M3 J2-4A: Smart Motorway for Balfour Beatty, Highways EN

As part of our £2.8m contract with Balfour Beatty, Davey Civils installed a challenging temporary works scheme, which allowed the construction of an interceptor chamber.

The temporary works consisted of:

  • Dewatering of Camberley Sands & River Terraces
  • Installation of a 16 x 7 x 5m deep cofferdam to exposing a live 1.2m diameter concrete road drainage outfall pipe
  • Support of the existing outfall pipe
  • Provision of an over-pumping solution, to allow the construction of a reinforced concrete interceptor.

Early engagement in the scheme, resulted in the development of an innovative pipe support solution allowing almost unhindered access for the construction of the interceptor. Davey Civils also provided dewatering of the surrounding grounds strata’s, reducing water ingress through the piles and the risk of ground settlement to the adjacent motorway.

The contract used was New Engineering Civil Contract (NEC) 3 Option B priced contract with bill of quantities.

Our over-pumping configuration utilised a telemetry system which measured flows. During times of high flows additional pumps were turned on by the telemetry to ensure the cofferdam remained dry throughout the duration of the works.