October 18th, 2021
Soletanche Bachy brings its expertise to water and sewerage projects | Part 1: Water capture and storage
Soletanche Bachy plays an active role in numerous projects allowing the storage and collection of raw water. Here are three large-scale projects completed in France and the United Arab Emirates…
Water capture and storage – an essential first stage in the water cycle!
Water adduction is the starting point for any collective water and sewerage network. Raw water is carried via collection wells or pumping stations to a treatment plant where it will be made drinkable.
Restoration of a storage basin in France
At Marly-le-Roi in Yvelines, leaks in the Deux Portes storage basin were reducing the operating volume of this raw water treatment plant. Repair work was therefore initiated to restore the original volume. Soletanche Bachy France contributed to the project by enclosing the basins in watertight Trenchmix® walls up to 9m thick.
The water is therefore stored in tanks of various sizes and shapes, either underground or on the surface. As in Port Marly, for example, a neighbouring town where Soletanche Bachy France has built an underground circular basin with a storage capacity of 600m3, along with its ancillary structures, also underground.
The basin has been constructed from a diaphragm wall, 23m deep and 0.6m thick. The gaps between the panels have been made watertight with CWS® seals. A groundwater drawdown system with a single pumping well has also been installed to ensure the hydraulic stability of the bottom of the excavation and the completion of dry earthworks.
The site is bordered directly by the Seine on one side and a busy street on the other. The teams had to adapt to minimise disturbance while also closely monitoring the water table and the river level throughout the project (flood zone).
What is Trenchmix ®?
Trenchmix® is a Deep Soil Mixing process which involves digging continuous trenches and mixing the excavated soil with a binder. The process has numerous advantages. For example, Trenchmix® is not very environmentally disruptive, can be completed rapidly and provides excellent mixing permeability, better than a grouting wall.
Construction of an underground water reserve in the Emirates.
In the United Arab Emirates, Zetas, a Soletanche Bachy subsidiary, installed and operated a borefield for one year to test its effectiveness. It was the first stage in an ambitious project whose goal is to build up a reserve of groundwater by pumping it from a captive aquifer in the heart of a desert region. Eventually, it will therefore serve as a natural water reservoir – a strategic structure for the nearby urban area.
The project included the boring, construction, development and testing of 42 exploration wells and 42 observation wells.
After boring the wells, wireline coring was carried out in five exploration wells to a depth of 200m and six others to a depth of 72m, as well as geophysical borehole logging of 61 wells.
Pumping tests, progressive drawdown tests and discharge tests were carried out, as well as water sampling from the exploration wells.
Finally, the teams built a test infiltration basin with constant-rate pumping.
Did you know?
An aquifer is a reservoir of originally porous or cracked soil or rock, containing groundwater and sufficiently permeable for water to circulate freely.
Expertise to support water and sewerage projects
Via our subsidiaries all around the world with expertise in foundations and soil technologies, Soletanche Bachy is involved at every stage of water management, through the construction and maintenance of water collection and storage structures. These can be delivered “turnkey”, from the design and execution of the foundations to the civil engineering works and delivery.
