Abingdon reservoir trial gets green light

Planning approval for Thames Water’s trial reservoir embankment has been granted ahead of a new strategic reservoir being built in Abingdon in response to residents’ calls for “assurances”.

The project is designed to test how much water is absorbed in the clay walls of an embankment to understand how it changes when compacted and under different conditions.

Leonie Dubois, Thames Water’s head of engagement, land and consents said the trial was being carried out in response to local stakeholder concerns about the design and integrity of the reservoir.

She said the company is beginning work to understand ground conditions at an early stage because residents “want assurances”.

The trial will use land within the site earmarked for the 150 billion litre strategic reservoir in Oxfordshire.

During the trial the company will excavate the clay and layer it into three mounds, each 50 metres long, 20 metres wide, and up to two metres high. The programme of work will complement ongoing ground investigations.

“As the population grows and the effects of climate change continue to take hold, demand for water will only increase,” Dubois added. “We’re serious about tackling water leakage and reducing consumption levels, but that alone isn’t enough. We must build more resilient infrastructure to avoid a future crisis and the reservoir has a vital role to play.”

The 12-month trial will inform the engineering design and embankment construction proposed for the new water supply source.

The project has been classified as a nationally significant infrastructure project (NSIP) for securing future water supply for Oxfordshire residents and beyond. It will serve customers in Southern and Affinity catchments as well as Thames.

Water Resources South East (WRSE), the organisation that brought together planning between water companies across the region, described the reservoir as “critical”.

Lee Dance, organisational director at WRSE said: “It’s critical we have the right infrastructure in place to meet the challenges ahead, including climate change and population growth, and to help us leave more water in our rivers and streams to help protect our region’s environment. It’s encouraging to see Thames Water progress plans for a new reservoir with its clay compaction trial.”

Thames needs government approval for the site, it will then seek permission to construct and maintain the new reservoir from 2026. If granted, construction is forecast to begin in 2029 with the reservoir intended to be operational in 2040.

Next steps will include a public consultation with communities being asked for their views on the latest proposals and feedback used to shape the plans.