Supply Chain - River & Coastal Flood Protection - Coastal Defences

Faden’s 1797 map of Norfolk shows numerous wind pumps scattered around the Broads. The wind pumps helped drain the marshland and worked in combination with gravity drainage during low tides. However, marshland ground levels reduced due to shrinkage of the peat and with rising sea levels the gravity drainage became increasingly ineffective. The traditional wind pumps were replaced by more reliable steam, diesel and more recently electric pumps.

Norton Pumping Station, constructed in 1945, had suffered major structural failure and required urgent replacement. Funding was secured in January 2022 to consolidate the Norton and Raveningham pumped catchments and build a single replacement pumping station at Norton.

The design and Early Supplier Engagement (ESE) contracts were awarded in April 2022 with the detailed design completed in May 2023. The main construction works commenced in August 2023 with the new pumping station commissioned in August 2024.

The Waveney, Lower Yare & Lothingland Internal Drainage Board (IDB) are part of the Water Management Alliance, a group of seven IDB’s which includes the Broads IDB. Together they operate 55 pumping stations, managing water levels within 22,000 hectares of low-lying land within the Broads, preventing permanent inundation.

The replacement station manages water levels within 788 hectares of sensitive conservation grazing and agricultural land. This land provides important habitat for populations of qualifying species associated with designated nature conservation sites within the Broads. These are termed ‘functional habitats’ and are critical to maintaining Favourable Conservation Status by maximising the ecological potential and enabling the habitats and species, associated with the designated sites, to thrive.

Without pumping, the catchment would fill with water causing flooding and permanent damage to the habitats and key qualifying species such as rare aquatic plants found within the dykes, diverse flora, rare molluscs and breeding and over-wintering birds.

Failure of the pumped system would be a breach of statutory environmental obligations to manage water levels within functionally linked habitat. The result would be uncontrolled flooding of property, agricultural land, National Rail infrastructure, public highways, and utility infrastructure. This would also have serious repercussions for recreation and tourism which generate hundreds of millions of pounds annually for the local economy.

Rising sea levels and a changing climate make the Broads increasingly vulnerable. The project aligns with the objectives of the Broadlands Futures Initiative, a partnership investigating and establishing future flood risk management.

Climate resilience is improved with a 50% increase in duty capacity accounting for climate change predictions for intense rainfall events. This also ensures the system can better cope with overtopping events, which are likely to become more frequent. Taking into consideration future adaptive pathways to mitigate climate change, the station has the capability to adjust water levels allowing for changes in land management such as paludiculture and wetland habitat creation.

The power, control and motors are elevated above the flood level to ensure continued operation during a flood event.

The screw pump is one of the oldest positive displacement pumps dating back over 2,000 years. The design by Fish Flow Innovations removes the leakage path by fixing the rotating screw augers to the outside casing, resulting in enhanced efficiency and the most fish friendly pump available. The screw is made from GRP composite material which does not corrode and is UV stable providing an expected design life of 80 years.

The replacement station features two Archimedes screw pumps operating in a duty/assist configuration. The 2m diameter screws lift water 4.5m over the flood embankment, and using variable frequency drives, are capable of delivering variable flow rates between 0.3 to 0.75m3/second.

Working closely with National Fisheries specialists, to minimise external stresses on fish and eels passing through the station, a number of initiatives have been incorporated including:

The lessons learnt report has been shared to prevent this issue on future projects using this arrangement.

As part of a national research project, a trial will be undertaken using sensor loaded drone fish and live specimens which will be passed through the station and recovered to confirm fish/eel friendliness.

Prior to awarding the main construction contract, high inflation significantly increased costs. To help mitigate this, several value engineering opportunities were implemented resulting in £1.1m in cost savings.

These included:

Significant cost, capital and operational carbon savings have been achieved by combining the Norton and Raveningham catchments and building a single replacement pumping station. This also optimises available water resource during drought periods, improving wetland sequestering capabilities.

Early Supplier Engagement during detailed design ensured the design represented the least cost and carbon option. This included an early decision to maximise the use of steelwork and minimise concrete. Steel coping provides support for the trash rake minimising works on site, speeding up construction and reducing construction carbon.

Additional funding was secured to account for inflationary increases which could not be mitigated through project efficiencies. This enabled the £5.2m NEC4 Engineering and Construction Contract to be awarded to BAM Nuttall Ltd in June 2023.

IDB’s are risk management authorities and can apply for Grant In Aid (GiA) funding for Flood & Coastal Erosions Risk Management projects. The partnership funding calculator attracted 43% Flood Defence GiA with the remaining supplemented by Environmental Statutory Allowance (ESA) funding. ESA funding was introduced in 2021 for projects required to meet statutory environmental obligations.

A carefully planned and implemented water vole mitigation strategy ensured overall net gain of water vole habitat by improving 130m of watercourse.

Reptile mitigation required hibernaculum’s and reptile fencing to be constructed prior to successfully translocating reptiles found within the working area. The old pumping station roof had bat roost potential requiring a ‘soft’ strip of the tiles prior to demolition.

Norton Raveningham Pumping Station Replacement Project

The ground is relatively weak (soft silt/clay/peat) up to 15m below ground level, requiring a boxed piled cofferdam with pile lengths up to 17.5m. The complexity of the ground and groundwater conditions and the need for multiple level propping during construction, resulted in Plaxis 2D numerical modelling being required to confirm the global stability, displacement and internal forces in the structure forming the pumping station.

Prior to the excavation of the pump chamber, to control the pressure head within the Crag Group, temporary dewatering and pressure relief wells were installed into the sand and gravels. Piezometers within the pump chamber monitored groundwater pressure during the dewatering operations.

Vibro-piling was selected to minimise damage of adjacent sensitive receptors. Disturbance to wintering birds was avoided by monitoring cold weather and imposing restrictions on piling in the event of a cold spell.

An innovative cloud-based telemetry system allows remote real-time monitoring and control of the station. The system records trends and numerous statistics, including the volume of water pumped providing a valuable record for future water resource planning.

An automatic greasing system on the lower bearing of the screw avoids the need to de-water and enter the inlet chamber. The motor and gearbox are easily accessible for future replacement avoiding complex lifting operations. The materials selected for the civils structure requires no treatment or future intervention.

The control kiosk has a black timber effect finish to mimic the traditional agricultural buildings helping minimise the impact on the local landscape. The external lighting, only required during urgent unplanned maintenance operations, has been designed to meet Dark Sky requirements and are bat friendly.

Proactive engagement has minimised disruption and kept the local community fully informed of how the project benefits and protects the local community.

The contractor looked to maximise a circular economy approach and created a modest site set up to complement and respect the sensitive environment. The site compound included two electric vehicle chargers, made available to close community neighbours for free as a gesture of goodwill.

The project team carefully planned and delivered activities relating to 13 government National Social Value Themes designed to boost Social and Local Economic Value (SLEV). These have included: site visits from the parish council and local schools, apprenticeship talks and attendance at careers fairs, hosting a T-level work-placement student and an apprentice, donating a community bench and undertaking repairs at the local parish church, and maximising local employment and supply chain spend, where possible.

The team worked with all the surrounding schools to educate the children about the important role pumping stations play in the local landscape. A STEM (science, technology, engineering, and mathematics) exercise and competition tasked Thurlton Primary School to design a pumping station of the future.

The design considered how it might look, work, improve the local environment and nature. The winning entry had the privilege of naming the pumps and starting them during the opening ceremony, further embedding the project’s social value into the local community.

The project was awarded the Large Project of the Year at the Institution of Civil Engineers awards in September 2024 in recognition of its importance to enhancing the regions resilience to climate change and protecting vital habitats and communities. The judges were particularly impressed by the project team’s outstanding collaboration during very complex operations, often with limited historic data and tight time constraints.

This project is the first to be delivered as part of a programme that will continue to protect the Norfolk and Suffolk Broads from flooding and help address the challenges associated with climate change.

The Broads IDB secured funding to deliver further replacement pumping stations on the River Thurne, with construction works commencing in 2025.

Previous business cases had failed to find a viable solution and detailed design work had developed plans for the project to completely renew the existing facility. However, multi-disciplinary teams from the Environment Agency, Arcadis, WSP and Galliford Try Binnies JV (GBJV) worked collaboratively to deliver value engineering achieving savings greater than £12m by re-using existing assets.

The new solution made a switch to fish-friendly electric pumps, avoiding the long-term management of fish and eel screening, and recommended refurbishing rather than replacing the station which would deliver environmental benefits, operational savings and a 90% carbon saving.

The upgrade included:

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 ensuring that stakeholder engagement was central to the delivery of the project.

GB JV Ltd, a joint venture between Binnies UK Ltd and Galliford Try, has been the sole engineering design and build provider for the Outline Business Case (OBC), Final Business Case (FBC), and design/construction stages. This ‘cradle to grave’ approach has provided many benefits including the complex construction sequence document (for the whole scheme) created during the FBC which considered severe site constraints and proved an invaluable guide during the design and build phase.

The design involved constructability challenges as the Environment Agency operational team could only allow the release of two pumps at any one time to ensure that the operational plant was never compromised in terms of readiness for flood resilience. It also involved innovative fish pass solutions as site constraints prevented the use of traditional fish ladders and passes.

Binnies’ design team provided a solution which allowed the retention of the existing structure while completely refurbishing the installation. This was achieved by replacing the existing ‘carbon-hungry’ diesel-driven centrifugal flow pumps with electrically driven permanent magnet motors and vertically mounted axial flow pumps within the existing building envelope.

Given the age of the buildings on site, the initial concept design was for the complete demolition of the existing reinforced concrete structure to make space for a new installation. A solutions-focused team looked at plans differently and included extensive early supplier engagement with pump suppliers that crucially unlocked the re-use of the existing structure; a cornerstone of the significant cost and carbon savings. A complete refurbishment rather than the replacement of the existing delivered effective resilience to future climate change.

The existing facility presented a barrier for fish and eel migration and The England and Wales Eels Regulations (2009) required the installation to be upgraded to allow migration of elvers past the facility.

Accordingly, the fish-friendly pumps allow fish to pass downstream safely when pumping and an innovative ‘Elver Mode’ was added into the software controlling the sluicing operation allowing elver access during their migration period and subsequently safe passage into the Three Rivers Catchment and the wider Isle of Axholme, with 224km of main river available to fish and eel passage.

Pentair Fairbanks Nijhuis, the pump supplier, developed a fish-friendly impeller design that ensures fish are not struck on entering the pump, by incorporating vanes to guide them unharmed through the system. The impeller design in conjunction with the variable speed drives ensures optimal efficiency at all times. Low running speeds also improve passage for fish and reduce noise and vibration.

Binnies’ design has also improved operational access to the culverts and flap valves which previously posed significant health and safety risks. Previously, some areas were accessible only by divers and other areas have never been accessed since the TAO was commissioned in 1939 as it was considered too dangerous.

The improved operational safe design has minimised ongoing maintenance difficulties.

Through collaboration with partners and the supply chain the team delivered the OBC and FBC stages to time and budget winning the Best Business Case of the Year at the Environment Agency’s ‘Flood and Coast Excellence Awards’ (2019). 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; the 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 upon successful integration of the two remaining pumps. This was achieved despite COVID-19 disrupting construction work and storms in 2019 and in 2020 when the Environment Agency needed to operate the diesel pumps to reduce flood risk to the catchment, preventing construction work for approximately three months.

The former pumping station had six large and dangerously loud diesel engines (over 98 dBA when measured outside with the doors closed) and emitted large amounts of exhaust fumes. It was not safe to be inside the building with the pumps operating (even with ear defenders). The building is within 100m of residential properties so pumping activities disturbed the local community.

The new pumps are much quieter with the standby generator designed to be less than 60dBA at 1m. As the pumps can run 24 hours a day for several weeks at a time, the local community have greatly benefited from the removal of noise and air pollution.

The site is immediately adjacent to the Port of Keadby on the tidal River Trent. Close management was required with both PD Ports Ltd and ABP who had equipment within the working area, so the team worked with the port to respond to and work around vessel movements and port operations. A new river fender structure was designed and installed to reduce the risk of damage to the outfall structure from berthing vessels.

In conclusion, the carbon footprint was reduced by 90% throughout the project’s lifecycle using modern efficient fish-friendly electric pumps negating the need for a 3mm eel screen and reduced ongoing lifetime operational expenditure by the use of the existing structure.

When COVID-19 restrictions prevented foreign travel to the pump supplier in Holland, the team implemented remote attendance to witness the programme-critical Factory Acceptance Testing, allowing us to maintain programme. This also enabled a wider team to witness the testing and provided a learning opportunity for team members that would not otherwise have been able to attend. The approach continued with Design Workshops that avoided the need for the Design Team to physically attend site, without compromising the quality of work. The reduced travel also contributed to carbon reduction.

The project has won a number of awards including:

The works were undertaken by JBA-Bentley, a joint venture between designers, JBA Consulting, and principal contractor, JN Bentley. This was through the EA’s £2.5 billion Water and Environment Management (WEM) Framework - Asset Delivery. The project was delivered under an NEC 3 Engineering and Construction Contract (ECC) Option C Contract.

The project was funded by key partners including Hull City Council, East Riding of Yorkshire Council, Highways England, Humber Local Enterprise Partnership, Northern Powerhouse, and DEFRA.

Climate resilience and adaption was at the heart of the design as evidenced by a 20% overdrive capability built into the East Hull controls, temporarily increasing pumping outputs to 12m3/s, delaying the need for future pump upgrades.

At Castlehill, multiple social, environmental, and economic benefits have been realised, increasing flood storage within the catchment, delivering new woodland habitat, and integrating ‘access for all’ walking routes around the site. This solution reduced the peak pumping requirements at East Hull and created a valuable social space for the community in dry periods, improving biodiversity.

Existing flood resilience was impacted by 3 key factors:

The project faced significant delivery challenges:

As such, JBA-Bentley were contracted to design, build and commission a replacement pumping station 50m North of the confluence of the Holderness Drain and the Humber Estuary (50-year life). This was a multi-disciplinary scheme, requiring civil, structural, MEICA, geotechnical and hydrological/hydraulics inputs. Completing this scheme as a joint-venture allowed an expedited programme through increased design-construction integration and buildability efficiencies.

The new pumping station consisted of four 2.5m3/s pumps (13T each) operating in a duty-assist-assist-assist configuration, two per wet well. A gravity channel was constructed for flows outside of tidal-locking scenarios, which can be isolated using new tidal pointing doors and a penstock sluice gate for secondary containment (see Figure 4 below). This improved reliability of the failing tidal defences in conjunction with new floodwalls.

The pumps were controlled by a motor control centre (MCC) kiosk, which is part of the site’s MEICA Village: MCC; NPG substation, providing a DNO mains connection; an EA Switchgear room; and a 2000kVA step-down transformer.

Rock armour, gabions and reno mattresses were installed for scour protection in-channel and on the drain’s banks, preventing the pumping station’s foundations from being undermined. An access causeway was constructed for safe crane access, up to 250T (see Figure 5 above). The pumping station and access causeway were founded on steel H-piles and concrete CFA bearing piles to minimise settlement.

To deliver the works effectively and safety, a large central 30m x 25m cofferdam was formed and incorporated a bypass channel. The bypass was sized to convey all river flows up to 30-40m3/s seen in winter months. As seen in Figure 6 (below), these temporary works would eventually be integrated into the permanent works saving time, cost, and carbon.

The complexity of the solution - particularly the phasing of the combined temporary and permanent works - led the team to deploy various digital delivery tools to aid the process. A 3D federated Revit model was created for the scheme that facilitated collaboration between JBA-Bentley and the many sub-contractor design packages and ensured effective clash detection was possible and that client and landowner input was communicated and captured.

Construction on East Hull Pumping Station started July 2020. During the works, the site and design team responded to many external challenges and worked closely with stakeholders to resolve them. For example, one of the existing tidal pointing doors sea defences protecting the drain from the Humber failed mid-works, requiring an emergency response to prevent an increase in flood risk.

This was not the most challenging issue faced. Nearing completion, a decommissioning process was required to remove parts of the cofferdam and return gravity flows to the new central gravity channel – closing off the bypass channel. Dry working options were preferred, but a new option emerged when JBA Bentley approached Yorkshire Water for use of their pluvial pumping station to redirect the Holderness Drain into the Humber directly (something they already did in emergencies). This option created a dry working area using temporary dams and stoplogs at the upstream listed Hedon Road bridge, allowing potential for 24/7 working to reduce the programme. This method was safer than alternatives like pontoon working in low neap tides, additionally preventing water stagnation and silt build-up from impacting the protected Humber. It was also less carbon-intensive than sheet piling across the whole drain, and allowed for more rapid demobilisation of temporary works if there was a storm event during the decommissioning.

24/7 working saved 3 months of planned programme time, reducing cost and carbon by 48%. However, it left the catchment completely controlled by pumping.

4D time and motion modelling (Synchro 4D) was used to garner stakeholder agreement for this. 4D modelling simulated a digital twin of the real life works, aiding virtual planning of the complex decommissioning phase. This significantly reduced construction risk by highlighting plant clashes and working room restrictions and became a critical stakeholder engagement tool.

Initially Castlehill formed part of the existing Holderness Drain floodplain, forming a buffer between the drain and local communities. The area was predominately agricultural, and its topography left it wet and inaccessible throughout the year.

Castlehill now delivers a multi-functional site. The scheme’s primary purpose was to deliver a more climate resilient solution by delaying overspill into the floodplain and making use of untapped storage within the drain itself. Secondarily, through consultation, the scheme created new social spaces, ‘access for all’ walking routes and a link-up with the TransPennine Trail. The local community were key stakeholders in this scheme, helping to form requirements for these social areas and participating in tree planting initiatives.

New woodland planted could sequester more than 6000T of carbon and will offset the Castlehill construction emissions within 10 years. Some 15 years later, it will also have absorbed 50% of the East Hull capital carbon - this provided not only new habitats, but also a direct resilience benefit. The table below compares capital carbon emissions to woodland sequestration.

The scheme worked directly to improve protection of neighbouring properties through re-alignment of Sutton Cross Drain further North-East (further into the floodplain), and through installation of over 140m of sheet piling along the length of Sutton Cross Drain and East Carr Drain. This also allowed for the space to create a joint wetland shelf/fish refuge in dry periods along the re-aligned drain’s route.

Overall, the scheme provides biodiversity net-gains for the following protected and priority species:

Another aim of Castlehill was to improve access to and understanding of the historic environment, due to the presence of a Scheduled Ancient Monument on the site. Information boards were installed, and inclusive K-gates and barriers were fitted to provide safe entry and prevent unauthorised site access e.g., by motorbikes etc. This will protect the historic site and preserve it for future generations.

Finally, and in keeping with the requirements for improved resilience, the project also incorporated new elevated gravel laydown areas to assist effective flood incident response, see Figure 9.

To conclude, this multi-faceted design has made provisions for a new online pumping station at East Hull and has increased resilience and social-environmental value of the flood storage area at Castlehill, achieving significant improvements to the Standard Of Protection to properties along the course of the Holderness Drain. These works were technically complex, but thanks to the ‘One Team’ focus of the JBA-Bentley joint-venture, significant design and construction challenges were overcome using innovative temporary works and digital rehearsal/delivery strategies at every step.

The solution became operational in December 2023 and has already supported effective incident response and recovery by protecting properties during six recent and consecutive storm events (Elin, Fergus, Gerrit, Henk, Isha and Jocelyn). The flood alleviation works has delivered significant improvement to the Standard Of Protection afforded to around 1000 properties, increasing from approximately 20% AEP to 0.5% AEP from fluvial and tidal events, in-line with the Humber strategy.

The Don Regulators comprise three regulator gates on the River Rother that are owned, operated, and maintained by the Environment Agency (EA). The purpose of the regulators is to reduce the risk of flooding to settlements within the River Don catchment by attenuating flows in the River Rother. JBA-Bentley has completed the design and installation of the first regulator gate. The detailed design of the second gate is currently being undertaken, while the third regulator is being modelled as part of the optioneering phase. In addition to the installation of the first regulator gate, a bespoke full-channel fish pass has been installed directly downstream to improve migratory fish passage.

The Meadowgate Regulator is located within the Rother Valley Country Park. The historic regulator consisted of a single fish belly bottom-hinged tilting gate, operated by a single electrically powered hydraulic ram.

In 2023, JBA-Bentley replaced the gate with a top-down vertical control gate, improving the resilience of the structure. Alongside the regulator gate, a new control building and EA Office have been constructed. Both buildings have green roofs and EV charging. The gate was commissioned in February 2024 and is ready to operate during a flood event.

The gate is operated to ensure a maximum of 60m3/s forward flow is always maintained. When flows exceed 60m3/s the new gate is lowered and water levels in the Rother rise and begin to spill into the washlands located within the Rother Valley Country Park, which can retain approximately 1.5 million m3.

The removal of the bottom tilting gate provided an opportunity to improve fish passage on the River Rother through the installation of a unique full-channel width fish pass. This fish pass is designed with 4-tonne reinforced concrete ‘fish tiles’ featuring varied-height upstands supplied by Craven Concrete Ltd.

The tiles were designed with the aid of computational fluid dynamics modelling to ensure they influenced the nature of the flow to allow for varied fish species to migrate upstream while also withstanding hydrodynamic forces during extreme events. The fish species focused on are coarse fish, European eels, brown trout, large migratory salmonids, and lamprey.

The 40m long stilling basin has been removed by building up the existing concrete channel bed and grading out the levels to create a uniform slope. The ‘fish tiles’ have been laid onto the regraded channel. This is the first fish pass of its kind in the world.

The fish pass installation required the full channel as a dry working area. To achieve this, an innovative syphon system, designed by Dutch water specialist Vanderkamp UK, was installed. The solution involved complex temporary works and contingency planning.

To form the upstream dam, the new regulator gate was dropped to bed level, allowing upstream water levels to build up. The gate was designed to operate this way; hence no further calculations were required. Four syphon intake pipes were installed upstream of the gate to divert up to 12m3/s of flow out of the channel for 115m, around the working area.

The syphons were primed using electric vacuum pumps which expelled all the air from the system to draw water through the pipes. By utilizing the existing gate and power supply, the syphons had a far lesser environmental impact than a typical cofferdam and over-pumping solution. The total embodied carbon associated with the syphon solution was 464 tons.

Due to the scale of the flows being diverted, the loads imposed on the riverbanks by the pipes when full were considerable. JBA-Bentley and Vanderkamp UK worked together to design a temporary support system involving ground-bearing improvements, steel and timber supports, and retaining structures. Checks were also carried out on the existing channel wall where the forces from the syphons acted upon it.

In addition to work to ensure the stability of the syphons, an energy dissipation system was designed and installed at the syphon outlets to combat scour, and a bubble curtain was installed upstream to deter fish from entering the syphons. The installation of the system was done via a temporary crane pad. Due to the nature of the site and its space constraints, this was a challenging design. JBAB worked closely with the landowner, Rother Valley Country Park, to balance the desire to allow continual access into the park with ensuring the crane was safe to carry out the required lifts. To achieve this, the crane had to be placed in close proximity to the riverbank. Slope stability modelling and bearing capacity calculations were undertaken to ensure the crane could be operated safely.

Recent storm events have recorded flows higher than the syphon capacity. To manage the risk of this occurring during the programmed works, a contingency plan was developed.

The basis of the plan was developed from a bespoke JBA flow forecasting system, which forecasted the flow over a 2-day period. Using the data from the forecasting system, flow monitoring data provided by Vanderkamp UK, upstream gauge data, and the storage capacity of the washlands upstream of the gate, JBAB could make informed decisions on whether the gate needed to be raised to allow flow to pass forward.

This decision was made with the aid of hydraulic calculations and decision flow charts within the contingency plan, allowing for quick and effective decision-making, ensuring flood risk was not impacted upstream and the safety and well-being of the site team working in the channel was never put at risk.

The Canklow Regulator is the furthest downstream of the three Regulators, approximately 3.5km upstream from the confluence of the River Rother and the River Don at Rotherham.

The existing structure consists of a single electrically powered vertical lifting sluice gate operated by an electric wire rope hoist, comprising a drive motor gearbox assembly, cross shaft with integral rope drums, and support bearings.

To improve resilience and the operation and maintenance of the asset, JBA-Bentley is completing the detailed design and build of a new vertical regulator gate and associated MEICA and civils infrastructure.

The MEICA structure consists of a 20.3-ton vertical gate, mounted on a new steel bridge and working platform, which shall also house 13.5 tons of drive equipment for operating the gate.

Two 4kW motors, working in a duty/standby configuration, will provide drive to the gate via bevel and gearboxes, which turn a single driveshaft spanning the width of the gate. On this driveshaft, one at either end of the gate, are rack and pinion gear assemblies, which convert the rotation of the driveshaft to the vertical motion of the gate. The total gear ratio from motor to driveshaft is an approximate reduction of 4410:1, allowing relatively small motors to be specified.

To support the new gate structure over the next 50 years, a new anchor restraint system has been designed. A buried sheet-piled ‘dead-man’ wall will be installed with ten 36mm anchor rods, evenly spaced, connecting to a waling beam on the wet side of the existing channel wall. This will be mirrored on both riverbanks.

The new infrastructure replicates the existing system, which has been determined to be past its design life and insufficient in supporting the new gate.

The existing superstructure of the control houses will be demolished, the foundations will be retained and extended where required to support the new gate structure using cast-in bolt sets.

A new permanent crane pad will be constructed on the south bank for the construction, maintenance, and decommissioning of the gate. This will double as parking spaces for EA operatives when not being used by a crane.

The JBA-Bentley team worked collaborative to optimise the delivery. This meant that site constraints were identified, and the design was completed with buildability and safety as the focus. A key constraint on the scheme is the proximity of the Northern Power sub-station and overhead power lines. The design of the dead-man walls, crane pad, and steelwork platform was completed to ensure that the plant and temporary works required for construction and installation were outside of the powerline exclusion zones.

The Woodhouse Mill Regulator is situated between Canklow and Meadowgate. It uses a single electrically powered vertical lifting gate to retain water. This gate is operated by an electric wire rope hoist, which includes a central drive motor and gearbox assembly, half shafts, spur and pinion driven rope drums, and support bearings, all counterweight assisted.

JBA-Bentley is currently carrying out hydraulic modelling on behalf of the EA as part of the optioneering phase. The options include passive solutions, such as a baffle or orifice plate spanning the width of the channel to continue to utilize the upstream storage. Due to the size of the Don catchment, the modelling required three individual models to be run together:

Multiple return periods are being considered, resulting in hundreds of models runs. The modelling also uses a continuous simulation approach, which adds to the complexity of the model runs.

The upgrading of infrastructure of the Don Regulators will ensure continued flood risk benefits into the future for the Don Catchment and surrounding area with improved resilience and reliability of the new assets. Alongside the reduction in flood risk, the environment and biodiversity will improve in the River Rother as a result of the Meadowgate Fish Pass.