Network Rail owns and operates most of the railway infrastructure in England, Scotland and Wales. Its ‘Ipswich Chord’ project was designed to help take more freight traffic off the roads and onto its rail network. The construction of the new railway line required the sewer networks to be diverted to accommodate the widening of embankments and the construction of new bridges in the area. Owls Hall Environmental designed and installed 250m of open cut sewers in a challenging working environment that included working at depth and a high water table and close to the live railway.
Identifying risks and challenges
We were contact by Network Rail’s main contractor for the Ipswich Chord project, Spencer Rail (part of one of the UK’s largest privately owned multidisciplinary engineering businesses, the Spencer Group). Spencer Rail had been commissioned to build the new 1.2km double track railway linking the East Suffolk Line and the Great Eastern Main line. After conducting ground surveys we identified a number of significant risks associated with working on the sewers in the area. The risks included subsidence, a very serious concern when working close to a live railway, working at depth (up to 5m) and working below the water table.
Purpose built solutions
Having identified the risks and challenges associated with the complex project, 1.5m diameter concrete pipes, each weighing 4.5 tonnes, were installed along a 250m stretch, working from the outfall of the river to a connection 250m upstream. We used sheet piling and well point dewatering to ensure that we were able to work at the 5m depth required, even with the water table at 2.5m. The piling ensured that the ground surrounding the railway was not compromised at any point.
Our vast experience working on complicated jobs in challenging conditions was one of the key reasons why Owls Hall was selected for this project. Our ability to work at depth had been demonstrated previously in the Balfour Beatty project and provided reassurance that the railway track would remain safe and secure throughout the work. We devised a plan that would enable our team to work safely in a confined space using 34 tonne machinery just 10 meters from the live railway line.
First class delivery
The project was completed safely and on time, with no injuries or risk to the railway. Both Network Rail and Spencer Rail were pleased with the professional conduct, design skills and quality of output from the Owls Hall team throughout the project.