Keadby terminal assisted outfall sustainment project

Project overview
Keadby Pumping Station is an important asset, protecting homes, businesses and agricultural land from flooding. The terminal assisted outfall (TAO) required upgrading and modernisation to ensure the continued operation of the pumping station as resilience and reliability had been lost due to age, obsolescence and general wear and tear, resulting in the need for a major investment. Previous business cases had failed to find a viable solution but Binnies reduced costs by £10 million through an alternative design, enabling the reuse of the building structure and avoiding a complete rebuild. This cost reduction made the project viable and reduced the carbon footprint of the project.

Our role
The project team assisted in the development of the strategic case for investment alongside an update to the Isle of Axholme Flood Risk Management Strategy and worked closely with the strategy asset management and delivery group to ensure that stakeholder engagement was central to the delivery of the project.

GB JV Ltd, a joint venture between Binnies and Galliford Try, has been the sole engineering design and build provider for the outline business case, final business case, design and now the construction stage. This ‘cradle to grave’ approach has provided many benefits, for example the final business case created a construction sequence document for the whole scheme, taking into account the severe site constraints, which has guided the design and build phase. The design involved constructability considerations as the Environment Agency operational team could only allow the release of two pumps at any one time during the construction phase. It also involved innovative fish pass solutions as site constraints prevented the use of traditional fish ladders and passes.

We have installed fish-friendly pumps so fish can pass downstream safely and we provided eel access, giving them safe passage to and from the Three Rivers catchment. The supplier has developed a fish-friendly impeller design that ensures fish are not struck on entering the pump and incorporates vanes to guide them unharmed through the system. The impeller design also vastly improves efficiency and used with variable speed drives, ensures optimal efficiency at all times. The low running speeds improve passage for fish and reduce noise and vibration.

Binnies’ design has improved access to the culverts and flap valves when previously it was prohibitively expensive, with significant health and safety risks. Previously, some parts were accessed only by divers and other parts were never accessed as it was considered too dangerous. The improved safe access design has minimised ongoing maintenance liabilities.

Team members won an internal award for their flexible approach during COVID-19 lockdown. The team investigated and implemented remote attendance via Microsoft Teams, enabling the factory acceptance tests to continue when COVID-19 restrictions prevented travel to Holland. This enabled remote witnessing of the programme-critical factory acceptance tests and kept the programme on track. The approach gained client approval and commendation and has since been used for other factory acceptance tests that are equally programme-critical.

Outcome
We delivered the outline business case and final business case stages to time and budget. Due to Binnies’ collaborative approach to design, GB JV Ltd attained partial sectional completion of the flood defence asset at the end of April 2021 (four pumps operational and available for beneficial use), resulting in the Environment Agency attaining 80% of its stated outcome measures, i.e., reduction in flood risk to 2484 of the total 3105 properties to be delivered by this project. The remaining 621 properties were realised in November 2021.

This is despite COVID-19 disrupting construction work and storms in 2019 and 2020 when the Environment Agency took over the site to operate the pumps, which stopped work for approximately three months in total.

As the new pumps are much quieter and cleaner, the social value benefits of removing pollution (noise and air) on the local community have been enormous.

Challenges

  • Previous design made project prohibitively expensive with significant health and safety risks
  • Need to manage risk
  • Very tight timeframe

Solutions

  • Improved design reduced costs and enabled a viable solution
  • Early collaboration with the supply chain, particularly the pump supplier, throughout the process, to reduce risk and uncertainty in design and build phase

Benefits and Achievements

1
Client satisfaction

The Binnies team became an integral part of the project team and provided expertise to develop the project from concept/outline through to detailed design. The Binnies team was proactive and highly knowledgeable and worked with the client’s team to develop the project requirements and solution. This work was delivered collaboratively, at pace and on programme.”

ROBIN DRAYCOTT, Senior Project Manager

2
Carbon savings

The carbon footprint was reduced by 90% throughout the project’s lifecycle by the use of modern efficient fish friendly electric pumps negating the need for a 3mm eel screen and the re-use of the existing structure.

3
Award winning

The project won “Business Case of the Year 2019” at the Flood and Coast Excellence Awards.
Consistent delivery has enabled efficiencies to be delivered to the client over the life of this project.

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