertise to the development and rehabilitation of the island’s drinking water infrastructure. With great success.
A paradise of green tourism with a highly contrasting climate, Réunion Island is subject to heavy rainfall during the austral summer (November to March). In the absence of appropriate treatment, these intense rainfall episodes lead to a deterioration in the quality of the drinking water distributed to the people of Reunion. Added to this is a structural delay in the construction of potabilization units and equipment capable of treating surface water (more than half of the island’s water withdrawals), which is less well protected from pollution or turbidity phenomena. To remedy this situation, the public authorities have been providing aid to local authorities for over ten years to enable them to upgrade their facilities to the required standards, with the ultimate aim of equipping every commune on the island whose water is drawn from surface waters with potabilization units.
In the city of Le Tampon, Stereau has won the design-build contract for Reunion’s largest water treatment plant, awarded by the Communauté d’Agglomération du Sud Ile de La Réunion (CASUD).
With a capacity of 30,000 m3/d, the new unit will be commissioned by the end of 2022 and will treat water pollution from the Pont du Diable, Hirondelles, Edgar Avril and Puits du Bras de la Plaine surface water catchments. A population of almost 75,000 in the communes of Le Tampon and Saint-Joseph will thus be supplied with high-quality drinking water all year round.
The construction of two 5,000 m3 reservoirs on the same site will enable production to be adapted to consumption needs. The additional storage capacity will also boost CASUD’s ability to cope with water shortages in the region. The partnership with Cise Réunion will also enable the plant to be operated during the year of industrial commissioning. Distribution of treated water to the population of the central buffer will take place in mid-December.
In the Plaine des Palmistes city, in 2021, Stereau was awarded a contract by the Communauté Intercommunale Réunion Est (CIREST) to rehabilitate the Bras des Calumets drinking water plant (100 m3/h), with the aim of remedying problems of turbidity, color (COD) and degradation of water quality during rainy episodes. Work began in April 2021, with the chosen technological process consisting of clarification, sand filtration, disinfection, elimination of color and organic matter. Disinfection has been stepped up in particular to eliminate parasitic bacteria and viruses naturally present in raw water. “In the event of a resource shortage, or if one of the resources is too high in organic matter, and in order to limit the use of reagents, the borehole resource will be used to compensate for the volumes to be treated,” explains Christophe Tardivet, Stereau’s Director on Reunion Island. Distribution of the treated water is scheduled for the end of November 2022.
Other projects entrusted to Stereau on Reunion Island are currently underway, including:
- equipment work on the pumping station of reservoir 13 in the commune of Saint-Joseph on behalf of CASUD. This work to reinforce the drinking water supply will make it possible to secure and increase the filling of a storage reservoir known as R14, improving the availability of drinking water to subscribers in the area.
- the installation and connection to the Bras de la Plaine perimeter of the Ligne Paradis borehole in the commune of Saint-Pierre. With an operating flow rate of 150 m3/h, the borehole pump will be installed at a depth of 200 m. At the end of a ten-month construction period, this borehole will secure the island’s water requirements for agricultural irrigation.
- rehabilitation work on the lift stations on route nationale 1A, in the commune of Saint-Leu. Currently in the design and equipment procurement phase, this project will renovate all the lift stations in the center of Saint-Leu. Work will start in February with the installation of the first substation.
