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Cowley Trunk Main Project


Installation of 2km pipeline in Oxford Eastern Bypass to replace a 24” burst trunk main

Following a burst on the existing 24” trunk main running along Oxford Eastern Bypass in September 2014 which caused severe flooding, Thames Water made the decision to replace a high risk section of the main to prevent future pipe failures. The construction work started in June 2015 from the northern section of the new pipeline, which mainly consisted of open-trench sections.The Optimise Joint Venture which is made up of Barhale, Clancy Docwra, Murphy and MWH (now part of Stantec) delivered the £6M project. Installing 2km of a replacement trunk main along the busy dual carriageway, whilst minimising disruption to local traffic and effectively engaging with third parties and the local community.

The selected pipeline route and installation methods for the pipeline sections is shown in the figure below. The new main was generally routed on the opposite side of the road from the existing main. In terms of the pipe installation methods, open-trenching was planned in the carriageway and foot / cycle paths where possible, and the trenchless method was adopted where the new main crosses the roads and pedestrian and cycle subways.

Engagement with the local community was a key element of this project. A community drop-in session was organised by Thames Water and Optimise prior to commencement of the construction work, to inform residents of the local community of the proposed work and to discuss any project related issues. A local school also took part in a competition organised by Optimise, to name the tunnel boring machines and design artwork to decorate them, to get local children involved in the project.

The construction of the new pipeline was successfully completed and the new main was commissioned in February 2017, along with the new trunk main monitoring system. Following this, the old 24” main was decommissioned, which removed the risk of pipe failure and flooding to the local area.

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