Supply Chain - Contractors

Westerton was developed to replace the function of the existing service reservoir and provide a more resilient, maintainable potable water supply arrangement capable of accommodating future growth across the supply area. The new infrastructure comprises a four-pump booster station and approximately 800m of rising main, forming part of a network that supplies Westerton Village, Coundon, Ferryhill and Kirk Merrington.

The scheme sat at the interface between new network resilience requirements and old asset uncertainty. The apparent simplicity of replacing a reservoir function with a booster arrangement was complicated by buried legacy pipework around the village green, incomplete records and uncertainty over the true function, diameter, route and condition of existing mains.

The preferred solution was to construct a new potable water booster station with four pumps, supported by associated valvework, chambers, rising main and connections into the existing distribution network. The new arrangement would replace the existing service reservoir, while maintaining service continuity and hydraulic performance across the affected supply zone.

This solution was selected because the existing asset was a single-cell service reservoir. Full surveys, maintenance and repairs would have required the asset to be taken entirely offline for an indeterminate, and likely significant, duration, creating concerns around security of regular supply to the area. The asset was also located within the perimeter of a Grade II listed structure, heavily restricting access for significant remedial works.

The design required close integration between civil, mechanical, electrical, ICA and hydraulic disciplines, with significant involvement from Northumbrian Water operations and maintenance teams. The resulting layout needed to be technically sound, buildable within constrained land and acceptable to the teams that would inherit and maintain the assets.

The defining engineering problem at Westerton was not just what to build, but how to design responsibly when key buried information could not be fully verified at the normal project stage.

Within the village green adjacent to the existing service reservoir, multiple water supply pipes were present; a 10” rising main inlet pipe supplying water into the reservoir itself via Ferryhill Pumping Station, an 8” pipe that bifuricated both eastward and westward to supply Coundon Village, a 9” supply pipe that headed east and a 4” pipe that provided potable water to Westerton Village itself.

Client records were not fully reliable due to the age of the installation and inherited records, and operational knowledge could not close every gap.

Trial pits were delayed by permissions associated with the village green, meaning the definition stage had to progress without the level of intrusive verification normally expected for this type of tie-in. Rather than assume certainty, the design team treated the unknowns as active design risks. They identified the critical assumptions, engaged operations staff, developed connection strategies that could tolerate discovery during later verification and kept the design flexible enough to be refined once intrusive information became available.

This is the project’s strongest technical lesson. Legacy water infrastructure often fails the neat logic of records-led design. The engineer’s job goes beyond producing drawings from the available data and it involves building a design process through risk and uncertainty. This includes identifying what is known, what assumptions are being made, what must be verified, which elements should remain flexible and what would cause a material change if discovered late.

The booster station and associated chambers required careful coordination of civil and mechanical interfaces. Chamber covers and access arrangements had to satisfy operational access requirements while also being compatible with structural support, cover loading and surrounding gradients.

Pipe penetrations, valve arrangements and dismantling joints required equal care. Thrust restraint could not be treated as a generic detail because changes in direction, chamber penetrations and connections into existing pipework created local force-transfer issues. Maintainability clearances around dismantling joints and valves were also important: a technically correct hydraulic arrangement would not be acceptable if the operations team could not safely isolate, dismantle and maintain it.

Developed in conjunction with the end-users, Access Lifting and Maintenance (ALM) Schedules were produced to ensure that future maintenance and operations would be both practical and safe. This consultation with NWG’s Operations team led to seemingly minor, yet crucial additions to the design, such as davit-arm sockets integrated into the pump skid itself at both sides to ensure individual pumps can be lifted both on and off the pump skid safely and easily, reducing risks during manual handling.

The project therefore demanded practical civil engineering judgement: balancing hydraulic performance, structural behaviour, construction tolerances, operational access and the reality of a constrained site. This type of interface work is not always visible in a finished asset, but is critical to avoiding or minimising risk of latent operational problems.

The Kirk Merrington PRV became a useful example of how the project avoided slow, document-led problem solving when the real constraint was physical geometry in the ground. The issue was not that the design team lacked a drawing; it was that the drawing alone could not answer the practical question:

“Could the chamber, valve train, fittings and working space be installed around buried pipework that could not be confidently be detected by non-intrusive utility survey at ground level?”

A non-intrusive utility survey including GPR (ground penetrating radar) had been completed in accordance with standard practice, but subsequent trial holes showed that the existing pipe did not follow the orientation indicated on the client records.

Rather than allowing the issue to become a prolonged loop of photographs, marked-up sketches and email queries, the team took the design process to the excavation.

The lead designer, site manager and project engineer attended site with GPS surveying equipment and a laptop running AutoCAD. Operatives exposed the relevant pipework progressively using an excavator, providing immediate physical verification while keeping excavation targeted and proportionate. The project engineer established control points and captured coordinates and levels, which were passed directly to the designer and dropped into AutoCAD in real time.

The designer then mocked up the valve arrangement using correctly sized CAD blocks for the fittings, fixtures and chamber components. The arrangement was tested at actual scale against the exposed pipework, measured back on site and sprayed out by the site engineer. This allowed the team to walk the proposed chamber footprint, valve train and working envelope rather than debate them abstractly from a desktop.

Crucially, the operatives who would install the chamber were directly involved. Their input on required working area, sequencing and installation constraints meant the agreed solution was not just geometrically possible; it was buildable, maintainable and acceptable to the people who had to construct it. The revised design was agreed in principle during the visit, then formalised through drawings and structural input from a much stronger evidence base. This exercise reduced a potential two-week ping-pong of correspondence to a 90-minute multidisciplinary field decision with the right people, the right information and the exposed asset in front of them.

Because the scheme served live potable water customers, commissioning and isolation strategy could not be deferred to the end of design. The design needed to be compatible with how the network could actually be operated during construction, testing, disinfection, tie-in and changeover. This required early operational input and a clear understanding of how the existing reservoir, mains and proposed booster assets would interact during transition.

The uncertainty around existing assets also made sequencing critical. Late discovery at a tie-in point could have programme, cost and customer-service consequences. The design therefore needed to retain decision points, verification hold points and constructability contingencies rather than locking the project into a brittle single route too early.

The principal safety risks were associated with working near live and uncertain buried services, deep pipework and chamber construction, potable water tie-ins, lifting and installing heavy pipework, and avoiding arrangements that would create unsafe maintenance tasks for operations staff. The project’s safety approach was therefore not limited to paperwork or site controls; it used design change, digital access to information and visible communication to remove or reduce foreseeable risks before they reached the workforce.

Several site-led design changes strengthened this approach. DN300 push-fit flowmeter chamber pipework at approximately 2m depth was changed to flanged pipework to improve alignment control and reduce installation risk. Precast concrete riser units were replaced with recycled plastic units, reducing manual-handling and heavy-lift exposure while improving maintainability.

The access track and compound proposals were challenged and developed from a concrete solution to TruckPave and then to a Neoloy cellular confinement system with granular top coat, reducing concrete use, construction burden and future maintenance impact.

Where hydrocarbon leachate was identified near historic quarry backfill, barrier pipe was introduced rather than treating the issue as a standard pipe material detail. In another case, excavation was extended to allow an asbestos cement main to be un-socketed and replaced with ductile iron and couplers, avoiding a poor-quality tie-in to a fragile legacy asset via handsaw cutting and couplers, removing the health risks associated with handsaw cutting to tie-in.

The Ferryhill PRV was also moved from the carriageway to a verge further upstream, removing the need for working in the carriageway during re-zoning and maintenance, and improving future operational access.

The site team also introduced a QR-enabled digital access system for safety-critical and compliance documents. An existing PUWER (Provision and Use of Work Equipment Regulations 1998) form was enhanced into a centralised digital equipment register, with each item linked directly to its certification. A site QR code gave operatives and supervisors immediate mobile access to the live records.

The same principle was scaled to remote service sites through QR-linked digital job packs containing NUAR (National Underground Asset Register) service information, excavation procedures, RAMS and drawings. This meant contractors could arrive at remote locations and access the required documentation within seconds, instead of relying on paper folders, delayed emails or local file knowledge.

The next phase of the system is to apply durable QR code stickers to individual assets so that certification can be accessed directly at the point of use. The same approach can also be applied to design and construction drawings so that site teams always reach the current revision rather than a printed or locally saved copy.

In practice, this is a low-cost route towards a paperless site: inspection records, RAMS (Risk assessment & Method Statement), COSHH assessments, the Construction Phase Plan and site registers can be accessed through controlled digital links, reducing the risk of outdated or misplaced information being used.

Safety communication was made more visible through a digital communication screen in the site canteen, displaying a rolling programme of toolbox talks, safety alerts and operational updates. The value was not simply that information was displayed; it was displayed in a welfare area where the workforce naturally gathered, creating repeated exposure and informal discussion without relying solely on formal briefings.

Two live visual control boards reinforced the same principle. A live operations RAMS board displayed the current activity RAMS relevant to works being undertaken on site, maintained so that only the latest approved documents were visible. A live COSHH board displayed up-to-date assessments for the substances stored in the COSHH locker, aligning the physical materials on site with the relevant control measures. Together, these measures improved day-to-day accessibility, audit readiness and workforce engagement with the controls that mattered on that day’s workface.

The sustainability case for Westerton is best framed around asset rationalisation, resilience and right-sized intervention. Replacing an ageing service reservoir function with a booster station can reduce future inspection, maintenance and asset-health burden while improving controllability across the network. The four-pump arrangement also supports operational flexibility, allowing demand and resilience requirements to be managed more actively than a passive storage asset arrangement.

At design level, the carbon discipline lay in avoiding unnecessary excavation, avoiding abortive works caused by record uncertainty, and resolving civil-mechanical interfaces before construction.

Every late change to a potable water tie-in risks additional excavation, temporary works, reinstatement, plant movement and customer-interface activity. The project’s risk-controlled approach to buried uncertainty therefore supported both programme resilience and carbon avoidance.

The site team’s material and access-track decisions also contributed to the sustainability story. Recycled plastic risers reduced reliance on heavy precast concrete elements. The move from concrete access proposals toward cellular confinement and granular surfacing reduced concrete use and provided a more adaptable access solution. The QR-enabled documentation system further reduced reliance on printed documentation and supports better version control as the project moves towards a paperless site model.

Westerton relied on unusually close collaboration between design, site delivery and operations because the buried asset uncertainty meant no single party held the answer.

At Kirk Merrington PRV this collaboration became deliberately physical and immediate:

That approach changed the decision quality. The GPR limitation was treated as a trigger for controlled exposure and live validation, not as a reason to rely on assumptions. Coordinates were captured, dropped into the CAD model, checked against full-size fittings and chamber geometry, then measured and sprayed out on site.

The team could then agree the chamber position, valve arrangement and working envelope before committing to formal drawings and structural engagement. This was collaboration in the useful sense: fewer hand-offs, fewer hidden assumptions, fewer late surprises and a faster route from uncertainty to buildable design.

The digital documentation innovations extended the same collaborative logic into everyday site management. QR-linked job packs and live boards made information less dependent on who happened to hold a folder, which email chain someone had seen, or whether a remote contractor had been issued the latest pack. They created a single practical route to current information at the point of work, improving mobilisation, supervision, audit confidence and consistency across main and remote sites.

Operational safety was also a design driver. Access covers, chamber layouts, valve positions and dismantling clearances were not secondary detailing matters; they determined whether future maintenance could be undertaken safely and efficiently. By resolving these interfaces in design, and by involving the people who would install and maintain the assets, the scheme reduced the risk of creating assets that were technically compliant but operationally awkward.

For local customers, the value of the scheme is resilience rather than visibility. The communities supplied by the network need a dependable potable water system that can be operated, maintained and renewed without avoidable disruption.

By replacing a legacy reservoir arrangement with a more controllable booster station and rising main, the project supports long-term supply resilience for Westerton Village, Coundon, Ferryhill and Kirk Merrington.

The village-green interface also created a local public-realm constraint. Managing permissions, trial pits, reinstatement and access sensitively was essential to maintaining confidence with local stakeholders. The engineering challenge was therefore bound to a social one: designing and delivering infrastructure in a way that respected a constrained village setting while still protecting a critical utility service.

The site team’s safety-information initiatives also have a workforce social-value dimension. Making current RAMS, COSHH information, PUWER records, service information and drawings easy to access improves contractor readiness and reduces friction for operatives and supervisors. That matters on dispersed water-sector projects where remote working, buried services and evolving site conditions can otherwise create avoidable uncertainty.

The Westerton Booster Station and Rising Main Project is a strong case study because it shows the hidden engineering value in disciplined uncertainty management.

Many water-sector projects begin with incomplete asset records and constrained survey access; the weak response is to push forward and hope the ground matches the drawing. The stronger response is to identify the assumptions that matter, make them visible, seek operational challenge, design flexibility into the solution and protect the commissioning route.

The project also shows that innovation does not need to mean complex technology. The most useful innovations were grounded: taking AutoCAD to the excavation, using correctly sized blocks to test the real valve-train geometry, marking the arrangement on site, moving the PRV out of the carriageway, challenging heavy or carbon-intensive materials, and making current safety information available through QR codes and live visual boards.

These interventions improved safety, buildability, programme confidence and audit readiness because they changed the way decisions were made at the point of work.

The long-term outcome is a more resilient potable water supply arrangement supported by assets that are more maintainable and operationally controllable.

Its transferable lesson is directly relevant to AMP8 delivery - with ageing infrastructure, incomplete records, tighter regulatory programmes and dispersed workfaces, success will depend on how well project teams convert asset uncertainty into structured engineering decisions before construction risk crystallises.

Tasked with reducing storm discharges to local watercourses, Avove developed a robust delivery model that ensured a seamless process to achieve key project objectives, whilst minimising disruption to residents. To overcome the project challenges, required blending collaboration and innovation in a way that unlocked measurable long-term benefits for Severn Trent and these included:

All risk reduction meetings and planning phases were underpinned by collaboration, as the combined expertise of the project team played an important role in strategising an effective response to ensure that the project did not deviate from the scope.

Collaborative planning and consistent communication was key to a successful delivery across all three sites. Avove prioritised early engagement with suppliers, particularly for precast items, to secure timely deliveries and reduce the likelihood of budget overruns caused by unforeseen delays. This detailed approach delivered important long-term benefits and facilitated open communication and mutual trust throughout the project’s lifecycle.

With overarching principles of communication and collaboration in place, the technical prowess of the project teams was enhanced. With confidence that key materials would be delivered on time, operatives could begin work, using their expertise to ensure an innovative and sustainable completion. This approach entailed:

To complete this approach, Avove supported the communication process between the client and local stakeholders, with the project team assisting with land and planning matters. This involved the distribution of letters to residents, the negotiation of land access with owners and occupiers and following up on any concerns during the execution of works.

The Scunthorpe WFD project aligned with Severn Trent’s organisational goals of sustainability, biodiversity and environmental responsibility. By constructing large, off-line shaft tanks to manage stormwater flows from existing CSOs, the BOD concentration in Bottesford Beck was improved.

It was through a careful combination of sustainability, innovation and collaboration that a highly effective solution was identified and implemented, helping us achieve a high degree of client satisfaction.

The Scunthorpe WFD project delivered a range of long-term benefits, many of which were wide reaching, both in terms of compliance and structural integrity. Beneficial to both the client and their customers, the project achieved:

Working diligently to achieve an expedited programme across all three sites, hard work and commitment ensured a seamless delivery, well within time and budget requirements. With regulatory deadlines to meet, it was imperative that a highly collaborative approach was adopted, with open communication and the implementation of a clear structure guiding the project.

The new off-line tanks effectively retain stormwater, reducing pressure from the existing network and improving water quality much to the benefit of the environment, Severn Trent and their customers.

The driver for the Kirklevington Transfer Scheme was a WINEP requirement to achieve a stringent 0.3 mg/l phosphorus compliance in the final effluent. While the challenge could have been viewed narrowly as a local treatment capacity constraint at the existing sewage treatment works, this would likely have led to adding to or upgrading processes within an already constrained site, bringing increased construction risk, operational complexity, and limited long-term flexibility.

Instead, the project team re-framed the challenge at a network level, identifying an alternative strategy to decommission the local treatment process and transfer flows to a larger treatment works with sufficient capacity to meet regulatory requirements.

The Kirklevington Transfer Scheme replaced the treatment function at Kirklevington STW with a new sewage pumping station and 380m3 balancing tank, supported by a valve chamber, MCC kiosk and chemical dosing arrangement. Calcium nitrate dosing from OMEX Environmental Ltd was incorporated to manage septicity risk within the transferred flows.

Existing assets were reused where they remained appropriate: the inlet screen was modified to accommodate increased inflow, existing storm tanks were retained, and the existing power supply and kiosk were reused where practicable.

Flows will be conveyed via approximately 1.7km of 225mm PE100 SDR17 rising main, discharging to a bespoke chamber before continuing through an upsized combined sewer. A key element of the solution was the adoption and upgrade of existing private sewer infrastructure at Conyers School, avoiding a longer route and removing the need for a more disruptive alignment, including a potential trenchless railway crossing.

The technical significance of Kirklevington is not a single isolated detail; it is the sequence of engineering judgements that changed the project outcome. The team followed a TOTEX-led hierarchy to avoid unnecessary new build, re-use assets where technically defensible, optimise existing network capacity, and only construct new infrastructure where it added clear system value.

This hierarchy materially changed the pipeline route. By establishing that the downstream network and the existing private sewer could accept the transferred flows, subject to targeted upsizing and adoption, the team reduced the length of new pipework by approximately half. This reduced material use, land disturbance, highway interface, programme exposure and community disruption.

The balancing tank also reflected practical delivery intelligence. The use of a modular precast concrete tank supported off-site fabrication, reducing site activities, improving installation certainty and shortening the period of open excavation. On a constrained live site, these choices reduced both construction risk and operational interface risk.

Kirklevington was delivered through intensive collaboration between Esh Stantec, Northumbrian Water, local stakeholders and specialist subcontractors. Collaborative planning sessions were used to hold the programme against a hard regulatory date. Weekly design and site meetings allowed design development and construction planning to progress in parallel, while regular client progress meetings gave visibility of risks and decisions.

The local authority highways team was engaged to avoid clashes with nearby contractors and to coordinate at pinch points. Regular communication with local schools enabled safe working during term time, reduced disruption, and ensured reinstatement was completed before the start of the academic year. Design engineers maintained regular site attendance, supporting fast resolution of buildability issues and reducing the risk of design intent being lost during construction.

One of the most sensitive construction interfaces was the 65m horizontal directional drilling crossing below a main road and a large-diameter raw water main.

The crossing avoided a disruptive road closure and reduced the direct interface with the strategic water asset. It required close collaboration between the site team, lead designers, geotechnical specialists, the HDD contractor, Northumbrian Water network operatives and other stakeholders.

The works were planned during the school summer holiday to reduce the exposure of pupils, parents and staff to construction movements. While this was the correct social and safety decision, it compressed the available programme and in doing so, increased the premium on planning, contingency and rapid decision-making. Joint risk meetings were used to agree the accuracy requirements, escalation strategy and contingency approach before the crossing was undertaken.

The main carbon benefit came from changing the asset strategy rather than adding a visible low-carbon product late in the process. By transferring flows to an existing downstream works with capacity, the scheme avoided a more substantial treatment upgrade at Kirklevington and reduced the whole-life operational burden associated with a small local treatment site.

The revised route reduced the new pipeline length by around 50%, cutting the volume of pipe, fittings, excavation, reinstatement and temporary works required. The project material records a 126 tCO2 saving from route selection. The use of existing assets, adoption of private sewer infrastructure, off-site precast construction and local subcontractors further reduced waste, site movements and construction exposure.

There was also a direct environmental outcome. The receiving watercourse now receives no final effluent from the former local treatment works, rather than receiving effluent treated to a lower phosphorus concentration. Archaeological Services Durham University undertook pre-construction archaeological surveys, and the pipeline alignment was selected to avoid working within the flood zone where practicable.

Safety management was integrated into planning and methodology rather than treated as a separate construction control. Toolbox talks were used for the key construction activities, remote-control plant was adopted where practical, and stakeholder interfaces were managed collaboratively across the delivery team and supply chain.

The decision to programme the school-interface works during the summer holiday reduced public interface risk. Operational safety was also improved through the automation of de-ragging logic, reducing the need for direct human intervention during future operation and maintenance.

The project’s social value was most visible in how it handled its immediate community interfaces. Working around the school calendar reduced disruption to pupils, parents and staff. The revised route and use of existing infrastructure reduced working in the carriageway and lowered the impact on local traffic. The scheme also reduced the need for tanker access through narrow residential streets to the existing works.

The team retained community value in smaller decisions as well as in headline engineering decisions. An ornamental tree carving of an owl was created instead of simply removing a tree, and football strips were provided to a local youth football team. These actions were modest individually, but they helped turn an intrusive infrastructure project into one with visible local benefit.

The scheme achieved operational completion ahead of the regulatory deadline and delivered a significant saving of 25% against the agreed target cost. It modernised critical wastewater infrastructure, reduced the need for future operational interventions at a constrained local works, and delivered a more resilient network-level arrangement.

Its strongest lesson is that the best infrastructure solution is often created before detailed design begins; by asking whether the project has been framed at the right asset boundary.

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.

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.

The project scope comprised the design, installation, testing, and commissioning of approximately 23.6km of PE trunk main, routed predominantly through agricultural land. The route was selected to optimise constructability while minimising environmental impact, landowner disruption, and interface with existing infrastructure.

Key elements of the scope included:

The pipeline alignment incorporated six directional drilling crossings, including three beneath oil and gas trunk mains, one beneath the Water of Cruden, and two beneath the A90 trunk road. These crossings were designed to avoid disruption to critical assets and key transport routes while reducing environmental risk.

The Newfield RCI project forms part of Scottish Water’s long‑term investment programme aimed at improving asset resilience, increasing network capacity, and supporting future growth across the region. It has been delivered by Caledonia Water Alliance (CWA), working in collaboration with supply chain partner AG Wilson.

Project planning commenced in April 2020, allowing sufficient time for route development, stakeholder engagement, land access negotiations, and statutory approvals. Construction activities began on site in August 2023, with the project reaching completion in June 2026.

Ground conditions encountered along the majority of the pipeline route consisted primarily of cohesive clay soils. These conditions proved favourable for open‑cut construction, providing stable trench formations and reducing the need for extensive temporary works or ground improvement measures.

The consistency of ground conditions allowed efficient trench excavation, bedding placement, and pipe installation, contributing to strong productivity rates across the rural sections of the route. Standard trench support systems were employed where required to ensure compliance with health and safety requirements and to maintain excavation stability.

Excavated material was reused where practicable to reduce waste and vehicle movements, supporting the project’s sustainability objectives.

Although the majority of the pipeline installation was undertaken in rural farmland, several sections required construction within urban and transport‑constrained environments. These included crossings of the A975 between Newburgh and Cruden Bay and Castle Road in Ellon, both of which presented logistical and stakeholder challenges.

Extensive planning and coordination were undertaken with local roads authorities, emergency services, and Stagecoach to develop traffic management strategies that minimised disruption to road users and local communities. For the A975 crossing, it was agreed that a full road closure would be the safest and most efficient approach. The closure was scheduled during school holiday periods and weekends to minimise impacts on schools, commuters, and public transport operations.

At Castle Road, the closure had the potential to isolate a residential area. To mitigate this risk, the project team implemented a free shuttle bus service for residents, ensuring continued access to local amenities and services. This proactive measure was well received by the community and demonstrated the alliance’s commitment to minimising social impacts.

A comprehensive communications strategy was delivered in conjunction with the project’s Customer Communications Team, including advance notifications to affected residents, variable message signage (VMS), letter drops, and local newspaper advertisements. This ensured that stakeholders were informed of planned works, diversion routes, and programme durations.

The pipeline route included six trenchless installations, delivered using directional drilling techniques. Drive lengths ranged from 90m to 220m, with installation depths between 6m and 10m, depending on local constraints and asset protection requirements.

The trenchless crossings were located beneath:

Given the sensitivity of these assets, early engagement with asset owners and regulatory bodies was undertaken to identify constraints, define protection measures, and agree installation methodologies. Detailed risk assessments and method statements were developed, and continuous dialogue ensured that all necessary permissions, wayleaves, and technical approvals were secured in a timely manner.

The successful delivery of the trenchless works avoided disruption to traffic, protected environmentally sensitive areas, and reduced the overall footprint of construction activities.

The pipeline installation and testing activities were completed ahead of programme, reflecting strong collaboration between the alliance partners, effective planning, positive relationships with landowners, and a sustained period of favourable weather conditions.

The new trunk main underwent multiple pressure tests, with test pressures averaging 11 bar, in accordance with Scottish Water standards. Following successful pressure testing, a comprehensive cleaning and chlorination regime was undertaken to ensure water quality compliance.

On completion of chlorination and receipt of approval from Scottish Water Public Health, the pipeline was placed into supply and fully integrated into the existing network. The commissioning process was completed without incident, and the asset was handed over in line with operational requirements.

A range of carbon reduction and sustainability initiatives were implemented throughout the project lifecycle, aligned with Scottish Water and Caledonia Water Alliance sustainability objectives. These included:

These measures contributed to a reduction in embodied and operational carbon while supporting responsible construction practices.

Scottish Water and CWA maintained proactive engagement with stakeholders, landowners, and local communities throughout the planning and delivery phases. Early engagement helped build trust, address concerns, and facilitate access arrangements across agricultural land.

Recognising the importance of education and community outreach, the project team engaged with Slains Primary School, delivering a presentation on the project and the water cycle. This initiative helped raise awareness of water infrastructure, environmental stewardship, and engineering careers among young people.

The Newfield RCI Project represents a significant investment in the resilience and capacity of the north-east Scotland water network.

By replacing an ageing asset and increasing pipeline diameter, the project ensures the continued supply of high‑quality drinking water to existing customers while providing the additional capacity required to support future growth across the Ellon corridor.

The successful delivery of the scheme demonstrates the effectiveness of collaborative working between Scottish Water, Caledonia Water Alliance, and the supply chain, and highlights the benefits of early planning, stakeholder engagement, and sustainable construction practices.

The new infrastructure will play a vital role in supporting communities and economic development for generations to come.

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.

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.

During the optioneering stage, a range of interventions were assessed to address the storm overflow impact, including catchment‑scale rainfall disconnection, increased pass‑forward flow, nature‑based treatment and conventional storage. Catchment disconnection was discounted due to the high levels of customer disruption required, while increasing pass‑forward flow was not feasible due to downstream hydraulic constraints. Given the overflow’s location adjacent to open land by the river, a nature‑based solution was identified as the most effective and deliverable option.

A two-stage approach was chosen to maximise success, with an aerated reed bed providing initial intensive solids capture followed by two Integrated Constructed Wetland (ICWs) in series, providing effluent polishing and an opportunity for the industry to research wetland treatment in this application.

The favourable topography enabled a gravity system, eliminating the need for lifting flows and in turn, reducing operational energy demands. The field’s proximity to New Inn’s residents also allowed for place-making features for the local community, such as footpaths, an outdoor classroom and natural play areas, enhancing community engagement and educational opportunities.

The indirect monetary value of these wider benefits was captured in the decision-making stage via the use of CIRIA’s B£ST estimation tool, which estimated £12m in realised benefits over the next 40 years across social, natural and other capitals; something none of the grey solutions offered.

The existing storm overflow (SO) was located amongst trees on the edge of the field. The incoming pipe laid in the eastern corner of the field meant the SO could be relocated into a new compound, which will contain the following chambers and plant:

Design for Manufacture and Assembly principles were adopted to several elements of the compound. The screening and bypass chamber were fabricated off site by FP McCann Ltd, reducing the need to cast these chambers in situ.

Both the kiosks were prefabricated off-site by Morgan Marine Ltd to save time and reduce on-site activities in the construction phase.

The design team carried out a catchment Flow & Load Survey to ensure a better understanding of the design parameters required to achieve the ‘No Impact’ outcome. The survey gave insight into the challenges around pollutant loads in intermittent discharges, with varying concentrations of biochemical oxygen demand (BOD) and ammonia found in the excess diluted sewage; especially the difference between accommodating the ‘first flush concentration’ and weaker dilutions as a storm event continued.

Working collaboratively with the reed bed and ICW suppliers early in this stage, increased confidence in achieving the necessary pollutant removal in the final effluent.

A Flood Consequence Assessment (FCA) was completed as part of the planning application and the findings required the reed bed and wetlands to be moved further away from the river, reducing the size of the originally allocated footprint. The revised layout however, still provided sufficient treatment area (3,000m2 for the reed bed and a combined ICW treatment area of 2,400m2) and created additional space for the public to enjoy.

The planning application was critical to the success of this project, which was well received by local councillors and relevant bodies, in part, due to the extensive up-front work done by Arup’s planning team. Arup specialist teams carried out predictive odour and noise modelling of the solution to address concerns raised by the planning authority. The project team also engaged extensively with the local community through both in-person and online events, ensuring the design met local needs and preferences.

To align with the Sustainable Approval Body (SAB) requirements as part of planning approval, the design team implemented sustainable drainage features across the site. The maintenance track and vehicle areas in the compound were constructed from permeable TruckCell™ paving, made from recycled plastic, whilst vegetated swales and depressions were incorporated alongside the impermeable access track and footpaths. This reinforced the project’s low‑carbon and sustainable design ethos.

Construction started in January 2024, with Morgan Sindall Infrastructure mobilising to bring the nature-based solution system online before the regulatory deadline of 31 March 2025. The team navigated challenges including invasive species within the compound area and persistent groundwater during the large excavations, requiring an extensive dewatering activity (under approved Abstraction Licences).

Working with the sub-contractors, Natural Wastewater Solutions (NWS) for the reed bed, and Salix River and Wetland Services and Vesi Environmental Ltd for the integrated constructed wetland, 33,904 tonnes of soil were removed and the ground re-profiled. 30,000 tonnes was re-used off site, whilst 3,000 tonnes was recycled and re-used on site, with the final 904 tonnes taken to landfill, due to the presence of Japanese knotweed.

Due to the impermeable nature of the soil, the reed bed and constructed wetland both required under-draining to minimise the impact on the groundwater table. Once the under-drains were installed, the basins were constructed, which included the following:

The site team pushed to see the first flows through the system just 12-months later, ahead of the 31 March deadline and handled the heavy rainfall from Storm Eowyn on 24 January without any issue.

A robust sampling regime is currently underway to understand the performance of the individual stages and final effluent from the nature-based solution. This will inform future permitting of these types of solutions in cooperation with the environmental regulator, Natural Resources Wales (NRW).

The initial sampling results are promising, with significant reductions in BOD, ammonia, total suspended solids (TSS) and phosphorus in the final effluent. River water quality sampling upstream and downstream of the outfall is also being carried out to understand the impact of the scheme on the Afon Lwyd.

Welsh Water is participating in the Chemical Investigation Programme (2025–2030) with UKWIR, where samples from the wetlands are currently being used to help understand bio-accumulation of emerging substances such as pharmaceuticals in intermittent discharges.

With the site due to open to the public soon, Pont-y-felin Lane exemplifies a paradigm shift in storm overflow management, demonstrating how nature-based solutions can deliver technical excellence, environmental restoration, and community enrichment, all while setting a precedent for low-carbon infrastructure in the water sector. The forward‑thinking optioneering, combined with the client’s commitment to selecting a nature-based solution, over traditional ‘grey’ options, has resulted in a scheme that proves natural solutions can deliver more sustainable outcomes, for less.

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.