17 Apr

Drax Emergency Embankment Stabilisation

Keeping Britain’s Lights on

February 2020 was the wettest on record in the UK with over 200mm of rainfall in the month. The persistent rain combined with the gales of Storm Ciara, Storm Dennis and Storm Jorge brought havoc to many parts of our country, and severely weakened vital infrastructure routes.

When we received the call in late February to attend the Drax Power Branch line 3 miles out from the power station, the River Aire had consumed hundreds of acres of the surrounding landscape. Only the ballast shoulder and railway itself was all that was visible above the water along a 6 metre high rail embankment running into Drax. Many roads, houses and businesses in the local area had already lost the battle to hold back the onslaught of flood waters.

The lake that formed around the railway (aerial photo shown below during the peak flood level) not only limited access to the site, but was clearly going to take several days, even weeks to dissipate. Unfortunately, the weather wasn’t kind, and high winds resulted in wave action on the water, eating into the railway embankments causing damage to the earthworks, the extent of which was largely concealed until the flood water would drop.

Drax relies on the branch line to deliver over 20,000 tonnes of biomass fuel into the power station every day, so the continued safe operation of this vital rail route was crucial in keeping the power station operational, which is responsible for around 12% of the UK’s renewable power.

With the flood water severely restricting access, and also our understanding of the extent of the damage, we initially established a programme of monitoring, using STE7 qualified dive teams to undertake underwater examinations and check for scour around the structures, and continuous monitoring of the earthworks and track as the water levels receded. The Down line was closed due to significant damage to the embankment undermining the track support, and a speed restriction was put in place on the Up line, putting significant pressure on the freight operators and Drax using single line working until we could implement a repair.

Whilst water levels were still high preventing any practical repair, we initiated ground investigation works, utilising Road Rail mounted drilling rigs to complete a series of up to 15 metre deep boreholes along a 900 metre stretch of railway embankment. Working closely with design engineers at Pell Frischmann, we developed a two phase approach, initially focussed on exploring solutions that would enable the Down line to be re-opened safely and as quickly as possible, after which a more permanent repair could be developed for the full extents of the site.

Over the last 9 days, CML’s earthworks team have installed 126no. 8m long piles, complete with retention beams and backfill to provide a rapid and robust solution to reinstate support to the Down side embankment. All works have been completed without interruption to the Up line, which has still managed to carry around 96 trains per week into Drax. This solution has been designed and constructed in compressed timescales, and will enable the railway to be re-opened much sooner than a heavy permanent solution which is likely to take several months to design and build due to the extent of the flood damage.

Plans for the full permanent repair are now well underway, and it’s thanks to all involved who have helped to make this job happen, particularly in recent weeks with the added constraints and measures associated with COVID-19. Collaborative working between CML and all our suppliers, Network Rail & Drax power station was critical for the successful and safe delivery of this project which should see both lines running in to Drax again next week.