Supply Chain - Networks - Water Supply - Water Pumping Stations

The Ayrshire Resilience Scheme delivers a two-way connection between the drinking water networks  in Greater Glasgow, Ayrshire and East Renfrewshire; significantly enhancing the security and resilience of the water supply. It is Scottish Water’s largest ever water infrastructure investment benefiting almost one million customers across the west of Scotland. The 12km Glasgow Resilience Programme (C1a) is the third phase of the Ayrshire Resilience Project, and involves the transfer of water from Milngavie WTW located north of Glasgow to the Ayrshire and East Renfrewshire regions to the south-west of the city. C1a is a duplication of the southern section of the existing C1 trunk main that currently runs through the centre of Glasgow, however, design optioneering identified routes to minimise impacts to the local community during the construction phase rather than following the existing C1 route.

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.

The primary objectives of the Kilkenny City Regional Water Supply Scheme Upgrade Project included:

The upgrade integrates enhanced treatment processes, a robust disinfection strategy, and advanced automation and control systems to ensure high-quality drinking water delivery well into the future. A detailed description follows.

To replace the decommissioned Radestown WTP and existing River Nore intake, a new intake structure was constructed 70 metres upstream of Troyswood Weir to ensure water was abstracted from a less turbulent part of the river. Raw water is abstracted from the River Nore at a maximum rate of 1031.6m3/hr for a max duration of 18hrs /day to adhere to the current abstraction license.

Water enters the intake structure through a 25mm coarse bar screen installed on the face of the intake structure which is aligned diagonally at a 45⁰ angle counter current to the river flow to facilitate a sweeping and self-cleaning passage of floating river debris off the coarse bar screens.

A sedimentation channel was constructed downstream of the coarse screen. This allows any large solids to settle out before reaching the end of the channel and entering a mechanical fine screen. The width was calculated to allow a max velocity of 0.15 m/s at max design flow allowing any fish that enter the sedimentation channel to swim against the current and back into the River Nore.

Raw water sampling is carried out immediately after the coarse screen via two duty/assist sample pumps feeding back to a local sample instrumentation board in the raw water building. Having the board situated locally significantly reduces lag time in real time sample results ensuring any exceedances in raw water parameters are detected immediately and pumping to the treatment process is inhibited.

At the end of the settlement channel, a Beaudrey mechanical screen was installed with a ‘catch and return system’ which is fitted with a spray bar and fish buckets providing fish, eel and elver protection with respect to both impingement and entrainment.

Troughs on a moving screen lift any debris and fish out of the water. A low-pressure jet removes the fish and loose debris from the trough and into the fish return launder and back to the river.

Once the trough passes through the low-pressure system it is then hit with a high-pressure jet, dislodging any debris and materials from the 3mm mesh. This water returns to the river in the debris launder. Water for jetting is provided via submersible pumps downstream of the fine screen. The screen is operated continuously to ensure no fish are trapped in the sedimentation channel for a prolonged period. After passing through the mechanical fine screen the raw water is pumped to the treatment process via a newly installed rising main by three 65kW duty/assist/standby pumps fitted with vibration/temperature monitoring to ensure the system is operating to maximum efficiency.

The Troyswood treatment plant is made up of three areas:

A critical element of the upgrade works was to ensure the existing plant remained operational and consistently maintained customer supply. This was achieved with extensive planning and collaboration with Glanua Group’s Operational Department and other stakeholders adding to the success of this project.

A new chemical and treated water pumping building was constructed to house storage and dosing systems for pre-treatment chemicals including:

A new tapered flocculation system replaced the older configuration to accommodate the increased throughput, enabling improved particle agglomeration ahead of filtration.

Raw water enters the chemical building below ground. Inside the chemical building, the pipe is accessed by means of the raw water dosing culvert, where it is dosed with sulphuric acid to lower the pH to a target value suitable for coagulation using PACL 18%; dosed downstream of the sulphuric acid post-mixing. To save space and reduce the culvert size, two static mixers were used for each of the dosing setups.

Dosing is controlled by means of UVT bands. UVT is measured at the raw water instrumentation board. Based on process calculations, %UVT bands are given a dose rate for the two chemicals. This was fine-tuned at the commissioning stage and adjusted based on experience of conditions when operating the plant.

Raw water then enters two new flocculation tanks with a combined retention time of approximately 30 minutes at design flow. Here, poly-electrolyte is added to water via a sparge bar at the top of the tanks. The water is mixed in Tank 1 at ~15 RPM before passing onto Tank 2 where it is mixed at ~10 RPM.

On leaving Tank 2, water passes through an existing mixing chamber now denoted as Flocc Tank 3. Poly-electrolyte dosing and gradually reduced mixing in addition to the PACL 18% leads to flocc formation in advance of the settlement process in the clarifiers.

Process tanks within the WTP were both hydraulically and mechanically upgraded to handle the full abstraction capacity from the new intake. The existing plant was made up of two flat bottomed clarifiers and three rapid gravity sand filters. To achieve the required throughput of the plant, the capacity of the clarifiers and filters needed to be increased. The contract also required that the full throughput of the plant could be achieved with 1no. clarifier and filter out of service. This is to allow for scenarios where tanks need to be taken offline for maintenance.

The existing system was reviewed in terms of capacity and hydraulics. Retrofitting the existing clarifiers with tube settlers and installing one additional clarifier allowed for the design throughput of 1031.6m3/hr while maintaining the maximum clarification rate of 6m/h. The additional tank was designed to be a replica of the existing cells. This ensured hydraulics matched over the three cells and ensured even dispersal of water across the three clarifiers.

Water enters the clarifier through lateral PVC pipework at the bottom of the tank before rising to meet the tube settlers. The tube settlers are supported on a stainless-steel frame with a hatch incorporated for future maintenance. The tube settlers encourage settlement of any solids that make it past the formed sludge blanket with clarified water exiting through the top and into launders that convey the water to a common clarified channel and on to the filters. Sludge is then drained off the clarifiers via a sludge bleed channel and eight pinch valves working sequentially on each clarifier.

Automatic time intervals are based on raw water UVT with higher UVT meaning closer intervals to ensure the clarifier sludge blanket is maintained at a constant depth and level.

Filtration capacity was increased by the addition of a new rapid gravity sand filter. To support higher filter backwash rates, the existing backwash pumps and air blowers were upgraded in accordance with IW-TEC-900-04 specifications. The existing clear water tank was reconfigured to act as both a filtrate water sump and backwash pump sump, reducing carbon footprint by reusing existing infrastructure.

A similar study of the filters to that of the clarifiers showed that N+1 flows could be achieved for the design flow by adding one filter and installing an under drain filter floor. This achieved capacity of 1/3 design flow through each filter, allowing one tank to be taken out of service if required. Again, the new tank was constructed to match the existing tanks to maintain similar hydraulics and ensure even throughput across the filters. Additional filter upgrades included increasing the backwash weir to allow expansion of the newly installed media. To avoid a prolonged shutdown of each filter, this was carried out by installing a prefabricated stainless-steel wall, allowing the install to be carried out over 2-3 days rather than waiting for concrete curing.

Filtered water enters an existing combined filtered water culvert and makes its way to the low lift sump. The low lift sump was originally the final clear water tank for the existing plant, including a backwash section by means of a dividing wall. However, due to sizing and increased throughput, this now became a break tank before water is pumped onwards via three 30kW duty/assist/standby pumps through the UV and into the newly constructed 2ML clear water tank.

In addition to the low lift pumps, two new 75 kW backwash pumps extract from this tank during the backwash phase of the filtration cycle and required the capacity of the whole tank, not just the existing backwash section. This meant that the tank needed to be hydraulically balanced with three cores carried out on the existing dividing wall, sized to allow design throughput of the plant. Further to this, the new backwash pipework was increased from DN300 to DN600 meaning very little space between the suction pipework and existing walls.

A detailed survey was carried out on the existing sump. This allowed the backwash and low lift suction pipework to be installed, and cores to be located, to prevent cavitation in the suction pipework. Part of the survey included cores to determine the existing makeup of the roof slab to allow design of the backwash and low lift pump support system.

The ‘brownfield’ nature of the works meant multiple and complex interfaces with the existing live water treatment plant while also ensuring treated water compliance at all times. These works included multiple shutdowns and confined space entries which required extensive planning and coordination with Glanua Group’s operations teams to ensure supply to the network was maintained at all times; a testament to the team that ensured the works were completed safely and within the allowable timeframe.

The final part of the treatment process involves the transfer of water from the low lift sump to the clear water tanks via two duty/standby UV units; a calculated Dose UV System with real-time control minimising power requirements. This achieves the additional 2 log reduction for cryptosporidium, ensuring the 5-log total required. The UV units are validated to a minimum UVT of 80% which is monitored by a constant UVT reading from the low lift sump upstream of the UV dosing. The new UV system was added within an extension to the existing WTP building and included:

High lift pumping is carried out on a duty/assist/standby basis by five 75kW pumps conveying 8.78 MLD to each reservoir. To save costs, all high lift pumps for both reservoirs are located on a common manifold with one pump acting as standby for each reservoir. This pump can be swapped between each rising main by means of an actuated valve when required.

A new 2,980m DN450 treated water rising main was constructed to convey treated water to Radestown Reservoir with the existing rising main to Thornback retained, with valved tee connections enabling flexible operation. These changes ensure efficient delivery to both reservoir systems and form part of a robust dual supply strategy for Kilkenny City RWSS.

A new residuals treatment system was also built to manage washwater and sludge:

Two washwater settlement tanks take water from the filtration backwash process. Settled water is decanted to the river Nore with interlocks ensuring a maximum turbidity of 10NTU preventing any negative effects on the river and associated wildlife. Sludge is combined with clarified bleed sludge in a PFT where it is thickened before being stored and sent to a centrifuge for dewatering. Rationalisation of the specimen design allowed removal of two equalisation tanks by combining equalisation and settlement tanks and removal of a proposed sludge building by condensing the required infrastructure into a smaller setup that could be installed in the chemical building sludge room while still maintaining access for O&M requirements

SCADA upgrades were implemented across the site to allow real-time process control, Critical Control Point (CCP) monitoring, and automated alarm systems. The upgraded control system ensures consistent operation and provides remote monitoring capabilities.

The project adopted several forward-thinking solutions:

The Kilkenny City RWSS upgrade represents a significant milestone in the modernisation of water infrastructure for the region. With construction and commissioning successfully completed, the scheme now delivers up to 17.56 MLD of high-quality potable water, meeting the latest Uisce Éireann regulatory standards and future-proofing supply to a growing population.

Lab analysis shows results of between 30-50 µg/l THM at both Thornback and Radestown Reservoirs, well below the recommended limit of 80µg/l which was one of the main drivers of the project. UVT of 90% is consistently achieved along with chlorine residuals and turbidity all in compliance.

The Troyswood WTP was a brownfield site upgrade that more than doubled the original capacity of the treatment plant and added additional stages to the process to make the system more resilient. Installing the required equipment in the existing buildings and tanks, while operating and maintaining the current supply was a challenge for the Glanua Group team, but one that was ultimately successful. This is clear from the little to no interruption to supply during the install and the successful operation of the plant after commissioning.

Not only was the project technically successful, but it has also delivered on a sustainability level, with carbon footprint and cost savings achieved by the rationalisation of the design gaining efficiencies in many areas such as removal of an entire building and non-critical lighting along with utilising latest technologies and automation to reduce the amount and size of concrete tanks, and infrastructure required.

The integration of advanced process technologies, energy-efficient pumping solutions, and automation control systems ensures long-term operational resilience and environmental sustainability. Future upgrades and maintenance works can now be executed with minimal service disruption due to the built-in redundancy and improved system flexibility.

Project success was achieved by Glanua Group working closely with the key project stakeholders, Uisce Éireann and design consultants Ryan Hanley, in collaboration with Kilkenny CC where required. Ryan Hanley recently won an award under the category of Sustainability Natural Environment which was presented at the ACEI Awards on 4 April 2025.

The Water Resources Management Plan 2019 (WRMP19), and subsequently updated for WRMP24, sets out Southern Water’s response to the water supply challenge in Hampshire. The response consists of a strategic new source of supply, new and increased bulk supplies from neighbouring water companies, demand management, and new strategic transfer pipelines across the region. SWS were required to identify the optimal infrastructure and associated operational controls required to transfer the new supply from Otterbourne Water Supply Works (WSW) to the’ existing distribution networks supplied from Testwood WSW (Southampton) and River Way WSW (Andover).

The Southampton and Andover Link Main Schemes are potable water transfer schemes which are required to link up key SWS operational sites across Hampshire to ensure continued sustainable, reliable water supplies.

Principally, the proposed schemes consist collectively of approximately 41km of new trunk mains ranging in size from DN500-DN900, operating in conjunction with a number of existing strategic trunk mains, connecting key WSW’s and Water Service Reservoirs (WSR) across a number of Water Resource Zones (WRZ). Additionally, the schemes include new pumping and storage assets to support the water transfers.

Through the scheme optioneering phase, which started in early 2022, a Network Control and Optimisation (NCO) study was undertaken to align with and build on previous work undertaken in WRMP and other strategic network modelling studies.

The aim of the NCO study was to assess the resilience of the proposed new strategic transfer pipelines, often referred to as the Western or Hampshire Grid, and how different options might exhibit varying levels of resilience across business as usual (BAU) and drought operation. The study was completed with the understanding that the infrastructure architecture could not be determined unless the associated operation was also defined. The study was conducted in parallel to engineering design development to determine the preferred options for design, construction and commissioning as part of the wider Water for Life Hampshire programme, ensuring a holistic approach across the region.

The study utilised a proprietary AI software product, Optimizer, to develop optimal asset configurations and was chosen to reduce program costs and expenditures. A traditional approach would typically involve hydraulic models using an iterative “trial and error” method, but the large number of options would make it impossible to evaluate all possible outcomes.

Using Optimizer, with which the Southern Water InfoWorks network model was linked as an embedded hydraulic engine, enabled the automatic evaluation of thousands of trial solutions computing cost and performance, and incorporating operating constraints and design criteria. Optimizer produces a range of least-cost network solutions, including asset sizes and maximising the efficiency of network operational performance, considering both BAU and drought supply/demand scenarios.

The tool produces a set of plans along a Pareto front that represents the optimal-performing configuration for a budget cost, and therefore quickly identifies options to be analysed in further detail. This process enabled efficient development of the engineering design as the scheme architecture was refined quickly with focus on key assets required.

Through 2022 as the scheme transitioned into concept design, various route corridor options were considered between the fixed strategic sites identified within Otterbourne, Southampton and Andover.

Options considered additional alternative Southern Water operational sites to interconnect with and how to transfer water between these sites to provide further system resilience. These options were refined initially through careful review of desktop environmental, ecological and heritage constraints information, later supplemented by data obtained through site visits, and field surveys (non-intrusive and intrusive).

Options considered the location of the pipeline easement, access routes, pipeline materials and construction methodology. A key intermediate site selected to integrate into the system was Yew Hill WSR, located to the south-west of Winchester. This provided opportunity to utilise common sections of pipeline transfer from Otterbourne to serve SLM and ALM whilst maximising existing transfer capability. This also provided opportunity to expand potable water storage capacity in a network location capable of providing numerous resilience options.

From the initial assessments, high level route corridors were established and broken down into a series of segments. The segments were then appraised in detail following a Red, Amber, Green (RAG) classification by environmental, ecological, heritage, engineering and construction specialists.

Different route options were demonstrated with different segments, with some segments having sub options within. Through a desk-based process, each discipline provided their feedback on the key constraints within each segment, and where mitigation could be required and the form it could take.

Where there were options between or within segments, a preference was stated by each discipline with clear factual reasoning. From these preferences, the route was selected depending on which constraints for each segment were most critical to avoid, whilst balancing constructability and land access constraints.

Following internal SWS project delivery process, agreement on a single option to progress to outline design was made based on a combination of technical, operational and environmental considerations.

The general design and construction principles used to develop the initial pipeline route of the schemes were to minimise:

The proposed pipeline routes and design were subsequently further refined taking into account environmental constraints identified through field surveys, archaeological investigation, community considerations and engineering capabilities clarified through intrusive ground investigation.

All desktop and survey data was made available to all project disciplines via the utilisation of Mott Macdonald’s Moata digital platform, specifically Moata Geospatial and Moata Land Management. This provided all teams withs access to information at every stage of the project, allowing cross-disciplinary teams to collaborate in real time.

The integration of the Moata platform was so successful that it won Best Project – Innovation at the Institution of Civil Engineers South East England Engineering Excellence Awards in 2025.

The key components selected to form the scope for the SLM are as follows:

The scheme will provide a transfer between Hampshire Southampton East WRZ and Hampshire Winchester WRZ and a transfer between Hampshire Winchester WRZ and Hampshire Southampton West WRZ. Specifically, the scheme will transfer water from Otterbourne WSW to Yew Hill WSR and onward to Rownhams WSR and Testwood WSW.

Key design constraints for the scheme included:

The key components selected to form the scope for the ALM are as follows (NB: At the time of writing (July 2025) scheme refinements are ongoing and some of the following may be subject to change):

The scheme will provide a transfer between Hampshire Winchester Water Resource Zones and Hampshire Andover Water Resource Zones, specifically the scheme will transfer water from Yew Hill WSR to Crab Wood WSR and onward to Micheldever Road WSR and the Andover distribution network.

Key design constraints for the scheme included:

In 2022, MGjv was appointed as Principal Contractor and Principal Designer to undertake Early Contractor Engagement (ECE) support across both schemes; assisting with development of the concept design. As scheme development moved into 2023, MGjv coordinated and undertook extensive site investigation works to verify ground conditions. The scope of the investigation comprised trial pitting, cable percussion boreholes, rotary core boreholes, downhole geophysical testing, surface geophysical surveying, laboratory testing and the preparation of factual reporting.

In parallel, numerous excavations at different locations along the two proposed pipeline routes were undertaken to explore the potential for buried archaeological remains. Initially, an extensive programme of archaeological trial trenching was completed which informed the requirement for subsequent selected strip, map and sample works.

In late 2023, Southern Water submitted requests for EIA Screening Opinions on each scheme to the Local Planning Authorities to confirm requirements for planning consent. Final responses were received in Spring 2024. The outcome of the requests was that SLM was not deemed EIA Development and therefore retained Permitted Development (PD) Rights where applicable. In comparison, ALM was deemed EIA Development and requires a full Planning Application and Environmental Statement (ES) to be submitted for approval.

A summary of site investigation works is as follows (as of early 2024):

Following confirmation of the planning requirements for both schemes in Spring 2024, MGjv was contracted to deliver the full design and delivery of the SLM as the scheme was able to progress under PD Rights for the pipeline. Separate discrete assessments were undertaken that clarified the new Yew Hill WSR, which was also confirmed as PD. The expansion of the Otterbourne WSW HLPS would be subject to a planning application.

The requirement on the ALM scheme for full planning and ES required additional design and survey/investigation works to be undertaken and so MGjv has continued in an ECE role until mid-2025 to support the application, due late 2025. The procurement strategy for the full design and delivery is currently being developed.

The Southampton and Andover Link Main Schemes will provide a new strategic supply backbone across Hampshire to maintain security of supply to customers and help protect the county’s rare and sensitive chalk streams.

The schemes will provide additional BAU resilience whilst also providing capability to mitigate important drought restrictions being placed on the River Test and River Itchen, impacting key operational sites within the region.

Further articles will follow in due course covering the detail design, construction and commissioning phases of the schemes.

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 flow from Angelinos WBS feeds Duns Tew Reservoir via the Middle Aston Valve, and feeds Bretch Reservoir from the Banbury Ring Main, with assistance from Milton WBS. The AMP6 pipeline extends from Angelinos WBS to the Banbury Ring Main, providing dual pipelines from Angelinos to Middle Aston Valve and from Middle Aston Valve to the Banbury Ring Main. This provides resilience to the system by providing redundancy against burst failures both upstream and downstream of the Middle Aston Valve.

There are several operating modes of the system whereby there is insufficient head available to fill Duns Tew Reservoir, either due to outages of network assets or during dual operation of the pipelines from Angelinos due to the reduction in hydraulic gradient.

It was identified that a new water booster station constructed at the location of the Middle Aston Valve would enable a continued supply to the Duns Tew Flow Monitoring Zone for multiple different operation/outage scenarios, providing resilience to the network. Ward & Burke Construction was appointed by Thames Water to design and build the new pumping station.

Early-stage design calculations conducted by Stantec UK were carried out to determine the different operation regimes of the network, and the associated head/flow rates required at the new Middle Aston Water Booster Station. Building upon this, Ward & Burke developed the detailed design of the pumps and internal pipework arrangement to suitably deliver the necessary operating regimes.

This led to the provision of pairs of 30 kW and 7.5 kW pumps in a duty/standby arrangement, with an actuated valve controlled bypass. The combination of the larger/smaller pumps enables efficient operation of the pumps over all of the operating regimes, which have a broad range of head requirements from the pumps.

A surge analysis was conducted by Hydraulic Analysis Ltd to assess the pressure transients in the network during operation, confirming that additional surge protection was not required in the network following the introduction of the new pumping station.

Planning permission for the new WBS was obtained by TWUL prior to Ward & Burke’s involvement, which allowed for the construction of a cladded ‘barn’ style building 8m wide x 18m long; divided into a pump hall and an MCC room. The roof level of the building approved within the planning permission was low relative to the adjacent access road and existing levels in the area, to prevent the visual impact of the building such that it was entirely screened from view by the surrounding plantings.

During the detailed design of the site, it was recognised that it would not be practical to provide vehicle access to the south side of the building bordering the access road (as required for maintenance) with the proposed access route approved in the planning permission. To overcome this, Ward & Burke revised the site layout to provide access to the west of the site boundary situated at higher level, allowing for a more gradual access road which could follow the natural gradient of the site which slopes steeply from west to east. The level difference between the road at the south of the site and the desired level of the new road to access the south side of the building was then managed with precast retaining walls (supplied by FP McCann Ltd) to maximise the accessible area in front of the building.

As part of this redesign, a significant increase in hardstanding area was introduced to the site, leading to new considerations for the site drainage. Originally, it was intended that the drainage from the new WBS building and surrounding hardstanding would be served by a single soakaway, due to favourable sandy ground conditions at the site. Following the increase in hardstanding area, the size of soakaway required to serve the entire site became no longer practical to fit within the site boundary.

To resolve this, the site drainage was redesigned such that only the catchment area of the building and a small bunded hardstanding for fuel delivery to a standby generator would pass to the soakaway, and all other new hardstanding would be provided by permeable asphalt. Due to the potential for spills when refuelling the backup generator, the drainage from this hardstanding is passed through an oil interceptor prior to the tie-in to the soakaway.

Using the soil infiltration rates determined by on site testing to design the soakaway, it was determined that a permeable asphalt road with a thin, Type 4/20 stone subbase would provide sufficient infiltration/storage to prevent the roads from surcharging for the critical design rainfall.

The depth of subbase required was minimised by utilising CellWeb TRP from Geosynthetics Ltd, a cellular root-protection system which provides additional reinforcement to the sub-base allowing for a reduction is thickness when compared with the Thames Water asset standard road detail. This provided a significant material (and therefore cost/embodied CO2) saving, as well a reduction in excavation depth (and therefore man-hours and muckaway) required to construct the road.

The WBS building consists of a pump hall and an MCC room, with a roller shutter door to the south side of site to allow vehicular access for pump maintenance/removal. A full basement foundation was designed for the building, decked out with a combined steel/GRP mezzanine flooring to provide the internal floor level. This arrangement provides both ample access to the MCC for cabling works and allowed for the entire pipework assembly to be positioned beneath the finished floor level of the pump hall.

By lowering the pipework and instrumentation into the basement, with only the pumps mounted at the internal floor level on concrete plinths, full access to the pumps is provided with minimal pipework congestion that would otherwise necessitate alternative means of raised access, leading to issues with the available headroom fixed by the planning levels.

A range of different construction and material approaches were considered for the main superstructure of the building, balancing both the financial and embodied carbon costs for both the construction and the in service use.

Additionally, it was required that the booster station satisfies a C5 LPS 1175 Issue 8 security rating (equivalent to Issue 7 SR3). It was identified that the preferred means of achieving the required security rating with the above construction considerations was to install 3m high concrete walls enveloping the perimeter of the building.

To mitigate the risks associated with pouring 3m high walls in situ, precast concrete walls were utilised. Due to the close control of reinforcement cover and high concrete strength achieved by the precast, very thin wall panels can be used which offers savings in embodied CO2 due to reduced material volume and also elicits less onerous craneage requirements for lifting into position.

Initially a steel portal frame design was considered for the WBS, however for the size of the WBS, it was assessed that a more efficient construction sequence could be achieved by utilising concrete columns and beams all provided from the same supplier.

All precast elements were designed and supplied by Shay Murtagh Precast Ltd (from County Westmeath in Ireland), which were designed to interface with starter bars from the in situ basement foundation. This approach led to a safe, quick construction of the building super structure; in just 6 weeks. A site team of 6 workers (including a crane operator and banksman) tied the in situ foundation reinforcement, poured the foundation, and installed the completed super-structure.

There were significant Health & Safety benefits gained by moving the construction of the super-structure to an off-site DfMA solution. In particular, the work at height required was reduced to simply grouting the connections of the beams and columns which could be safely carried out from a MEWP. The exposure to wet concrete for the super-structure was reduced to just the grouted connections between the precast and in situ base/other precast elements, which also required fewer concrete wagons through the small local roadways which provide access to the site.

To clearly communicate the residual risks on site to the ground workers, detailed construction graphics were produced which detailed the exact construction sequence drawn specifically for the WBS, with each residual construction risk clearly identified.

Additionally, building elements were detailed into the concrete structural elements to reduce additional works wherever possible. For example, gantry crane support corbels were formed into the columns to reduce the support steelwork required for the gantry crane in the pump hall, designed and supplied by Bramley Engineering (Lifting Gear) Ltd.

A rebate was formed in the top of basement wall and pump support plinths to support the steelwork for the mezzanine floor to eliminate the requirement for support columns throughout the basement. Openings in the walls were provided to receive ventilation louvres, with ventilation being a key consideration due to the significant heat output of the pump motors and associated VSDs within the MCC. The site is located adjacent to a residential house, and to ensure that the building would not be disruptively loud during operation, a noise assessment was carried out by AtkinsRéalis.

A new MCC with ICA section was designed and built in-house at Ward & Burke, with the electrical installation carried out by LDC Electrics Ltd.

The MCC is situated in a dedicated MCC room which is separated from the pump hall by a dividing wall. The provision of a full size basement foundation greatly aides the electrical installation works and yields a neat and tidy bottom entry into the MCC. The relevant operational regimes of the WBS are controlled by the head readings from common inlet and outlet pressure transducers.

The common outlet transducer is used to infer the top water level in Duns Tew Reservoir, while the appropriate selection of the 30 kW and/or 7.5 kW pumps is inferred from the head available at the inlet as read by the common inlet pressure transducer. The delivery flow rate is monitored by the common outlet flow meter.

Ward & Burke commenced the on-site works in August 2024, and the new booster station is currently undergoing its commissioning and final completion of the minor ancillary civil engineering and road construction works.

The project is due to be handed over to Thames Water in October 2025, from when the new Middle Aston WBS will provide added resilience to the supply network for years to come