Sarens Produces Innovative Technical Solution for London’s Lee Tunnel Project
First-of-its-kind engineering solution developed and deployed by Sarens UK
9
October 2019

Sarens is known for its innovation in engineering, so when a London-based project called for specialised technical solutions, Sarens stepped up to the challenge. Sarens engineers created a first-of-its-kind system to install several props for the £627m Lee Tunnel project owned by Thames Tideway. 

The client, MVB, first contacted Sarens because the solution they needed had become too complex for their existing supplier. Sarens could deliver the original solution but went one step further and proposed a completely new system that would save on costs, planning, and preparation time. The innovative system Sarens proposed featured a gantry on top of an SPMT, with two 70-tonne strand jacks and 130-metre long wires that were self-contained in the re-coiler system. 

Sarens’ proposed solution had three major advantages:

  1. Greater safety. The client’s original solution had called for two crane operators performing a tandem lift with two large crawler cranes. However, Sarens’ gantry
  2. Greater precision. Installing each of the props required extreme precision, and one     SPMT operator would be able to work with greater precision than two different crane operators could.
  3. Lower costs. Because of down time, using two crawler cranes would have been 50% more expensive for the client. The Sarens gantry system made the project a more economical choice for the client.

The client selected Sarens’ solution because of its many advantages, and because of Sarens’ dedication and professionalism throughout the process. Working in the UK requires a thorough approval process for design and mobilisation, and Sarens stood out from other suppliers by delivering the engineering approval in the form of a thorough CAT 3 level check and by dedicating considerable effort and resources to ensuring acceptance.

In total, it took just six weeks for Sarens to design, engineer, mobilise and assemble this innovative new solution. As part of the custom-designed system, two 40-metre beams were built in-house at Sarens Belgium and transported to London via road. Only seven transports were needed to mobilise the equipment, and it took three days to assemble the gantry. The crew worked carefully to ensure the gantry was built exactly as specified, using the correct bolts and tools for each piece and assembling it within a very limited working space, directly next to the 130-metre deep shaft.

With the equipment in place, Sarens’ work on the complex Lee Tunnel project then commenced in two phases. During Phase 1, Sarens installed 40 75-tonne props approximately 120 metres into one of the city’s deepest and widest shafts, executing a difficult installation sequence. Every two days, the 4-person Sarens crew would lower and install a prop into London’s main sewage works. Next, during Phase 2, Sarens installed an additional two 200-tonne props. During installation work, CCTV was mounted on the props to monitor their positioning and ensure a precise installation.

The gantry remained on site for both phases of the project, which Sarens executed between August 2014 and May 2015. 

According to the client, “The mobilisation process was efficient and effective, the design surpassed expectations, and the accuracy of install was met perfectly. At each point during the installation process Sarens were able to provide professionalism and a very capable on-site team which integrated very quickly into our site  team. The process ran to schedule and as a result for the next elements of work Sarens have now become our first port of call.”

“I was honoured to have been passed this project to manage,” said Simon Crawley, Senior Sales Manager Special Projects. “To me and Sarens UK, this was not just a large technical solution project in the UK, but a first of its kind in the UK, using a gantry built on top of an SPMT. Safety came first as always at Sarens and it was also the most economical solution by far!”

Congratulations to everyone at Sarens who helped make this custom-engineered solution a success! Sarens is proud of the dedication of all the engineers, crew members, and employees across the globe who embody our spirit of innovation and quality each and every day.