Sheet Piling UK Plays Part in Flood Mitigation in Derby
Sheet Piling UK has recently used all of its sheet piling expertise on a complex project in Derby, destined to help the city mitigate the impacts of climate change, by reducing flooding events and the extensive damage those can cause.
Munio is a project with various elements, which will together build flooding resilience. Sheet Piling UK’s sheet pile installation work has assisted the creation of a new off-line pumping station – Mill Fleam – and other flood mitigation infrastructure.
The sheet pile installation works are designed to reduce the flooding risk associated with the Markeaton Brook at the Bass Recreation Park. The pumping station will over-pump flood water from the Mill Fleam’s channel into the River Derwent, should any extreme flooding events occur.
In addition, sheet piling works upstream of the Mill Fleam are designed to prevent flooding in that location, whilst downstream of the Mill Fleam, they will again mitigate flooding and support the effectiveness of new flood gates.
Tackling Derby’s flood mitigation brief with top sheet piling expertise
Sheet Piling UK was employed by J N Bentley of Skipton, having been recognised as a sheet piling specialist that could design the sheet piling works required and also supply and install sheet piles that could form a temporary, anchored ‘Wet Well’ cofferdam at the site of the new pumping station. The sheet piles selected for this purpose were top-quality Emirates Steel EZ26-700 sheet piles.
The complex project required Early Contract Involvement, to determine the methods that would be used. This ensured that a detailed design could be submitted to Derby City Council, for its approval.
One obstacle was the problematical access at the site, with access possible only from Bass Recreation Park and the other side of the site being adjacent to the A6 trunk road, running through the centre of Derby. With no road closures permitted, all had to be handled from the park side – an area of overgrown vegetation and steep slopes either side of the channel.
Designing the sheet pile works
To assist in the design process, Sheet Piling UK appointed York-based Byland Engineering Limited, to progress the works’ designs. This included the design of the wet wall cofferdam with passive tension piles, able to cope with an excavation depth of 8 metres. Other progressed designs included those for flood defence retaining walls for the upstream and downstream installations, a temporary works crane platform and a bridging detail associated with a syphon sewer running under the site. All was progressed in compliance with Derby Council’s AiP document for works adjacent to the A6.
In total, around 350Te of Emirates Steel EZ26-700 sheet piles were required for the project. J N Bentley secured these early in the programme to safeguard availability and to benefit from fixed-priced security. This was achieved by allocating the required piles from Sheet Piling UK’s extensive stock of sheet piles, thus avoiding inflationary pressures on these construction materials.
How were the sheet pile flood defences installed?
Due to site restrictions, the sheet piles had to be installed using a 300Te crawler crane with PVE40M vibratory hammer. Given the ground conditions, the sheet piles needed to be installed around three metres into the ground, into earth consisting of Weathered Mudstone. To achieve this, the sheet piles were impact-driven, using a CX85 impact hammer handled by the crane.
Once sheet piling works for the ‘Wet Well’ Cofferdam were completed, 13 self-drilling, 19.5-metre-long, passive tension pile anchorages were installed. This provided the stability required whilst temporary construction works were progressed. To facilitate installation within the cofferdam, the Klemm rig used for undertaking these works was also used for lifting into and out of the cofferdam.
The upstream and downstream works are being carried out in two different phases, to suit the installation sequence required for construction of the flood gates. Phase one was completed over a six-week period in July and August 2022, with this phase including the installation of a waling beam support over the syphon sewer, as well as anchorage works.
Delivering another flood mitigation construction brief
Sheet Piling UK’s managing director, Andrew Cotton, says: “This complex project has required strong co-ordination and dialogue between ourselves, J N Bentley and Byland Engineering Limited, with this allowing Sheet Piling UK to tackle the various obstacles that needed to be overcome, in order to deliver the flood mitigation brief.
“Backing this with our installation expertise, problem-solving approach and extensive stock of sheet piles, we have been able to ensure that all has run smoothly and, most importantly, to time and to budget.”
More information about Sheet Piling UK Limited, which is increasingly being appointed to handle flood mitigation and other climate change-focused sheet piling projects, can be found at www.sheetpilinguk.com or by calling 01772 794141.
- Ends -NOTES TO EDITORS
Sheet Piling (UK) Limited is one of the UK's leading piling contractors. Owning and operating a comprehensive range of specialist piling equipment Sheet Piling (UK) Ltd also carry extensive stocks of new and used piles enabling rapid reaction to any urgent requirements or emergency situations.