Limiting storm water overflow and pollution to protect Biarritz beaches

The seaside tourist destination of Biarritz on the southwestern coast of France is home to some 30,000 people, but that number quadruples in size during peak summer months. The municipality's wastewater, which is being managed by the Basque Country Agglomeration Community, is collected along with rainwater and put through the same treatment process before being released back out to sea.

While the city has significant water storage and processing facilities, the network was being overwhelmed by an unprecedented increase in rainfall occurring in the region in the past decade. Frequent, more intense storms were causing overflows of the sewage system. Subsequently, the wastewater diluted by the runoff flowed partly into the sea and polluting beach areas. These events require the preventive closure of beaches due to unchecked pollution, posing major health and economic consequences for the city's tourism sector.

To address this increasingly critical problem, the Basque Country Agglomeration Community chose to implement the AQUADVANCED® Urban Drainage solution from SUEZ. Its Advanced Control Module is a predictive system that provides a global overview of wastewater network operations and analyses real-time data gathered from installed network sensors and weather forecasts. This tool enables the Basque Country Agglomeration Community to assess the impact of rainfall in terms of volume and pollution potential even before it lands.

The software processes the data, calculates the scenarios, and gives operators up to an hour's notice on the risk of storm water retention tank overflows that could result in beach water being polluted. At the same time, it also suggests the best strategies for optimising stored water and reducing untreated water discharge.

The Collectivity has built a new storage basin of approximately 10% of the existing storage volume and AQUADVANCED® Urban Drainage, providing 24/7 surveillance from the sewage system, has enabled the Basque Country Agglomeration Community to reduce polluted water discharge into its beaches by 30% to 40% by predicting the impact of impending rainfall and its related polluted overflows. This helped the tourist area to reduce public beach closures, as well as accelerate its re-opening times. These conclusive results, which resulted in overall better water quality for the municipality, give the client an impetus to further invest in this smart solution.