Vault 8, the first of the engineered vaults to be constructed on the site, is an open, multi-barrier concrete structure set partially into the ground and comprising concrete lined walls and a drained floor slab.
Containers are stacked inside the vault in a similar arrangement to that used in a container port. Vault 8, which opened in 1988, has a total capacity of 200,000 cubic metres of waste and is nearly full. Vault 9 was completed in 2010. The project required timed deliveries of over 140,000 tonnes of aggregates and other building materials which had to be achieved with minimum disruption to local communities. The vast majority of construction materials were delivered to the site by rail rather than road, reducing potential road deliveries by 27,500 as over 98% of all construction materials were brought to the site by rail. The Vault 9 construction incorporates advances in technology, with its multiple layers of protection to provide both for the safe storage and final disposal of LLW. This vault has a capacity of 110,000 cubic metres – space for 5,500 containers – and is expected to be utilised for several decades, based on current waste estimates. When needed, further vaults will be constructed in line with National Waste Programme requirements.
It is important that each container disposed of at LLWR Site contains minimal voidage. This is achieved by introducing a cement based grout into a container. This operation is carried out at the Grouting Facility, located close to the centre of the LLWR Site. First commissioned in 1995, the Grouting Facility returned to operations in December 2015 after a 12-month £1.8m upgrade.
Leachate Management System
Water from the trench drains and within Vaults 8 and 9 is collected as leachate in the leachate management system and is routed, predominantly by gravity flow, through interceptor drains. All leachate is routed to the Marine Holding Tanks.where it is pumped via a buried pipeline, to a discharge point in the Irish Sea. Every discharge is sampled to ensure the requirements of the Environmental Discharge Permit are achieved. The pipeline discharges into the sea through three diffusers at a distance of around 1.2 km off shore.
In order to make best use of the available transport networks LLWR operates its own railway sidings. The rail sidings form the transport hub for the import and export of waste and the import of construction materials. Although the vast majority (88%) of LLW arrives by rail some deliveries are also made to the site by road. All waste containers are is checked and unloaded at the receipt area on the rail sidings.
LLWR manages and maintains a fleet of re-usable containers. They are used to transport LLW from waste-producing sites to treatment facilities around the UK. LLWR undertakes a programme of inspection and maintenance of the fleet to ensure containers continue to be fully compliant with transport regulations.
Asset Care and Management
An Asset Management (AM) system is implemented which helps LLWR manage its physical assets in an optimal manner, achieving best value. These assets range from buildings to work equipment and the majority are found on the site, though some, such as off-site boreholes are found elsewhere. The system incorporates all lifecycle stages, covering lifetime operations, maintenance and disposal.