Mât de forage sur pelle hydraulique et aiguilles filtrantes

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)
Logo entreprise SPAC Logo entreprise GRT GAZ

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
Fosse de sortie rabattement de nappe aiguilles filtrantes
Techniciens DSL qui enfonce l'aiguille filtrante dans le sol
Technicien DSL qui ins
Fosse d'entrée rabattement de nappe aiguilles filtrantes