Known as the southern trench interim membrane (STIM) project, the capping work involves placing a new membrane, or engineered protective layer, over legacy disposal trenches; this membrane will remain in place for up to 100 years. The STIM project will replace a current interim membrane over part of the legacy disposal trenches.
The project: Earlier this month, working collaboratively with U.K. transport and logistics provider Nuclear Transport Solutions (NTS), civil engineering firm Graham Construction delivered the first rail shipments of capping aggregate to site. According to NWS, eight deliveries of aggregate will be delivered to the site each week over a three-year period, for a total of about 280,000 tons.
The capping project will lead to the final closure of the repository, which is currently expected in 2135. The Low-Level Waste Repository is the U.K.’s primary disposal facility for LLW.
Graham was awarded a four-year contract for the repository capping work in August 2024. NWS and NTS are both part of the U.K. government’s Nuclear Decommissioning Authority.
They said it: Mike Pigott, NWS repository site director, said that NTS’s rail division, Direct Rail Services (DRS), played a pivotal role in the project with the launch of a new rail service. “It’s the first time DRS has used its JNA-Z box wagons, with each train making the journey from Shap quarry to the repository to deliver over 750 tons of material,” he said.
Gottfried Eymer, NTS rail managing director, added, “Rail is the obvious choice for bulk movements like these, taking many thousands of lorries off the road, reducing congestion, and improving the environment. This phase of the project will see 46,000 tons of aggregate delivered by 64 trains, [eliminating] an estimated 2,320 lorry journeys . . . that’s over 150,000 miles.”
