Supply Chain - Water Mains - Underpressure Connections

The Trimpley to Hampton Loade Pipeline Project is a strategic infrastructure initiative designed to enhance water supply resilience for 65,186 customers currently served by Trimpley Water Treatment Works (WTW). The project involves constructing an 11.5 km, 500mm internal diameter (ID) single-directional pipeline from South Staffordshire Water’s Hampton Loade WTW to Severn Trent’s Trimpley Top Service Reservoir (SR). This pipeline will enable the transfer of up to 20 Ml/d in the event of a failure at Trimpley WTW, ensuring continuity of service and supporting the company’s AMP7 Second Source Resilience commitment and delivering the project in a phased, efficient, and minimally disruptive manner. Second Source Resilience

Trimpley WTW is a critical asset in the regional water supply network. However, its single-source dependency presents a significant risk in the event of operational failure, which would result in widespread service disruption, posing risks to public health, customer satisfaction, and regulatory compliance.

As part of the company’s AMP7 programme, which includes a 9% commitment to Second Source Resilience, this project has been identified as a key enabler of supply continuity.

[caption id="attachment_23925" align="alignnone" width="1200"] 52-ton and 70-ton HDPE pipe strings welded and awaiting winching into the bore on the larger HDD crossings - Courtesy of Coffey Construction UK[/caption] Project scope

The project was divided into three main sections to facilitate phased delivery and allow for Coffey to begin construction of the critical infrastructure in August 2023.

Section 1: The first section of works involved the installation of 2.75km 500mm internal diameter (ID) ductile iron pipework whilst also undertaking the site investigation (SI) and ground investigation (GI) for the subsequent sections which were under design.

Section 2: The second section of works comprised the installation of 5.54km of ductile iron pipework including four horizontal directional drilling (HDD) 630mm (OD) SDR9 drill shots 1960m in total under carriageway works (A442) and river crossings.

Section 3: The final section of the pipeline encompassed the remaining 3.21km of ductile iron pipework, including two 660m and 400m HDD drill shots located in Coal Authority land and drilling under ancient natural woodland. This phase also includes the connection to Trimpley Top Service Reservoir and installation of 250mm (ID) washout pipework, actuated valves, bypasses, and monitoring equipment as well as the final pressure testing and commissioning of the entire pipeline.

The complex project included myriad of activities to enable seamless construction throughout the phased delivery of the works. Through early contractor engagement, Coffey was able to advise and assist the client in elements such as ecological assessments, design constraints, aerial photogrammetry and third-party utility liaison.

With a strong supply chain of valuable and efficient suppliers, all aspects of the project were constructed with minimal disruption to stakeholders resulting in a long-term valued pipeline and a critical investment in water supply resilience.

The key elements of the project delivery are detailed below.

[caption id="attachment_23922" align="alignnone" width="1200"] Easement fenced and topsoil stripping underway with geo-referenced UAV position in foreground - Courtesy of Coffey Construction UK[/caption] Ecology

As part of the project, a series of ecological assessments and reports were conducted to ensure compliance with environmental regulations and to support biodiversity. These included:

Ecological desktop & constraints mapping: A comprehensive review and mapping of ecological data to identify environmental constraints and inform route planning and construction methodology to be used. Protected species surveys: Water vole and otter surveys: Field assessments of watercourses to confirm the presence of protected species and ensure legal compliance. Dormouse surveys: Habitat suitability evaluations and targeted surveys for dormice were undertaken along the full length of the pipeline alignment. Tree constraints schedule: Identification and classification of mature and protected trees and critical habitat within the project corridor to assess ecological value and potential construction impacts. Managing laying pipeline either through or drilling under Ancient Natural Woodland. Hedgerow classification: Assessment of hedgerows along the route to determine their ecological significance under the Regulations. Habitat suitability & mitigation reporting: Detailed evaluations of habitat conditions for protected species, with recommendations for mitigation where necessary. Ecological enhancement reporting: Proposals for biodiversity improvements, including habitat creation and restoration measures along the pipeline corridor. Surveying & geospatial data

As part of the Trimpley to Hampton Loade Pipeline Project, an unmanned aerial vehicle (UAV) photogrammetry survey was conducted along the full pipeline route within a 50m corridor. The aerial data was processed into Autodesk Civil 3D-compatible formats to support precise terrain modelling and route planning.

[caption id="attachment_23934" align="alignnone" width="1200"] (left) UAV support played a pivotal role during the pipeline project, (top right) implementation of remote-guided advanced navigation systems during the pilot bore phase of the complex HDD crossings and (bottom right) Combining GPR survey data within the machine control files to achieve a zero-service strike rate across the full pipeline - Courtesy of Coffey Construction UK[/caption] The terrain modelling, apart from supporting construction planning and method of pipelaying, provided a baseline for the machine control element of the installation and reinstatement process.

In addition, a utility and ground penetrating radar (GPR) survey was carried out within a 30m corridor to identify existing underground infrastructure and third-party assets and support safe excavation.

Desktop utility mapping complemented the GPR data, reducing the risk of service strikes. Up to date desktop utility searches (DURS) reports were undertaken and, with the data being incorporated with the GPR survey and incorporated into the machine control element of the excavation works.

Value engineering

To facilitate the successful delivery of the pipelaying element of the project, a series of coordinated construction and reinstatement activities were utilised to ensure the efficient delivery of the pipeline using specialist earthworks contractor Collins Earthworks to provide the plant, equipment and expertise suitable for constructing a pipeline of this magnitude.

Through carefully coordinated and planned activities and with the added value of machine control systems, the efficiency and accuracy of the installation process was greatly improved.

[caption id="attachment_23928" align="alignnone" width="1200"] (left) Advanced excavators using the latest in machine control technology for precision pipelaying activities and (right) Utilisation of halo keel cold cutter to provide a safer means of cutting pipework - Courtesy of Coffey Construction UK[/caption]

Coupled with the GPR survey data, this ensured a zero-service strike rate was achieved across the entire length of the pipeline.

By using the latest technology in machine control systems, this not only accelerated construction timelines but also minimized material wastage and environmental impact.

Additionally, real-time data feedback improved quality control, reduced the risk of human error, while enhancing operator productivity and site safety supporting a cost-effective delivery in adherence to the pipeline design.

Coal Authority land and historic shallow mine workings

The final section of the pipeline encompassed certain areas designated under the jurisdiction of the Coal Authority, which oversees land affected by historical and active coal mining operations. Traversing these areas necessitated specific engineering and monitoring strategies.

Undertaking the horizontal directional drilling within this zone dictated meticulous planning, strict regulatory compliance, and robust risk mitigation strategies to safeguard both public safety and environmental integrity.

Prior to any works commencing, a formal permit was acquired from the Coal Authority, supported by comprehensive documentation including site-specific risk assessments, method statements, and ground investigation reports. These assessments were critical for identifying the potential hazards the land may contain such as subsidence, mine gas emissions, and the presence of abandoned mine workings.

[caption id="attachment_23930" align="alignnone" width="1200"] (left) Pre-construction drainage installed along easement, and (right) 500mm (ID) ductile pipe laying in progress - Courtesy of Coffey[/caption]

Construction methodologies were adapted to account for ground instability and contingency measures for unexpected ground movement through subsidence.

Continuous engagement with the Coal Authority and the client’s geotechnical representative ensured that all activities aligned with statutory requirements and best practice guidance.

Horizontal directional drilling: Gun Hill Crossing

The Gun Hill crossing, comprising a technically complex and challenging 660m section of 630mm SDR9 water main, was delivered using horizontal directional drilling to minimise surface disruption within an environmentally sensitive and geologically challenging area within the Coal Authority Land and in proximity to Ancient Natural Woodland.

Located in the South Staffordshire Coalfield, Gun Hill features challenging geology consisting of a mixture of part of the Pennine Coal Measures Group; prone to instability and mine gas emissions and, Early Devonian Clee Sandstone Formation which varies from hard, abrasive layers to softer, friable sections impacting borehole stability.

Coffey collaborated with specialist HDD contractor Johnston Trenchless Solutions (JTS) to execute the HDD crossing using advanced technology and a state-of-the-art 220 tonne capacity drill rig (the only one in the UK) to navigate the geological challenges and install the 70 tonne HDPE pipe within the permitted land. An advanced de-sander was used to recycle and clean the drilling mud thereby reducing water demand and reduction in disposal costs.

[caption id="attachment_23926" align="alignnone" width="1200"] (left) 630mm (OD) SDR9 pipe welding progressing on the HDD crossings and (right) 70-ton HDPE pipe string being winched into the bore on Gun Hill - Courtesy of Coffey Construction UK[/caption]

The pilot bore was drilled along the predetermined path using advanced navigation systems for accuracy through coal seams and sandstone. Reaming of the bore to 900mm was conducted in multiple stages to ensure stability. The 70 tonne 630mm SDR9 pipe was then winched into the bore during a 12-hour shift.

The Gun Hill crossing, part of a 1800m trenchless installation across six ground conditions, was a critical milestone.

Drilling fluid management & environmental mitigation at Gun Hill

During the horizontal directional drilling operations at the Gun Hill crossing, the team encountered heavily fractured substrata formations. These geological conditions, combined with the high-pressure fluid injection required for pilot bore advancement, led to instances of drilling fluid loss particularly evident at river crossing points along the alignment.

To address this, Coffey implemented a proactive and robust environmental management strategy. A dedicated frac-out containment team was deployed to monitor the drilling corridor in real time, utilising unmanned aerial vehicles for aerial surveillance and rapid detection of surface fluid emergence. Pre-positioned frac-out mitigation materials were strategically placed along the route, enabling the team to respond swiftly to any fluid escape events. These measures ensured that any drilling fluid that reached the surface was immediately contained and managed, significantly reducing the risk of environmental harm. Through continuous monitoring, rapid response protocols, and effective containment practices, Coffey successfully mitigated the environmental impact of fluid loss incidents, maintaining compliance with environmental standards and safeguarding sensitive habitats throughout the drilling operation.

[caption id="attachment_23923" align="alignnone" width="1200"] Identification and proving of third-party assets using vacuum excavation pre-pipelaying activities - Courtesy of Coffey Construction UK[/caption] Trimpley to Hampton Loade Pipeline Project: Supply chain - key participants Principal contractor: Coffey Construction UK Ltd Topographical surveys & mapping: Murphy Geospatial Civils & site support: Three Shires Ltd Pipe laying: Draper Civil Engineering Ltd Horizontal directional drilling: Johnston Trenchless Solutions (JTS) | Joseph Gallagher Ltd HDD equipment: Vermeer UK Earthworks & pipe laying: Collins Earthworks Ltd Civil & site support: CGL Paving & surface reinstatement: Brad-Pave Ltd Excavation plant & machinery supply: P Flannery Plant Hire (Oval) Ltd Pipe supplier: Electrosteel Castings (UK) Ltd Flow controls: AFFCO Flow Control (UK) Ltd Valve supplier: AVK UK Ltd Innovations

To support accurate and high-quality land reinstatement following pipeline installation and testing, a UAV-based terrain capture survey was conducted prior to construction commencement. This pre-works aerial mapping provided a precise digital record of existing ground conditions, enabling the reinstatement process to closely match original landform profiles and ensuring compliance with environmental and landowner expectations.

Ground penetrating radar scanning was used across the full working easement and the existing service results were integrating into state-of-the-art computer systems installed into all excavators (machine control technology). This system disabled any excavator working within close proximity to existing services and achieved a groundbreaking milestone: a zero-service strike rate throughout the entire pipeline project. This innovative approach not only enhanced safety and efficiency but also set a new benchmark for precision in underground infrastructure delivery.

Advanced excavators equipped with tilt-rotating attachments were introduced, enabling precise and flexible material handling from outside the trench. This innovation significantly reduced the need for pipelayers to enter the excavation zone, thereby minimizing the people–plant interface. This resulted in a substantial improvement in on-site safety and operational efficiency, setting a new standard for safe excavation practices. During the pilot bore drilling phase, remote-guided advanced navigation systems were implemented to maintain absolute precision in both line and level. This cutting-edge technology ensured that the pipe installation adhered exactly to design specifications. By leveraging real-time data and remote-control capabilities, we enhanced accuracy, minimized manual intervention, and delivered a more efficient and reliable installation process.

The integration of the TONGHAND® XS system into horizontal directional drilling operations marked a significant advancement in safety and automation. This innovative tool enables a single operator to remotely make and break pipe joints directly from within the excavator cab, eliminating the need for manual wrench handling. By reducing physical strain and removing personnel from high-risk zones, both safety and productivity were enhanced, setting a new standard for safety in tough conditions.

[caption id="attachment_23927" align="alignnone" width="1200"] (left) Integration of Tonghand XS to eliminate manual wrench handling during HDD crossing works and (right) Installation of a permanent cross connection setup within the existing pump house to facilitate the new resilience flows - Courtesy of Coffey Construction UK[/caption]

The continued deployment of unmanned aerial vehicle  technology played a pivotal role in supporting both the design and construction teams throughout the pipeline project. By providing high-resolution aerial imagery, real-time site monitoring, and accurate topographical data, UAVs have enabled faster decision-making, improved planning accuracy, and enhanced progress tracking.

This innovative approach has not only streamlined workflows but also fostered greater collaboration between teams, ensuring a more agile and informed construction process.

Conclusion

The project is recognised as a strategically important investment in strengthening the resilience of the regional water supply network for Severn Trent. It addresses a critical operational vulnerability by establishing a reliable secondary source, thereby enhancing service continuity and reducing the risk of supply interruptions.

Through meticulous planning and a collaborative approach, Coffey successfully delivered the project in alignment with the client’s expectations. By proactively identifying and managing risks, the team ensured that all works were executed safely, efficiently, and to the highest quality standards. This disciplined execution not only met the technical and regulatory requirements but also reinforced Coffey’s commitment to excellence and client satisfaction.

With approximately 60km of new 800/900mm pipeline required to replace the existing potable water mains, some of which are over 150 years old, the Tees and Central Strategic Pipeline will directly improve water quality, network resilience and operability within the Tees Network. The pipeline will serve approximately 50,000 properties and link a number of strategic assets serving the Barnard Castle, Darlington and Teesside conurbations, providing significant resilience to the overall system by 2028. The scheme will provide strategic connections between Lartington Water Treatment Works (WTW) and the existing service reservoirs (SRs) at Whorley, Shildon, Beaumont Hill and Long Newton. The works are being phased over two AMP cycles with Phase 1 currently under construction and Phase 2 in the definition stage. The scheme forms part of NWG’s wider Tees Network Strategy with further improvements to follow. Project organisation Northumbrian Water Group’s (NWG) framework technical design and design and construction delivery partners, Mott MacDonald, Stantec UK, Mott MacDonald Bentley and Esh-Stantec, are working together as part of a collaborative team called IDeA (Integrated Delivery Alliance) to deliver a major infrastructure project spanning across Darlington and County Durham. A key focus throughout the multi-disciplinary project has been effective collaboration which has been aided by involvement from specialist companies such as Lichfields and Bell Ingram. Figure 1 (below) shows the project organogram for this project. The delivery methodology, design, and construction principles have been developed jointly by all parties in the IDeA team. There have also been opportunities for carbon reduction by using low carbon water and a carefully considered material selection methodology. [caption id="" align="alignnone" width="1200"] Figure 1: Project team organogram - Courtesy of IDeA[/caption] Project scope In addition to the new pipeline, the scheme also involves the decommissioning and abandonment of over 80km of ageing pipeline as well as other assets including pipe bridges and booster pumping stations. To facilitate the abandonment of these assets, existing local networks will ultimately be connected to a combination of new or re-purposed pipelines, ensuring approximately 16,000 properties between central Darlington and Winston village to the west are among those that will benefit from the investment. Carbon reduction Carbon quantification has been an important part of the scheme in order to align with the transition towards a net zero carbon economy, and every attempt has been made to ensure the design solutions are not only hydraulically sound, but that carbon as well as total expenditure is reduced. NWG’s customers in this area are predominantly supplied from two water treatment works, depending upon prevailing supply and demand conditions: Lartington WTW: Source water is delivered under gravity into the water treatment works from upland impounding reservoirs and supplied into the potable water transmission network also via gravity. Broken Scar WTW: Source water is pumped from the River Tees into the works, treated and further pumped into the potable water transmission network. Potable water supplied from Lartington WTW is therefore more energy efficient and the construction of the new pipeline allows NWG to maximise this more cost-efficient water by delivering it into key locations of the potable water supply network in lieu of water from Broken Scar WTW, which may have passed through up to three water pumping stations. Typically, this will mean energy savings on the production and distribution of up to 30 Ml/d of potable water. [caption id="" align="alignnone" width="1200"] Figure 2: Overall pipeline schematic - Courtesy of IDeA[/caption] Design collaboration To deliver technical excellence, the project team has worked closely with NWG’s network operatives, controllers, and analysts to help them enhance their network control and to provide future planning for resilience. Extensive hydraulic modelling and scenario planning has been undertaken to ensure the network is robust, can meet requirements to support other areas of the system to the north and east of the new strategic network, as well as meet future aspirations for enhancements in the downstream network. Peer reviews of all design aspects is a continuous process on this project, utilising technical expertise from all parties. Design reviews are scheduled weekly to engage with NWG’s wider project team as well as internally within the IDeA team, meaning there is early challenge of key design aspects and collaboration to innovate and use best practice on technical issues. IDeA have been appointed as Principal Designer to ensure that CDM 2015 (Construction Design & Management Regulations 2015) is adhered too. IDeA has used the reach-back into their two parent organisations to maximise innovation, technical best practice, and the use of digital tools to assist in optimisation of the alignment, carbon assessment and delivery of the common data environment (CDE). ArcGIS online ArcGIS has been used as a CDE for this project to ensure the project team has a single source of information for making and recording design decisions. This software application was selected due its visual, interactive and geospatial environment. Geo-environmental constraints mapping, aerial photogrammetry, route alignments, utilities, local development information, hazards and design decisions are all recorded within the CDE allowing various data sets to be displayed across several geospatial maps. Alignment adjustments made within the CDE are immediately shared with the rest of the project team ensuring the team has access to information that is up to date, accurate and relevant. This CDE was also used to host the data for tenderers for Phase 1 to ensure they were provided with a common platform of information, see Figure 3 (below). [caption id="" align="alignnone" width="1200"] Figure 3: Phase 1 ArcGIS online tender package - Courtesy of IDeA[/caption] Stakeholder engagement Engaging and communicating with stakeholders at the earliest opportunity has been critical to moving the project forward. IDeA and NWG’s communications team have worked together to ensure a wide range of stakeholders have had early sight of the project including local MPs, affected councils, Environment Agency and local wildlife trusts, with letter drops and planning consultation drop-ins. IDeA has worked alongside Bell Ingram and NWG’s Estates team, to deliver early consultation and land entry notices to over 150 different landowners and their tenants impacted by the pipeline route and the significant associated site investigation works. These have included environmental/ecological surveys, ground investigation, geophysical surveys, and archaeological trial trenching. This collaboration is continuing throughout the concept design and definition stage of Phase 2 of the project. The outputs from the CDE have enhanced stakeholder engagement, allowing stakeholders to understand the scale of the project and the full constraints requiring the chosen alignment. The CDE has also been used to assist with the creation and management of land entry notices across the full scheme. Health, safety and environment There has been an extensive hazard logging process during the project concept and definition phases, using data sources such as NWG’s GIS system and from utility companies. Hazards in the vicinity of proposed works have been logged within the CDE, assigned a risk significance, and then fed into design decisions across the scheme; this process has been made more collaborative and visible by using CDE and easier to pass on into the detailed design and construction phases, see Figure 4 (below). [caption id="" align="alignnone" width="1200"] Figure 4: Hazards recorded and managed within a geospatial CDE - Courtesy of IDeA[/caption] Planning and environmental impact assessment Due to the scale of the works, planning permission is required for both phases of the main pipeline alongside an Environmental Impact Assessment (EIA). This work has required collaboration between the design teams, construction experts, the environmental and geotechnical teams and NWG’s planning consultants, Lichfields. The CDE has been used to collate the information for the EIA and has been instrumental in providing a visual platform to assist the team in defining the red line boundary to meet the requirements for the construction of the works, including working areas, access points, site laydown area and compounds. Planning permission has been granted for Phase 1 and is in process for Phase 2. The planning documentation for Phase 2 is anticipated to be ready for submission in Q1 2024. Design principles and key design aspects To optimise the pipeline route, a number of guiding design principles have been utilised including keeping the route as short as possible, keeping a uniform gradient fall in the vertical alignment, maintaining the pipeline below the hydraulic grade-line and favouring curvature over formed bends to reduce headloss. Geo-environmental impacts have been minimised by avoiding areas of significant ecological or archaeological importance and avoiding high risk ground conditions and potential ground or groundwater contamination. The route alignment has also been developed carefully considering landowner and customer impacts. Early engagement of material suppliers, ground investigation teams, early contractor engagement, and working closely with the environmental team has allowed IDeA to optimise the pipeline design and flag any potential hazards so design adjustments can be made with relative ease. Lessons learnt from Phase 1 are being used for efficiency and best practice in design and specifications for Phase 2. Steel was selected as the pipeline material via material selection matrix with input from suppliers, installers, world renowned technical specialists, NWG operational experience, as well as geotechnical, carbon and civil teams. [caption id="" align="alignnone" width="1200"] Delivery of steel pipes to the site and (inset) pipes arriving in the UK - Courtesy of FT Pipeline Systems[/caption] Tees & Central Strategic Pipeline: Supply chain - key participants Design - pipeline & tunnels: Mott MacDonald Design - pipeline & strategic connections: Stantec UK Planning consultants: Lichfields EIA: Mott MacDonald Land management consultant: Bell Ingram Land drainage design: Land Drainage Consultancy Ltd Design & construction: Farrans Construction Lead designer for Farrans: Atkins Tunnel design & construction subcontractors: Joseph Gallagher Ltd Pipe laying & associated welding: Grant Plant Hire Ltd Slide rail shoring: National Trench Safety UK Steel pipes: FT Pipeline Systems Pipe fittings: George Green (Keighley) Ltd Shaft segments: Macrete (Ireland) Ltd Tunnel precast pipes: FP McCann Strategic crossings and connections Strategic crossings and connections have all been identified, developed, reviewed, and enhanced with input from stakeholders from both NWG and IDeA through formalised design sprints, meetings and workshops. Resilience has been considered at every strategic crossing taking consideration of future maintenance access and redundancy of the system as a whole. Crossings and tunnels There are various major road crossings including the A1(M), three river crossings and two railway crossings. To determine the most suitable method of strategic crossing, all significant environmental, geotechnical and civil constraints have been carefully considered, with options being the subject of stakeholder review meetings. As a result of these discussions, tunnels have been proposed for one major road crossing, one river crossing and both railway crossings. The tunnels are all proposed at 1.8m diameter and will contain twin pipes of 700mm diameter. Lengths range from 60m to 250m and depths from 8m to 50m. The remaining major road crossings will be open cut. The two river crossings are to be traversed by pipe bridges both approximately 25m in length. [caption id="" align="alignnone" width="1200"] Tunnel shaft at the River Tees crossing - Courtesy of Mott MacDonald[/caption] Strategic connections into service reservoirs Five service reservoir strategic connections are required to deliver this project, one at the WTW and the others to SRs, with the end result giving enhanced resilience and operability to the pipeline and network as a whole. Significant consideration and collaboration with NWG stakeholders has been undertaken for each connection to de-risk construction operations and avoid interruption to supply to a significant number of customers. New flow meters, turbidity monitoring and control valves will be installed on these connections to provide further monitoring and control, enabling more flexibility in control of the system and improve water quality and efficient movement of supply throughout the network, maximising operating efficiencies. Reconnecting district metered areas Due to the extensive abandonment of pipework required, 20 district metered areas (DMAs) (approximately 16,000 properties) require re-connection to an alternative water supply. The DMA works use a combination of re-purposing existing mains, laying new mains and abandoning pumped supplies in favour of pressure-managed gravity solutions. DMA enabling works were discussed as part of the early engagement with NWG including flow reversal, flushing and conditioning. A key priority in these discussions has been the commissioning and decommissioning sequence of individual elements of the reconnection works to ensure minimum customer and operational impact. Asset abandonment and decommissioning As for the reconnection works, the abandonment works could have significant customer impact without proper consideration of sequencing and significant collaboration with NWG operational staff. The abandonment works will be sequenced to suit the commissioning of the pipeline in Phase 1, the Phase 2 pipeline and the reconnection works in Darlington and the surrounding area. The abandonment works will require a number of interfaces with the existing network requiring double isolation, thrust restraints, asset removal and trunk main drain-down and de-chlorination. Consideration is also being made to the reduction in resilience in the hydraulic network once abandonment has taken place, with contingencies being developed so that reconnected DMAs can still be reliably supplied. [caption id="" align="alignnone" width="1200"] FP McCann jacking pipes - Courtesy of Mott MacDonald[/caption] Conclusion At the time of writing (July 2023), Phase 1 of the project is under construction by Farrans Construction and the pipeline is expected to be in service by March 2025. The Phase 2 planning submission is anticipated to be made in Q1 2024, with detailed design and construction works starting in 2025. Lessons learnt from Phase 1 during the detailed design and construction phases will be used for efficiency and best practice in Phase 2. The collaborative environment created by the project team and use of ArcGIS as the CDE have enabled this project with multiple stakeholder interfaces to be delivered to efficiently and effectively. Where possible, the IDeA team involved in Phase 1 of the scheme have continued to support NWG in detailed design and construction and continued into development of the Phase 2 concept and design to retain project experience and carry lessons learnt forward throughout the project’s lifespan.

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.

Project background & scope

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.

[caption id="attachment_26619" align="alignnone" width="1200"] Pipe laying operations - Courtesy of CWA[/caption] They were four tunnelled crossings incorporating deep shafts and microtunnelling. These trenchless crossings included tunnelling below railways, motorways and watercourses.

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.

Glasgow Resilience Programme: Supply chain - key participants Project delivery: Caledonia Water Alliance (CWA) AECOM M-Group Water Engineering support: DST SurvConsult Ltd Civils contractor: Cleantech Civils Civils contractor: Luddon Construction Excavations & earthworks: RJT Excavations Foundations: LB Civils Ltd Mechanical & electrical contractors: IDS Mechanical contractor: Dustacco Engineering Ltd Temporary works/shoring: Mabey Hire Ltd Tunnelling subcontractor: HB Tunnelling [caption id="attachment_26612" align="alignnone" width="1200"] TBM in place prior to tunnel excavation - Courtesy of CWA[/caption] Pipe manufacturer: Saint Gobain PAM UK Surge vessels: Quantum Engineering Developments Ltd Valves: AVK UK Ltd Pumps: Celeros Flow Technology Steel pipework & fittings: Freeflow Pipesystems Systems & process software: Lintott Control Systems Temporary access solutions: TPA (Vp Group) Fencing & TrakMats: Safe Fence Ltd Solar PV system: RI Cruden Overhead cranes: Konecranes Demag Underpressure drilling: Swan Pipelines Steel fabricators: WM Services Scotland Ltd Steel fabricators: MacGregor Technical Services Ltd Plant hire: Gap Group Blackwood Plant Bedrock Plant Barrmill Plant Traffic management: Sunbelt Rentals Re-surfacing: Hamilton Tarmac DGM Surfacing Ltd Arbuckle Mclean Landscaping & Fencing: Alter Supplies & Contracting Vegetation management: Ayrshire Tree Surgeons Security: Proficient Security Ltd [caption id="attachment_26616" align="alignnone" width="1200"] Pipe laying operations - Courtesy of CWA[/caption] Excavations

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.

[caption id="attachment_26610" align="alignnone" width="1200"] Tunnelling under the Levern Water - Courtesy of CWA[/caption] Pipe laying through urban environments

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.

[caption id="attachment_26613" align="alignnone" width="1200"] Shaft construction for TBM tunnel excavation underneath a railway line and Water Cart Water - Courtesy of CWA[/caption] Trenchless construction

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.

Ibrox Pumping Station construction

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.

[caption id="attachment_26611" align="alignnone" width="1200"] Pumping station construction - Courtesy of CWA[/caption]

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.

[caption id="attachment_26609" align="alignnone" width="1200"] Inside the new pumping station - Courtesy of CWA[/caption] Connections to existing networks/commissioning

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.

[caption id="attachment_26617" align="alignnone" width="1200"] (left) Render of temporary works installation by Mabey Hire on Edmiston and (right) east tie-in to existing main on Edmiston Drive - Courtesy of CWA[/caption] The project then had to perform various pump trials to support the resilience element of the project. Approximately 7.6 ML per trial had to be both received and discharged into the existing network which required detailed discussions and approvals with Scottish Water. Risk and constraints to the network had to be considered, however an open, honest and collaborative relationship between all parties allowed this highly complex operation to be completed successfully. Carbon reduction techniques/sustainable approach

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.

Engagement with stakeholders throughout planning & delivery

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:

Planting over 9,000 daffodil bulbs along the pipe route at Mosspark Boulevard with the local primary school at the end of the project. Returning to schools after the project to attend their careers fairs to promote engineering and STEM subjects. Volunteering with local groups such as installing a new woodland park with the Dams to Darnley Group and planting trees with Friends of Bellahouston Park. [caption id="attachment_26614" align="alignnone" width="1200"] (left) Daffodil bulb planting and (right) TBM “Cruella di Drill” and name competition winner - Courtesy of CWA[/caption] Conclusion/summary

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

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

Anglian Water’s Strategic Pipeline Alliance (SPA) is delivering one of the largest infrastructure projects in AMP7; a new water main network, hundreds of kilometres long, which will allow Anglian Water to move water around the region from areas of surplus to areas of deficit, future-proofing supply to customers. The network is being constructed in 11 sections and pipelaying for the first two sections started in summer 2021; the 34km Lincoln-Grantham pipeline and the 12.5km Norwich-Wymondham pipeline. The SPA partners are Anglian Water, Costain, Farrans, AtkinsRéalis, Jacobs, and Mott MacDonald Bentley. Pipe ploughing technique Pipe ploughing is a technique that was developed for long distance cable duct laying, that has evolved and innovated into a method for laying pipes for potable water transmission and distribution pipelines across Europe and Australia. Pipe ploughing causes minimal disruption to the ground, as the blades of the plough cut through the earth creating a precise trench and then immediately lays the pipe and backfills in one operation; meaning there is no need for digging or re-filling. It is a cleaner, greener, safer and more cost-effective way of laying water pipes. When the pipeline route is across large fields, long lengths of pipe can be laid without interruption, with up to 1km achievable in just one day. When there are important environmental habitats and archaeological interests along the route, the narrower easement provided by the pipe plough reduces the number of surveys required and result in environmental improvements. [caption id="" align="alignnone" width="1200"] (left) Ground heave and (right) minimal ground disturbance during trial - Courtesy of SPA[/caption] Strategic Pipeline Alliance construction methodology trials As this would be the first time in the UK that this method of pipelaying has been used for potable water pipes, Anglian Water’s Strategic Pipeline Alliance opted to trial the pipe ploughing methodology on a 1.1km section of the Norwich to Wymondham pipeline. The trials were necessary to ensure key parameters for success of the main works were established, including trials to test compaction methods to ensure the pipe will be suitable for the design life. Concerns at the trial stage included: The final pipe embalmment characteristics. Scraping damage by stones. Ovality of the pipe; stresses from the installation method remaining in the pipe. Accuracy of pipe slope. Compaction of the soil heave caused by ploughing. The pipe plough construction trial took place in October 2021. The compaction methods trials were undertaken in November 2021 and the Low Water Commissioning, water quality and pressure testing trials in January 2022. All concerns needed to be investigated thoroughly and key acceptance criteria were specified to be achieved before proceeding with the main works. Embedment acceptance The acceptance criteria for embedment were as follows: The allowable compaction of the bed and surround is to be minimum 85% measured by clegg hammer. Compaction of the backfill in the trench above the bedding and surround to be minimum 95% Any stones present in the bed and surround shall be assessed by the pipe manufacturer Radius Systems who will state their recommendation. Other factors for the main works included rate of pipelaying, the depth of pipe in relation to the pulling force and ground heave, easement width, disturbance to the landowners’ field, and the accuracy of laying. [caption id="" align="alignnone" width="1200"] (left) Two winches in use and (right) excavation of ploughed pipe to test compaction and scraping - Courtesy of SPA[/caption] Compaction methodology Following the trials, the selected compaction methodology was as follows: 13 ton excavator with a compaction plate fitted to it follows behind the plough whacking the open trench that the plough leaves. (5 passes of 2100 kg plate). Followed by a 21 ton excavator pulling into the trench the heaved soil in layers no deeper than 200mm. Again the 13 ton excavator will whack the trench with vibrating plate. Finally, the last of the spoil is levelled through and tracked in using the 21 ton excavator. Structural design of the pipe For the structural design of the pipe, calculations were carried out in accordance with BS9295:2020. Given that pipe ploughing is a trenchless technique, the worst-case pipe embedment condition of unsupported (S4) was selected. The geotechnical investigation indicated that most of the ground would be Spanglers modulus (SI) of 1 or greater. Where the ground was found to be softer, then trenched embedment class S1 was used. An SDR 13.6 (12.5 bar pressure rating) pipe was calculated to be acceptable for this situation of S4 embedment class, 10.6 bar operating pressure, and SI equal to 1, however an increased SDR rating of SDR 11, which is 20% thicker than the SDR 13.6 pipe was selected for the following reasons: The presence of stones in the bed and surround. The compactive effort needed to compact the plough heave. Scraping of the pipe against stones during installation. Strength in the unsupported condition. Low Water Commissioning, water quality & pressure testing trials To ensure the pipe met the Key Decision Criteria for proceeding to the main pipe section, the trial pipe was cleaned, disinfected and pressure tested using a method of Low Water Commissioning that was under test and development by SPA, and deviations to AW standards were developed to deliver this new commissioning strategy ‘deliberately delivering differently’. To clean the pipe, the pipe was air swabbed using dual swabs with wash water between. The wash water consisting of up to 1% pipeline volume of potable water dosed up to 10ppm chlorine content driven by clean, filtered, and cooled air, applying less than 1.5 bar air pressure. The first swab was very dirty, but after only two more swab runs the wash water was with less than 10 NTU and sufficiently clean to commence air disinfection. [caption id="" align="alignnone" width="1200"] Air swabbing schematic for Low Water Commissioning - Courtesy of SPA[/caption] Under the normal Anglian Water standards for swabbing this would have taken three pipe volumes of water to achieve, the water savings for SPA using the air swabbing techniques is therefore enormous. The pipe was then disinfected by a slug of super-chlorinated water, introduced between two swabs and driven at a low speed through the pipeline by air. The trial pipe was then filled with drinking water and then pressure tested to 1.5 times the maximum operating pressure. The pressure test passed first time. Finally water quality samples were taken to ensure that it could be put into service as a water supply pipeline and further significant water savings were made at this stage. Kevin Ensell, part of the SPA team who spearheaded the strategy said:

“Low Water Commissioning in particular is an environmentally friendly, cost-effective solution that is transforming Anglian Water’s work and an innovation we anticipate will be adopted across the water industry”.

Norwich to Wymondham - main works construction The Norwich to Wymondham pipeline runs from Little Melton (east of the Norwich Southern Bypass) to the existing High Oak Reservoir, near Wymondham. Following the successful trials, the pipe plough methodology was selected as the optimum method of pipelaying the full length (12.5km) of the main works. Under the supervision of the main contractor Mott MacDonald Bentley (MMB), specialist contractor ATP Cable Plough undertook the pipelaying using a ‘Spider Plough’ manufactured by the Föckersperger Group in Germany. The ‘Spider Plough’ was towed by a crawler winch pulling at a force of 180 tonnes with the front of the crawler sunk into the ground. Norwich to Wymondham Pipeline: Supply chain - key participants Client: Anglian Water Delivery partner: Strategic Pipeline Alliance Anglian Water | Costain | Farrans | AtkinsRéalis | Jacobs | MMB Main contractor: Mott MacDonald Bentley Specialist contractor: ATP Cable Plough HDPE pipe: Radius Systems Pipe plough manufacturer: Föckersperger Group Lessons learned As a result of the trials and completion of the main works the following lessons were learned: An up and over method of installation of the pipe is preferable to looped method. In wet conditions ski shoes fitted to the wheels of the plough rigger reduce damage to the land. At depths greater than 2m the pulling force on the plough is high and the heave is large, minimise depth when possible. An easement width of more than 20m is recommended for the pipe plough and wider where trenched excavation is needed to cross roads and utilities. On pipe strength grade higher than needed to provide extra strength to allow for stones and compactive effort. Planning the length of pipe strings to reduce the number of post installation joints. Pre-construction land drainage to be installed. Tight end caps in temporary situation to prevent contamination and maintain high, food-grade hygiene standards. [caption id="" align="alignnone" width="1200"] Route of the Norwich to Wymondham pipeline - Courtesy of SPA[/caption] Conclusion Construction of the 12.5km, 315mm outside diameter high density polyethylene pipe (PE100) Norwich to Wymondham Pipeline was completed in April 2022. The pipeline (including the 1.1km trial length) was commissioned successfully, passing the pressure test first time and achieving the required water quality to put into supply without incurring delay. Air swabbing for the main pipeline was carried out in sections of not more than 5km length, and the full length of pipeline was pressure tested in one go. The pipeline can now deliver 58 l/s of potable water during critical periods of operation. Key to the success was the flange management strategy implemented by the team to ensure the quality of jointing and the food-grade hygiene strategy ensuring that maximum hygienic practices were undertaken so that drinking water quality was the highest standard and the least amount of water used, saving water and achieving a highly sustainable result.

Northumbrian Water’s County Durham and Tees Valley Pipeline, which is approximately 57km in length, is designed to improve water quality and increase resilience and operability within the Tees Network. The pipeline will replace existing potable water mains across the North East of England, some of which are more than 150 years old. The new pipeline will connect Lartington Water Treatment Works (WTW) to service reservoirs at Whorley Hill and Shildon, and the route includes a major crossing of the River Tees, 12m below the riverbed. Upon its completion, the pipeline will serve approximately 200,000 customers and link strategic assets serving Barnard Castle, Darlington, and Teesside, improving overall system resilience. Construction began in November 2023 and the project is currently progressing well on site. Cross country pipeline installation

The full route of the steel welded pipeline (Phases 1 & 2) includes crossings of the A1 motorway, three river crossings and two railway crossings. Farrans Construction is contracted to deliver Phase 1 of the project, the pipeline from Lartington to Shildon Service Reservoir, via Whorley Hill Service Reservoir. The chosen pipe material is robustly coated thin-walled steel, with individual pipe lengths of varying sizes (14m maximum) and generally 800mm in diameter. The Phase 1 pipeline is approximately 34km in length, including a section of twin 800mm diameter pipe, with one of the sections forming the starting point for Phase 2.

Shafts & tunnel at River Tees

Various options were explored to determine the most suitable method of the crossing of the River Tees, near Cotherstone Village, Barnard Castle, including pipe bridges and open cut trenches in the riverbed. However, there were several constraints that limited the viability of these options, including significant aquatic life disturbance and differing riverbank heights. The chosen option for the crossing was the construction of a tunnel under the river between two access shafts. The eastern shaft is approximately 46m deep and 7.5m diameter, whilst the western shaft is approximately 32m deep and 8m diameter, with the difference in shaft depth due to the rising topography of the eastern bank of the river. Each shaft has a 221 tonne reinforced concrete base.

Farrans Construction appointed Joseph Gallagher Ltd, an experienced specialist shaft and tunnelling contractor, to construct the river crossing under a sub-contract arrangement.

[caption id="attachment_14149" align="alignnone" width="1200"] Pipe laying - Courtesy of Farrans Construction[/caption] Project Pipeline - County Durham & Tees Valley: Supply chain - key participants NWL designer - pipeline, tunnels & EIA: Mott MacDonald NWL designer - pipeline & connections: Stantec UK Design & construction: Farrans Construction Lead design for Farrans: AtkinsRéalis Tunnel design & construction: Joseph Gallagher Ltd Planning consultants: Lichfields Land management consultant: Bell Ingram Land drainage design: Land Drainage Consultancy Ltd Drainage installation: DMJ Drainage Ltd Groundworks: GR Potter Contracts Ltd Archaeological surveys: ECUS Ltd Geotechnical surveys: Dunelm Geotechnical Seismic surveys: Rees Onshore Seismic Ltd Trial holes at strategic connections: Waitings Ltd Slide rail shoring: National Trench Safety UK De-vegetation of hedgerows: ATM Ltd Steel pipes: FT Pipeline Systems Pipeline welding: Environmental Fabrications Ltd Pipe laying & associated welding: Grant Plant Hire Ltd Weld testing: Responsive Engineering Pipe fittings: George Green (Keighley) Ltd Pipe fittings: APP Fusion Ltd Pipe fittings: Franklyn Yates Engineering Ltd Pumps: Pioneer Pump Solutions Underpressure connections: UTS Engineering Ltd Shaft segments: Macrete (Ireland) Ltd Tunnel precast pipes: FP McCann Supply/install temporary bridge: Groundforce Silt fencing & flumes: JR Hind Ltd Shaft & tunnel construction

To construct the shafts and tunnel, the first 2m of rock was excavated and 1m shaft segments bolted together to form a ring. The rings were surrounded with an in situ concrete ‘collar’ to provide structural integrity and ‘set’ the shafts. These rings were checked for plumbness, as this is critical to ensure the overall verticality of the shafts.

Excavation began with each subsequent precast concrete segment ring bolted to the underside of the one above, known as underpinning. To provide structural support, the rings were then back grouted through holes in the segments. This process was repeated with each new metre of rock that was broken, installing the next ring of concrete segments until the required depth was reached. The excavators and mechanical breakers used were relatively small for the hardness of the ground and the excavation depth, due to the constricted dimensions of the two shafts. The excavation process began in June 2023 and was completed in March 2024.

Once the shaft construction was complete, the bases were poured, followed by installation of the 2.24m diameter tunnel boring machine (TBM). The TBM system has a hydraulic jack that pushes it forward through the ground as it excavates the rock strata. The TBM was launched on rails from the east drive shaft. Following the excavation of the rock, the hydraulic jacks were retracted and a 2.5m section of precast reinforced concrete pipe was lowered onto the launch railing at the bottom of the shaft using a 70 tonne crane. The hydraulic jack re-engaged to push the new length of pipe behind the previous one and continue pushing the pipe and TBM forward. The tunnel is 220m long, which required 88 (No.) 2.5m long pipes segments.

The ground material, that consisted of abrasive sandstone and other materials such as quartz, caused significant wear on the cutter heads and pumps of the TBM. This slowed the excavation process significantly, but continuous work by Joseph Gallagher Ltd meant that an average of four pipe sections, or 10m of earth, were still excavated each day.

Video captures the moment tunnel boring machine completes journey under the River Tees

The concrete tunnel acts as a sleeve for the water pipes that will transfer the water supply under the river. Two parallel pipes were used to provide water supply security in case one should fail, and ductile iron was selected as the pipe material to provide additional strength and resilience. Due to the constricted diameter of the shafts, the pipes were lowered down in 5.5m sections, with each section of the pipe being joined to the next as they were fed into the tunnel. Spider supports were used to locate the pipes which were winched through the tunnel from the east to the west shaft. The spider supports, which were used as spacers, were clamped to the pipes at regular intervals and hold the pipes steady as they are pulled through the tunnel. Once the pipes were completed and tested, they were sealed, and grout was pumped in to fill the remaining void space.

Once all piping works are complete and the pipes connected to the cross-country pipeline, the shafts will be backfilled with sand to make future excavation easier should it be required. Approximately 3,500 tonnes of sand will be needed for the eastern shaft and 2,500 tonnes for the western shaft.

Management of ingress water

During construction of the shafts and tunnel, the hydrogeology of the area and consequent water ingress made the excavation technically difficult. During excavation, there was up to 45 litres/second water ingress in the western shaft; the wettest of the two shafts. To manage this, the water is continually pumped out into a lagoon system located 50m away. The water is then processed in lamella clarifying units, which remove fine sediments, to ensure the water meets the required environmental standards to allow it to be pumped into the River Tees. This was an extensive water management operation, conducted under a permit issued by the Environment Agency, ensuring all activities complied with regulatory requirements and environmental protection standards.

[caption id="attachment_14146" align="alignnone" width="1200"] Water processing lagoons - Courtesy of Farrans Construction[/caption]

The water management issues continued after the shafts had been excavated, and it was decided that the western shaft would require a concrete plug to be inserted beneath the base slab to halt further water ingress. Consequently, the team had to excavate deeper than originally anticipated so that the plug would not interfere with the tunnel alignment. The plug, which is 2.7m thick and made of approximately 167m3 of concrete, was left to cure for seven days before the water was pumped and work began on the shaft’s structural base. A plug was not required for the eastern shaft.

Environmental constraints

There have been numerous environmental constraints that have had to be considered and mitigated during the project. A prominent issue facing the construction activities is compaction of excavated soil leading to soil degradation. When soil is compacted, the pore spaces within the soil are reduced, leading to poor soil structure and the erosion of the soil surface layer. To mitigate against this, the topsoil is stripped, stored, and only reinstated when in a suitable, friable condition. Low ground pressure tracked vehicles are also used on the site and traffic restricted prior to topsoil stripping. The topsoil and subsoil are then segregated and stored according to DEFRA codes of good practice.

Construction activities within freshwater environments can pose a significant threat to aquatic life through the release of pollutants, including silt and sediments. Fluming was therefore implemented in several local watercourses to minimise pollution and sedimentation by isolating construction areas and diverting the natural flow of water through temporary piping.

[caption id="attachment_14147" align="alignnone" width="1200"] Topsoil bund at Lartington - Courtesy of Farrans Construction[/caption]

Before fluming was implemented on site, several fish species, all of which are sensitive to almost all types of anthropogenic disturbances, had to be captured and safely relocated. Electrofishing was used to temporarily stun the fish so that they could be collected and moved to a safe location, ensuring the protection of several important species including salmon and trout. The combination of flumes and electrofishing minimised the disruption to the ecosystem, whilst regular monitoring ensured the flume remained effective, preventing leaks and blockages, and allowing for the assessment of fish population health and diversity.

Ground nesting birds were also present at some locations along the pipeline site, including populations of lapwing and curlew; both of which are listed on the UK Red List of Birds of Conservation Concern. To minimise disturbance to these species and other protected species such as badgers, great-crested newts, bats and otters, work was suspended during the nesting/breeding season. In addition, any active nesting sites located near the site were protected, and local authorities such as Natural England and the Environment Agency, were consulted.

Social value & community engagement

Community and stakeholder engagement has been a crucial part of the project to date, with Farrans delivering several schemes in line with Northumbrian Water’s values. Farrans began the engagement process through a ‘Meet the Contractor’ event, held in a local parish hall with attending stakeholders including community groups, local schools and colleges, parish councils, local businesses, and residents. A digital Microsoft form was also sent out to capture the thoughts of those who could not attend the event.

Representatives from Northumbrian Water were also present, and the information gathered was used to identify key issues and concerns raised by the local community and how those issues could be tackled during the project.

To involve the local community, mark the beginning of the tunnelling process, and the arrival of the TBM, Farrans and Joseph Gallagher Ltd ran a competition to name the TBM. This was won by a local girl called Penelope who attended the event with her family, naming the TBM after herself as it was ‘strong, like her.’ Farrans and Joseph Gallagher also asked the community to nominate a local charity that would receive a £1000 donation to mark the project milestone. The Great North Air Ambulance received the most votes and attended the event on the day.

[caption id="attachment_14144" align="alignnone" width="1200"] (left) Penelope named the TBM after herself and (right) £1000 donation to Great North Air Ambulance - Courtesy of Farrans Construction[/caption]

Farrans are also involved in educational engagement by joining in with established local programs such as the ‘Start Small, Dream Big’ school initiative, run by the North East Local Enterprise Partnership. The scheme is a national DfE funded pilot aimed at raising aspirations, challenging stereotypes, and helping children connect with the world around them.

Farrans took part by running several STEM workshops, with local children taking part in exercises to design and build water filters, in the context of surviving a ‘Zombie Apocalypse’. In doing so, they learnt about the work Farrans is doing for Northumbrian Water in delivering the Tees Pipeline, as well as the importance of transferable skills and the diversity of roles within the construction and civil engineering sector.

Stakeholder engagement (farmers and landowners)

Northumbrian Water appointed a land agent to streamline the engagement of landowners and farmers along the pipeline route who would be impacted by the works. The land agent, Bell Ingram, conducted detailed conversations that began during pre-construction, and have continued throughout the project. This liaison has ensured that key stakeholders are kept fully informed of the progress of the works and any potential impacts it may have on them, including pre-construction investigation, access, and post-construction drainage designs.

Conclusion

Despite some of the technical challenges and ongoing poor weather conditions faced during construction, the project is progressing generally to programme. By July 2024 the Tees tunnel had been completed and approximately 20km of cross-country pipeline had been laid. Proactive stakeholder engagement has contributed significantly to the ongoing success of the project, with positive engagement with landowners and farmers being particularly noteworthy.

The project is on schedule to deliver water into service in early 2025, with reinstatement works to be completed by August 2025.

The existing A428 route had long been known for its congestion, resulting in unreliable travel times and compromised safety to the daily road users. To address these challenges, Skanska was tasked to construct a new dual carriageway to bypass the existing route; enhancing connectivity and boosting economic growth. However, this ambitious infrastructure development intersected with several key water mains essential for maintaining uninterrupted water supply to local communities and businesses. The water mains spanned multiple locations, including Black Cat Roundabout, Chawston, Wyboston, Barford Road, and Potton Road near the Potton Road Reservoir.

Given the critical nature of these water mains, the construction of the new A428 demanded a carefully orchestrated diversion strategy to ensure minimal disruption to the water supply network. This case study explores the challenges faced by the Anglian Water @one Alliance, the innovative solution that was implemented, and the benefits that the project delivered to the community and the region’s future growth.

Background

The A428 corridor is a vital route connecting key regions in Bedfordshire and Cambridgeshire. Stretching between the Black Cat Roundabout at the junction of the A1 and the A421 in Roxton, Bedfordshire, and Caxton Gibbet at the junction of the A428 and the A1198 in Cambridgeshire, this stretch serves as a critical link for commuters, local communities, and businesses in the area. The area is made up of a mix of residents, agricultural land, and growing commercial hubs, highlighting its importance as a dynamic economic region.

[caption id="attachment_21147" align="alignnone" width="1200"] Diversions underway - Courtesy of Anglian Water’s @one Alliance[/caption] Introduction to the issue

The construction of the new A428 dual carriageway presented a significant infrastructure challenge, with several existing water mains needing to be diverted to facilitate the road’s development. These water mains are integral to the region’s water distribution network, supplying water to residential, commercial, and agricultural users along the A428 corridor.

Specifically, the project involved diverting eight water mains of varying sizes, as well as replacing an outfall pipeline from the Potton Road Reservoir. The impacted areas included:

AW01 at Black Cat Roundabout: An existing 5” ductile iron (DI) water main centrally located within the A1. AW02 at Barford Road: A 5” asbestos cement (AC) water main along the eastern verge of Barford Road. AW03 to AW08 at Potton Road: A complex network of water mains including overflow, inlet, and outlet pipelines connected to Potton Road Reservoir. AW09 at The Lane: A 6” AC water main affected by a new road junction. AWF01 Eltisley: 4”PVC rising foul main from the existing A428 to the new proposed A428. [caption id="attachment_21146" align="alignnone" width="1200"] Diversions underway - Courtesy of Anglian Water’s @one Alliance[/caption]

These diversions were critical to allow for the construction of the new A428 without compromising water supply reliability or impacting the hydraulic performance of the network. The challenge lay not only in the physical relocation of these pipelines but also in ensuring that water flow rates and pressure levels remained consistent throughout the transition.

Also, the design criteria for this project required a 50-year design horizon, necessitating robust engineering solutions to accommodate future demand growth and operational resilience. The project also navigated complex geographical and environmental constraints, including road crossings and land ownership boundaries.

Black Cat Roundabout Mains Diversions: Supply chain Project funding: National Highways Project delivery: @one Alliance Directional drilling: O’Connor Utilities Ltd (OCU) PE pipe: Radius Systems PE pipe: Aliaxis - GPS Pipe Systems DI pipe: Saint Gobain PAM UK Pipe fittings: Wolseley Valves: AVK UK Ltd Outfall headwall: Stanton Precast (now Tracey Concrete) Plant hire: Flannery Plant Hire (Oval) Ltd Plant hire: L Lynch Plant Hire & Haulage Ltd Aggregates: Drummond Aggregates Ltd [caption id="attachment_21149" align="alignnone" width="1200"] Potton Road diversion pipes - Courtesy of Anglian Water’s @one Alliance[/caption] The solution

To address these challenges, Anglian Water’s @one Alliance was tasked with implementing a strategic and meticulously planned solution. Funded by National Highways, the project required the diversion of eight water mains; each carefully designed to meet the required flow rates and maintain system integrity. The construction approach included directional drilling to minimise environmental impact, reduce excavation requirements, and limit disruption to local communities and traffic. The works included:

AW01 at Black Cat Roundabout: The existing 5” DI water main was diverted over approximately 2300m and replaced with a 180mm PE100 pipe. This new pipeline followed a more accessible route outside the central A1 corridor, minimising traffic disruptions during construction. AW02 at Barford Road: A 5” AC water main located along the eastern side of Barford Road was diverted into adjacent fields, with a section drilled and dualled beneath the new A428. The diverted main spanned approximately 1000m and was upgraded to a 180mm PE100 pipe, enhancing durability and hydraulic performance. AW03 - Potton Road Outfall Pipeline: The overflow pipeline from Potton Road Reservoir was replaced with a shorter, more efficient route to a newly constructed ditch east of the A428. A new headwall at the outfall enhanced flood management and environmental protection. AW04 to AW08 - Potton Road Diversions: These diversions involved multiple water mains connected to Potton Road Reservoir, including inlet, outlet, and boosted supply lines. The existing pipelines were replaced with PE100 pipes of various sizes, dualled where necessary under the new A428 road. Notably, the reservoir outlets (AW04 and AW05) were consolidated into a single 355mm PE100 pipeline to enhance operational efficiency. AW09 - The Lane: Relocating a 6” AC water main to the north of The Lane. The new 130m section of 180mm PE100 pipe enhanced accessibility for future maintenance. AWF01 – A428 Eltisley: This diversion relocated a 4”PVC rising foul main, replacing 1070m of pipe (including a total of 150m of dualling – in two sections of 45m and 105m) of 125mm HPPE SDR17 and connections to the existing 4”PVC rising main in the A428 at Eltisley and the B1040 to the north of Eltisley.

All new pipelines were designed as ‘like for like’ replacements, ensuring that water flow rates and pressures were maintained across the network. To future-proof the solution, the design horizon was set at 50 years; ensuring the new infrastructure met long-term demands.

[caption id="attachment_21151" align="alignnone" width="1200"] Potton Roadflow controls and DI pipe - Courtesy of Anglian Water’s @one Alliance[/caption] Benefits of the solution

The successful diversion of water mains ensured an uninterrupted water supply for local communities and businesses throughout the construction period. By maintaining consistent flow rates and pressures, the project safeguarded the reliability of water services, allowing daily activities to continue without disruption. This seamless transition was crucial in maintaining public confidence and supporting local economies during the infrastructure upgrade.

In addition to maintaining continuity of service, the project significantly enhanced infrastructure resilience. The newly installed pipelines, made from PE100 materials, offer superior durability and resistance to corrosion compared to the previous cast iron and PVC systems. This upgrade reduces the risk of leaks or failures, enhancing the long-term reliability of the water network. The robust design ensures a stable water supply, minimizing the need for emergency repairs and contributing to overall operational efficiency.

Environmental and safety considerations were central to the project’s planning and execution. By employing trenchless construction techniques, the project minimised ground disturbance, preserving environmentally sensitive areas and reducing the ecological impact.

Additionally, the implementation of dualled pipelines beneath the new A428 increased safety and reliability, ensuring the security of water supply even in the event of unexpected issues with one of the pipelines. This strategic design choice highlights the project’s commitment to both environmental stewardship and public safety.

Beyond technical achievements, the water main diversions were essential for the construction of the new A428 dual carriageway. The new route will significantly reduce congestion, cut travel times and boost economic growth across Bedfordshire and Cambridgeshire. By facilitating better transport links, the project supporting is local businesses, encouraging investment, and contributing to the prosperity of the surrounding communities.

Looking to the future, the new water mains have been designed with a 50-year horizon, ensuring they can accommodate projected population growth and increased water demand. This future-proofed approach guarantees a sustainable and reliable water supply for generations to come. By anticipating future needs, the project demonstrates a forward-looking vision, laying a strong foundation for continued community and economic development.

This comprehensive infrastructure upgrade showcases a successful blend of innovation, environmental responsibility, and strategic planning, delivering long-term benefits to both local communities and the broader region.

[caption id="attachment_21145" align="alignnone" width="1200"] Pipes string ready for installation - Courtesy of Anglian Water’s @one Alliance[/caption] Conclusion

This project exemplified how strategic infrastructure planning and innovative engineering can harmoniously integrate essential utility services with large-scale development projects. By delivering these water main diversions efficiently and effectively, the Anglian Water @one Alliance not only supported the construction of a vital new road but also safeguarded the water supply network for the future.

This collaborative effort showcased the commitment to sustainable infrastructure solutions that balanced community needs, environmental stewardship, and economic growth. The successful completion of the new A428 symbolizes progress, connectivity, and a brighter future for the region.

The success of this project is a testament to the power of strategic planning, technical excellence, and a commitment to delivering long-term value to the communities served by Anglian Water. The @one Alliance is proud to have played a key role in shaping a resilient, connected, and stronger future for the region.

Witches Oak Water is a series of gravel pit lakes south-east of Derby, on the River Trent. The 80 ha site, part of a larger sand and gravel quarry, was acquired by Severn Trent more than 20 years ago to store water as part of a drought resilience project. Severn Trent constructed an intake, pumping station and pipeline to the nearby Church Wilne WTW. Water quality was poor and required more treatment to meet drinking water standards than was originally anticipated, so abstraction ceased and the site mothballed until a solution could be found. Severn Trent is now bringing Witches Oak Water back into operation by recommissioning the existing infrastructure and increasing raw water supplies to a maximum of 93 MLD. The additional water will improve Severn Trent’s resilience to hot and dry summers and secure water resources for future generations. Solution

Severn Trent is keen to explore the potential of low-carbon, natural, biological water treatment processes in conjunction with conventional, chemical treatment to remove pollutants from the water abstracted from the River Trent. Historic data revealed that nitrate levels in the River Trent have occasionally exceeded the 50 Mg/l concentration value prescribed by the DWI, and regularly breached Seven Trent’s own, more stringent standard.

As a result, a natural, biological solution in the form of floating wetlands to provide preliminary water treatment is being combined with refurbishing the existing abstraction infrastructure at the lakes (called the Raw Project) to supply water to the new water treatment works being constructed in Church Wilne.

[caption id="attachment_14685" align="alignnone" width="1200"] Installing the floating wetlands - Courtesy of Matthew Nichol Photography[/caption] Floating wetlands

This is the first time in the UK that wetlands have been used for operational water pre-treatment on this scale and in the ‘real world’, but theoretical studies show that, on average, these floating wetlands could remove in the region of 40-60% of both total nitrogen (ammonia, organic and oxidised nitrogen) and total suspended solids (particles >2 microns), helping to considerably reduce the amount of energy and chemicals used in the traditional water treatment process.

Floating wetlands were selected over conventional or static wetlands because Witches Oak floods regularly during the winter.

The pontoons can rise and fall with the water level, so are resilient to changes in load and seasonal fluctuations, whereas a static wetland would be submerged during a flood event, diminishing process benefits provided by the vegetation. This has been thoroughly tested in winter 2023/24 when the site experienced extensive 1 in 100-year flood events. The floating solution also typically requires less maintenance, including no watering or fertilisation.

The Biomatrix floating ecosystems selected for Witches Oak mimic elements of self-sustaining, naturally occurring riparian wetlands. Water quality is improved by the root mass, which provides a large surface area for the microbial communities needed to remove pollutants. Planted with several types of sedge, hard rush and flowering species, including purple loosestrife and meadow sweet, these islands provide biological treatment to reduce the turbidity and nitrates in the raw water.

[caption id="attachment_14682" align="alignnone" width="1200"] Floating wetlands (2023) - Courtesy of Matthew Nichol Photography[/caption]

In December 2022, Mott MacDonald Bentley initially focused on the construction and launch of three trial wetlands in Lake 2, as well as the removal of a redundant man-made wetland from the lake. Since then, a further 28 floating wetlands have been installed on the three northern most lakes during summer 2023.

The 31 floating treatment wetlands were positioned in the natural water flow path in Lakes 1, 2 and 3.

Work is also being undertaken to upgrade of the existing pumping station and river intake, along with the installation of a new fish recovery system and three new transfer pumps.

Undertakings

This is a true ‘One Mott MacDonald’ project with members of the consultancy teams having worked on the feasibility of the wetlands’ abilities to pre-treat water and then their outline design, before handing over to colleagues at Mott MacDonald Bentley through early contractor involvement and then design and build delivering the detailed design, pre-construction and construction activities.

Witches Oak RWPS: Supply chain - key participants Client: Severn Trent Principal designer & contractor: Mott MacDonald Bentley Outline design & specialist input: Mott MacDonald Floating wetlands: Biomatrix Water Civils installation: Aquatic Engineering Ltd Fish recovery: MEM Fisheries Consultants & Services Ltd Cofferdam: MGF Ltd Piling: Elite Sheet Piling Ltd Formwork: Doka UK Formwork Technologies Ltd Steelfixers: MTN Structures Ltd Electrical: Main Electrical Ltd Electrical: BGEN Ltd Dewatering: Selwood Dewatering: Alba Dewatering Services Ltd Pumps: Xylem Water Solutions Fish & eel screens: Intralox LLC Pipework supply: Freeflow Pipesystems Pipework Installation: Utiliqo Ltd Valves: AVK UK Ltd Flow controls: AFFCO Flow Control (UK) Ltd Penstocks: Waterfront Fluid Controls Kiosk: Morgan Marine Ltd [caption id="attachment_14687" align="alignnone" width="1200"] Pumping station refurbishment - Courtesy of Sky Revolution[/caption] Environmental measures

To minimise the environmental impact, temporary track mats were used for the base of the works’ compound and launch area at Lake 2, allowing the site to return to managed grassland when the mats were lifted.

A silt curtain was erected in the lake to prevent debris from the old wetland polluting the water. This was important because the wetland was colonised by invasive species, mostly Himalayan balsam on land and zebra mussels below water. The curtain also ensured that sediment disturbed by the removal work did not spread.

The design has also had to accommodate regular site flooding; in particular for the temporary works around the river intake where, as an example, the cofferdam was designed specifically to account for controlled and safe flooding of the excavation to manage the high river levels experienced on-site.

Programme

Launching and anchoring the 31 floating wetlands was the first phase of the Raw Project. Phase two is refurbishing the abstraction pumping station built in the 1990s to enable raw water to be supplied to Witches Oak WTW.

Located on the western shore of Lake 3, the pumping station is undergoing a complete refurbishment, including the installation of three new transfer pumps to deliver up to 96 Ml/d of pre-treated water; enough for a city the size of Derby.

[caption id="attachment_14690" align="alignnone" width="1200"] River intake - Courtesy of Sky Revolution[/caption]

The design layout for the station also includes a new water quality kiosk and a wash-water booster set to clean the fish screens.

The river intake in the north-east corner of Lake 1 is also more than 25 years old and is being modified. The design will help to protect both fish and the gravel lakes. Two new 2.5m x 4m concrete channels will be constructed to create a flow low enough to allow fish and eels to swim back to the river, while two large, actuated intake penstocks will be installed to protect the lakes if there is a river pollution incident.

The introduction of new recirculation pipework will enable water to be pumped back to the river from the pumping station when necessary. Under the proposals, river water quality will in future be monitored upstream of the intake as well as at the intake itself.

Barbel, bream, chub and roach are common fish species found in the River Trent and two new screens will be fitted to filter fish and debris out of the water drawn in by the pumps at Witches Oak Water. The fish recovery system will consist of an above-ground pipe connecting the pumping station intake culverts to Aston Brook, which runs alongside the river, and from where fish can eventually return to the Trent.

Summary

Witches Oak is one of seven projects that form Severn Trent’s Green Recovery Programme, worth more than £700m, which aims to develop low-carbon water resources, improve river water quality, replace redundant lead pipes, install smart metering and make urban areas more resilient.

The additional water supply from Witches Oak will help meet demand for water from a growing population and improve the resilience of supplies during hotter, drier summers.

[caption id="attachment_14683" align="alignnone" width="1200"] Installed wetlands - Courtesy of Sky Revolution[/caption] The 31 constructed wetlands use naturally occurring biological processes to contain and treat ammonia, suspended solids and trace metals. Coupled with installing ceramic membranes at Witches Oak WTW (to provide a filtration barrier, reduce turbidity and remove pathogens such as cryptosporidium), the project is a more carbon-friendly treatment solution.

By restoring natural functions to these gravel lake ecosystems, the project is promoting biodiversity recovery and contributing to enhanced ecosystem services. The wetlands provide amazing biodiversity benefits including:

Above the water, the planted vegetation is a haven for wildlife, including nesting birds. Below the surface, the floating beds provide habitat for fish, eels and other aquatic species. On the fringes of the lake, retained coppiced woodland from the construction activities has been used to create further wildlife habitat.

In addition, positive social outcomes and community engagement are key elements of Severn Trent Water’s 25-year water resources management plan. The delivery team presented to the local girl guide group to tell them about the work we’re doing, and a visitor engagement centre has been installed to showcase this exciting project to local school and community groups.

Essex and Suffolk Water, part of Northumbrian Water Ltd, supplies drinking water to 794,000 properties. Maintaining a supply to those customers requires the distribution of up to 670 Ml/d of high-quality drinking water. In Essex, the two primary treatment works are Hanningfield WTW, a physio-chemical works near Chelmsford and Layer WTW, a biological works, near Colchester. These are supplied by raw water stored in two large reservoirs at Abberton and Hanningfield. In 2016, and more recently in 2022 low levels of rainfall and hot weather compromised the raw water quality in Abberton Reservoir which led to significant challenges to the biological process at Layer WTW. This meant unprecedented demand was placed upon the chemical works at Hanningfield WTW, which in turn drew down the water level in Hanningfield Reservoir to levels not seen since the summer of 1996. The challenge Whilst this low water level at Hanningfield Reservoir was observed, the level in Abberton was healthy due to the process constraints of the biological works at Layer. To mitigate the scenario of having two reservoirs, one relatively full, and another extremely low, occurring in the future, Northumbrian Water applied for enhancement funding in AMP7 to construct a 20km pipeline between Layer WTW and Langford WTW, also a physio-chemical works, where water from Abberton could be reliably treated. This in turn would allow water from the River Chelmer and River Blackwater that would normally be treated at Langford, to augment the water level in Hanningfield Reservoir by utilising existing transfer pumping facilities between Langford and Hanningfield Reservoir. Providing this connectivity, albeit by substitution, will allow Northumbrian Water to balance the water levels in both Abberton Reservoir and Hanningfield Reservoir, and mitigate a potential scenario where no water is available to supply Hanningfield WTW. The project In 2019 Essex & Suffolk Water teams began to plan a pipeline route between Layer WTW and Langford WTW for a pipe that could support flow rates up to 50 Ml/d. This figure was determined as the optimum flow rate to allow balancing of the reservoirs to take place and ensure security of supply when faced with long term drought conditions. The pipeline will take advantage of the capacity and capability of the existing pumping station at Abberton which can deliver up to 255 Ml/d to Layer WTW. The route would begin with a strategic connection into the existing raw water mains that deliver water from Abberton Reservoir into Layer WTW. From this point a route was sought that would allow water to run under gravity conditions to Langford WTW where it would be discharged into two existing bankside storage reservoirs each with a capacity of 35 Ml. The pipeline from Layer to Langford would operate as a gravity main, with the upstream head being set by the pressure in the rising main at the take-off point. With approximately 5 bar of available driving head, the flow out of the pipeline will be controlled by a downstream flow control valve. The pipe sizes have been selected to ensure a positive pressure is available throughout the pipeline and to provide sufficient differential pressure at the outlet at maximum flow. Hydraulic profile The hydraulic profile shown below (pipeline pressure is shown in red) extends from Abberton Pumping Station to the outlet at Langford WTW. Chainages are measured back from the Langford outlet (at chainage 0m) and the start of the new pipeline construction is at approximately chainage 20,000m. Note the falling available head due to friction losses along the pipeline and its change in gradient at approximately chainage 12,000m. This change in gradient is due to a change in pipe size which is the result of the pipeline optimisation. [caption id="" align="alignnone" width="1200"] Hydraulic profile - Courtesy of Stantec UK[/caption] The direct connection from the pumped rising main to Layer introduced a number of hydraulic complexities. A key issue was the control of transient pressures, particularly associated with a sudden loss of output at Abberton Pumping Station. Existing surge vessels provide robust surge control, however, the addition of the 20km extension to Langford would require careful consideration. The time to close the outlet valve at Langford, particularly following a sudden loss of pumping at Abberton, would need to be sufficiently long to avoid exacerbating transient pressures while a closing time too long would risk depressurising the pipeline and the risk of drawing air into the pipeline. The occurrence of transient air pockets at high points could create further transient pressures if encountered by the initial pressure waves. While these challenges could be largely avoided by separating both pipelines entirely with a break tank, the tank would need to be sufficiently large and elevated to provide the same driving head. The design team are, instead, progressing an optimised solution to avoid these additional capital works through thorough detailed understanding of the problem, careful selection of the control valves and the implementation of a control system that remains simple yet capable of maintaining pressures within acceptable limits. Ground investigations To support the design of the pipeline Essex & Suffolk Water has now completed ground investigation work along the route to determine ground and groundwater conditions and help inform excavated material management decisions. The ground investigation work comprised: 63 dynamic sampler boreholes up to 6m in depth. 11 cable percussion boreholes up to 10m in depth. 27 soil resistivity tests. Post-installation groundwater monitoring at approximately 12 locations. This work was completed by Essex & Suffolk Water’s framework partner Allied Exploration & Geotechnics (AEG) in October 2022 based on a specification written by Stantec UK. This ground investigation work will help Stantec to determine the appropriate pipeline material. [caption id="" align="alignnone" width="1200"] (left) Ground investigation work and (right) pipe installation - Courtesy of Essex & Suffolk Water[/caption] Pipe material selection The use of steel, ductile iron (DI) and polyethylene (PE) were all considered. Due to aggressive ground conditions, appropriate corrosion protection would be needed for ferrous materials. PE would remove the corrosion risk but the large diameters needed and the associated pipe thickness would require careful control of welding during construction. At the time of writing (June 2023), final selection is ongoing but, following initial assessment of cost, constructability and maintenance issues, either an all DI pipeline or a mix of DI and PE are considered most favourable. Project planning The project is currently moving through the detailed design phase and one activity that has been conducted concurrently is the liaison with the council districts that the pipeline crosses, both Colchester City Council and Maldon District Council. In the experience of Essex & Suffolk Water, large diameter cross country pipelines have typically required Environmental Impact Assessments to support the planning process. For this project, an alternative approach was taken where the team designed the pipeline and its construction methods, including associated compound areas, to have the least possible impact from a number of perspectives including ecology, visual impact and traffic and transport in advance of submitting our EIA Screening Request. This design, including examples of how measures were introduced to provide a less impactful route than one that may have been presented prior to completing these mitigations, helped support the EIA Screening request. In response to that request both Councils viewed the screening request favourably and allowed the team to complete the work using permitted development rights recognising the efforts of Essex & Suffolk Water to plan and design the least impactful route possible. Archaeology Essex & Suffolk Water now plans to complete the archaeological work associated with the project over the summer period of 2023. Throughout the early phase of the project Essex & Suffolk Water has worked closely with AECOM to complete a desk based assessment and then develop a Written Scheme of Inspection. This has now been approved by the council archaeologist and comprises 552 trenches measuring 2m x 30m across a 40m corridor along the 20km pipeline route. This work will be completed over a 16 week period, 8 weeks for the field work and a further 8 weeks for recording and report preparation. Due to the archaeological history in the area it is expected that some archaeological artefacts of interest will be uncovered. This may in turn necessitate further mitigation trenching along the route. Layer to Langford Pipeline - Supply chain (as of June 2023) Principal designer: Stantec UK Ground investigation: Igne Land owner engagement: Savills Technical input: Saint Gobain PAM UK Archaeology: AECOM Pipe installation: Northumbrian Water Pipe supplier: Electrosteel Castings (UK) Ltd Schedule The installation of the majority of the 20km pipeline will begin in February 2024 in order to complete the work in March 2025, allowing Essex & Suffolk Water’s in house team to complete the installation in one pipelaying season. Work has already commenced on a number of minor road crossings to coincide with the work of other developers in the area and minimise impact on our customers. Work is also scheduled to commence on the directional drill crossing that will be required beneath two main rivers as part of the project, the River Blackwater and the Langford Cut in September 2023.

Located south/south-east of the River Foyle in Derry, Co. Londonderry, a new trunk main was installed from Tamnymore Service Reservoir (SR) along the Strabane Old Road, Trench Road, Irish Street, Bann Drive, Dennet Gardens and Dungiven Road. During periods of high water usage, the existing Crescent Link Trunk Main failed to meet demand, causing low pressure and loss of supply in certain areas of the local network. NI Water is committed to improving the resilience of the water supply infrastructure across Northern Ireland and as part of their IF105 Integrated Partnerships Framework, identified the need to carry out works to replace 3.3km of the existing 10” diameter spun iron trunk main in the Waterside area of Derry/Londonderry to provide an effective and sustainable water supply to a growing population. Project scope

The project included the following scope:

3km of new 450mm HPPE (SDR17) trunk main from Tamnymore Service Reservoir to Dungiven Road, Derry. 0.3km of new 280mm HPPE (SDR17) trunk main on Trench Road. 70m of new 125mm HPPE (SDR17) distribution main on Trench Road. Installation of new a 250mm electromagnetic flow meter at Tamnymore Service Reservoir. Installation of a new 250mm electromagnetic flow meter, PRV and strainer at Sheskin Gardens. Abandoning existing 10” spun iron main from Corrody North BPT to Altnaglevin roundabout. Early Contractor Involvement (ECI), detailed design & engineering challenges

Farrans/Glanua Group Joint Venture was engaged in early 2021 under an NEC4 Option ‘E’ contract to carry out site investigation works to enable detailed design. This provided the opportunity to liaise with the necessary specialist contractors and gain their experience, knowledge and input into developing detailed design and construction methodologies.

[caption id="attachment_18229" align="alignnone" width="1200"] (left) Meter strainer and PRV construction and (right) connection to existing network from new trunk main - Courtesy of Farrans[/caption] Construction

The proposed route for the new trunk main was along the Strabane Old Road; a dense urban area often used as an alternative route to the existing A5, for commuters coming in and out of the city. Traffic surveys recently completed identified that 7000 vehicles per day (VPD) were using the road.

As a result, early engagement and liaison between DFI Roads, Translink, Farrans Construction and the Traffic Management Contractor were required. A collaborative approach among all stakeholders ensured effective traffic management measures were implemented to protect the safety of road users directly affected by the works and those passing by, minimising disruption as best as possible while the works progressed.

The works were carried out under local road closures and lane closures. Due to the size of the pipe, existing services and rock, all the pipe was installed via open-cut methodology.

A 1m wide asphalt planer was utilised to remove the asphalt layer in the pipe track. This greatly saved time in comparison to the traditional method of an excavator and breaker.

Due to a limited working area, 12m lengths of 450mm diameter PE pipe were delivered from compound to the works area as required via a Hiab. The pipe was then butt-welded and pulled into the trench using rollers and pipe trolleys.

Crescent Link Trunk Main was chosen to trial Control Point’s Bluebox Quality Assurance System (Joint Assist). Joint Assist is a mobile application that records and uploads data for electrofusion joint assemblies, enabling real-time inspection, compliance and comprehensive asset management. In addition to Farrans’ own quality procedures, Control Point’s Bluebox provided NI Water with third party quality assurance.

[caption id="attachment_18228" align="alignnone" width="1200"] (left to right) (i) Pipe trench excavated around services (ii) placement of pipe bedding (iii) pIpe bedding and marker tape and (iv) 450mm PE pipe installation - Courtesy of Farrans[/caption] Crescent Link Trunk Main: Supply chain - key participants

The construction contract was awarded under NEC4 Option ‘C’ Target Cost Contract to Farrans/Glanua Group JV. Construction began in May 2022 and took place over a 12-month period at a total cost of £2.5m.

Delivery contractor: Farrans/Glanua Group JV Design/project management: WSP UK Ltd Civil design: Jacobs Design Main contractor (Civils): Farrans Construction M&E works: Enisca Ltd Traffic Management: McVeigh Contracts Ltd Surveyors: Geodynamics HDPE pipe & fittings: APP Fusion Group Quarry products & reinstatement: Northstone Materials Ltd MP Coleman P Woods & Son Ltd Dungiven Road Crossing

The Dungiven Road is categorised as type 1 road with recent traffic surveys recording approximately 1500 VPD using the road. As a result, the works were carried out at night (7pm to 6am) to minimise disruption.

Lengths of 600mm twin wall pipe were installed in the road via open-cut methodology and completed in sections. This allowed time for the road to be backfilled, temporarily reinstated at the end of each shift and opened in time for the morning traffic.

Once all the twin wall pipe was installed, a 450mm string of pipe was welded and successfully sliplined through the twin wall pipe with only one joint/bend required. Once all works were completed in the road, a planer was used to remove the temporary asphalt and allow the permanent reinstatement to be completed.

Following testing (Type 2 pressure test), commissioning works were undertaken in preparation for connections to the existing network.

[caption id="attachment_18227" align="alignnone" width="1200"] PE pipe butt welding adjacent to Dungiven Road - Courtesy of Farrans[/caption]

Seven new connections were made to the existing network which allowed for the existing 10” spun iron main to be abandoned.

Utilising existing kiosk and telemetry units, new electromagnetic flow meters and pressure transducers were fitted as part of a new PRV, meter and strainer arrangements at Tamnymore SR and Dennett Gardens to allow NI Operations to monitor flows and pressures over the telemetry network.

Public relations & social engagement

Farrans’ PR manager, Sarah Heffernan, worked closely with NI Water Comms to implement a proactive engagement strategy to ensure all key stakeholders were informed of the work in a timely manner. Letter drops took place in advance of each section of pipelaying to advise the residents and businesses of the planned works and variable message boards were erected along the route. Business-specific signage was installed around each works area and press releases issued to inform the wider public. Communication with other stakeholders, including elected representatives, landowners, roads and transport authorities was maintained throughout the scheme.

NI Water’s 24-hour dedicated customer care ‘Waterline’ number, was issued on all correspondence to the public and displayed on all signage which ensured that any queries about the work were dealt with quickly and effectively.

To minimise the impact to the public while working on the Dungiven Road, works were carried out at night with increased working hours in order to complete the pipelaying in the shortest possible timescale. Additionally, roads were temporarily reopened around holiday periods to minimise disruption.

[caption id="attachment_18226" align="alignnone" width="1200"] Planer in operation in Dennet Gardens - Courtesy of Farrans[/caption]

Whilst working through the most congested and built-up area of the project (Strabane Old Road), Farrans’ in-house Stakeholder and Social Value Team along with NI Water engaged with the local primary school. The site team visited the school delivering a site safety talk, ensuring the pupils understood the dangers that construction sites can bring and how to stay safe around the works.

Following this, the site team facilitated two site visits where the pupils were brought onto the live construction site to see works and the watermain being laid. They were given a presentation by the site engineer covering a variety of topics on all things engineering, the water cycle, how water gets from source to tap and why works were being carried out in their area. There was great engagement from the pupils during the visits and pupils went back to their classroom with an engineering superhero colouring competition to help remember everything they had learnt on their site visit.

Seeing first-hand the construction works and learning why the work needed to be undertaken hopefully helped the pupils to think further about STEM subjects and the different career options available to them in the future.

Project summary

Testing and commissioning of the new 450mm trunk main began in March 2023, with the final connection to the network completed in April 2024. The new Crescent Link Trunk Main will provide a sustainable supply in of wholesome drinking water to the Waterside area in Derry/Londonderry, bolstering Northern Ireland Water’s existing infrastructure and reinforcing supply to approximately 17,500 customers.

Forming part of Southern Water’s (SW) Hampshire supply region, the Isle of Wight (IoW) is located just off the south coast of England and is divided into two water distribution zones (WDZ), namely IoW North and IoW South. The IoW South comprises major towns of Ryde, Sandown, Shanklin and Ventnor with multiple villages and more remote rural areas forming the wider distribution network. The water sources and distribution systems have been brought together, with their origins being from former smaller localised systems developed in the late 19th century, which were added to in the 20th century as the IoW population grew, to form an integrated system. Today, there are five existing small and medium sized water supply works (WSW) with a combined daily output of 18 ML supplying customers via several small water service reservoirs (WSR). The water distribution network totals approximately 547 km of mains, serving a population of approximately 45,000 people. Project driver The Cooks Castle WSR has been identified for replacement based on asset condition and the associated security of supply risks to customers. This project aims to provide a long term solution for storage requirements and enhance the network associated with the removal/replacement of this existing WSR. To validate the need and determine the optimum size, top water level and location of any new WSR, a solution needed to be developed considering a wider, integrated view of water sources, network storage and water distribution now and into the future. The business planning objectives were broadly defined as: Create a more resilient water supply network for future generations (Southern Water Network 2030 rationalisation). Maintain levels of service to customers and mitigate water quality risks. Ensure future growth and proposed new sources can be integrated (Water Resource Management Plan - WRMP) and reduce dependency on the bulk transfer from the mainland via the Cross Solent Mains. Increase operational flexibility through optimisation of existing/new assets. Improve security of supply to customers (zonal storage provided in line with Southern Water Asset Class Policy). Decommission surplus assets to reduce cost of maintenance. [caption id="" align="alignnone" width="1200"] Figure 2: The planning process developed - Courtesy of Southern Water[/caption] Optimisation The Optimatics’ OptimizerTM tool was used, allowing the team to analyse up to 35,0000 plans (the group of assets the Optimizer chose to test) in a single optimisation run (see Figure 1 - top of page). OptimizerTM was allowed to generate plans incorporating both new asset options and removing or retaining existing assets. New options tested included a total of approximately 80km of strategic mains in varying diameters, over 20 WSR configurations in five different locations, decommissioning of existing WSRs and associated rezoning, rationalisation of WSWs and provision of new pumping stations. The OptimizerTM evaluated plans using input ‘design criteria’ which were formulated and aligned with the project planning objectives and Southern Water standards. More complex ‘rule-based adjusters’ were formulated to allow automation of controls and prevent Optimizer from selecting options which conflicted with one another, e.g. to prevent Optimizer’s ability to select multiple sizes of WSR at the same location. The evaluation of these design criteria by the OptimizerTM produced a cost and performance evaluation for each plan. The best performing plans were then compared with each other on a Pareto curve - see Figure 3. [caption id="" align="alignnone" width="1200"] Figure 3: Typical Pareto curve showing best performing plans - Courtesy of Southern Water[/caption] Incorporating environmental performance into the optimisation was a particular challenge. The team approached this by taking the results from a high level environmental feasibility assessment and factoring in WSR and pipe costs proportionally to reflect better and worse performing options. This then carried through into the overall cost/performance results for that plan. In the example, the Pareto curve shows about 216 OptimizerTM plans (from 30,000) from which 10 plans have been identified as feasible options. The OptimizerTM tool is very powerful at testing several configurations (plans) based on the given inputs, design criteria and formulations. Review and validation are critical parts of the process, and this involves the team checking outputs (individual plan performance), tweaking inputs (adjusting costs/penalties/formulations) and refining the optimisation until several tangible plans are derived. Figure 4 shows typical age of water results for several WSRs with shortlisted plan 7639, 8142 & 8041 compared against the existing system performance. This demonstrates how the optimised plans can significantly reduce the age of water meeting one of the projects key objectives. [caption id="" align="alignnone" width="1200"] Figure 4: Age of water optimisation - Courtesy of Southern Water[/caption] Defining outputs: the optimal integrated solution Taking a short list of tangible plans from the optimisation is a starting point which allowed the team to define the pathway to the final integrated solution. Not all factors can be simply incorporated into OptimizerTM therefore these external factors need consideration alongside the optimisation outputs to form the final integrated solution. One important factor was implementation of solutions over several AMP cycles and ensuring that staged development did not detrimentally impact on customer levels of service. Similarly, consideration of outage scenarios, e.g. WSW shutdowns and mains bursts were considered outside of the optimisation, then retrospectively tested against the shortlisted network configurations. The solution The final integrated solution comprised: Network connections to a single rationalised WSW using three input water sources (currently two separate WSW with two sources). This aligns with WRMP and improves IoW drought resilience. Removal of seven existing WSRs reducing asset risk through deterioration, maintenance costs and age of water issues. Provision of one new strategic WSR providing wider security of supply to several district metered areas (DMAs) compared to current configuration. Trunk mains reinforcements and new installation/upgrading of network pumping stations to support strategic transfers from proposed WSWs to WSRs and customers. Increased operational efficiency and lower OPEX by considering rezoning, triad periods and exploiting opportunities to modify the current network via simple valving operations.

Since 1892, the Vyrnwy Aqueduct, which runs from Lake Vyrnwy through to Merseyside, has helped deliver clean wholesome drinking water to customers and communities across Cheshire, Merseyside and the North West region. However, the pipeline now requires maintenance work to ensure the quality of customers’ drinking water is resilient for generations to come. Vyrnwy Aqueduct comprises three parallel pipelines, referred to as Lines 1 and 2 (cast iron pipes) and Line 3 (steel pipe). Each line is 42 inches (over 1 metre) in diameter and has a combined distance of 139km in length between Malpas and Prescot. The challenge

Over time, deposits of iron and manganese have accumulated within the pipelines. While these minerals do not pose any health risks, they can result in discolouration of the water and be detrimental to the internal condition of the pipe. Due to the ages of the lines and the accumulation of minerals deposited, they now require cleaning and/or rehabilitating. To maintain the water supply, the refurbishment programme will be completed over a phased approach with work on the lines being carried out at different times.

[caption id="attachment_23853" align="alignnone" width="1200"] (left) Pipework set-up for vertical launch or air ‘pig’ and (right) launching the air 'pig' - Courtesy of Avove[/caption] The approach

Avove was chosen as the contractor for modernising the Vyrnwy Aqueduct pipelines, adopting innovative ways to inspecting, cleaning and relining the large-scale pipes throughout Cheshire. This includes designing, constructing, testing and commissioning the three pipelines in Phase 1 of the works between Malpas and Tarporley; a distance of approximately 18.75km per line. Avove’s approach will see a significant reduction in carbon emissions across the project.

Lines 1 & 2 - Cast iron pipe: A new slightly smaller diameter plastic pipe will be slip-lined into the old main, creating a brand-new pipe within the host main.

Line 3 - bitumen lined steel pipe: The original scope was using a traditional method of high-pressure jet washing, however, Avove’s design team reviewed the project and recommended the use of air pig technology working with specialist smart pigging partner iNPIPE PRODUCTS™. Air pigging has never been used before to clean this size and length of water pipeline, but after careful consideration, Avove and iNPIPE PRODUCTS™ designed and commissioned an effective, compliant and efficient process, that was approved within the United Utilities specification C05-i2-Spec document for large diameter bitumen lined mains.

[caption id="attachment_23855" align="alignnone" width="1200"] Launching the smart air 'pig' - Courtesy of Avove[/caption] Vyrnwy Aqueduct Maintenance Programme: Supply chain - key participants Main designer & contractor: Avove Air pigging designer & contractor: iNPIPE PRODUCTS™ CCTV: Ipsum Hydro demolition: Buxton Water Ltd Special steel fabrication: PMJ Mechanical Ltd AMEX 10 seals supply & installation: PMP Utilities Nova Siria pipe fittings: R2M Limited Special steel fabrications fittings: Water Engineering Services Ltd Manway installation: JOD Engineering Services Ltd Security covers: Technocover Ltd Site accommodation: Garic Specialist plant hire: Sunbelt Rentals Demarcation fencing: SP Environmental Demarcation fencing: GTS Haul road construction: Miles Macadam Haul road construction: Ecofill Group Ltd Air pigging system & its benefits

The air pigging system utilises an air-propelled cleaning tool, known as a ‘pig’, travelling through the 1m diameter pipes to remove any sediment that has built up from the natural minerals in the water.

The innovative process uses air to push a pig-train, containing a slug of water between two pigs down the host main to lift off and suspend waste deposits off the internal wall for removal at the receiver. Flow rates and pressures are carefully monitored at all times during the cleaning process and after each pigging run.  If required, brush pigs are used to remove hardened materials. These brush pigs have been designed to remove materials without damaging the existing bitumen lining. Following cleaning, a camera pig is run through the pipeline to ensure internal cleanliness is assured.

[caption id="attachment_23856" align="alignnone" width="1200"] Air 'pigs' - Courtesy of iNPIPE PRODUCTS™[/caption]

The ‘pigs’ are vertically launched to reduce the excavation size but can be launched horizontally when height is a concern. ‘Pigs’ are inserted into the pipe section at ground level to reduce working at height and the pipes will then be attached to the host main.

’Pigs’ are traditionally propelled by water, but by using air, the benefits for the Vyrnwy Aqueduct include:

Saving 15 million litres of water compared to using traditional techniques for the whole of this siphon. Saving 118.2 tonnes of CO2 across the whole project. Avoiding 1,104 water tanker journeys which has significantly reduced costs, time, carbon emissions and environmental impact. Saving 2,208 journeys and reducing the impact of traffic congestion and noise as well as supporting road safety. Achieving better results by using a close-fit, full contact, cleaning technique. The air pig technique cleans the pipes significantly faster, reducing the time from weeks to days. For example: 2,542m of Section 1 were completed in 4 days. Air pigging only requires a launch and reception pit for each section; reducing the number of access pits required from 37 to 12. The solution

For a large diameter main with manganese deposits, air pigging was a safer system to use and improved the quality cleaning method, due to the contact motion and flexible material of the bespoke cleaning air pig.

Avove designed the type of ‘pigs’ required for the project and worked with partner iNPIPE PRODUCTS™ to manufacture the type of cleaning tool; collaboratively agreeing on the frequency of the ‘pig’ run to ensure optimum cleanliness based upon more than 40 years of experience.

[caption id="attachment_23858" align="alignnone" width="1200"] The Avove and iNPIPE PRODUCTS™ teams - Courtesy of Avove[/caption]

Avove and iNPIPE PRODUCTS™ subsequently ran an integrated camera/data logging system which incorporated gyroscopes and a tracking module mounted within the ‘pig’. This system recorded high-definition quality footage of the water main as it passed through and allowed the team to analyse the pipeline.

The adopted method requires the ‘pig’ passing through the pipe six times:

Pass one: Prover camera ‘pig’. This also purged any standing water. Pass two: First cleaning train. Pass three: Second cleaning train. Pass four: Third cleaning train. Pass five: Fourth cleaning train. Pass six: Camera swab. The final camera ‘pig’ acts as a final clean with a bareback swabbing of the main to provide cleanliness and will be part of the Quality Assurance procedure. Progress

Avove is continuously striving to innovate and drive carbon reduction within the design and build aspects of the Vyrnwy Aqueduct Modernisation Project. By January 2025, all six sections in Siphon 1 Line 3 had been successfully cleaned and the aqueduct was commissioned and returned into service.