Lowering the Water Table by Needle-Type Filters
Lowering the water table by needle-type filters to install gas channelling under a roundabout
Context
Project Type :
Dewatering
Location :
Moirans (38)
Problem
- To install gas channelling under a roundabout, the client needed to dig an entry trench and an exit trench on either side of the roundabout, to enable a micro-tunneller to do the drilling. To do this, it was necessary to lower the water table by 3.50 m.
- Considering the fineness of the equipment present, monitoring the suspension materials was undertaken during pumping so as not to destabilise the existing highway.
Solution
- Lowering the Water Table by Needle-Type Filters
- Using our drilling mast on 10 T excavator
- Height lowered: 3.50 m
- Creation of a first curtain of needles from a preliminary trench of 1.50 m under the natural terrain, then a second curtain by jetting, at 3m depth
- Area of trenches: 24 m²
- Complete pumping installation:
- 1 line of needles along the trench
- 1 vacuum pump
- 2 generators, 1 of which back-up
- 20 metres of riser pipe
- 1 decantation vat
- Remote monitoring of pumping by flow meter, with on-call service
- Monitoring suspension materials
- Duration of the site: 2 months
