Marlborough Water Treatment Works

Marlborough Water Treatment Works

Marlborough Water Treatment Works


eight2O Partnership Alliance

Primary Client:

Thames Water Utilities Ltd


Marlborough, Wiltshire



Key Facts:

  • Water Treatment
  • Multi apparatus hazards including two strategic aviation fuel lines
  • Live working environment


Marlborough WTW is situated one kilometre south east of Marlborough off the Salisbury Road. Raw water is pumped from a suction well to be treated by super-chlorination and de-chlorination. Treated water is pumped by submersible borehole units to reservoirs at Salisbury Hill and Forest Hill.

This was a complex, technically demanding project undertaken in challenging circumstances. The site remained live and operational throughout the works. Only a small, restricted work area was available and access was limited. A substantial new housing construction site bounded the site. The two sites shared access ways. Work was undertaken on high pressure mains and in close proximity to multi cables, pipelines and mains including HV cables and two aviation fuel pipelines running to Gatwick and Heathrow airports.

The principal works comprised the design and construction of a run to waste pipeline; a 215 metre 315mm HDPE gravity main to divert waste process water and surface water run-off away from the site and back to groundwater via a new 32 metre deep soakaway borehole on the third party land. The scope included a new concrete diversion chamber, new headworks to the borehole in a chamber, actuated valves, a pressure sustaining valve, flow meters, MEICA equipment and construction works including new footpaths.