New water intake adapted to flood conditions
The Bataille water intake in the Hérens valley is no longer vulnerable to the onslaught of debris flows. HYDRO has replaced it with a model better suited to its environment.
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Location: The Bataille intake is located upstream of the La Luette dam in the Hérens valley. It collects water from the Torrent de la Mounire and conveys it to the La Luette dam. The accumulated water is then turbined at the Forces Motrices de la Borgne power station in Bramois. |
During a storm in 2021, a debris flow engulfed and partially destroyed the intake. Lateral in design, with a retaining wall, the installation proved ill-suited to prevailing bed load conditions. The mechanical components were swept away and the rubble penetrated several metres into the feeder pipe.
State of the intake after the debris flow. Part of the catchment chamber can still be seen on the right.
To improve its performance and limit the risks associated with repeat flooding, the intake has been replaced by a different model of the Tyrolean type, capable of handling a flow of up to around 130 l/s. Placed in the river bed without obstructing the passage of sediments, it provides better resistance to debris flows. The new intake also incorporates a Coanda-type screen, which reduces maintenance through its “self-cleaning” properties.
Cross-section of the Tyrolean intake fitted with a Coanda screen.
The reconstruction work took place in November 2023 amid challenging weather conditions (snow, rain). Nevertheless, the deadlines were met and the quality of the work ensured.
The catchment chamber being moved to its final position using a spider excavator.
A backhoe was used to move the steel catchment chamber to its final location in steep forest terrain, where it was laid on a pre-prepared reinforced concrete foundation.
View of the catchment chamber in situ.
Upstream of the catchment, an approach ramp was built using rock armour to ensure the stability of the river bed and to slow any future debris flow. A buffer basin was also built downstream to prevent scouring.
General view of the water intake.
Four months after entering service, the intake is working perfectly. The new installation has considerably reduced the time required to maintain and clean the screen. It also withstood last winter’s floods without a hitch.
Finally, to meet the requirements of the building permit, consultants specialising in biology were commissioned. Their advice enabled us to integrate the structure as effectively as possible, so as to minimise its impact on the environment.
