ELCIMAÏ ENVIRONNEMENT is delivering a set of ponds and a pumping station
Elcimaï is constructing a series of retention basins and a pumping station in the municipality of Loos-en-Gohelle (62), which has no natural waterways, to manage stormwater overflows during heavy rainfall. However, since it mixes with wastewater in a largely combined sewer system, this water is polluting. To prevent this water from seeping into the groundwater, the Lens-Liévin Urban Community (CALL) commissioned Elcimaï Environnement to design a solution.
Elcimaï Environnement’s Project
The engineering firm specializing in ecological transition is currently finalizing the delivery of a set of storage basins, as well as a return basin and a stormwater basin with infiltration. Elcimaï Environnement designed and supervised the construction of an underground structure with diaphragm walls. This first basin, with a capacity of 7,000 m³, intercepts runoff water before it spreads into the natural environment. It channels the water to the metropolitan area’s main wastewater treatment plant. Additionally, a second landscaped basin, with a capacity of 6,500 m³, is designed to handle exceptionally heavy rainfall.
As the project contractor, the teams at Elcimaï Environnement and their partner SB Conseil began work in 2018. Obtaining the necessary administrative permits proved complex, as they involved the water table.
“While this type of project is common in northern France—a humid region with few perennial watercourses— the facility delivered in Loos-en-Gohelle is of a rare scale, especially since the town has only 7,000 residents,” comments Christophe Yzet, head of development, water, infrastructure, and hydropower at Elcimaï Environnement. The site will be fully revegetated, and since the main structure is buried and covered with grass, the complex will blend almost entirely into the landscape.
“Water management is a major priority for the Lens-Liévin Urban Community, which combines significant investments with awareness-raising initiatives for all residents,” explains Pierre Sénéchal, its vice president in charge of water and sanitation. In 2023, it completed the renovation of the Loos-en-Gohelle pumping station. A €6.1 million project (including tax), funded by the CALL, the Artois-Picardie Water Agency, and under the DSIL program. The work triples the facility’s capacity, which consists of a wastewater storage basin and a clear water infiltration basin. The system improves sanitation, reduces the risk of flooding, and preserves water resources as well as water quality.”
The work was carried out by the companies BALLESTRA, SPIE Fondations, SADE, CLAISSE Environnement, and RAMERY.