Supply Chain - Water Mains - Contractors

The  Wells to Glastonbury Pipeline will ensure that approximately 13,000 customers have resilience of water supply by providing a secondary source and route to Windmill Hill Reservoir for the purposes of maintaining a safe supply of water to Glastonbury and Street in the event that the primary main from Cheddar WTW to Cooks Corner is temporarily lost or compromised. The £6m capital investment by Bristol Water will provide an 8km pipeline by March 2023. Undertakings Procurement of the scheme was made via Bristol Water’s two existing Network Maintenance Service Contract Strategic Partners. On completion of a thorough value and quality competitive tender process, envolve infrastructure was appointed as the delivery partner for the project in the form of an NEC Term Service Contract (Option C). The existing framework incentive mechanisms were applied, scoring scheme specific and framework performance KPI’s in calculation of any pain/gain on project completion. The anticipated programme duration of 34 weeks substantially reduced regulatory risk for Bristol Water with significant improvements on the original anticipated programme duration (anticipated completion October 2022), comfortably achieving the regulatory in use date (March 2023). [caption id="" align="alignnone" width="1200"] Ongoing construction works - Courtesy of envolve infrastructure[/caption] Early contractor involvement (ECI) ECI was integral to the delivery model from the outset. Envolve infrastructure’s proven relationship with Bristol Water on ECI holds successes in providing both robust technical solutions, meeting needs of the operational teams and its customers, whilst providing a cost-effective and value driven solution. Detailed ECI commenced partnering with the Bristol Water in house design team in developing the detailed design. The ECI strategy was investigating and minimising risk whilst extracting and exploring opportunities for an efficient and cost beneficial delivery programme for Bristol Water. This included: Development of access and egress routes. Consultation with external stakeholders (landowners, EA, Highways). Environmental management. Value engineering opportunities. Engagement with specialist supply chain - for example, horizontal directional drilling (HDD). Engaging and developing relationships with local organisations and communities. Exploring social value objectives and opportunities. [caption id="" align="alignnone" width="1200"] (top left) 360° view stretching from Glastonbury Torr in the South to Wells in the north, (top right) pipeline easement at Wells and (bottom) the internationally important Somerset Levels and Moors, demanding the utmost of environmental and biodiversity care and attention - Courtesy of envolve infrastructure[/caption] Design The in-house design team was immediately integrated into envolve infrastructure’s ‘One-Team’ model and, in conjunction with the expertise of the design manager and construction team, formed an integral part of the ‘One-Team’ delivery model. The ‘One-Team’ approach guaranteed a collaborative partnership from the outset and facilitated an efficient and coordinated design process for Bristol Water. Envolve’s responsibility during the design process reviewed suitability and efficiency of the outline design, planned construction methodology, and proposed route to collaboratively develop the final design. During this stage, envolve infrastructure developed the delivery strategy. HDD would be delivered by GMAC Utilities; a long-term strategic supply chain partner. Open cut sections were being delivered by envolve’s directly employed skilled workforce. Paramount to the success of the scheme was the ‘One-Team’ approach between the stakeholders, which reinforced the utmost confidence from Bristol Water in the delivery strategy and structure. Expert review and value engineering proposals identified multiple potential improvements to both installation technique, route and process. Key proposals determined major design decisions and changes, ensuring the most efficient and risk-mitigated product for Bristol Water. [caption id="" align="alignnone" width="1200"] Drone views of works areas - Courtesy of envolve infrastructure[/caption] In addition to this, investigations during the design process provided Bristol Water with £240,000 of potential value engineering opportunities: Use of excavated material as bed and surround: £100,000. Alternative route: £100,000. Specification of pipe material: £40,000. As part of the outline design review, the profile of the pipeline through each section was challenged to ensure it would not only be the most cost-efficient method of delivery but also offered a benefit to the operating cost of the pipeline. A section of the pipeline passes through a layer of peat. Along each field there are regular drainage ditches that would require drilling, which led to an irregular profile requiring washouts and air valves, reducing the efficiency of pipe and increased energy usage to pump the water. The design solution  proposed a constant gradient below the layer of peat in a band of clay, which increased its efficiency and removed the need for unnecessary apparatus. Once works commenced on site, envolve infrastructure was appointed as principal contractor with Bristol Water retaining the role of principal designer. Although Bristol Water’s in-house team retained ultimate control of producing the design, envolve’s commitment and appointment through the ECI process and the value engineering proposals were integral to completing the final design as a combined collaborative delivery partnership. [caption id="" align="alignnone" width="1200"] An open cut section of pipeline at Wells - Courtesy of envolve infrastructure[/caption] Construction A review of the route identified the most efficient installation technique and HDD was selected for over 1.5km of the pipeline to mitigate ground and environmental risk through the internationally important Somerset Levels and Moors. Depth, route adjustments and methodology all forming part of the design proposal with a focus on the location of permanent operational apparatus in line with the project brief. During the pre-construction phase, an access/egress plan was agreed with all stakeholders through early engagement by identifying all landowners and agreeing the most efficient routes and locations for compounds. This ensured enabling and reinstatement works were agreed in advance; mitigating third party late changes and future programme risk. A central main compound location housed the shared project office facility, material storage and waste processing facilities. The yard team operated a quarantine zone for deficient/damaged materials to reinforce envolve’s uncompromised quality standards. Three satellite compounds housed the site-based welfare and material storage, facilitating direct to site deliveries, mitigating double handling, and reducing vehicle movements. A delivery gang structure was created from envolve’s highly experienced directly employed staff and workforce. [caption id="" align="alignnone" width="1200"] Welding activities - Courtesy of envolve infrastructure[/caption] The in-house training team facilitated training requirements ahead of commencement. Self-delivery teams were supplemented with specialist subcontractors with whom envolve had long-standing relationships. Works were constructed offline on up to six work-fronts, varying between site preparation, open cut, directional drilling and reinstatement, simultaneously working across the 5km route.  Construction operations were managed by envolve’s highly experienced, directly employed, site management team supported by the in-house SHEQ department. The scheme comprised two critical interfaces with Bristol Water live assets and these connections will be undertaken by Bristol Water Operations. Throughout the commissioning stage, assistance from envolve’s expert management and delivery teams will ensure a seamless interface between the specialisms. Wells to Glastonbury Pipeline: Supply chain - key participants Client: Bristol Water Delivery partner: envolve infrastructure Horizontal directional drilling: Gmac Utilities Ltd Pipeline materials: Aliaxis UK Chlorination: Suez Water UK Fencing & reinstatement: Huw Jones Fencing Road surfacing: Walton Civil Engineering Traffic management: Renteq Highways Limited [caption id="" align="alignnone" width="1200"] Horizontal directional drilling - Courtesy of GMAC Utilities Ltd[/caption] Carbon management To assist with achieving our net zero carbon commitment by 2040, envolve installed a permanent power supply connection for the main compound with a ‘green’ electricity supplier, removing the need for temporary diesel power generation. The use of hydrotreated vegetable oil (HVO) is key to meeting this target. A trial of HVO fuel and fueling stations conducted on the project achieved a 90% reduction in C02 emissions across the diesel consuming fleet and was regarded as a runaway success. The design solution to drill at a constant grade across the peat locations enabled the design to remove unnecessary apparatus from the pipeline. In turn, this enabled the pumps operating the network to operate at a more efficient output thereby reducing the energy consumption and carbon emissions in the ongoing running and management of the pipeline. Construction design management CDM15 regulations were discharged through the development of a detailed construction phase plan and through collaborative working. The design was approved through a detailed design process review, regular meetings and early engagement, retaining a collaborative relationship with the team. Stakeholders remained at the heart of the delivery, through conducting weekly progress meetings for the duration of the scheme covering design, construction progress, environmental and 3rd party interfaces. [caption id="" align="alignnone" width="1200"] Construction activities - Courtesy of envolve infrastructure[/caption] Social value During the summer of 2022, the team engaged with St Cuthberts Parish Council to work together and deliver a community benefit project. The Parish Council required a stream crossing on a public footpath at Coxley Recreation Ground, which needed to be completed in time for the Platinum Jubilee. With only 4 days notice the team started construction of the river crossing and handed over the crossing ahead of time to the delight of the Parish Council. Summary The success of this project will ensure future resilience in the water supply to the residents of Glastonbury for decades to come. Envolve infrastructure’s role through design and construction has reinforced the company’s commitment and expertise as the strategic partner of choice for Bristol Water and is testament to the trust and collaboration forming the foundation of our partnership. Hannah Milliner, Head of Capital Delivery, Bristol Water commented:

“Envolve’s Collaborative approach to delivery achieved a one team approach. We collectively worked to overcome challenges, delivering a successful project ahead of programme. This approach resulted in project risks either being mitigate or managed by drawing on knowledge from across the team, resulting in the overall project being delivered under budget.”

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.

Located just outside Randalstown, Co. Antrim, the new trunk main was installed along the Thornhill Road, Creevery Road, Lisnevenagh Road (A26) and Barnish Road. The existing 560mm ring main around Antrim town was susceptible to frequent failures and replacement of this main was practically and economically unfeasible. To combat these problems, NI Water developed a resilience solution to prevent future issues and reinforce supply to approximately 4,000 properties and businesses in the Randalstown and Antrim areas. Project scope

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 4,200m of 9” diameter asbestos cement (AC) main along the Creveery and Barnish Roads (crossing a dual carriageway and a railway line) with 315mm diameter HPPE main.

This would provide an effective and sustainable alternative supply to Randalstown, providing mitigation for ongoing issues with the existing supply located on Stiles Way.

The project included the following scope:

Installation of 4.2km of new 315mm HPPE (SDR17) trunk main and decommissioning of existing 6” and 9” asbestos cement mains including: Crossing of the main Belfast to Derry/Portrush Railway line and River Millburn via Horizontal Directional Drilling methodology. Crossing of the A26 Dual Carriageway linking Barnish Road and Creevery Road. Service transfers from the existing 6” and 9” Asbestos Cement mains to the new 315mm HPPE main. New PRV arrangements at Creevery Road/Thornhill Road and Barnish Road/A26 connection points to optimise network pressures. Eight connections to the existing network. [caption id="attachment_16494" align="alignnone" width="1200"] Site overview - Courtesy of Farrans/Glanua Group JV[/caption] Early contractor involvement (ECI)

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

Stiles Way Trunk Main: Supply chain - key participants Delivery contractor: Farrans/Glanua Group JV Design/project management: WSP UK Ltd Civil design: Jacobs Design Main contractor (civils): Farrans Construction Surveyors (under-track crossing): Clifford & Gregg Ltd Surveyors (survey & as-builts): Geodynamics Specialised drilling contractor: Markey Drilling Ltd Pipe welding: PE3 Pipeline Services Limited M&E works: Enisca Ltd Traffic management: McVeigh Contracts Ltd HDPE pipe & fittings: APP Fusion Group Supply of flow meter: Park Electrical Services Precast concrete manholes & cover slabs: FP McCann Quarry products & reinstatement: Northstone Materials Ltd Quarry products & reinstatement: James Stevenson Quarries Ltd Construction

The construction contract was awarded under NEC4 Option ‘C’ Target Cost Contract to Farrans/Glanua Group JV. Construction began in February 2022 and took place over a 14-month period at a total cost of £2.4m. Due to the proximity of the works to the A26 and the Belfast to Derry railway line, early engagement and liaison between DFI Roads, PSNI Traffic Branch, Translink, Farrans Construction and the traffic management contractor were required. A collaborative approach among all stakeholder ensured effective traffic management measures were implemented to protect the safety of road users directly affected by the works and those passing by.

[caption id="attachment_16499" align="alignnone" width="1200"] Ditchwitch ready for action on Barnish Road - Courtesy of Farrans/Glanua Group JV[/caption]

Due to favourable ground conditions, sections of the 4.2km stretch were installed via horizontal directional drilling (HDD) methodology.

This trenchless technique provided savings on aggregates, bitmac reinstatement and spoil disposal, while reducing the impact/footprint on the road. The site team strategically placed launch and retrieval pits at air valve and washout hydrant locations, removing the need for additional excavations. The excavations were also located away from driveway entrances, minimising impact and ensuring access was maintained for residents. The remainder of the pipeline was installed via open-cut methodology.

Following testing (Type 2 pressure test), commissioning works were undertaken in preparation for service transfers and bringing the new trunk main into service.

Eight new connections were made to the existing network with 66 services transferred from the existing 6” and 9” AC mains to the new 315mm main. Utilising the existing kiosk and telemetry unit, a new electromagnetic flowmeter and pressure transducer was fitted as part of a new PRV, meter and strainer arrangement to allow NI Operations to monitor flows and pressures over the telemetry network.

Belfast to Derry railway line and river crossing

Translink was engaged during the ECI phase of the works to understand the requirements/restrictions for installing the trunk main under the railway tracks. Following several months of design and documentation review, a Permit to Work was obtained.

As it was a strategic crossing, NI Water asset standards required the 315mm trunk main crossing to be sleeved inside a 450mm pipe.

[caption id="attachment_16497" align="alignnone" width="1200"] (left) Site compound complete in advance of HDD crew arrival, (middle) towing head installed on pipe ready for pulling and (right), pipe pull completed - Courtesy of Farrans/Glanua Group JV[/caption]

The Belfast to Derry railway line under-track crossing (UTX) was completed by horizontal directional drilling (HDD) methodology. During ECI, several bore holes were carried out parallel to the proposed drill shot (launch, centre and retrieval). All bore holes encountered rock (fractured basalt). However, as drilling operations commenced, the specialist contractor identified changing ground conditions.

As the drill shot progressed towards the river, the rock formation ended and changed to a softer ‘clay-like’ formation. This was confirmed via the change in colour and viscosity of the drill muds, indicating a soft formation with a high clay content. The ground conditions did return to rock approximately 15m from crossing under the railway line, but again, changed back to a softer formation as the drill shot approached the retrieval pit. The lack of consistency posed a serious problem for the rock drilling motor as it was difficult to steer back to ground level because of the soft clay formation.

To proceed with the drill shot and deal with the varying ground conditions, the contractor alternated between the rock drilling head and conventional drilling head. However, this meant pulling the drilling rods in and out to change the head and as its size increased, the risk of the bore hole collapsing also increased.

Following an on-site review with the contractor, NI Water and designers, it was decided to abandon attempts to install a 450mm sleeve and instead install the 315mm main directly. Following several weeks of drilling works, the 315mm main was successfully installed under the rail and river.

The railway line was surveyed for a period of two weeks prior to commencement of the works in order to establish baseline level readings via small targets attached to the side of the rails at 2m intervals. For the duration of the works, surveys were undertaken three times per day to monitor settlement and heave. The track was monitored for a further two-month period following completion of the UTX.

[caption id="attachment_16492" align="alignnone" width="1200"] Fluid recycler in operation - Courtesy of Farrans/Glanua Group JV[/caption] A26 dual carriageway crossing

The A26 is a major arterial route in Northern Ireland connecting Coleraine in the north to Banbridge in the south of the province. It carries in excess of 30,000 vehicles per day, making it one of Northern Ireland’s busiest carriageways.

Due to the staggered junction between Creevery Road and Barnish Road, lack of available land and ground conditions (rock), a trenchless crossing of the A26 was not feasible. As such, the works were staged and completed in sections to maintain traffic and minimise disruption:

Stage 1: North-bound inside lane Stage 2: Outside lanes and central turning lanes (north and south bound). Stage 3: South-bound inside lane.

Lengths of 450mm twin wall pipe were installed crossing the carriageway via open-cut methodology. Upon completion, a 315mm string of pipe was welded and successfully slip-lined across the carriageway.

A 1.2m wide tar planer was utilised to remove the asphalt layer on the parallel stretch of carriageway and two main-laying crews worked round the clock to ensure the works were completed on time.

[caption id="attachment_16493" align="alignnone" width="1200"] 315mm pipe welding - Courtesy of Farrans/Glanua Group JV[/caption] Public relations

Farrans and NI Water Communications, issued press releases and engaged with a range of stakeholders including Councillors (for roads affected and programme), council staff (bin collections etc), Roads Service (roads impact), Translink (school bus routes), Rivers Agency (River Millburn), landowners, businesses, and schools.

Letter drops took place in advance of each section of road works and closures to advise the residents and businesses of the planned works. Variable message boards were erected on the A26 (north and south bound) and business-specific signage was installed around the works area/diversion routes to reduce the impact to business owners and customers. 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 A26, 24-hour working was employed to complete the pipelaying in the shortest possible timescale. Additionally, roads were temporarily reopened around holiday periods to minimise disruption.

Project summary

Testing and commissioning of the new 315mm trunk main began in December 2022 with the final connection to the network completed in February 2023. The new main provides a strategic backup system, bolstering NI Water’s existing infrastructure to reinforce supply to approximately 4,000 properties.

The water network in the western end of the Thames Valley Supply Area is dominated by local borehole water sources. Over time, population growth coupled with general environmental drivers to reduce reliance on groundwater sources in sensitive chalk stream areas, Thames Water has sought to improve supply resilience and deployable output by linking local sources via trunk mains. This allows movement of water from one area to another as well as to reliably supply the intermediary supply zones. Typically, water from Oxford that is produced at Farmoor Water Treatment Works is transferred via a series of trunk mains to maintain resilient customer supplies to approximately 90,000 people in Swindon and the surrounding supply areas. Background The existing Faringdon Water Booster Station (WBS) to Blunsdon Reservoir transmission system comprises a 700mm diameter asbestos cement pipe and a 900mm diameter glass reinforced plastic (GRP) pipe built in 1987 and 2001 respectively. This transmission system is approximately 15.8km long and has various interconnections between the pipes to provide resilience in service. The Faringdon WBS to Blunsdon Reservoir 900mm GRP main represents one leg of this network. Due to the high frequency of failures, which had a significant impact on Thames Water’s ability to transfer treated water into the Swindon area, work began in AMP6 to replace the highest risk section in the Highworth area and 2.8km was completed, including a crossing of the River Cole. Following the successful replacement in AMP6, and an increased deterioration of the existing 900mm GRP main, the remaining balance of scope (13.7km) was approved for delivery in AMP7. To mitigate the frequency of bursts and the impact of the deteriorating asset on customer supplies, temporary emergency abstraction licences at Baunton WTW and Latton WTW were secured with the Environment Agency to allow the existing GRP main to be operated at a lower duty. Project summary The principal drivers for the project are: To reduce the supply interruption risk to customers in Swindon and the Cotswold area. In a reasonable worst-case scenario, without the current mitigations it could equate to over 14 million minutes. To minimise the risk of customer complaints associated with low pressure and/or no supply. In a reasonable worst-case scenario, without the current mitigations this could equate to over 90,000 properties. To eliminate reliance on groundwater sources under emergency licences to cover the loss of flow during a burst. To reduce reliance on groundwater sources that draw from chalk streams and the River Kennet during high demand and drought conditions. To increase trunk main capacity and transfer rates to accommodate increasing flows for future population growth (principally in the immediate Swindon area). To eliminate the frequent and expensive repair costs of the existing GRP main sections. To restore Thames Water’s trunk main network resilience and bulk transfer capability in this area, which is fundamentally impaired when the Faringdon to Blunsdon main is operating at a reduced duty rating. [caption id="" align="alignnone" width="1200"] Google Maps image showing pipeline route[/caption] Planning and design Pipeline route: Initial design work was completed during AMP6 by Stantec UK as part of the Phase 1 delivery. The proposed route closely follows the existing 700mm asbestos cement and 900mm GRP mains, and there are several advantages to following this existing route: This represents the most direct route between Faringdon WBS and Blunsdon Reservoir thus minimising the overall length of pipework required. It is mainly through farmland and minimises the need to work in residential areas. It minimises impact on landowners. Ease of access for Thames Water through use of existing way leaves Existing information from previous investigations can be utilised. The AMP7 project was awarded to Kier Infrastructure and Overseas Ltd when detailed design of the pipeline route was reviewed and refined, taking account of ecological constraints, requirements from landowners and planned developments along the route. Archaeological mitigation: A programme of archaeological mitigation was undertaken by Wessex Archaeology following consultation with the relevant county archaeological advisors. A mitigation strategy comprised excavation, recording and the strip, map, and sampling. The archaeological excavations formed part of a staged approach consisting of an archaeological desk-based assessment, geophysical surveys, and archaeological evaluations. Through collaboration with the approving authorities, Thames Water adopted targeted route changes to avoid known areas of high archaeological interest. Generally, a small number of finds were found with possibly the most significant being a crouched burial in the Blunsdon section of the pipeline. [caption id="" align="alignnone" width="1200"] Archaeological investigations and (right) crouched burial - Courtesy of Kier Infrastructure and Overseas Ltd[/caption] Pipe material: As part of the design deliverables a technical note was prepared comparing ductile iron, carbon steel and HDPE as the three commercially feasible materials for this diameter range. The recommendation was to adopt HDPE PE100 as the preferred pipe material, using 1200mm OD SDR17 from Aliaxis UK. Pipework used in cross connections, existing utility crossovers, shafts and other special cases was designed using ductile iron supplied by Saint Gobain PAM UK, with mechanically restrained VE joints as required. Furthermore, for the tunnel sections, steel pipework with the E-Joint system was utilised supplied by Noksel España. To ensure asset design life, steel pipework was maximised for the critical tunnel sections with pipe wall thickness specified at 10mm, which was greater than Thames Water’s asset standard of 6mm. Based on the pH levels of the water the pipe would be conveying, a far superior asset design life of 100+ years could be theoretically achieved. Environmental impact assessment (EIA): During the initial stages of the project, several desktop and detailed environment, archaeological and third-party assessments and reports were compiled. This highlighted areas where further surveys and investigations were later completed ahead of an Environmental Impact Assessment Screening Opinion being submitted to the relevant councils for review. A full EIA was requested but this was, however, successfully challenged with the Secretary of State who did not consider the environmental impact would be of a magnitude necessary to suggest a scheme of this scale would result in significant environmental effects, which would exceptionally necessitate an environmental statement. This successful challenge still obligated Thames Water to work closely with the local approving authorities to deliver a comprehensive programme of environment and archaeological mitigation works for the route. [caption id="" align="alignnone" width="1200"] Pipes laid along route - Courtesy of Kier Infrastructure and Overseas Ltd[/caption] Faringdon to Blunsdon Trunk Main Phase 2: Supply chain - key participants Project delivery: Kier Infrastructure and Overseas Ltd Designers & specialist consultants: WSP Sahara survey: Water Research Centre Ltd Archaeological investigations: Wessex Archaeology Civil Engineering Contractor: CPC Civils Civil Engineering Contractor: OCC Services Ltd Trenchless crossings: HB Tunnelling Limited Shoring/temporary works: GroundShore Ltd Tunnel boring machine: Herrenknecht Precast jacking pipes: FP McCann HDPE PE100 pipe: Aliaxis UK Ductile iron pipes: Saint Gobain PAM UK Steel pipework: Noksel España Tunnel roller spacers: FT Pipeline Systems Pipe fittings, bends, tees & collars: George Green (Keighley) Ltd Pipe fittings: Wolseley Pipe fittings: Electrosteel Castings (UK) Ltd Pipe fittings: PTS (SA) Limited Valves: AVK UK Ltd Welding: Fabricon Ltd Welding: PTS Group Butt fusion welding machine: McElroy Manufacturing Independent weld inspector: Technical Innovation Servis Ltd Temporary fencing & gates: RF Gardiners Ltd Construction The project was classified as a ‘high consequence project’ requiring an enhanced level of quality assurance. To achieve this, several measures were implemented. As part of this strategy, the delivery contractor Kier Infrastructure and Overseas Ltd was briefed to deliver the project in phases to tactically reduce Thames Water’s operational risk until the project was fully commissioned. The project brief also included decommissioning of the existing fragile 900mm GRP which will be safely decommissioned following commissioning of the new DN1200 pipeline. The contractor will make allowances to ensure that the existing 900mm GRP main can be slip-lined in the future for additional resilience. [caption id="" align="alignnone" width="1200"] (left) Drive shaft, (middle) tunnel pipe insertion and (right) the completed tunnel - Courtesy of Kier Infrastructure and Overseas Ltd[/caption] Tunnelling: Open cut techniques were the predominant pipe installation methodologies and were undertaken by CPC Civils and OCC Services Ltd. However, several trenchless crossings were required for the major roads and rivers crossed by the pipeline route. The relatively straight forward digger shield tunnel boring machine was the predominant method used for trenchless crossings, including Bydemill Brook and the A361. The crossing of the B4019 proved more challenging however, when hard rock was discovered. This was because of a last-minute change in the location of the micro-tunnel shaft to avoid a new attenuation pond being built by a developer in the immediate area. Following a review of the new geotechnical investigation completed, it was agreed that the previous digger shield tunnel boring machine was not suitable to overcome the hard rock. Instead, the more robust variable density tunnel boring machine was employed with a specialist drill head brought in from Herrenknecht in Germany to cope with the density of the rock. Although the deployment of this complex machine took four weeks to set-up, the 180m long, 1.5m diameter tunnel was constructed in no time at all and was successfully completed in just over eight weeks. The trenchless crossings were undertaken by HB Tunnelling Limited. Pipe welding: An automatic butt fusion welding machine was utilised on the project to enable the joints to be made in what was an industry first. The machine from McElroy Manufacturing was shipped from the United States for the project, and enabled butt fusion joints to made up to 1200mm in diameter; a first of its kind in Europe. The automatic nature of the machine enabled far higher quality welds to be made and on a consistent basis as the human element of checking temperatures, raising of the welding plates etc. was eliminated. [caption id="" align="alignnone" width="1200"] Pipe welding operation and (inset) McElroy Manufacturing welding machine - Courtesy of Kier Infrastructure and Overseas Ltd[/caption] Welding work was undertaken by Fabricon Ltd and PTS Group with Technical Innovation Servis Ltd employed as an independent weld inspector to provide an additional level of assurance on the quality of the butt fusion joints made on the 1200mm OD PE100 SDR17 pipework. Commissioning Due to the large volume of water involved in commissioning each section of the new pipeline and significant flow rates required to achieve water quality standards, flushing lagoons were constructed to allow the safe and controlled disposal of the flushing water. Working in the community/customer communications Following disruption to landowners over many years due to frequent bursts on the existing GRP pipe, all contractors have been fully focused on maintaining and improving relationships with all landowners. At the time of writing (May 2023), Kier Infrastructure and Overseas Ltd and CPC Civils have worked very successfully with all landowners along the new pipeline route developing great working relationships. This has been demonstrated on a few occasions particular during the funeral of one landowner who CPC Civils had developed a great relationship with, when works were stopped so all workers could pay their respects. [caption id="" align="alignnone" width="1200"] (left) Funeral cortege - Courtesy of CPC Civils, and (right) Salvation Army Christmas present appeal 2022 - Courtesy of Kier Infrastructure and Overseas Ltd[/caption] Kier have also worked well with local councils donating materials for community initiatives, with CPC Civils also donating two portable defibrillators to support local campaigns, as well as supporting a Salvation Army present appeal on the run into Christmas 2022 to support families who would otherwise be unable to afford gifts for their children. The project has also given the opportunity to work with the royal agricultural university and bring students to site to understand the ecological and environmental impact and considerations on a project of this scale, as well as visiting their workshops to build owl boxes to be installed along the route of the pipeline. Summary Design of the £45m Faringdon to Blunsdon Pipeline Project commenced in November 2020 followed by a construction start in May 2021. [caption id="" align="alignnone" width="1200"] Flushing lagoons - Courtesy of Kier Infrastructure and Overseas Ltd[/caption] Commissioning and beneficial use of the pipeline is expected in November 2023 with all site works being completed by August 2024. This will complete replacement of the 15.8km transmission system providing resilience to supplies to help meet future supply and demand requirements.

Northern Ireland Water’s Cushendall Water Pumping Station (WPS) is housed on the outer perimeter of Dundonnell Water Treatment Works (WTW) situated on the outskirts of Cargan village in the middle of County Antrim. The WPS solely supplies Parkmore Service Reservoir (SR) with potable drinking water, which in turn gravity feeds three other downstream SRs (Knockans, Mullarts and Knockenny), which provide for the surrounding Glen’s of Antrim district. Parkmore SR has a capacity of 1.3 ML suppling a population equivalent of approximately 2000 with an average day demand in peak week (ADPW) of 17.6 l/s. The existing trunk main The Cushendall Water Pumping Station to Parkmore Service Reservoir Trunk Main was constructed back in the 1970s using 6” PVC pipeline across bog land on mountainous terrain outside Cargan village. This has posed operational problems over the years when locating and repairing any leakages or bursts. Repair machinery has become stuck and unable to navigate the poor ground conditions raising access issues and Health & Safety concerns for staff and operatives attending repair works. Some bursts in the off-road pipeline have caused expensive tankering operations to keep the ~2000 customers with a reliable supply of potable drinking water to the villages of Cushendall, Cushendun and Glenariff. In addition, the existing Cushendall WPS has been difficult to maintain due to the age of the surge vessel, panels and pumps. Project scope NI Water, as part of the IF105 Integrated Partnerships Framework, identified the need to relocate the Cushendall WPS and associated trunk main due to the ongoing operational problems and supply outages. The new scheme included the following scope: A new modular, prefabricated, modular, plug and play water pumping station located in the verge close to a picnic area off the Glenravel Road, approximately 0.5km south of Cargan Village, Co. Antrim. Connection to the existing 18” trunk main in the same picnic area, and approximately 400m of new suction main to deliver water to the new pumping station. Approximately 2km of new 225mm HDPE rising main to deliver water to Parkmore SR installed in the carriageway for improved access. Alternative connections to live tanks at Parkmore SR (non-siphoning), including baffle curtain works and the addition of a 200mm bypass and meter. Civil and MEICA abandonment works of existing Cushendall WPS, and re-tapping the existing chlorine residual pump. [caption id="" align="alignnone" width="1200"] Dual lay pipework inside steel sleeves - Courtesy of WSP[/caption] Detailed design and engineering challenges Following ECI works in October 2021 by the Farrans/Glanua Group Joint Venture under a NEC4 option ‘A’ contract, engineering designs were undertaken comprising of a range of elements including: Proposed trunk main route, longitudinal sections, and connection details. Scheme plans with details on bridge crossing and new water pumping station location. Reinforced concrete slab drainage and ducting detail for modular pumping station. Surge analysis report and proposals. Hydraulic assessment of the new trunk main with total head loss, average flow, and peak flow information. From these reports it was concluded that surge could occur when the pump flow increased or decreased to suit changing water demands or uncontrolled sudden pump failure. From this the WPS was designed with a 500-litre bladder type surge vessel in accordance with the selected 38Kw pumps chosen for a 35 l/s and 7 bar charge arrangement. The rising main was designed with six air valves to aid high/low pressure spikes or transients during operation. The hydraulic analysis of the new rising main from the picnic area to Parkmore SR, using the average day demand in peak week (ADPW) of 17.7l/s, calculated a total head loss average flow of 1.10m and peak flow 3.09m for the total 4.2km of the 225mm HPPE pipeline. Construction The construction contract was awarded under NEC4 Option ‘C’ Target Cost Contract to Farrans/Glanua Group JV. Construction began in December 2022 and took place over a 14-month period at a total cost of £1.3m. The scheme was situated in an Area of Outstanding Natural beauty, this brought its own unique constraints and limitations. Due to ground conditions, opencut excavations was the method of installing the 2km of 225mm HPPE pipe under a DFI Roads approved lane closure using a rolling traffic light system operated and maintained by traffic management company, McVeigh Contracts Ltd. [caption id="" align="alignnone" width="1200"] (top left) traffic management barriers, (bottom left) notice of works and lane closure for pipeline installation and (right) pipeline track excavation - Courtesy of WSP[/caption] Bridge crossing Following trail holes and liaison with DFI Roads at ECI stage, two sections of 180mm HPPE pipework were installed inside 250mm steel sleeves and C30 concrete and steel mats used for protection over the span of the 35m bridge structure. A reduced road cover level of 700mm was agreed and approved with DFI Roads to ensure the structural integrity of the underside of the bridge remained unchanged. Parkmore Service Reservoir works In tandem with the construction of the pipeline, a specialised company Waterworx Ltd carried out the alteration works to the live Parkmore SR. Each cell was shut off and drained individually to aid the installation of the inlet pipework and repositioning/installation of the new baffle curtains. All of the SR works were undertaking in close liaison with NI Water Operations who ensured stringent drain down and sampling timelines to ensure continuous water supply the local area. [caption id="" align="alignnone" width="1200"] (left) the existing baffle curtain and (right) new anti-siphon inlet pipework and baffle curtain at Parkmore Service Reservoir - Courtesy of WSP[/caption] Modular pumping station The new modular ‘plug and play’ WPS included the following elements: Pumping system and associated ancillaries. Control panels. Telemetry. Surge suppression. Building services. The kiosk and skid base of modular pumping station was supplied by Morgan Marine Ltd. The assembly of the mechanical and electrical items were completed at Profitec Solutions’ headquarters in Cookstown. Electrical switchgear was built into the kiosk to facilitate an external portable generator in the event of mains supply failure. Following a factory acceptance test, the modular WPS was delivered to site in November 2022 and craned into position on top of the 450mm reinforced concrete base slab. For the inlet supply to the WPS an under-pressure Tee was installed onto a live existing 450mm cast iron trunk main, this allowed for seamless transfer to the new section of trunk main without any disruption to current trunk main supply in the district. Parkmore Water Pumping Station & Trunk Main: Supply chain - key participants Delivery contractor:  Farrans/Glanua Group JV Design/project management: WSP Civil Design: Jacobs Design Main Contractor (Civils): Farrans Main Contractor (M&E): Glanua Group Civil team: McCormick Contracts Ltd Electrical works: Profitec Solutions Traffic Management: McVeigh Contracts Ltd Kiosk for new WPS: Morgan Marine Ltd Pumps: Grundfos Under-pressure tee connection: Waterworx Ltd Quarry products & reinstatement: Northstone Materials Ltd HDPE pipe: APP Fusion Group WPS automatic control (PLCs & HMI): Mitsubishi Mechanical, electrical and instrumentation works The Parkmore WPS consists of two Grundfos 38 KW CR125 booster pumps working on a duty/standby regime which can be controlled manually or automatically by way of variable speed drives. The duty/standby system is set to switch over after each pump stop its programmed cycle. [caption id="" align="alignnone" width="1200"] (left) The existing Cushendall WPS and (right) the new Grundfos pumps and inlet/outlet pipework - Courtesy of WSP[/caption] The two modes of control available are the primary, level-based control, and the secondary, pump fixed speed mode control. The chosen method by the client is the level-based method, remotely controlled on Telemweb with agreed low and high Parkmore Service Reservoir set-point levels (pumps on at 2.2m and off at 2.8m). The WPS automatic control is achieved using a Mitsubishi iQ-R series Programmable Logic Controller (PLC) system attached to a 12” Mitsubishi GOT Human Machine Interface (HMI). The PLC communicates status/alarms/events and exchanges set-points between the PLC and the telemetry talus unit via Modbus RS232. Critical status, alarms and controls are hardwired to/from the telemetry talus unit. The HMI provides information to the MCC for pumps 1&2 with the following list of options for NIW operatives to manually operate inside the WPS: Plant data. Plant mimics. System screen. Control system settings. I/O test pages. Trends and alarms. [caption id="" align="alignnone" width="1200"] (left) HMI screen and (right) Parkmore Dungonnell WPS - Courtesy of WSP[/caption] Project summary Commissioning of the new pumping station began in early January 2023 and the existing pumps at Cushendall Pumping Station were turned off, allowing the 28 days commissioning period to begin. Following a successful testing period and training of NI Water Operatives, the new Parkmore Pumping Station is solely suppling the strategically important Parkmore Service Reservoir regularly during the day. The redundant Cushendall WPS has been electrically isolated and associated pipework has been sealed and capped off. To date the new pumping station has supplied over 60,000m3 of clean drinking water to Parkmore SR and has proven to be a resilient and reliable trunk main asset to NI Water.