The river crossing puzzle

The river crossing puzzle
By Roy Peary, North West Section Treasurer

The North West Section co-hosted a technical paper evening with the Yorkshire Gas Association, on the 13 March, at the Gomersal Park Hotel. Phil Croft, National Grid’s Senior Project Manager for Capital Delivery, gave a presentation on the topic of National Grid’s multi-million pound project to replace a gas pipeline which stretches 5km, 35m beneath the River Humber. Consent for the work was granted in August 2016 and the project is expected to be complete by 2020. 

On a peak winter day, this 42in steel pipeline transports around 20 per cent of the UK’s gas. The existing pipeline crossing lies in the bed of the river and is at risk of being exposed by strong tidal currents. Phil explained the work carried out a few years ago to keep the pipeline buried on the river bed, but a long-term solution was needed. He started by outlining several alternative routes that had been considered and why they were discounted. He also explained why the flooded segmental tunnel option was chosen over other possible methods, a technique not unique to this project, but at 4.86km long would be the world’s longest tunnelled pipeline river crossing. 

He then went on to explain the type of contract National Grid used, how the contractor selection process worked and details of the partnership that won the contract. In fact, the contract was awarded, and other preliminary work complete under planning approvals, before the Development Consent Order was approved, both to ensure the earliest possible commissioning date. Phil went on to describe the traffic management arrangements needed to deliver the massive logistical challenge of material delivery and spoil disposal. 

Phil described the pipe string area and the bespoke pipe handling equipment built to deal with such a unique project. He explained the insertion and reception pits, plus how the tunnel boring machine (TBM) was manufactured and delivered to site in 16 sections. He also explained how the 4m diameter bore is cut (a few centimetres per hour, to an incredible level of accuracy), how air, power, water and personnel are delivered to the cutting head, and how the slurry is removed, fully treated on site, compacted and taken off site for reuse. 

Throughout the presentation, Phil detailed the safety, environmental and ecological considerations being made at each stage. Phil also suggested one of the greatest successes of the project has been the early and continuous engagement of other stakeholders, enforcement agencies and the local community. This community engagement is typified by the competition held to name the TBM. Kacey Doney, a local pupil won by suggesting the TBM be named ‘Mary’, after Mary Fergusson, the first woman Fellow of the Institution of Civil Engineers. 

Tommy Knott, IGEM North West Section Chair, said: “Phil’s presentation was one of the most engaging and interesting I have ever heard.” Mary is now over halfway to reaching the world record. Check her progress at 

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