Supply Chain - Contractors - Welding

Bearwood Service Reservoir (SR) is fed from Sindlesham Water Booster Station (WBS) and boosts flows to customer demand and to the downstream Arborfield Cross WBS. Bearwood WBS previously had capacity to deliver approximately 85 l/s during peak demand, however a capacity assessment completed in 2021 showed that peak demand for 2024 and beyond will rise to 122 l/s, therefore creating the project driver for the upgrades to the pumping station.

The major challenge associated with the proposed scheme is network demand. If Bearwood WBS is inhibited or not operational for any reason, there would be direct customer impact within 20 minutes. Also, during peak demand of the summer months, it is critical that all three cells of the Bearwood Service Reservoir must be in operation to ensure capacity to serve the network. These limitations were the main considerations for the resultant upgrade solutions and construction methodology and sequencing.

The existing installation at Bearwood comprised three 18.5 kW pumps, capable of delivering approximately 86 l/s to the network while sustaining a target pressure of approximately 2.1 bar. The proposed solution comprises four 22.5kW axially split centrifugal pumps in a duty/assist/assist/standby configuration.

An analysis of the existing network by Hydraulic Analysis Ltd outlined the requirement for a 50m3 discharge surge vessel to protect the network. This was to be served by two compressors in a duty/standby configuration, housed within a GRP kiosk.

A new MCC from Ward & Burke supplies power and control for the site, while a new standby generator and dedicated double skin fuel tank provided backup power for the site. Building ventilation works and a new access staircase and gantry arrangement were prescribed to improve operability of the pump station.

Replacing the existing assets raised major risks around the operation of the pumping station and the direct impact any downtime or failures would have on customers. The solution therefore needed to allow for the required redundancy for the site assets and overall system, ensuring that power supply and pump operation had sufficient redundancy and automatic control in the case of any failures.

Visibility and feedback of the site on regional site SCADA for both existing and new assets also added another layer of protection for site operations should any failures occur, meaning they could be addressed promptly.

Works commenced in November 2025 with initial enabling works. This started with the installation of the temporary site backup generator, which allowed for the existing defunct diesel generator to be removed from the WBS building and the accompanying external fuel tank to be removed from the rear of the building.

These works freed up much-needed space both inside and outside the WBS, without reducing the site’s redundancy with respect to power supply. Further enabling works included removal of the internal wall of the WBS which previously divided the generator from the main room.

Removal of the precast ceiling in the generator room was identified in the project’s Design Risk Assessment as a high-risk activity, and as such, solutions were sought to remove the risks associated with its removal, while still allowing the block wall dividing the building to be removed. The solution combined support steelwork for the slabs with the new gantry crane structure. Installing the gantry crane early also reduced the risks associated with movement of materials to/from the basement level later in the project. With the wall removed, the electrical installation for the new MCC could begin.

Concurrently, works began outside at the rear of the WBS. A new discharge main from the WBS was installed, and with this in place, other civils work could be completed including ducting, drainage and slab construction for a surge vessel, compressor kiosk, standby generator and fuel tank. The arrangement for the surge vessel from Quantum Engineering Developments Ltd and future discharge pipework included double isolation valves and washouts for future surge vessel inspection access and commissioning.

Due to the future flow demand, the existing outlet pipework from the reservoir to the booster pumps would fall outside the allowable velocities and therefore required upsizing. Replacing the existing pipework would require deep excavations (~4m) in a heavily congested area of site with respect to other services, as well as being close to the reservoir and the busy adjacent road.

This would introduce major risks around service strikes, traffic management and disruption to site services which could lead to customer impact.

The solution was to lay a new manifold at the opposite end of the reservoir, with new pipework from each of the three cells. This new manifold would lead into a new main which would feed the booster pumps. This removed the risks associated with traffic management, and significantly reduced the risks associated with service strikes and site operability. A key consideration with these works was that two of the three reservoir cells were in operation at any one time, to ensure no impact to site operation or customer impact.

To ensure the client’s construction assurance, site operations and water quality teams were all aligned with the planned commissioning sequence, a detailed visualisation of the commissioning plan was prepared.

As the new manifold would be installed and commissioned in sections, in line with the individual reservoir cell outages, sacrificial commissioning chambers were installed where test spades were required to be removed in the future, greatly reducing the risks associated with working around deep excavations on site. The installation of the cross-connection T and in-line valve on the existing outlet pipework were completed as underpressure connections by R2M Limited; removing the need for a shutdown and the risk of customer impact.

To lay the new pipework into each of the cells, the reservoir walls were cored and a section of pipe cast in. Due to the timings associated with the reservoir works, it was undesirable to rely on a drop test once the cell was recommissioned to determine if the cast in pipe was adequately sealed. If any issues became present, the cell would need to be drained again, works re-completed, and the cell recommissioned before being put back into service, a process which would take up to 2 weeks.

To remove this risk, the cast section was hydrostatically tested externally to the tank, to mimic the hydrostatic pressure of the internal water level. A DN600 pipe spool was bolted to the wall over the cast section and pressure tested, with the seal between the spool flange and the reservoir wall completed using a custom-made gasket. Once the test was passed, the internal reservoir pipework could be installed and external connection to the manifold completed.

In parallel to these works, a number of key equipment deliveries were made, including the installation of the new MCC provided by Ward & Burke, as well as the 50m3 surge vessel and associated compressors and kiosk from Morgan Marine Ltd. The delivery of the generator and fuel tank soon followed, meaning the pump upgrade could begin.

To enable the pump upgrade, flushing and commissioning activities for the new reservoir outlet pipework, a single isolation valve had to be fitted in place of a blank plate on the existing live discharge manifold. This would be the only shutdown of the booster station, of just 30 minutes, allowing for contingency. Significant network injection tankering had to be arranged with Site and Network Operations, to enable the shutdown and ensure no impact to the network or customers. With no existing point of isolation on the discharge main, a second in-line valve was installed to establish an isolation point as close to the work area as possible, thereby minimising drain-down times and any shutdown durations.

Once this valve was fitted, the new outlet main and Cell A pipework could be flushed, meaning it could then be commissioned, At the same time, work commenced on the temporary pump arrangement.

Power upgrades for the site were also completed, with the existing 50 kVA supply upgraded to a 140 kVA supply, alongside the installation of a new CT meter. The site was run on the standby generator during these works to remove the need for any shutdown.

The temporary arrangement, which utilises two of the four permanent pumps, can provide the full current customer demand, meaning that once operational, the existing pumps can be removed. The system is powered and controlled by the new MCC and is backed up by the new generator. The surge vessel was also commissioned and put into service at this point, to provide extra protection to the existing network.

As part of the wet commissioning of the temporary arrangement and using the washout arrangements upstream of the surge vessel, the pumps were run and used to flush the Cell B pipework. This provided an opportunity to run the pumps with flows prior to going live to the network, while also ensuring the Cell B pipework got a full design flow rate flush.

The temporary arrangement then went through a 14-day reliability period before the existing pumps were removed. During this period, the pump status signals were hard-wired back to the existing panel, so that if one of the new pumpsets was to trip or fail, the existing pumps would start to provide additional support without operator intervention. This also ensured the new pumps were visible on the existing site SCADA, for monitoring by site operations.

With the reliability period complete, the remaining existing equipment from the building could be stripped out, including the old pumps, existing MCC, ventilation and any other ancillary equipment. This allowed for the final new pump units to be installed and commissioned, while the Cell C pipework was installed and commissioned also. Once the final two pumps were installed and operational, the first pump installed, which was in the temporary location, could be repositioned to its final permanent position.

The last major element of the scheme was the new outlet main from the booster station. The project driver for this was similar to that of the new reservoir outlet, in that the future flow rate would make the existing outlet main fall foul of pipework velocities.

To avoid modifying the existing pipework, which would disrupt the existing supply to customers, a solution was sought to install a second outlet main to run in parallel with the existing and split the flow rate between the two. This pipeline was to be installed via open cut methodology, but to minimise the impact on neighbouring landowners, the majority of the pipework was installed via horizontal directional drilling (HDD). The final connection to the network trunk main will be completed as part of a separate project.

Finally site fencing, pump cover installation, and floor coating works were undertaken along with final concrete works, site top soiling and planting of fruit trees in line with biodiversity net gain target.

At the time of writing, July 2026, the site is fully operational under Thames Water and final demobilising works alongside handover documentation is being completed, with full handover expected by the end of the month.

Sindlesham Water Booster Station (WBS) is fed from Early Service Reservoir (SR), boosting flows to the service reservoir at Bearwood, where a separate WBS feeds the network demand. Sindlesham WBS previously delivered approximately 84 l/s during peak demand, however, a capacity assessment completed in 2021 showed that peak demand for 2024 and beyond will rise to 100 l/s, thereby creating the project driver for the upgrades described in this case study.

The maximum permissible outage at any time for Sindlesham WBS is 2 hours, at which point the level in Bearwood SR will be such that the Bearwood WBS will be inhibited from operation to protect its assets. Furthermore, if Bearwood WBS is inhibited or not operational for any reason, there would be direct customer impact within 20 minutes. These limitations were the main considerations for the resultant upgrade solutions and construction methodology and sequencing.

The existing installation at Sindlesham comprised of two 18.5kW pumps, which delivered approximately 84 l/s to Bearwood SR via a 4.2km, DN300 pipeline. The solution requires two 55kW end suction centrifugal pumps in a duty/standby configuration.

A transient  analysis carried out on the existing network by Hydraulic Analysis Ltd on behalf of Ward & Burke, outlined the requirement for a 1.5m3 suction side surge vessel to be installed, as well as a 10.5m3 discharge vessel to protect the network. These were to be served by two compressors in a duty/standby configuration, housed within a GRP kiosk.

A new MCC from Bilfinger UK will supply power and control for the site, while a new standby generator and dedicated double skin fuel tank provided backup power for the site.

Replacing the existing assets raises major risks around the operation of the pumping station and the direct impact any downtime or failures would have on the network.

The solution therefore needed to allow for the required redundancy for the critical assets and overall system. The result of which ensured that power supply and pump operation had sufficient redundancy, and automatic control in the case of any failures.

Maintaining visibility and feedback of the site on regional site SCADA for both existing and new assets added another layer of protection for site operations should any failures occur, meaning they could be addressed promptly.

Works commenced late April 2025, with the installation of the temporary site backup generator. This allowed for the existing defunct diesel generator to be removed from the WBS building and the accompanying external fuel tank to be removed from the rear of the building.

These works freed up much-needed space in an already confined site for new equipment, without reducing the site’s redundancy with respect to power supply.

The construction sequence then centred around completing as much of the off-line works as possible, so that once pump changeover started, the site overall always had backup power and pumping capabilities. Civil works could now be undertaken which included ducting, drainage and slab works for the new kiosk, fuel tank and standby generator.

Full site shutdowns meant that all pumping was stopped for a short period of time. The first of these required a 90 minute shutdown to complete the necessary enabling works on the existing pipework and replace two 90° bends with tees on the suction side of the WBS.

This was required for:

Completing these pieces of work together ensured that the surge vessel could later be connected and commissioned without disturbing supply to customers. Following these connections, the civils works to the southern and eastern sides of the WBS could be completed.

Due to the limitations on site, shutdowns, and the availability of existing valves, underpressure tappings and in-line valves were used wherever possible, to ensure minimal disruption to the pumping operations and customers. One of these opportunities was for the discharge surge vessel connection.

The second full site shutdown was required to provide the discharge connection for Pump No. 2 within the WBS. Again, opportunities to reduce shutdowns as far as practicable was priority and so works were also planned to coordinate the removal of a non-return valve on the same line, but 4km away at the Bearwood SR site.

Hydraulic analysis indicated that an existing non-return valve on the rising main entering Bearwood was a major contributor to potential surge events associated with the operation at Sindlesham. The valve posed such a risk that the analysis recommended its removal.

As these works would also require shutdown of Sindlesham WBS, they were scheduled to be undertaken together during the 105 minute shutdown.

A temporary air valve was fitted to the new connection to ensure adequate air removal during refilling of the line and reverting the pumping station back to normal operation.

Works within the building continued in parallel to external works with installation of steelwork to support the existing precast slab ceiling that previously enclosed the generator room. Removal of this precast ceiling was identified in the project’s Design Risk Assessment as a high-risk activity and as such, solutions were sought to remove the risks associated with its removal, while still allowing the block wall dividing the building to be removed.

Once the block wall was removed, the new MCC could be installed, behind the existing MCC, in preparation of the pump installation.

External to the building, the generator and fuel tank were being installed, followed by the kiosk and the surge vessels.

The final site shutdown could be scheduled, and this was to install a new valve on the existing discharge manifold. The installation of this valve ensured that the first booster pump could be replaced off-line, removing the risk of unplanned pumping outages and ensuring undisturbed supply for customers. The shutdown lasted approximately 60 minutes.

Works then continued to remove Pump No. 1 and replace with the new 55kW Lowara end suction unit from Xylem Water Solutions.

During this period, the site was operating without a standby pump. Provisions were made for the removed pump to be kept on site, adjacent the existing operating unit and beneath temporary lifting equipment. This would allow site operations and/or Ward & Burke to act promptly should an issue arise with the duty pump, when the first new pump was being commissioned and put into service.

At this juncture, the site was ready to begin operating on the new pump and begin a 14-day proving period. This new pump was powered and controlled by the new MCC, with backup power provided by the new standby generator. Pump signals were temporarily hard-wired to the telemetry outstation to ensure site operations and regional SCADA had remote visibility of the new pump operation status.

A hard-wired duty signal was also installed between the new MCC PLC, and the existing MCC control logic, which replaced the old pump input signals. This meant that if the new pump tripped, or failed in any capacity, the existing MCC would be provided an input and automatically start the existing pump. In other words, the site was running on two separate pumps, power and control systems during this period, working in a duty/standby arrangement, ensuring complete redundancy of the new system.

Following successful completion of this proving period, the existing pump and MCC could be removed and close out works could begin.

A partition wall was erected between the new MCC and the pumps to create an MCC room, separate to the pump room. The new ventilation system was installed and commissioned, alongside completion of all electrical installation works. Finally, a new non-slip floor finish was applied, walls and ceilings painted and new floor trench covers were installed to complete the project.

Handover was completed in December 2025, marking the end of the first phase in the wider contract, ensuring sufficient flows for future demand are fed to Bearwood Service Reservoir. The second phase of works requires a full upgrade of Bearwood WBS, to ensure that the future flow demands can be delivered directly to customers in the growing Arborfield area.

At the outset, the £95m Glasgow Resilience Programme was Scottish Water’s largest ongoing capital investment, which comprised the installation of 12km of ductile iron pipe through a predominantly urban environment with significant surface features impacting the route. The pipeline was installed through a mix of carriageway, public parks, urban and rural environments.

To achieve the resilience driver for the project, a new 78 MLD pumping station with MCC was required, powered by two new HV transformers and solar PV panels.

Planning for the project started in 2016, with construction starting on site in May 2020 and completing in August 2025. It required highly complex interactions with the existing water network and multiple modes of control at the new pumping station.

Bedrock was encountered throughout the pipe laying route, predominately for the final 500mm before achieving formation level. Whilst this had an impact pipelaying productivity, the depth of the pipe installation did mean that the vast majority of existing utilities did not clash with the new pipeline and no diversions were required. However, due to the close proximity of residential properties, offices, shops, etc, precondition surveys were completed and vibration monitoring in-stalled to record and monitor any issues whilst the rock breaking was being completed.

The new pipeline route called for installation through several public spaces being Bellahouston Park, Lochar Park, Househill Park and Dams to Darnley Country Park. These parks have high amenity value whether it be major music events, local organisation events, sporting events or general walkers, dog walkers and runners.

Health & Safety was the primary concern through these areas and involved careful planning around upcoming events and robust security arrangements.

In addition, a number of the deep shafts were required for the trenchless works within these areas, again calling for alternative security arrangements which included semi-permanent security fencing to secure these works areas.

Approximately 60% of the pipeline was laid within public highways, through residential streets. The 900mm diameter ductile iron pipes were 7m in length and weighed approximately 2.4 tonnes. The project had to consider the most efficient and safest methodology of working in such areas and it became clear that this would involve significant road closures, traffic management and likely disruption through the centre of Glasgow.

A close relationship was developed with the local roads authorities with plans put in place to allow such major road closures. In conjunction with the project’s Customer Communications Team, information on the closures, diversions and timelines were issued to nearby residents whilst the wider public were informed through VMS and radio adverts. Post completion of the works, it was apparent that the road closures actually minimised disruption in comparison to traffic lights as motorists were likely to find alternative routes.

As expected in laying pipe through urban environments, the project encountered multiple utilities; both charted and uncharted. The pipeline design considered this aspect, with the crown level of the new pipe being such that it would be below the standard installation levels of other assets. This proved to be a success with no utility diversions needed, however, it did slow production as the teams had to carefully identify all utilities in the area and feed the new pipeline both between and under these exposed utilities.

The incredible utility avoidance record achieved throughout the course of the pipelaying activities should be highlighted; with 720 utilities encountered along the pipeline route, 33% of which were uncharted. All utilities were successfully located and crossed. This outstanding record of zero damage was achieved through industry leading utility location and safe excavation practices across the project.

In addition to the management of traffic movements, the project also had to consider the logistics of moving such large pipes and materials around the pipeline route. This involved the procurement of bespoke pipe cradles for transportation as well as procuring additional storage areas throughout the route.

The pipe route included four sections where trenchless methods were required to install the pipe. The drive lengths ranged from 54m up to 264m. Shaft depths ranged from 9m to 24m incorporating shaft diameters of 6m and 8.2m to allow a 1500mm tunnel boring machine (TBM).

Within these drives, assets that were crossed included one of the busiest motorway sections in Scotland (M8 motorway) leading into Glasgow, three separate Network Rail under-track crossings (UTXs) and two watercourses. Engagement with the asset owners (Network Rail & Transport Scotland) were sought at an early stage to understand any constraints that there may be and continued, regular dialogue ensured that all relevant permissions were obtained in a timely manner.

On completion of the tunnels, the project team then had to install the permanent 900mm diameter DI pipe. This involved a complex operation by lowering the pipe into the shafts, connecting and winching the pipes through the concrete jacking pipe. Bespoke spiders were procured and installed ensuring a smooth transition where on completion, the pipe was pressure tested before subsequently being grouted into place.

Through the design process, it became apparent that the flows from Milngavie WTW to the next downstream pumping station could be managed hydraulically via gravity only. This is a route of approximately 30km. However, to achieve the resilience driver, it was identified that a new pumping station would be required.

The pumping station is required to manage 78 MLD which saw the design incorporate three 250kW pumps on a duty/duty/standby basis. To power these pumps, and again to support the resilience element, two independent HV power supplies were installed via two HV transformers which allows a backup supply should there be a power outage on the primary supply.

To support the power requirements of the pumping station, the footprint of the pumping station roof allowed the installation of 50kW SolarEdge solar PV system comprising of 135 Trina Vertex-S panels. In addition to the PV panels to helping work towards Scottish Water’s Net Zero targets, electrical vehicle charging points have been installed with the facility to upgrade to 75Kw chargers in the future.

The pumping station is linked to additional Scottish Water assets  (including Thornliebank and Gorbals PS) via a SoGEA inter-site communications system. This allows the full network to be controlled remotely, ensuring a calm network response to any issue. The software enables monitoring of tank levels and control of the overall network, primarily fed back via a flow control valves, flow meters, needle valves and a comprehensive array of level sensor instrumentation. This allows the main to be predominantly controlled in gravity flow mode, reducing pump use, power usage and ultimately, lowering operating costs and CO2 emissions.

The new asset discharge into two existing distribution service reservoirs (DSR) within the Gorbals PS footprint. Both discharges required access to the reservoirs to complete civils elements of works which required close engagement with the Scottish Water CSD Team, Networks and Public Health.

One of the DSR’s was constructed relatively recently which allowed a clearer understanding of previous construction techniques so the project teams methodology to break into the tank was therefore well understood, however, the second DSR was constructed around 150 years ago. There was a degree of the unknown whilst breaking through into this tank, however, a careful and methodical approach was implemented to minimise risk to the structure.

The new pipeline was subjected to several pressure tests, to an average of 11 bar as well as completing a thorough cleaning and chlorination regime. This involved early dialogue with Scottish Water Networks as well as the reservoir engineers for the raw water reservoir where the flows would be discharged.

On completion of the chlorination activities and subsequent approval from Scottish Water Public Health, the water was able to be put into supply to allow the future commissioning activities to commence which required large volumes of water. This was an important project milestone.

Wooden bog mats in conjunction with reusable plastic track mats have been used extensively instead of the traditional temporary stone access roads throughout the parks. This has saved the requirement of 12,000 tonnes of stone being brought in and out and saved approximately 1,200 HGV movements in the local community. This has proved an exceptional sustainable approach as the wooden bog mats and reusable plastic track mats can be reused and helps reduce the carbon impact in many ways while making the community streets greener and safer.

Restrained joints have been used on the project pipeline to allow CWA and Scottish Water to remove concrete thrust blocks, therefore further reducing embodied carbon associated with the capital aspects of the project. This totals an estimated 5,500m3 of concrete which has reduced carbon by approximately 16,000 tonnes; 15,000 from concrete and 1000 from transporting the concrete.

Solar panels will also offset the power demands at the new pumping station, with the new trunk mains also utilising increased gravity capacity to further reduce operational power consumption by 60%. The project site welfare and accommodation also utilised solar power and hybrid options. They also have a number of energy saving features which improve U-values such as high levels of insulation and passive infrared sensors to operate LED lighting.

The team also hosted a virtual consultation platform to share project information with customers and stakeholders to avoid the need to travel to community events.

Scottish Water and Caledonia Water Alliance have supported impacted customers and communities. The project team recognised that working closely with local schools would be important. The team arranged to supply pupils with school branded high-vis vests to make sure they are safe when they leave the school for outdoor learning.

They also spent time facilitating talks to teach children how to stay safe around construction sites; pupils were able to visit the site to learn more about the project and took part in a site safety poster competition. The school’s Head Teacher said that there was no doubt that the team had put the needs of the school community at the heart of their work.

The extent of the pipe route gave the opportunity to engage with a number of local schools. For the tunnelling operations, CWA set up competitions to name the tunnel boring machine. Fantastic winning names were chosen and got the community talking about the project. One name was ‘Cruella di Drill’ and another winner was named by the local primary school Crookston Castle as the ‘Crookie Monster’.

Other activities which CWA undertook with stakeholders included:

Linking supply systems ensured that the high quality drinking water continues to be supplied to current customers and for generations to come. The investment in new pipelines and associated infrastructure below ground will also support the continued development above ground in communities across these areas and will enable them to continue to grow and thrive. CWA tapped into the skills from their diverse, integrated team to ensure they delivered an innovative, sustainable and cost effective project whilst supporting a flourishing Scotland.

CWA employed self delivery teams locally, trained a number of apprentices, and engaged local suppliers throughout the project.

Anglian Water’s supply-demand balance is under increasing pressure due to population growth, climate change and the requirement to protect the environment while maintaining reliable customer supplies. Through the Water Resources Management Plan 2019 (WRMP19), a number of interventions were identified to maintain long-term supply resilience and ensure sufficient capacity is available across the network.

Following the assessment of future supply requirements, the need was identified to transfer 1.5 ML/d from Stoke Ferry to Didlington to support Anglian Water’s commitment to maintaining secure and resilient water supplies.

The additional transfer capacity will provide greater flexibility within the existing network, helping Anglian Water respond to periods of increased demand and reduced resource availability while supporting long-term supply resilience. However, the delivery of the new infrastructure also presented a number of engineering and environmental constraints.

The proposed pipeline route passes through predominantly rural areas and required crossings beneath roads, watercourses and areas where construction activity needed to be carefully managed. The project team needed to develop a solution that provided the required hydraulic capacity while minimising disruption to landowners, customers and the sur-rounding environment.

Early investigations were undertaken to inform the construction approach. Archaeological trial trenching was completed during the enabling phase to allow sufficient time for evaluation works before construction commenced. In addition, extensive trial holes and boreholes were undertaken along the proposed alignment to confirm ground conditions and support detailed design development.

The preferred solution was the construction of a new 8.3km, 225mm outside-diameter HPPE pipeline connecting Stoke Ferry with the Didlington area. The pipeline has been designed to provide the required transfer capacity while integrating with existing Anglian Water assets.

The solution combines open-cut pipe installation with horizontal directional drilling (HDD), allowing the construction methodology to be adapted to different sections of the route.

The works includes:

Different pipe specifications were selected depending on the construction methodology. SDR21 HPPE was used for open-cut sections, while SDR11 HPPE was selected for HDD installations where additional pipe strength was required. Finally, the combination of construction techniques will enable the pipeline to be installed efficiently while responding to the geographical and environmental constraints along the route.

Construction commenced in May 2026 following completion of enabling works, including archaeology investigations and detailed site investigations. The delivery approach has been structured around maintaining construction progress while reducing disruption at individual locations.

The works include:

The use of HDD has been a key element of the construction strategy. Following route assessment, HDD was selected at locations where traditional excavation could have created greater disruption or environmental impact.

By installing the pipeline below ground between entry and exit points, HDD reduced the requirement for surface excavation at road and watercourse crossings. This approach supported the protection of existing features and helped the team manage works through areas affected by water and flood constraints.

A phased approach to construction has also enabled completed sections to progress through testing and reinstatement activities while works continue elsewhere along the route.

The delivery of a linear infrastructure project across multiple land parcels requires close coordination between the @one Alliance team, the supply chain partners, landowners and local stakeholders.

For example, G&V Gallagher Ltd worked closely with the @one Alliance project and site teams throughout construction, by coordinating mains laying activities across both open-cut and HDD sections of the route. This collaborative approach has supported the team in managing different construction environments, coordinating interfaces between work areas and maintaining progress as the pipeline is delivered in phases.

The @one Alliance project team and land agents have maintained regular engagement with affected landowners, providing updates on planned works, access requirements and potential impacts. Consideration has also been given to individual land characteristics, including agricultural activities & high-value crops to help minimise disruption and manage potential impacts.

Customer and stakeholder communication has been integrated throughout the construction programme. The works require temporary traffic management arrangements, including road closures on Eastmoor Road and Gooderstone Road. Advance communications have been issued to affected customers, including diversion information, while parish councils and local stakeholders are receiving regular updates. Approximately 238 customers have been identified through the project’s customer engagement process and are being contacted through a range of communication channels.

Improved operational resilience

Once complete, the pipeline will increase flexibility within Anglian Water’s existing supply network & the additional capacity will support Anglian Water in managing changing supply and demand requirements, improving resilience during periods where the network is under increased pressure.

The integration of flow monitoring equipment, network connections and pressure control modifications will allow the new infrastructure to operate effectively alongside existing assets. And by improving the ability to transfer water within the existing network, the project provides additional operational flexibility without relying solely on additional abstraction. This supports the balance between customer needs, regulatory requirements and environmental protection.

Reduced construction impact

The use of HDD technology has reduced the requirement for open excavation at sensitive crossing locations. The approach has supported the protection of watercourses, reduced disruption at road crossings and enabled the pipeline route to be delivered through challenging areas while maintaining environmental considerations. Archaeological investigations, ground surveys and early route assessments have also supported a more informed construction approach.

Overall, the Stoke Ferry to Didlington Water Transfer Scheme represents an important investment in strengthening the resilience of Anglian Water’s potable water network. The £5 million project is delivering approximately 8.3km of new HPPE pipeline, providing the capability to transfer up to 1.5 million litres of water per day between Stoke Ferry and Didlington.

With construction progressing across the route, the @one Alliance delivery team is using a combination of open-cut and HDD techniques, alongside detailed planning and early investigations, to deliver the new infrastructure while managing environmental, landowner and community considerations.

Once complete, the scheme will provide additional flexibility within the existing water supply network, helping Anglian Water respond to changing demand and resource availability while strengthening the resilience of supplies for customers across the region.

The Green Recovery Leamington Spa Sewerage Scheme is a flagship initiative under Severn Trent’s Green Recovery programme, aimed at moving a stretch of the River Leam towards bathing quality. This ambitious project addresses the performance of six critical Combined Sewer Overflows (CSOs) in Royal Leamington Spa, Warwickshire, through a suite of technically advanced designs that test a variety of complementary solutions.

Few projects manage to balance technical complexity with community benefit as seamlessly as the Leamington Spa Sewerage Scheme with live public functional spaces is technically complex but also requires attentive and agile stakeholder engagement, delivering large measurable environmental improvements.

While early guidance targeted storm overflows with direct discharges into these areas, the programme has since expanded to include overflows that pose wider environmental and public amenity impacts. This includes high amenity areas such as recreational waters and areas of interest to businesses and other organisations, even if they are not formally designated as bathing waters.

The shift reflects a more holistic approach to water quality management, prioritising interventions based on environmental sensitivity, public usage, and the potential impact of overflows. This broader targeting ensures that improvements are aligned with community expectations and environmental stewardship goals.

The project leveraged the Longbridge Strategic Sewerage Growth model, enhanced with updated flow monitoring and surface water network refinements. Hydraulic solutions were identified early through iterative hydraulic modelling and refined through feasibility and Early Contractor Involvement (ECI) with Forkers Ltd.

By integrating advanced hydraulic modelling and real-time control, the scheme exemplifies the kind of forward-thinking infrastructure needed to meet the challenges of climate resilience and urban growth.

Preferred interventions included surface water separation, pumped and gravity storage, and network optimisation.

A major surface water separation scheme was implemented between Campion Road and Milverton School, delivering significant benefits in surface water management. The project successfully disconnected impermeable areas from the combined sewer network, reducing the volume of stormwater entering the system. Additionally, it incorporated below-ground storage to help manage flood risk, enhancing the area’s resilience to heavy rainfall events and contributing to improved environmental outcomes.

The Lower Avenue Combined Sewer Overflow (CSO) scheme involved the installation of an 880m3 shaft tank with a return flow capacity of 30 l/s, located in the Station Approach car park. The shaft tank was designed and constructed by Active Tunnelling Ltd. At Princes Drive 19B, the scheme increased the flow into the existing storm tanks by an additional 75 l/s. Both storage systems were equipped with real-time control (RTC) logic to optimise return flows and minimise the risk of spills into the river, ensuring more efficient and environmentally responsible stormwater management.

To ensure long-term resilience and performance under changing climate conditions, the design rainfall was uplifted by 15% to reflect projected 2050 scenarios. Spill frequency assessments were carried out using Severn Trent’s Technical Standard Rainfall Dataset, representing worst-case conditions to ensure robust system performance. All conveyance infrastructure was sized accordingly to accommodate future climate impacts, supporting sustainable and reliable operation over the asset’s lifetime.

The project was delivered under tight AMP7 deadlines, requiring early contractor involvement and agile design development. Forkers Ltd and WSP played key roles in feasibility, site investigation, and outline design.

Key construction innovations included the use of GEOlight® blocks from SDS Limited for modular storage. GEOlight® blocks offer a significant advantage in large-scale infrastructure projects due to their lightweight, corrosion-resistant design, which simplifies installation and reduces long-term maintenance costs compared to concrete or steel alternatives.

Reducing the impact from CSOs has had significant social implications. Access to clean and safe recreational waters promotes public health and well-being, encouraging outdoor activities and fostering a connection with nature. This initiative does not just solve a problem, it redefines what is possible in urban water management, setting a precedent for future projects across the UK and beyond.

The Green Recovery Leamington Spa Sewerage Scheme stands as a testament to the power of innovative engineering and sustainable practices in addressing modern environmental challenges. This project not only resolves immediate issues related to CSOs but also sets a benchmark for future initiatives aimed at enhancing urban wastewater management.

The Leamington Spa Surface Water Separation Scheme, delivered as part of Severn Trent’s Green Recovery Programme, exemplifies a forward-thinking approach to sustainable water management.

Central to the project was the installation of a two megalitre GEOlight® attenuation tank from SDS Limited beneath a playing field adjacent to Milverton Primary School. The tank, connected to newly laid surface water sewers across several roads in Leamington Spa, significantly increases stormwater storage capacity within the network. This enhancement plays a critical role in protecting downstream sewage treatment infrastructure from overload and reducing the frequency of combined sewer overflows into the River Leam.

The project not only supports Severn Trent’s ‘Get River Positive’ commitments but also aligns with local and national planning policies. By integrating innovative technology with sustainable construction practices, the scheme delivers measurable environmental benefits. It demonstrates how targeted infrastructure investment can contribute to long-term river health, climate resilience, and community wellbeing; setting a precedent for future water management initiatives across the region.

Its success lies not only in the numbers (reduced spills, increased storage, improved water quality) but in the way it brings together engineering excellence, ecological sensitivity, and community engagement. The project’s legacy will be felt not just in the River Leam’s improved health, but in the model, it provides for sustainable, scalable, and socially conscious infrastructure.

The Green Recovery Leamington Spa Sewerage Scheme is a model of integrated water management, combining hydraulic engineering and community recreational benefit. It demonstrates how ambitious environmental goals can be achieved through technical excellence, collaboration, and innovation.

In a sector where impact is often measured in compliance, this scheme goes further; delivering outcomes that resonate with local communities, regulators, and the environment alike.

The project not only safeguards the River Leam for recreational use but also sets a precedent for inland bathing water schemes across the UK and beyond.

To achieve the goal of enhanced interzonal connectivity and meet regulatory requirements, the Carmoney to Strabane Strategic Trunk Mains Project was divided into three distinct phases:

This paper focuses in detail on Phases 1 and 1a of the project.

The primary objectives of the Carmoney to Strabane Strategic Trunk Main are to eliminate supply-demand balance deficit and to enhance resilience for 17ML/d within the Western Resource Zone in the event of incidents or outages at water treatment works.

This phase involved the complete demolition of the existing facility and the construction of a new, purpose-built water pumping station (WPS) to supply both Avish Service Reservoirs (SRs), with onward pumping to Corrody SR via the Edenreagh Road infrastructure. The station operates using three pump sets (duty/assist/standby) and was prioritised as Phase 1 due to planning application and approval constraints. The works were successfully completed in June 2024.

In addition to the three pump sets, the new installation includes a surge vessel, a new motor control centre (MCC), and associated pipework at both the water pumping station and Avish Service Reservoirs.

The upgraded WPS provides the NI Water Operations team with the ability to remotely manage and optimise system performance via telemetry, offering four distinct daily process control modes:

To optimise operational expenditure (OPEX), the system also incorporates controls for managing high-tariff and pre-high-tariff top-ups, ensuring more efficient energy use during periods of peak demand.

This phase involved the construction of 10 km of trunk main from the Edenreagh Road infrastructure to Corrody Service Reservoir (SR), consisting of approximately 9.6 km of 500 mm diameter ductile iron pipework and 0.4 km of 560 mm diameter high-performance polyethylene (HPPE) main installed via horizontal directional drilling beneath the River Faughan.

While the majority of the pipeline was laid through private agricultural land, the route also included several road crossings, most notably the A6; and a section along Trench Road within the public domain.

To support integration with the existing network, new flow meters, inlet control valves, scour and air valves, and cross-connections were installed, ensuring full inter-connectivity between the new and existing mains.

The entire works were delivered with no disruption to customers and successfully removed 17 District Metered Areas (DMAs) from the DG2 register. In addition to improving supply reliability, this phase significantly enhanced the resilience and security of supply within the Northern Resource Zone.

The scheme included two significant watercourse crossings: the previously mentioned horizontal directional drill (HDD) beneath the River Faughan and the construction of a pipe bridge across the Burngibbagh River. For both crossings, maintaining ongoing communication with the Northern Ireland Environment Agency (NIEA) was essential. In line with NIEA requirements, sheet piles were installed at the drill entry and exit points to prevent any potential contamination of the River Faughan; recognised for its ecological importance as a designated watercourse.

The project team also carefully considered the findings of the ecology survey and the Habitats Regulations Assessment to ensure full environmental compliance. Environmental challenges, including the presence of Japanese knotweed and active badger setts within the working area, were effectively managed and mitigated without impacting the programme.

Throughout the course of the project there were numerous archaeological and historical discoveries. Ancient structures and artifacts were discovered, with the team collaborating closely with archaeologists and HED to carefully document and preserve these findings, ensuring the site’s historical significance was respected throughout the construction process.

As the pressures of climate change and population growth in the North-East region increase, the Edenreagh Road to Corrody SR trunk main was constructed to ensure security of supply and cleaner water for the wider Northern Zone.

This 10km pipeline was constructed whilst adopting a number of cost saving and environmentally responsible methods, namely maximising the amount of reused excavated materials through a screening process. This minimised the amount of imported material and reduced the number of deliveries to site by a significant amount.

Additionally, where practicable, materials and aggregates were sourced from local suppliers near the site to reduce transportation distances and minimise the project’s carbon footprint.

It was recognised early in the Early Contractor Involvement (ECI) period that building strong relationships with landowners would be critical to the project’s success, with early engagement meetings held with the Ulster Farmer’s Union. As such, collaboration with local farmers and landowners remained a core focus throughout, ensuring minimal disruption to their land and promoting sustainable land use practices.

To support this approach, a dedicated Lands Liaison Officer was appointed for the duration of the works. Their role was to build and maintain strong relationships with landowners and to ensure transparent, ongoing communication with the local community—keeping all stakeholders informed and engaged throughout and contributing to the successful delivery of the project.

The project was recognised by the Considerate Contractors Scheme for its health and safety initiatives, with the Contractor (Murphy DAWSON-WAM JV) receiving a Gold award for the project as a whole, but in particular for the installation of single use defibrillators within all excavators across the project.

The Carmoney to Strabane Strategic Trunk Main is a great example of how the NI Water project team including consultants and contractors can successfully collaborate and engage with the local community to deliver a vitally important piece of infrastructure, whilst respecting the local environment.

The Burnley Road Pipe Bridge is situated within the village of Luddenden Foot, to the west of Halifax in West Yorkshire. The project encompasses two principal work sites: Holmes Park Football Pitch, and Calder Caravan Storage. These locations are geographically separated by the River Calder and are positioned approximately 50m to the east of the Rochdale Canal.

The works were undertaken within a constrained and environmentally sensitive corridor, requiring careful planning and execution throughout both the design and construction.

At outline design stage, the preferred solution involved constructing two shafts on either side of the river, connected by a micro tunnel acting as a conduit for installing the new syphon pipework beneath the riverbed. This would allow flows to be diverted away from the existing pipe bridge while maintaining continuity of service. However, upon further review during detailed design, Mott MacDonald Bentley (MMB) identified several constraints associated with this approach, most notably the extensive vegetation clearance and restrictions on the size and type of plant that would have been required. Such clearance would have had a significant environmental impact, particularly within a sensitive habitat.

In response, MMB challenged the initial concept and developed an alternative solution based on an inverted syphon arrangement. This approach involved installing three pipelines beneath the River Calder using Horizontal Directional Drilling (HDD) techniques. The configuration comprised one pipe designed to convey Dry Weather Flow (DWF) and two additional pipes for storm flows. This design allowed the system to achieve self-cleansing velocities under both normal and storm conditions, thereby reducing the risk of sediment deposition and operational maintenance issues.

To validate the proposed solution, comprehensive hydraulic modelling was undertaken. InfoWorks Integrated Catchment Modelling software was used to assess the impact of the syphon on the wider catchment, while HADES software was employed to evaluate the internal hydraulics of the syphon pipes. This dual-modelling approach ensured that both network-wide effects and asset-level performance were fully understood.

The hydraulic analysis identified a critical challenge associated with the inverted syphon design. Specifically, the head required at the inlet manhole to drive flows through the syphon at the necessary velocities resulted in an elevated hydraulic grade line within the upstream network. This increase in head led to a heightened risk of flooding at upstream manholes, particularly during peak storm events.

To mitigate this issue, the design team introduced a 1350mm diameter upstream storage pipeline. This additional storage provided attenuation capacity, effectively lowering the hydraulic grade line within the catchment. However, due to the pipe’s diameter and gradient, flow velocities within this storage pipe were lower than those required for self-cleansing conditions.

To address the risk of sediment accumulation and ragging within the storage pipe, a 150mm diameter dry weather flow channel was incorporated into the invert of the pipeline. This channel ensured that flows during normal conditions would maintain sufficient velocity to prevent deposition, thereby enhancing the operational resilience and longevity of the asset.

During construction, one of the key challenges encountered was the concentration of manholes within a relatively small footprint; due to proximity to overhead cables and an existing football pitch.

These manholes were necessary to provide access for maintenance activities, including jetting points for the storm syphons. However, the density of structures created potential logistical and safety challenges, particularly with respect to excavation and installation sequencing.

To overcome this, the site team adopted a reduced level dig approach. This involved excavating the area down to formation level across the entire footprint at an early stage, rather than constructing individual excavations for each manhole. While this approach required a greater initial investment in time and resources, it enabled the efficient installation of all manholes once formation level was achieved. As a result, overall programme performance was improved, and installation activities were completed ahead of schedule.

In addition to programme benefits, this methodology significantly reduced high-energy risks typically associated with deep excavations, such as the use of traditional manhole boxes and temporary works systems. By minimising the need for repeated excavation and reinstatement, the approach contributed to a safer and more controlled working environment.

A critical phase of the project was the removal of the existing pipe bridge. The structure spanned approximately 30m across the River Calder and was constructed from ductile iron, resulting in substantial weight and complexity in dismantling operations. The removal process required careful consideration of site constraints, environmental risks, and health and safety requirements.

Several removal options were initially assessed, including the use of large cranes, floating pontoons, and scaffolding systems. However, due to the restricted nature of the site and load limitations on local access routes and bridges, it was determined that cranes of sufficient capacity could not be safely mobilised. Similarly, the presence of weirs both upstream and downstream of the bridge meant that there were no suitable locations to launch pontoons onto the river.

Consequently, scaffolding was identified as the only viable and safe solution for accessing and dismantling the bridge. However, this approach was subject to detailed scrutiny by the EA during the Flood Risk Activity Permit (FRAP) application process. The EA raised concerns regarding the potential for the scaffolding structure to act as an obstruction within the river channel, increasing the risk of blockage and flooding both upstream and downstream.

To address these concerns, the project team undertook a comprehensive blockage analysis. This demonstrated that the proposed scaffolding arrangement would not significantly impede river flows or exacerbate flood risk under a range of design scenarios. In addition, the team maintained proactive engagement with the EA, including site visits and regular communication, to clearly articulate the safety benefits of the proposed approach compared to alternative methods.

As a result of this robust and collaborative process, the FRAP application was approved at the first submission, approximately eight weeks ahead of the timeframe indicated in EA guidance. This represented a significant programme benefit and highlighted the value of early engagement and transparent communication with regulatory stakeholders.

Following approval of the scaffolding approach, significant effort was directed towards the design and implementation of associated temporary works. One of the primary challenges was the lack of vehicular access to one side of the river, meaning that the scaffolding had to be erected from a single bank and cantilevered across the full 30m span.

The scaffolding system was therefore designed to accommodate not only construction loads but also potential impact loads during dismantling activities. Specifically, it was required to withstand the full weight of the pipe bridge in the event that sections were temporarily supported or inadvertently dropped onto the deck during removal. This necessitated a highly robust design, developed by the specialist scaffolding subcontractor and verified through detailed engineering assessments.

MMB undertook additional checks to confirm that the riverbanks could safely accommodate the loads imposed by the scaffolding footings. This integrated approach ensured that all elements of the temporary works system were aligned and that risks were fully mitigated prior to construction.

Throughout the project lifecycle, MMB maintained clear and consistent lines of communication with all key stakeholders, including the scaffolding subcontractor, demolition subcontractor, the Environment Agency, Canals and Rivers Trust, local authority and Yorkshire Water. This collaborative approach was instrumental in identifying and managing risks at each stage of the works.

A Hazard Study Level 7 was undertaken specifically for the demolition phase, ensuring that all foreseeable risks were systematically assessed. In parallel, a Failure Modes Analysis (FMA) workshop was conducted to identify potential failure scenarios and establish appropriate contingency and emergency response plans.

These structured risk management processes provided assurance that all activities were carried out in a safe and controlled manner, ultimately enabling the successful dismantling and removal of the pipe bridge without incident.

Sustainability was a key consideration throughout both the design and construction phases of the project. By challenging the original outline design, the team was able to significantly reduce the extent of vegetation removal, by approximately 90%, thereby preserving local habitats and minimising ecological disruption.

Pipework design was optimised to avoid the use of concrete, reducing carbon in favour of plastic alternatives.

In addition, a series of ecological surveys, including bat and fish assessments, were undertaken to inform the construction methodology and ensure compliance with environmental regulations. MMB and JN Bentley worked closely with ecological specialists to implement mitigation measures and ensure that the works were delivered with minimal impact on the surrounding environment.

The project is approaching completion and is scheduled to be finalised by the end of May 2026. Despite challenges including adverse weather conditions, the scheme has been delivered on programme through efficient site management and proactive problem-solving. Furthermore, the project has been completed under budget, delivering cost savings for both the client and contractor while maintaining high standards of quality and safety.

A key success factor has been the adoption of a “right first time” approach, supported by close collaboration with Yorkshire Water. This has resulted in minimal snagging requirements, with all outstanding works addressed prior to demobilisation.

The project has successfully delivered a modern, resilient wastewater asset that eliminates the risks associated with the ageing pipe bridge. By removing the potential for structural failure and associated pollution incidents, the project provides long-term environmental and operational benefits for the local community.

The scheme stands as an example of effective engineering innovation, stakeholder collaboration, and commitment to sustainability. The project team has taken considerable pride in its successful delivery, receiving positive feedback from both the client and local residents. The result is a future-proofed infrastructure solution that enhances the reliability of the wastewater network while safeguarding the natural environment.

Meadow Lane WwPS was identified as requiring significant base maintenance interventions due to the antiquated nature and condition of existing pumps, pipework and control assets which require a high level of maintenance; thus, imposing a risk of potential significant failure. The following observations were made on site:

NI Water Technical Support had also advised of occurrences of flooding within the dry well as a direct result of leaking pumps which required reactive maintenance and tankering operations.

Additionally, following completion of the 2007 Portadown Drainage Area Study, Meadow Lane WwPS was identified as a required output. It was outlined to NI Water the need for the existing Meadow Lane WwPS to deliver flow to full treatment (FFT) if the upstream network spill performances are to meet the Northern Ireland Environment Agency (NIEA) requirements for the Meadow Lane catchment area.

Model updates were completed in 2016 following flow monitoring surveys, and further inspections confirmed that the existing pumps could not deliver the required FFT. Therefore, the five CSOs identified by the NIEA as Unsatisfactory Intermittent Discharges (UIDs) could not be closed without significant intervention/upgrade at Meadow Lane WwPS. Model updates were also completed in 2020 to reflect predicted future 2040 flows.

The NIEA had identified the following five CSOs as UIDs:

Failure to address spills would lead to potential prosecution by NIEA and associated reputational damage due to potential serious sewage flooding and pollution to the Annagh River, Upper River Bann and the surrounding area.

NI Water appointed BSG Civil Engineering Ltd as the main contractor under an NEC3 Early Contractor Involvement (ECI) Contract. As the main contractor, BSG provided multi-disciplinary design, project and supply chain management and civil engineering and MEICA works for the contract from inception to completion.

The ECI phase allowed BSG to align resources and integrate objectives with the client, NI Water, and project managers, McAdam, at an early stage to benefit overall project delivery. This allowed for enhanced collaboration, innovation, value, efficiency and reduced whole life cycle costs for the project.

The purpose and drivers of this project were as follows:

The upgrade of Meadow Lane WwPS and the associated network was a large-scale infrastructure project located within a complex urban environment. The project saw:

Meadow Lane is an arterial route through Portadown town centre, providing access to several shopping facilities, restaurants and medical facilities. It was identified that significant traffic management, potentially involving lengthy diversions, would be required for an extended period to undertake the installation of the 1,500mm diameter tank sewer along Meadow Lane using open-cut methods.

Therefore, it was determined that a trenchless pipejacking method of installation would be adopted to install the full 380m of 1,500m tank sewer. Additionally, the use of a tunnel boring machine (TBM) would allow for a reduced potential environmental impact due to the reduction in surface disruption, dust, noise and vibrations; and provide enhanced safety for construction staff due to the automated installation process.

Due to the unstable ground conditions, a closed face slurry system was used as this technique allowed the area around the TBM to be supported with a pressurised bentonite mix, preventing collapse and ensuring stability. During this process the excavated material was pumped from the face of the TBM, through the installed tunnel, to an above-ground separation system where the excavated material was removed from the bentonite mix, allowing it to be recycled and returned to the tunnel face for reuse.

The tunnelling operation was undertaken in three stages with launch and reception pits installed to facilitate each drive stage alongside ancillary tunnelling operations; drive stages varied in length between 70m to 230m. Due to the varying and difficult ground conditions present along the proposed tunnelling route, launch pits and reception chambers were installed using a combination of both segmental shafts and traditional cofferdams.

The storm retention tank, inlet chamber, and wet well pumping station was designed as one structure. Due to the difficult ground conditions, high water table and proximity to existing NI Water assets, it was determined that secant piling would be implemented as a means of providing temporary support to facilitate safe excavation.

A specialist piling contractor was utilised to install 140 (No.) 750mm diameter secant piles to a depth of 18m below ground level before the installation of a reinforced concrete capping beam to complete the excavation support system. Once installed, the secant piled wall provided a watertight structure. Localised dewatering within the secant piled structure was used to ensure excavated material remained dry and suitable for reuse on site. Approximately 3500m3 of material was removed from the 21m diameter, and 10m deep excavation.

Construction of the storm tank consisted of a 1200mm deep reinforced concrete base, a 400mm thick external liner wall, and a 500mm internal dividing wall. The liner wall formwork was designed as a single sided system using Peri Rundflex and constructed in two lifts to meet temporary works restrictions.

The roof structure was constructed using 1250mm by 900mm precast beams and 450mm thick precast hollow core slabs. Structural screed was then poured to complete the structure.

The complex roof slab arrangement consisted of a variety of construction techniques including in situ reinforced concrete elements, precast concrete primary and secondary beams, structural steel beams and hollow core precast slabs. The complete design of the roof structure was provided by five different design companies working in collaboration ensuring each element adhered to the tight tolerances required for accurate placement.

Six sections of open-cut sewer installation were completed in this scheme. Boxed systems were used to provide temporary works excavation support for the pipe installations. Sewers were installed to depths of up to 7m below ground level in sites with limited working room. Traffic flows were controlled by complex traffic management systems.

The MEICA installation was completed in two stages. A new MCC was installed within the new GRP kiosk, and once all building services were installed, the NI Electricity supply was diverted to the new MCC panel which then backfed a supply to the existing MCC panel until turn of flows in April 2025.

Once civils construction had sufficiently advanced, the second phase of the mechanical fit out commenced, where the three 37Kw foul pumps and associated pipework were installed from the foul pumping station to the flow meter chamber. A 250mm Siemens MAG 5100w was then installed to measure the outgoing flow-rate. Two pump stools, 9Kw hydro ejectors and pipework were installed within the storage tank to jetwash the tank during storm events.

Three Eliquo Hydrok Ltd screens were installed into the following areas:

The main challenges faced during the delivery of Meadow Lane WwPS were a combination of site-specific constraints, environmental constraints and equipment/asset failures during the construction period. Some of the additional challenges experienced during the construction stage have been outlined below.

Portadown has been identified within the Northern Ireland Flood Risk Management Plan as an area of significant flood risk, due to regular fluvial flooding from the Upper River Bann and its tributaries. The most recent significant flood event was recorded in 2024, which saw substantial flooding across the entire work site. This fluvial flood event led to a halt in works on site for approximately one week and caused damage to plant.

The 500mm diameter outlet pumping main from the existing Meadow Lane Pumping Station ruptured on two occasions during the construction programme. To carry out the repair on the outlet pumping main, both Meadow Lane and Annagh WwPS had to be shut down and seven tankers were mobilised to transfer effluent to other NI Water treatment facilities. BSG Civil Engineering Ltd was able to utilise the newly constructed storm tank to create temporary storage and prevent any out-of-sewer flooding during the emergency repair works. BSG received positive feedback from NI Water on how these critical network emergency repair works were managed and rectified in a safe, collaborative and timely manner.

NI Water and the project team recognised the potential negative impacts which could arise from undertaking such a large-scale project within a busy town centre location and from an early stage embarked on a strategic communications strategy to ensure key stakeholders were informed of the works and kept updated throughout.

As part of the public relations programme the project team and NI Water Communications held early briefings with a range of stakeholders including elected representatives, town centre management, chamber of commerce, health care centre, council, roads authority, landowners and local businesses.

In addition to the numerous one-to-one meetings, letter drops were carried out in advance of each section of road works commencing and press releases issued to the local media to advise the wider public of traffic management. Variable message boards were erected on main routes and large-scale project boards helped to convey the huge investment being made by NI Water and the resulting benefits for the public.

Key project milestones were publicised along with facts and figures relating to the construction work and tunnelling exercise.

Regular project updates and lookahead bulletins were issued to stakeholders to keep them up to date on progress and advise them of future traffic management requirements. Town centre management were invited to site at key stages of the project to view progress and hear firsthand about the benefits the NI Water investment will bring to Portadown.

BSG provided a point of contact for operational queries and this, along with NI Water’s wider stakeholder communications, helped to ensure a smooth-running construction programme.

NI Water directed significant financial investment into upgrading the existing sewer network and Meadow Lane WwPS within the Meadow Lane area of Portadown. The proposed works oversaw the closure of five CSOs within the Meadow Lane WwPS catchment area through connection into the new 1,500mm tank sewer alongside the resolution of three DG5 properties.

The collaborative effort between NI Water, BSG Civil Engineering Ltd and McAdam resulted in the smooth completion of the programme and successful testing, commissioning and handover to NI Water in July 2025. The benefits of the new infrastructure will be realised almost immediately through a reduction in spill frequency and volume within the Upper River Bann and Annagh River.

This project showcased the capabilities of NI Water, BSG Civil Engineering Ltd and McAdam to coordinate and undertake sensitive high-risk activities such as a large-scale turn of flow without issue and within a complex urban environment.

Under the Water Retaining Structures Framework, OCU Group is delivering multiple service reservoirs, including schemes at Preston and Chaul End in Luton. These projects are designed to increase storage capacity, improve operational flexibility and support future strategic water transfers.

The WRS Framework is being delivered through an integrated design and build model, combining in-house engineering capability with specialist design partners and a coordinated supply chain.

An early contractor and supplier engagement approach was implemented to align structural design with off-site manufacturing capabilities. This enabled key decisions regarding construction methodology, sequencing and material selection to be made at an early stage.

Early engagement with FLI Precast Solutions enabled OCU Group to align structural design with off-site manufacturing principles. This ensured reservoir structures were optimised for precast construction, improving constructability and reducing interface risks between structural and mechanical elements.  OCU provided overall design coordination, construction delivery, and mechanical and electrical integration across the schemes.

This approach has enabled OCU Group to standardise key elements of design and delivery across multiple sites, improving efficiency, reducing risk and enabling a repeatable delivery model for future schemes.

The focus of this case study is Preston Service Reservoir which is a representative example of the design and construction approach adopted across the framework.

The Preston Service Reservoir comprises a single cell potable water storage structure with a total capacity of 20 megalitres (ML), constructed adjacent to the existing reservoir. Once operational, the combined assets provide approximately 38 ML of storage capacity.

The structure was formed using a reinforced concrete raft foundation combined with a semi-precast superstructure. Precast wall panels, columns and roof planks were manufactured off site and installed sequentially.

OCU Group selected precast construction in response to site constraints and programme requirements. Compared with traditional in situ construction, the approach reduced on-site activities including formwork, reinforcement installation and concrete pours, improving safety and reducing construction duration. It also enables concrete quality control to be carried out within a factory quality-controlled environment where the weather is not an issue.

Precast elements were delivered and installed sequentially upon arrival, minimising on-site storage requirements and improving efficiency within the constrained site footprint.

Off-site manufacturing also enhanced quality control, with structural components produced in a controlled environment, improving consistency and long-term performance.

OCU Group applied Building Information Modelling (BIM) across the framework to support design coordination and construction delivery.

At Preston, a detailed 3D model integrated structural, mechanical and process elements, enabling accurate coordination of pipework, valves and interfaces. This reduced delivery clashes during construction and improved installation efficiency.

The model also enabled assessment of operational requirements, including access, maintenance and asset management considerations. Stakeholders were able to visualise the completed facility and make informed decisions during the design stage.

The completed BIM model provides a comprehensive digital record of the asset, including manufacturing and installation data, supporting long-term maintenance and future upgrades.

The reservoir was constructed on a reinforced concrete raft foundation designed to distribute loads across underlying clay and chalk strata. Geotechnical investigations confirmed consistent ground conditions, allowing for a uniform foundation design. Any localised weak material encountered during construction was excavated and replaced with compacted structural fill to ensure stability.

A key feature of the construction approach was the retention and reuse of excavated materials. Topsoil and subsoil were stored and reused on site for backfilling and landscaping, maintaining a zero net cut-and-fill balance.

OCU Group’s approach reduced vehicle movements, minimised environmental impact and improved site safety. It also enhanced programme resilience by reducing reliance on imported materials and maintaining continuity during adverse weather conditions.

Topographic surveys were undertaken throughout construction to verify earthworks volumes and confirm compliance with design requirements.

At Preston, a carbon assessment undertaken in accordance with ISO 14064 standards identified total construction emissions of approximately 1,062 tonnes of CO2 equivalent.

A primary reduction measure was the use of precast concrete incorporating ground granulated blast furnace slag (GGBS) as a partial replacement for Portland cement. Approximately 50% of the cement content was replaced, with higher substitution levels achieved under favourable conditions.

This resulted in an estimated saving of 138 tonnes of CO2 compared with conventional concrete mixes. Additional reductions were achieved through the use of recycled aggregates, reducing reliance on virgin materials and supporting circular economy principles.

The semi-precast approach also reduced the volume of reinforced concrete required and limited on-site activities, contributing to an estimated 50% reduction in embodied carbon compared with in situ construction.

The Chaul End Service Reservoir in Luton has been delivered using the same design and construction principles established at Preston.

The scheme provides additional potable water storage and adopts a semi-precast structural solution, incorporating off-site manufactured components, a reinforced concrete base and integrated valve arrangements.

The same coordinated, off-site-led approach was applied, enabling efficient delivery within site constraints and maintaining programme certainty.

The application of a standardised delivery approach across both Preston and Chaul End has enabled OCU Group to refine its methodology, improving efficiency, reducing risk and enhancing sustainability performance across the framework.

Through the delivery of the Water Retaining Structures Framework (Bedfordshire and Hertfordshire), OCU Group has enabled significant new potable water storage capacity across multiple sites. The strong collaborative working relationship established between Affinity Water and OCU has been essential to this.

At Preston, 20 ML of additional storage capacity has been delivered, increasing total site capacity to approximately 38 ML and improving supply resilience for the surrounding network.

Across the framework, the adoption of a standardised precast construction methodology has delivered improved programme certainty, reduced embodied carbon and enhanced safety.

The repeatable delivery model established through schemes such as the Preston and Chaul End Reservoirs provides a scalable approach for future reservoir projects, supporting ongoing investment in water infrastructure and strengthening long-term resilience across Affinity Water’s network.

Gallows Corner water mains improvements - Courtesy of Joseph Gallagher

Construction underway - Courtesy of Jaseph Gallagher

Construction underway - Courtesy of Jaseph Gallagher

Construction underway - Courtesy of Jaseph Gallagher