Cramptons Road Water Treatment Works

Upgrade of Cramptons Road water treatment works (WTW)

Project outline 

This extensive upgrade of South East Water’s Crampton Road water treatment works at Sevenoaks, Kent formed part of the South East Water (SEW) £390m AMP5 investment programme.

Cramptons Road produces treated borehole water, which is pumped along mains to service reservoirs at Riverhill and Solefields.  SEW commissioned Murphy to conduct the design and construct a new building to house the new high lift pumping station, MCC, chemical storage and Dosing equipment, all associated suction and delivery pipework, chemical dosing and related water treatment arrangement. 

Key challenges

The pumping station needed to remain operational throughout the works.  The main construction challenge was the high number of partial or total plant shutdowns needed while installing new pipe connections.

Project delivery and innovations

Our commissioning and testing plan was devised with SEW to ensure it met all requirements and we met regularly with the operational staff to build a clear and thorough understanding of the old and new assets and the transition. 

Existing infrastructure due for replacement was leaking onsite, creating significant groundwater levels.  The team reviewed the temporary works and installed cofferdams rather than trench boxes.  To ensure the leaking infrastructure wouldn’t cause additional problems, the team negotiated with SEW to replace the pipes – this saved cost and minimised waste.  Other key features included:

  • connection to Riverhill Reservoir delivery mains was extended by 80m to bypass redundant fragile pipework
  • some flange connections involved new metric sized pipes bolted to the original imperial pipework
  • directional drilling was used to install pipes running beneath the site’s access road to ensure uninterrupted use for residents

Murphy was contractually obliged to provide six to ten weeks’ notice to SEW to have shutdowns approved.  However, in practice, close collaboration ensured convenient dates were agreed well in advance and constantly reviewed.   Detailed statements were provided to SE Water for each shutdown and loss of supply averaged between six and eight hours, predominantly during the night.   

Access to the site was shared with residents of a local housing estate.  At the beginning of the project we held a residents meeting to explain the works and transport requirements and set clear expectations.  We further fostered relationships by meeting regularly with residents throughout the project and by maintaining the shared access road.

The refurbished WTW is now one of South East Water’s most technically advanced water treatment works.  All lessons learned were collated and shared with SEW and their relevant partners for use on future projects.

Key facts

  • Cramptons Water Treatment Works ensures the quality and reliability of 565 million litres of potable water a day to a population of 2.1million people.
  • The site is home to great crested newts and bats, which were carefully protected throughout the project.
  • Over 2km of new pipework was integrated into the original site layout.



South East Water



Completion Date

October 2015



Capabilities Demonstrated

  • Pipelines
  • Engineering
  • Building
  • Design

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