Supply Chain - Site Preparation - Over Pumping

Both Hathershaw Fields CSO and Bardsley CSO are located within the borough of Oldham, Greater Manchester and line the River Medlock, which flows into the River Irwell, approximately 10 miles west of the sites in Manchester City Centre. Hathershaw Fields is located in a college playing field within a predominantly residential part of the borough, whilst the Bardsley CSO is located off a busy main road in a largely industrial area, but located close to some residential properties and the Manchester and Ashton Canal. Current facilities and reason for the work In 2019, United Utilities undertook the Medlock Quality Programme, a comprehensive investment which included the installation of below-ground detention tanks at existing sites to provide increased storage capacity and reduce spills into the River Medlock and adjacent CSO and pumping station, to comply with the Water Framework Directive (WFD) to improve water quality in the River Medlock. The programme was successfully completed, however there was a requirement to further reduce the amount of sewer litter by screening discharges from both overflows. This would be achieved by the installation new powered aesthetic screens within Hathershaw CSO and Bardsley PS to screen stormwater and retain solids such as wet wipes and cotton buds, reducing unscreened spills into the River Medlock and improving water quality during periods of heavy rainfall. There were a number of constraints at each site: both had to remain operational 24 hours a day and 7 days a week, and due to the location of each site within close proximity of residential properties, it was important to ensure that there was no detrimental impact in terms of noise and vibrations. [caption id="" align="alignnone" width="1200"] CSO chamber with at Hathersaw Fields with overpumping pipework - Courtesy of VJ Donegan Civil Engineering Ltd[/caption] Understanding the brief/design process United Utilities network modelling team had defined a notional solution as a starting point for this project. The Costain MSP team were then initially engaged to undertake some advanced investigation work, define the full project scope and advise on constructability, enabling residual risks to be quantified and managed via a lump sum design and build main award contract. During the main implementation contract, Costain worked with United Utilities, the lead design and build contractor, VJ Donegan Civil Engineering Ltd, and their appointed consultants to undertake the detailed civil, mechanical, electrical, ICA design, supply, install, commission and handover of the operational asset, updating DSEAR, Health & Safety file records for safe future operation and maintenance. Design development VJ Donegan Civil Engineering Ltd undertook the detailed civil design via their lead consultant Wood Group. The civil design was relatively complex in that it was necessary to modify pre-existing infrastructure to accommodate the new screens, on small site footprints. Assessments were made on the existing ground conditions and water levels as one of the main concerns was an increase in buoyancy of the Hathershaw structure resulting from the creation of a larger internal void to accommodate the screens and maintenance access. Solution model VJ Donegan Civil Engineering Ltd worked with their civil designer to prepare the design for solution model and integrate with the network baseline model provided by client. This was an iterative process requiring liaison with the UU modelling team and additional surveys to provide confidence in the verified solution model. During the build phase, a discrepancy was found between the network model parameters and existing sewer network, however the team worked collaboratively to engineer a solution within the constraints of the existing infrastructure, to ensure the screens performed as required by the terms of the discharge permit. [caption id="" align="alignnone" width="1200"] Exposed CSO chamber at Hathershaw - Courtesy of VJ Donegan Civil Engineering Ltd[/caption] DSEAR The introduction of new MEICA equipment required the DSEAR documentation to be re-assessed and updated to ensure compliance to the latest requirements. Identifying requirements for planning permission The installation of powered screens and associated motor control centre (MCC) kiosk at Hathershaw Fields were considered permitted development and did not require planning permission. However, as there was a requirement to establish a temporary access road off an existing highway in order to access the working area, planning permission was required. A detailed planning application package was prepared by consultants WSP and submitted to Oldham Metropolitan Council, the Local Authority within which the site is located. The planning application was approved by Oldham Council in December 2021. Hathershaw Fields CSO & Bardsley WwPS: Supply chain - key participants Client: United Utilities MSP principal contractor & designer: Costain Lead contractor: VJ Donegan Civil Engineering Ltd Lead contractor designer: Wood Group M&E subcontractor: Water Engineering Services Ltd Planning/ecology consultant: WSP HAZOP/ALM facilitator: FBW Engineering Powered screen supplier: Huber Technology Ltd Overpumping supplier: Selwood Precast concrete supplier: Macrete (Ireland) Ltd H&S fall protection: J-Safe Ltd Construction work at Hathershaw The site at Hathershaw was established in April 2022, starting with the installation of the temporary access road into the site and establishment of the compound and welfare. In the first instance it was necessary to expose the existing CSO chamber and the raise the level of the concrete roof. This was achieved by sheet pile excavation works and by cutting sections of concrete from the CSO roof. [caption id="" align="alignnone" width="1200"] (top left) Temporary access road, (bottom left) collaborative working, and (right) aerial view of the Hathershaw CSO site compound - Courtesy of VJ Donegan Civil Engineering Ltd[/caption] Before work could take place in the CSO chamber it was necessary to set up a system of over pumping from one chamber to the other. A safety monitoring system was later installed which included an alarm which would sound at times of heavy rain, acting as an early warning system for the team working within the chambers to ensure they could carry out work safely. Following the installation of the new powered screens and several tests it was necessary to modify the existing chamber adjacent to the CSO. In order to undertake this work successfully, sheet piling was installed prior to the modifications. This work was completed within 6-weeks, ensuring that the newly installed powered screens were correctly sized. Water Engineering Services Ltd was the mechanical and electrical sub-contractor responsible for the screen installation. Following completion of this work the temporary ramp was removed and the site reinstated. Construction work at Bardsley The site at Bardsley was also established in April 2022 and before work in the CSO could commence it was necessary to install temporary over pumping to ensure work could be carried out safely. The CSO required an in-depth survey to confirm that the finalised design was correct and so therefore following this survey there was a period of time whilst no work was carried out on the site. Main construction work at the CSO took place between August and September 2022, which included the cutting and removal of the existing reinforced concrete (RC) cover slab, modifications to the existing RC weir walls, installation of new powered screens, installation of associated instruments and cabling, installation of new control panels, dry and wet commissioning of the new system and finally the installation of a new RC cover slab and reinstatement of the site. [caption id="" align="alignnone" width="1200"] (left) Bardsley CSO chamber - Courtesy of Costain, and (right) the Bardsley precast cover slab - Courtesy of VJ Donegan Civil Engineering Ltd[/caption] Customer relations The Hathershaw Fields site is located in a quiet suburban residential neighbourhood with several residents overlooking the site. As extensive work had already taken place on site in 2019 to install a new detention tank as part of the original scheme, it was important to ensure that residents were engaged with regularly and made aware of any potential disturbances that could be caused throughout the construction process. Letters were distributed regularly to residents keeping them abreast of all activities on site at programme milestones. This was often undertaken by the team in person to give residents to opportunity to speak with the team should they have any issues or questions. As a smaller more compact site, Bardsley PS has fewer neighbouring residents but several adjacent landowners who share access with United Utilities. Site meetings were held on site at project milestones to explain upcoming work and answer question. During the main constriction programme weekly emails were issued to the landowners updating them on progress. Completion The project was completed on time, allowing United Utilities to meet key Regulatory Dates set by the Environment Agency for both sites, in turn improving water quality in the River Medlock - a key aspiration of United Utilities. The ambitious programme was achieved by working together, with a close team consisting of United Utilities, Costain and VJ Donegan Civil Engineering Ltd, holding regular collaborative planning meetings to successfully manage the programme. Good relations were maintained throughout the works, with positive comments received from residents in relation to the conduct of the team on site and a WOW award nomination was received.

The Don Regulators comprise three strategically important 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 Don catchment, by attenuating flows in the River Rother. JBA-Bentley, in a joint venture relationship, are working on the replacement of the three regulators, each being at a different stage of design or construction. Figure 1 illustrates the locations of the three sites. Canklow 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. It is located approximately 50m downstream of the A630 Rotherway near junction 33 of the M1. The existing structure, consists of a single electrically powered vertical lifting sluice gate operated by an electric wire rope hoist, comprising drive motor gearbox assembly and cross shaft with integral rope drums and support bearings. To improve resilience and the operation and maintenance of the asset, JBA-Bentley were required to provide a new guillotine gate and associated MEICA and civils infrastructure. The Canklow Regulator is usually the first of the three gates to operate and is activated when trigger levels are reached elsewhere within the catchment. Operating the regulators on the Rother during a significant flood event allows the flood peak on the river to be delayed until the peak on the River Don has passed Rotherham and prevents flooding from the Don. Lowering the gate at Canklow can hold back over 1.5 Mm3 of flood water across seven washlands. [caption id="" align="alignnone" width="1200"] The existing Canklow regulator gate - Courtesy of JBA-Bentley[/caption] Canklow is currently in the detailed design phase of works. Alongside the gate design some additional civil engineering works are required. This includes some remedial works to the existing sheet piled channel walls including new anchors, a new crane pad to be utilised during construction and to facilitate future gate maintenance as well as the substructure for the new motor control centre (MCC). One of the key constraints of the site are high voltage overheads; therefore, the crane pad location and the siting of the EA’s compound with MCC had to carefully considered. To assist in undertaking the design and developing the business case for the project, 3D survey was undertaken to create a 3D Matterport tour of the site. It allows the user to quickly navigate around the site and view all the infrastructure remotely. This proved particularly useful during the pandemic when restrictions were in place and site visits were limited. Woodhouse Mill The Woodhouse Mill Regulator is located on the Rother between Canklow and Meadowgate, upstream of the B6200 Retford Road. It retains water using a single electrically powered vertical lifting gate. It is operated by an electric wire rope hoist, comprising a central drive motor and gearbox assembly and half shafts, with spur and pinion driven, counterweight assisted, rope drums and support bearings. The proposal at this site is to decommission the current regulator and replace this with a passive solution, such as a baffle or orifice plate which spans the width of the channel, to further utilise some of the upstream storage in the washlands. JBA-Bentley are currently undertaking modelling of options for Woodhouse Mill regulator to inform the next phase of the project and the viability of the proposed solution. [caption id="" align="alignnone" width="1200"] The existing Woodhouse Mill regulator gate - Courtesy of JBA-Bentley[/caption] Meadowgate The Meadowgate Regulator is located within the Rother Valley Country Park. The existing regulator consisted of a single fish belly bottom hinged tilting gate, operated by a single electrically powered hydraulic ram. As per Canklow, the new gate will be a top-down vertical control gate improving resilience of the structure; as per the model above. When the new gate is lowered, water levels in the Rother rise and begin to spill into the washlands that are located within the Rother Valley Country Park, which can retain approximately 1.5 Mm3. Temporary set up The civils elements of the scheme have included demolishing the existing buildings and installing new control building. To ensure the gate remained operational during this time a temporary control centre was established during the early part of the scheme; once the gate has been commissioned this will be removed from site. River Don Regulators: Supply chain - key participants Project delivery: JBA-Bentley JV JBA Consulting JN Bentley Principal designer: Callsafe Services Ltd Gate design: Aquatic Control Engineering Electrical Installations: IMAC Ltd Building design: JP Chick & Partners Building design: Peter Wells Architects Supporting ECC Supervisor with new gate & associated equipment: KGAL Consulting Engineers Ltd Precast fish pass tiles: Craven Concrete Ltd In situ concrete works : Bells Construction Ltd Metalwork fabrications: Fabtek Green roof: ABG Geosynthetics Ltd [caption id="" align="alignnone" width="1200"] Model of the new Meadowgate regulator - Courtesy of JBA-Bentley[/caption] HAZOP Working closely with the Environment Agency’s Operational and Maintenance teams the gate design and associated infrastructure has been developed to ensure it allows safe access and operation; a Hazard & Operational Study (HAZOP) was undertaken during the early design stages to ensure all requirements were included. Full channel fish pass By removing the bottom hinged tilting gate, there was an opportunity to improve fish passage on the River Rother. Currently, there is a stilling basin immediately downstream of the gate approximately 40m in length, 12m wide and up to 3m deep at the upstream end. Through design development a unique full channel fish pass has been developed which removes the stilling basin by infilling to grade out the bed levels before installing reinforced concrete fish tiles with upstands of varying heights. Computational fluid dynamics (CFD) modelling of fish pass Due to the engineered nature of the channel in this location and the operation of the gate, the fish pass is required to withstand high velocity flows up to 8m/s during extreme events. This proved challenging to the more traditional fish pass construction leading to a heavily engineered solution. [caption id="" align="alignnone" width="1200"] (left) Screenshot of fish pass model - Courtesy of JBA-Bentley, (top right) fish tile mould - Courtesy of Craven Concrete Ltd, and (bottom right) the Meadowgate site - Courtesy of JBA-Bentley[/caption] To refine the design and prove passability for a range of species, the proposed arrangement was modelled using CFD. This allowed the upstand heights to be adjusted to provide the optimum depth and velocities through the range of design flows. Fish pass tiles Once the height and arrangement of the upstands was agreed with the Environment Agency’s National Fish Pass Panel, the structural design of the fish pass tiles began. Each tile measures 2.5m x 2.0m and weigh 4 tonnes; therefore, the design not only had to withstand hydrodynamic forces but also the lifting requirements for construction. In total, 80 fish pass tiles will be manufactured and placed into the channel, within a dry working area. [caption id="" align="alignnone" width="1200"] Precast fish pass tiles - Courtesy of Craven Concrete Ltd[/caption] Temporary works consideration To allow the fish pass to be installed within a dry area of channel, the full river channel needs to be dewatered. This will be achieved by installing an upstream dam and fluming the flow through the working area. The decision to install precast units reduces the risks of in-channel pours and to reduce programme duration for the in-channel works. Summary The replacement Don Regulators will protect Rotherham and the surrounding area from flooding, improve resilience, and ensure the gates can be operated as required both now and as we see the effects of climate change.

Sprowston Blue Boar Lane Rising Main in Norwich plays a crucial function in management of wastewater for the local community. The rising main connects the Sprowston Blue Boar Lane Pumping Station to the sewer network; facilitating efficient wastewater transport. The pipeline’s strategic location near housing developments, a roundabout, and a Tesco supermarket and fuel station underscores its importance to public health and safety. The region’s growth and the rising main’s proximity to high-traffic zones emphasise the need for a reliable and resilient infrastructure. The issue

As assets age, they start to work less efficiently than they did at their installation. Anglian Water Service had recently noticed this within the Sprowston Blue Boar Lane Rising Main, as it had experienced multiple bursts in recent years, including incidents on November 18, 2020 and August 20, 2021. These failures occurred near critical infrastructure, including residential areas and a busy roundabout adjacent to a Tesco supermarket and delivery bay.

The existing 450mm glass reinforced plastic rising main’s deteriorated condition necessitated immediate action. Additionally, the aging infrastructure had a rough internal surface, contributing to inefficiencies in flow and elevated operational risks. The bursts posed significant risks, including potential pollution events through contamination, which is a risk to the public health of the surrounding area.

Design considerations

Anglian Water’s @one Alliance sewer rehabilitation team acted quickly to come up with a solution for this issue; realising that a comprehensive rehabilitation plan was required to address the identified issues to ensure long-term reliability and compliance with performance standards. To complete this, the project’s execution followed a systematic approach to minimise disruptions and maintain service continuity.

[caption id="attachment_19175" align="alignnone" width="1200"] omplex overpumping arrangement - Courtesy of Anglian Water’s @one Alliance[/caption]

Thorough assessments were undertaken to ensure the most effective and future-proofed solution was selected, so during the design phase, the Anglian Water @one Alliance team carefully explored multiple options to determine the best approach for this project. Replacing the existing GRP pipe with a brand-new PE pipe along Blue Boar Lane was initially considered, however, trial hole investigations quickly revealed the area’s significant congestion of utilities, including gas mains and electric cables, which posed substantial risks to the project.

Further construction techniques were evaluated, but ultimately the installation of a 9mm thick, water-cured liner within the existing pipe was determined to be the optimal solution, offering a practical and efficient way to navigate the complexities of the site.

The solution required maintaining a flow rate of 142 l/s and thanks to the smoother surface of the new liner, hydraulic modelling confirmed that there was no adverse effect from the reduced bore resulting from the relining process.

Hydraulic modelling also accounted for maximum and minimum pressure conditions, including surge pressures during operation and pump trips, and it was determined that the liner needed to withstand pressures of up to 5.15 bar and negative pressures down to -0.5 bar.

The final design not only met hydraulic modelling criteria but also ensured sufficient pressure handling, making it robust and efficient under operational conditions.

Blue Boar Lane Rising Main: Supply chain - key participants Client: Anglian Water Project delivery: @one Alliance Bypass pipework: Vanderkamp UK Cured in place relining: OnSite Central Ltd Crane hire: Crowland Cranes Temporary works

The initial challenge the team faced was the need for the sewer to be empty while the relining rehabilitation works took place. To resolve this challenge and ensure uninterrupted service to customers during construction, a temporary 450mm diameter, above-ground pipe needed to be installed to divert sewage flows, complete with pipe bridges at road crossings and entrance points. The temporary pipeline allowed the existing GRP pipe to be isolated and the rehabilitation could commence.

[caption id="attachment_19176" align="alignnone" width="1200"] Complex overpumping arrangement - Courtesy of Anglian Water’s @one Alliance[/caption] The installation of the temporary pipework was a significant undertaking, and one that required close collaboration with Vanderkamp UK. Working together, the @one Alliance/Vanderkamp UK team considered sustainable solutions to mitigate flows and ensure the continued integrity of Anglian Water’s infrastructure. Liner installation

With the overland pipework in place, the team drained the existing GRP rising main and undertook CCTV surveys to assess its condition.

The works required the installation of a 9mm thick, water-cured liner within the existing pipe, which would create a smooth and durable interior surface with improved hydraulic performance. Alongside the installation of the new liner, a new air valve at the high point near the Tesco loading bay was installed to optimise the pressure going into the pipe.

Once the work was complete, the relined pipe was reconnected to the network and tested and commissioned for performance before being handed back to Anglian Water. The site team then decommissioned the overland pipework and restored the area back to its original condition.

The team relined 680m of the existing 450mm GRP rising main, providing a robust solution which will last for many years to come.

Benefits of the solution

The rehabilitation of the Sprowston Blue Boar Lane Rising Main delivered numerous operational, environmental, and community benefits.

The installation of the 9mm thick pressure liner significantly improved the rising main’s durability and hydraulic performance for many years to come. The smoother interior surface reduced the resistance, enhanced the flow efficiency and minimised the energy consumption. By installing the new air valve, optimal pressure was maintained which reduced the risk of future bursts. The solution also mitigates the risk of environmental contamination from wastewater spills and supports environmental compliance with regulatory standards. The temporary overland pipework ensured uninterrupted service to our local community and the water-cured relining method was a cost-effective solution compared to complete replacement; minimising excavation and associated costs. Thes solution provides longevity and resilience by providing over 50+ year’s lifespan of the pressure liner, which in turn reduces the need for frequent maintenance & also lowers the lifecycle costs. Conclusion

By implementing innovative technologies and meticulous planning, the £1.5m project addressed critical operational challenges while minimising environmental and community impacts. The success of this infrastructure improvement project ensured continuity of service and long-term reliability, safeguarding the region’s wastewater infrastructure for decades to come.

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.

Meadowgate Regulator

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.

[caption id="attachment_14798" align="alignnone" width="1200"] (left) location of the regulator gates and (right) the new Meadowgate top-down vertical control gate[/caption]

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.

Meadowgate full channel fish pass

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.

[caption id="attachment_14802" align="alignnone" width="1200"] Precast concrete ‘fish tiles’ from Craven Concrete Ltd positioned in the channel - Courtesy of JBA-Bentley[/caption] Meadowgate temporary works solution: Syphon pumps & contingency planning

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.

[caption id="attachment_14797" align="alignnone" width="1200"] (left) The dewatered channel and (right) ‘fish tile’ installation - Courtesy of JBA-Bentley[/caption]

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.

[caption id="attachment_14801" align="alignnone" width="1200"] Syphon outlet - Courtesy of JBA-Bentley[/caption] Don Regulators: Supply chain - key participants Client: Environment Agency Project delivery: JBA-Bentley JV JBA Consulting JN Bentley Ltd Principal designer: Callsafe Services Ltd Gate design: Aquatic Control Engineering Syphon design: Vanderkamp UK Electrical installations: IMAC Ltd Building design: JP Chick & Partners Building design: Peter Wells Architects Supporting ECC Supervisor with new gate & associated equipment: KGAL Consulting Engineers Ltd Precast fish pass tiles: Craven Concrete Ltd In situ concrete works: Bells Construction Ltd Metalwork fabrications: Fabtek Green roof: ABG Geosynthetics Ltd Canklow Regulator

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.

[caption id="attachment_14807" align="alignnone" width="1200"] (top left) the existing Canklow regulator gate (bottom left) 3D model of the new Canklow Regulator and (right) bathymetry of Woodhouse Mill Washland - Courtesy of JBA-Bentley[/caption] The power supply to the gate will be a three-phase supply routed via a new MCC, which will contain the control modules, centralised drive units, and the telemetry system for remote monitoring and operation of the gate. The operation of the gate will be from on-site or via telemetry, with some semi-automated functions. The facility for future full automation of the site has been incorporated into the design. The MCC and electrical components will all be located within a kiosk mounted on a raised steelwork platform to lift the electrical components above the 0.1% AEP flood level. Also on this raised platform will be the DNO kiosk bringing power onto the site from the national grid, and a standby generator to provide resilience in case of power failure.

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.

[caption id="attachment_14796" align="alignnone" width="1200"] Overhead power exclusion zones within model - Courtesy of JBA-Bentley[/caption] Woodhouse Mill

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:

The Rother. Don/Dearne. Lower Don.

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.

Summary

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.

Ise Valley, Wellingborough, is home to the £1bn Stanton Cross housing development just off the B571 in the east of England. In late 2022, parts of the development were struck with leaks in the underground rising mains, causing disruption to many new homeowners during the Christmas period. In November 2022, Anglian Water was made aware of several leaks on each of the 700mm ductile iron rising mains from Ise Valley Terminal Pumping Station (TPS), which pumps flows of up to 1500 l/s. Both rising mains are required for normal operation of the pumping station and to convey the maximum flow, however, surveys showed that both mains had reached the end of their asset life due to both internal and external corrosion, and further leaks would occur if no action was taken. Background

Once the team attended site, it became apparent that both the north and the south mains had leakage issues. Non-destructive testing confirmed external pitting and internal abrasion wearing in the upstream sections and an internal hydrogen sulphide (H2S) attack on the downstream section, which was determined to be the primary issue.

With two leaks occurring in close proximity, and previous leaks occurring over the last 10 years, there was a substantial risk of more. The @one Alliance was engaged on 1 December 2022 with the immediate priority being to design, install and commission an temporary above-ground bypass to mitigate the impact of any further potential leaks while the permanent solution was identified.

The Stanton Cross housing development was recently constructed over the area along the route of the rising mains, with houses as close to the asset as 4m in places and leaving no clear route to bypass the flows. As an added complication, some residents located close to the rising mains reported feeling vibrations from the mains;  the cause of which needed to be investigated.

[caption id="attachment_13372" align="alignnone" width="1200"] Temporary pipeline ready for assembly - Courtesy of @one Alliance[/caption] Temporary solution

It was identified that the rising main leaving the building from the north could be isolated and cut into, to provide a temporary overland pipeline fed by the existing pumps, which would avoid the need for temporary pumping equipment over what would have been the Christmas period. Although the five pumps had recently been mechanically overhauled, the team found several electrical issues that required repairs. As such it was arranged for three temporary variable speed drives to be installed as a matter of urgency, to better manage pump performance and to help prevent further bursts before flows could be diverted.

Utilising contacts across the @one Alliance’s supply chain, specialist overpumping contractor Vanderkamp UK was contracted to provide a temporary bypass in short order. The teams decided on a 1m diameter pipe to give the equivalent flow of the existing twin 700mm diameter pipes to avoid reducing pump capacity.

Working around the clock to find a suitable solution, Vanderkamp UK, the @one Alliance and Anglian Water’s Water Recycling Networks (WRN), allowed for a quick design and installation of the bypass. The whole team aided the process from construction design management documentation to hydraulic design, temporary works, customer and PR, supply chain and enabling.

Ise Valley Sewer Rehabilitation: Supply chain - key participants Project delivery: @one Alliance Bypass pipework: Vanderkamp UK Cured in place relining: OnSite Central Ltd CIPP liner supply: IMPREG GmBH [caption id="attachment_13369" align="alignnone" width="1200"] Road closures were necessary while installing the pipe bridges - Courtesy of @one Alliance[/caption] Overpumping bypass pipeline installation

In order to build the overpumping solution as quickly as possible, the @one Alliance team collaborated with the Integrated Operational Solutions (IOS) Alliance that provided provisional enabling works such as electrical isolation of services, excavation of the point of connection and temporary ground drainage/pollution avoidance provisions. With the initial works complete, the @one Alliance took full control of the site and initiated the installation of the pipeline.

Work of this scale required a coordinated customer strategy which was designed and implemented by the @one Alliance Customer Team who notified all affected customers of the planned works and continued to provide updates throughout the various stages of work making sure customers were informed and suffered the least impact possible over a busy Christmas period.

To make the connection to the bypass pipework, all flows were diverted to the south main and twin 600mm tee pieces were installed in the north main within the terminal pumping station compound. This arrangement allowed the south main to remain in service if required over Christmas. The connection was completed on 9 December with installation of the 1m diameter pipework commencing the following day.

Due to the new housing development, it was not possible to follow the route of the existing mains and care had to be taken to ensure the bypass pipework would not interfere with a permanent solution or the ongoing operation of the pumping station. A route along Driver Way and Irthlingborough Road was selected which included several pipe bridges in order to allow unrestricted customer access. Emergency road closures were agreed with both the local property developer and North Northamptonshire Highways to safely install the pipework.

[caption id="attachment_13373" align="alignnone" width="1200"] Installing the temporary overpumping solution - Courtesy of @one Alliance[/caption]

The pipework installation was completed in just 10 days during an extreme cold snap which saw the @one Alliance and Vanderkamp UK operatives installing the overpumping pipeline in temperatures of -6°C. Nevertheless, the team worked two consecutive weekends to ensure the bypass was live and operational before Christmas. On 20 December 2022, the bypass was commissioned on time and to ensure there were no customer issues, inspections were carried out every day over the Christmas period.

Permanent solution

Testing and inspection of the mains showed that in the base of the pipe there were a series of what could be best described as wave patterns. The waves - the result of erosion of the pipe material - has been caused over many years by grit within the flow of sewerage. As the pipes rise steeply uphill the grit had settled at the base. Coupled with external and internal corrosion, susceptible areas of the ductile iron pipes have locally pin-holed, which had allowed leakage, and confirmed zero life span remaining in places.

Following the inspection and testing of the pipework, an accelerated Risk, Opportunity & Value sprint was held with all stakeholders to confirm the most suitable permanent solution. The team decided against the removal and replacement of the existing main due to the amount of time it would have taken to execute, additional disruption to customers and local traffic, and the small working space available to the team. It was then determined that the most effective solution was to use a structural liner.

The location of the trial holes, which had been used for examination and non-destructive testing of the mains, had been carefully selected as potential relining pits in the event this solution was to be used. This allowed for an accelerated programme to prepare for the relining works and a reduction in carbon and costs.

[caption id="attachment_13371" align="alignnone" width="1200"] Re-lining rig - Courtesy of @one Alliance[/caption] Rehabilitation of the existing mains using specialist pressure-rated cured in place pipe (CIPP) liners was selected. Framework supplier OnSite Central Ltd installed the liners using a combination of ultraviolet and water cure techniques to suit the challenging pipe conditions. Aware of the time constraints, OnSite Central Ltd worked with the project team to ensure the liners were delivered promptly from IMPREG GmBH in Germany, and that installation gangs were available to work extended shifts to ensure the challenging programme was delivered.

Once the relining was complete Vanderkamp UK  began dismantling the overpumping, all of which was removed by the end of May 2023. Pressure and vibration monitoring of the temporary bypass pipework identified a correlation between pressure spikes and vibrations. This resulted in a change to the pumping station regime and, along with the new variable speed drives and the liner acting as a barrier, resulted in a large reduction of vibrations felt along the route once flows had been returned to the rising mains. Post works vibration monitoring at a number of previously affected properties confirmed the vibration issues had been resolved.

Challenges

The team had to take into consideration a plethora of potential risks during the entire project lifecycle. From contaminated ground, congested buried services, extreme weather conditions, an construction challenges such as relining through 45° bends. The team had to sufficiently ensure a timely plan was in place, following many detailed impact plans created to overcome these issues to ensure efficiency in completion of the project, and reduce the disruption to customers over the festive period.

[caption id="attachment_13367" align="alignnone" width="1200"] Overpumping termination point - Courtesy of @one Alliance[/caption] Customer liaison

One of the big challenges for this scheme was the disruption to the customers during the festive period, with the scheme attracting significant nationwide media attention over the duration of the works from national and local newspapers, BBC television (“Look East”), BBC radio (Jeremy Vine), and news and social media websites.

While this work went on, the @one Alliance Customer Team kept residents up to date with the team’s progress while helping manage expectations as to how long the work would take, and how long the temporary structure would be in place. Communications to the local residents were consistent throughout the project lifecycle (from 2/12/2022 to 24/4/2023), ensuring constant updates, programme times, and responses to queries were included at all stages.

Outcome

Anglian Water’s £2.8m spend and proactive response to this issue enabled the successful relining of the existing pipe. The relining solution, which will give the pipe an expected 100 years of extra service, has been in service for over a year with no issues.