Digging deep at Battersea
Battersea Power Station shut down in 1983. Now the iconic landmark is being resurrected and repurposed as the centrepiece of an exciting regeneration of London’s Nine Elms. With energy demand rapidly rising from an array of new homes and workplaces, UK Power Networks turned to its ED1SON ALLIANCE to deliver a complex electricity connection.
Transforming Nine Elms and sparking new life into Battersea Power Station has created one of the largest development zones in the country on London’s south bank.
While the apartments and offices being built have captured the public imagination, successful regeneration relies on power. Additional demand of 110MVA is expected over the next few years, equivalent to the energy required for more than 25,000 homes.
Increasing capacity on this scale called for a major new electricity network connection and substation. UK Power Networks – the distribution network operator with responsibility for the connection – drew on the expertise of its ED1SON contracting alliance to deliver the complex project above and below the streets of London.
Through UK Power Networks’ Alliance team, Clancy worked alongside tunnelling subcontractor Joseph Gallagher and specialist consultant Cowi on the challenging scheme – overcoming a number of obstacles to construct a new 320m cable tunnel beneath central London.
This included navigating centuries of the city’s unseen history. The tunnel needed to avoid a maze of sub-surface pipes and infrastructure including a Victorian brick trunk sewer just 12m above the proposed route and two rail viaducts only 10m away. Before any digging started, complex computer modelling took place to refine the route and avoid any collisions.
Martin McGovern, associate director at Clancy, said: “Maintaining power throughout was a key consideration. The team’s innovative approach made the Battersea Cable Tunnel project the first time that UK Power Networks had been able to extend a tunnel network without needing any power outages.”
The new 2.44m wide spur tunnel had to connect with the existing live cable tunnel, creating a considerable engineering challenge. Working in the proximity of 132kV cables required precise technical coordination to ensure the safety of the team and to keep the lights on.
The team’s solution was developing a junction chamber below ground from reinforced concrete. A compact and carefully built 9m by 6m by 6m box housed both the new connection and the old one, acting as a link between them.
Crucially, additional support was added to the existing tunnel to prevent any movement during the construction of the junction room. Health and safety remained a key consideration within the restricted environment, with close attention to detail and regular team briefings contributing to more than 180,000 hours worked without injury.
While activity continued apace underground, on the surface the team was equally busy working on the new substation. An existing warehouse was used to shield construction activity with the tunnel shaft located inside. This was specially modified to act as an acoustic barrier to minimise disruption for the local community.
The team’s determination to be a considerate neighbour ensured that no complaints were received throughout the project’s duration, despite the site being active 24/7.
While most of the activity was deliberately hidden from view, the team used the project to shine a light on the complexities and rewards of modern construction for budding engineers. A visit to the local Oasis Academy South Bank secondary school saw the Tunnel Boring Machine christened ‘Maggie’, in honour of the prominent space scientist Maggie-Aderin Pocock.
Martin said: “Maggie spent 11 weeks boring through over 300m of London clay to stop just 4m away from the existing network to allow for the construction of the junction chamber. Forward planning meant that we were able to recycle 95% of the waste material generated by the tunnelling.”
The ED1SON Alliance
The ED1SON Alliance was launched by UK Power Networks in 2015 as a ground-breaking new model for delivering a £1billion investment in energy infrastructure across London, the East and the South East of England.
It brings together the skills of contractors and consultants within a continuous work programme – ensuring greater efficiency and innovation which brings value to UK Power Networks’ customers.