12th January 2024

Cutting-edge LINAC bunker expansion at Southend Hospital

Perega is taking an active role in transforming Southend Hospital’s radiotherapy department. Assigned with crafting a cutting-edge linear accelerator (LINAC) bunker and refurbishing the existing hospital building, our team of structural engineers are contributing their expertise to this ambitious project.

With excavation works wrapped up, the endeavour now focuses on the next stage, a single-story extension consisting of a protective bunker structure to house the LINAC, which is used for external beam radiation treatment of patients with cancer. The structure also extends above the bunker with a plant room to house necessary equipment.

The bunker, constructed from large concrete blocks, is no ordinary build. The walls of the bunker boast a thickness of 1 meter (1220mm), leaving no room for radiation leakage, while the top slab measures an impressive 1400mm, ensuring unparalleled protection for hospital visitors and staff. The LINAC bunker sits upon a meticulously engineered concrete raft foundation, specially tailored to adhere to stringent radiation safety protocols.

This process was not without its quirks, with our team facing unique challenges with uneven pressures on soil beneath the bunker. To conquer this, instead of the originally intended ground-bearing raft foundation, a piled solution was devised. A standard regular grid layout of the piles was not an option; as it would have overwhelmed the piles, causing inefficiencies. They had to get creative, opting for an irregular grid, ensuring a more balanced load distribution, transferring the bunker’s weight and keeping the piles to a reasonable length with a minimum number to be constructed.

Furthermore, the Perega’s team headed by our senior structural engineer Witek Hendzel, planned the foundation around active underground service tunnels, maintaining a safe distance to ensure the hospital services continued operating smoothly.

Initially, the focus was on minimal intervention. However, due to the weight of the required plant and extensive service penetrations, utilising the existing roof was not feasible. We collaborated with the rest of the design team to develop a lightweight timber and blockwork solution to extend the walls and replace the roof. This strategic alteration enabled the accommodation of the services within the building and a smooth integration of pipework, demonstrating our agile approach to developing practical solutions.

Sustainability is ingrained in every Perega project, and Southend Hospital is no exception. This drive for sustainability led us to implement a drainage system with an attenuation tank, which reduces the load on the existing hospital area’s drainage system by managing rainwater discharge efficiently.

Witek Hendzel says “This is the start of a very different and exciting project at Southend Hospital. The project team has already overcome several challenges to ensure the LINAC bunker is safe and fit for purpose and  we’re excited to complete this transformative work by September 2024.”

To find out more about our work in the healthcare sector, click here.