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)
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
