BTS | HARDING PRIZE COMPETITION 2025
- WATER TREATMENT IN TUNNELLING AT CHILTERN TUNNELS
SUSTAINABILITY INNOVATIVE
The Harding Prize Competition is named after the founder of the British Tunnelling Society, Sir Harold Harding, and is for entrants under the age of 33. Shortlisted papers were presented to the BTS evening meeting on 20 March, at the Institution of Civil Engineers, in London.
Christopher Prince, STP and WTP Engineer for Bouygues TP at Align JV, was runner-up in the 2025 Competition with a paper entitled ‘Innovative sustainability - Water Treatment in Tunnelling drawn from Experiences of Recycling water whilst constructing the Chiltern Tunnels’
1. EXECUTIVE SUMMARY Water, the most precious and relied upon commodity on the planet; yet despite its significance it is taken for granted. This paper follows the actions I took during my tenure at Align JV working with our supplier to launch the first full-scale testing of a polymer in the Slurry Treatment Plant (STP), the success of which has seen it produced in the UK and used as the sole treatment option across other tunnelling projects. The paper then focuses on the development of my
role as I gained interest in the next steps for the water being discharged from the STP; to lead writing the specification of a new Water Treatment Plant (WTP), taking the specification to tender, awarding and then managing the chosen sub-contractor for the new WTP. The work resulted in a new water stream being created for use and, as such, I then championed the use of this stream around the site.
Through this process, hundreds of deliveries were
taken off the roads, millions of pounds saved in tankering costs and 80% of water used on site came from recycled sources, removing the reliance on the local water supply and through the treatment and reuse removing waste streams to already overworked treatment facilities.
2. INTRODUCTION
2.1. Constructions Environmental Challenges With a growing population there is a greater need for more infrastructure capacity and increased development from an ever-decreasing resource pool, and within the context of an evolving awareness of impacts on the natural environment. Therefore, both the tunnelling and wider construction industries are receiving elevated levels of pressure to reduce their impact on
Above, figure 1a: Slurry Treatment Plant (STP) early concept model for Align 14 | May 2025
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