![Pompe à vide et pointes filtrantes alignées vue rapprochée](https://www.dsl.fr/app/uploads/2020/08/rabattement-de-nappe-en-terrain-sableux.jpg)
Lowering the Water Table in Sandy Ground
Lowering the water table in sandy ground to build a wastewater treatment plant, the wellpoint technique was used
Context
Project Type :
Dewatering
Location :
Vézeronce-Curtin (38)
![Logo entreprise Perriol TP](https://www.dsl.fr/app/uploads/2020/08/logo-perriol-tp.gif)
![Logo entreprise VAL TP](https://www.dsl.fr/app/uploads/2020/08/logo-val-tp.gif)
Problem
- To construct a wastewater treatment plant, the customer requested that we lower the alluvial water table present at 2 m under the natural ground, with a height to lower of 2.40 m over an area of 1000 m². For the raising station, the water table had to be lowered by 3.40 m over an area of 400 m².
Solution
- Installation of 3 water table lowering assemblies by wellpoints:
- 1 for the feeder channel over a length of 100 m
- 2 water table lowering assemblies terraced for building the structures of the wastewater treatment plant (aeration tank and clarifier)
- 1 additional dewatering setup with boreholes of 10 m of 150 nominal diameter for the rasising station and the emptying equipment station
- Complete pumping installation:
- Power supplied by 2 generators 80 kVA one of which is back-up
- 3 vacuum pumps of 7.5 kW
- 200 m needle collector
- 100 m leader line
- 7 borehole pumps 4″
- 1 decantation vat
- Overall duration: 7 months
![Pompe à vide et pointes filtrantes alignées](https://www.dsl.fr/app/uploads/2020/08/rabattement-de-nappe-en-terrain-sableux-1.jpg)
![Pointes filtrantes avec une pompe à vide vue rapprochée](https://www.dsl.fr/app/uploads/2020/08/rabattement-de-nappe-en-terrain-sableux-2.jpg)
![Double étage de pointes filtrantes avec un puisard et 2 pompes à vide](https://www.dsl.fr/app/uploads/2020/08/rabattement-de-nappe-en-terrain-sableux-3.jpg)
![Double étage de pointes filtrantes avec un puisard](https://www.dsl.fr/app/uploads/2020/08/rabattement-de-nappe-en-terrain-sableux-4.jpg)