“Ganay” flood relief basin (France)
Verification of the complex hydraulic operation of the storm basin feeders
Client: Vinci Construction - Model scale: 1:20
Context
A 50,000 m3 wastewater retention pond, which is able of filling in one hour (14 m3/s of flow) to relieve the Géolide wastewater treatment plant in wet weather: this is the extraordinary underground structure that was built in Marseille, on the right-of-way of the Ganay sports complex. Below the stage is Outfall No. 1 of the city’s sewerage network, dating from the 19th century, and a new collector is now added to this outfall to collect water during heavy rainfall events. ARTELIA laboratory was commissioned to build and study the hydraulic physical model of the water supply structures of the basin, in order to verify its proper functioning for the entire range of hydraulic conditions expected.
Description of the physical scale model
The model represents the following components :
- The structure diverting flows from the existing storm sewer outfall to the basin
- The sewer connecting the diversion structure to the basin
- The basin equipped with safety weirs, screen rakes and a vortex drop shaft
Aims of the physical scale model
The objective of the model is to check and optimise the operation of the structure.
The diversion structure must have an inlet capacity of 14m3/s, whatever the conditions inside the basin (clogged screen rakes, basin filling percentage, etc.). It will also provide a greater understanding of complex hydraulic phenomena (flows in the vortex drop shaft, local head losses, flows on weirs under lateral and dissymmetric inlets, etc.)