Third STIM rail campaign begins

Rail deliveries of capping material to site begin again

The Southern Trench Interim Membrane (STIM) project is taking another step forward.

Nuclear Waste Services (NWS), which manages the disposal of the UK’s low level radioactive waste, is carrying out important work on the final capping of legacy disposal trenches and vaults to permanently dispose of radioactive waste safely.

NWS is currently replacing the protective membrane (liner) over the southern part of the legacy waste disposal trenches at the Repository site. This is known as the Southern Trench Interim Membrane (STIM) project and needs to be done before capping of the northern trenches. The liner will remain in place for up to 100 years.

The project involves bringing a large amount of aggregate materials to site by rail (using our existing rail sidings on the site), and stockpiling the materials ready for use in STIM and the construction of the final engineered cap.

From 27 January until September, NWS is preparing for approximately 200 trains to transport over 175,000 tonnes of aggregate to the Repository site.

To date, by using 161 trains instead of lorries, 7,037 lorry journeys and 914,781 road miles have been avoided, reducing traffic and minimising disruption for the local community. As the third round of deliveries gets underway – scheduled to finish in September 2026 – this number is set to increase again.

Christine Bradley, Interim Head of Repository Site Project Delivery, said:

“The restart of the rail deliveries marks the next phase of the STIM project and builds on the strong safety and delivery performance and successes achieved during previous rail campaigns.

“This is an example of a shared commitment to coordinated delivery and close collaboration between our delivery partners NWS, Nuclear Transport Solutions (NTS), GRAHAM, SLR (our construction quality assurance contractor, previously known as Wardell Armstrong) and Breedon’s Quarry.

“I’m really looking forward to another great year of making safe progress, hitting delivery milestones and quality standards, and getting that bit closer to successfully capping the Repository.”

Over the four-year contract, a total of 280,000 tonnes of aggregate will be delivered to the Repository – a huge logistical achievement made possible through close collaboration with GRAHAM, specialist transport provider NTS and SLR.

Collaboration with NTS’ rail division has played a pivotal role, with the launch of a new rail service for this project yielding significant environmental benefits.