Supply Chain - Water Treatment - Contractors

Lee Road Water Treatment Plant (WTP) provides approximately 70% of Cork City’s total treated water supply. Water is taken from the River Lee, treated and then pumped to reservoirs in the north-west of the city through a system of rising mains. Water is distributed to consumers throughout the city via a network of gravity distribution mains. The treatment of drinking water began at this site in 1879, and whilst there have been several upgrades throughout its lifespan, none have been completed since the 1950s. This treatment plant upgrade is the first major investment in over 60 years and will support continued population growth and economic development in the city. The upgraded treatment facilities have safeguarded the water supply for Cork City and the works have enabled the supply to be removed from the Environmental Protection Agency’s (EPA) Remedial Action List. Undertakings Murphy Ireland are one of eight contractors that have been on the Uisce Éireann framework to deliver major non-infrastructure projects since 2017. Murphy was awarded the €40m Lee Road WTP contract via competitive tender in 2019 and was required to complete these key works by July 2022, while the existing plant remained in full operation. Uisce Éireann issued a high-level outline design brief with Murphy responsible for completing the full detailed design. A significant amount of optioneering, value engineering and constructability reviews were undertaken. The end solution offered better value for money and Murphy was appointed Project Supervisor Design Process (PSDP), equivalent to Principal Designer under CDM regulation, and Project Supervisor Construction Stage (PSCS), equivalent to Principal Contractor, for the duration of the project. [caption id="" align="alignnone" width="1200"] Lamella plate sedimentation tanks - Courtesy of Murphy Ireland[/caption] Scope of works The upgraded facility designed and delivered by Murphy included: Reconfigured raw water intake inclusive of a raw water band screen and bypass arrangements. Coagulation, flocculation, and clarification system. Six rapid gravity filters utilising Xylem Water Solutions' Leopold underdrain filters. Chemical and UV disinfection. Installation of pH correction facility via dosing sodium hydroxide. Washwater and sludge handling facilities, incorporating a sludge plate press. New treated water pumping station and refurbishment of existing pumping station, complete with high efficiency frequency inverters and motors. EICA infrastructure including PLCs, communication links and SCADA system. Prevention measures to protect the works from flooding during extreme weather events. Full Murphy managed operation and maintenance of the facility for 12-months. Construction challenges All process wastewater is collected and treated, ensuring it is suitable for discharge to the adjacent river Lee within the specified discharge standards. During construction, Murphy encountered and resolved a number of construction challenges due to the high-water table on the site adjacent to the river Lee. This led to challenging working conditions. Murphy addressed this issue by installing deep sheet pile cofferdams to lower gravel beds and installed a ringed dewatering system to manage groundwater. The site was raised following construction of tank structures to provide a new ground level 2m above previous levels. [caption id="" align="alignnone" width="1200"] Overview of site showing the build complexity - Courtesy of Murphy Ireland[/caption] Another key challenge on this project was keeping the existing plant operational for the entire construction phase to its full capacity. It was essential that the works were carried out with no interference to the existing water treatment process. Working within a city presented several logistical constraints including constrained and restricted site access. Therefore considerate, efficient, and well-planned logistics plans and methodology were integral to minimising disruption for the locality and the smooth running of the construction works. Construction Site Traffic Management (CSTM) was meticulously managed and ensured no interference with the existing plant operations. Staged infill operations were undertaken to minimise this disruption. Significant off-site construction was undertaken in addition to rigorous off-site factory testing, resulting in a reduced number of construction defects and a smooth and efficient commissioning process. The commissioning plan was developed throughout the life cycle of the works and signed off by the client three months ahead of planned commissioning. This gave enough time for all parties to be briefed and understand commissioning requirements, durations, key activity outputs and agree standards to be reached. [caption id="" align="alignnone" width="1200"] UV disinfection - Courtesy of Murphy Ireland[/caption] Lee Road WTP - Supply chain - key participants Principal contractor: Murphy Ireland Process/MEICA design & systems integrators: Murphy Process Engineering Civil design: Finbarr Gannon Ltd Electrical design: Seamus Byrne Electrical Ltd Groundwater dewatering: WJGL Ltd Groundwater monitoring: Priority Geotechnical Ltd Formwork: Hickey Formwork ltd Precast concrete tanks: Shay Murtagh Precast Sheet piling: Ward Piling Steel reinforcement: James’s Street Steel Manufacturing Ltd Tower crane hire: Mantis Cranes Security fencing: Irish Fencing Services General & specialist fabrication: Russell Metal Fabrication Ltd Gantry crane: Ballinphellic Engineering PLCs & MCCs: Omron CPU35/ASC Intake band screens: Beaudrey Process pipework: Freeflow Pipesystems UK Process pipework: Superior Pipeline Products Ltd Sludge plate press: Micronics UK Ltd Pumps: Celeros UK Flow controls: Rotork Inverters & motors: ABB Valves: Talis Leopold underdrain filters: Xylem Water Solutions Air compressors: Atlas Copco Ltd UV disinfection: Hanovia Chemical dosing: Colberge Water Systems Bulk chemical storage tanks: SILOTANK Bulk chemical storage tanks: Phaser Limited Surge vessels & walkways/access systems: Murphy Design Protection of assets Situated beside the River Lee, the existing water treatment plant experienced significant flooding in the past and was at the end of its useful lifetime. The design solution delivered a state-of-the-art treatment facility whilst raising the site by 2m to protect against future flooding during extreme weather events. For instance, the existing ground consisted of porous gravel beds that facilitated easy passage of groundwater. Careful dewatering design ensured good management of resulting groundwater flows. [caption id="" align="alignnone" width="1200"] UV-treated water - Courtesy of Murphy Ireland[/caption] Achieving a successful delivery Collaborative working was central to Murphy’s approach, and in conjunction with Uisce Éireann, continual updating of the three week look ahead and the Master Information Delivery Plan (MIDP), ensured effective planning and minimised unforeseen events. Murphy’s in-house expertise designed and delivered the project with strict adherence to Uisce Éireann Asset standards, and provided mechanical, electrical, instrumentation and control automation (MEICA), and civil services, including in-house process design, piling, and structural steel design and fabrication. Mid-programme planning changes were introduced to help achieve an improvement to the delivery programme. The original plan for the project was to reuse the existing sedimentation tanks, however Murphy suggested building entirely new ones as this would provide a better overall product, improving programme, in addition to improving the whole-life cost and de-risking the supply concerns for the locality. The upgrade works on Lee Road WTP will also reduce the energy consumption and running costs by more than 40%. Sustainability, as on all Murphy projects, was a key part of the strategy at Lee Road. Various measures were put in place to protect local wildlife such as bats and otters, in addition to ensuring, waste material was reused where possible. [caption id="" align="alignnone" width="1200"] Alum bulk storage - Courtesy of Murphy Ireland[/caption] Meeting Uisce Éireann’s customers’ needs Independent testing of raw water, treated water, sludge parameters, noise, and other parameters were undertaken during the Performance period to confirm compliance with EU Drinking Water Regulations. Murphy provided leadership for the following: Uisce Éireann have an ongoing water network upgrade programme around Cork City and Murphy supported Uisce Éireann’s needs to managing reservoir demands, alter final chlorine residual and optimising final water pH. Leading demonstrations of shutdown controls, water despatch control and interlocks with service reservoirs during EPA audits. Working collaboratively to commission an automated coagulation control system, which optimises use of aluminium sulphate coagulant, yet reacts quickly and efficiently to changing raw water characteristics such as colour, turbidity and UVT. Holding regular operational team meetings to agree the O&M programme approach. A three-year spares assessment vetted by the client to reach collective agreement. [caption id="" align="alignnone" width="1200"] Rising main pressure vessel - Courtesy of Murphy Ireland[/caption] Working throughout the pandemic With the project being delivered during the Covid-19 pandemic, multiple different challenges presented themselves. For example, throughout the start of the project at peak periods there could be upwards of 80 people working on site at any one time. However, following the onset of Covid-19, Murphy had to adapt the working practices, incorporating social distancing measures, rotas for breaks and shift start and completion patterns. Despite working throughout the Covid-19 pandemic and with the variety of risks, the safety record from the project was exemplary. Across two years of works the team had zero lost time incidents. Lee Road was selected for an external ISO Quality audit by Lloyds Accreditation and passed with distinction. Community liaison School visits during the operation phase continued to form a part our interaction with local groups and community, dovetailing with Cork City Council’s adjacent visitor centre which highlights the history of waterworks at Lee Road since the 1850s. During the construction phase local labour was utilised along with local suppliers. During Covid while many other workers in the city were furloughed, construction works continued at Lee Road which was deemed an essential construction project. The design processes included regular HAZOPs workshops to include at least 20 people from the client ranging from plant operators to statutory body representatives. [caption id="" align="alignnone" width="1200"] Final pumping - Courtesy of Murphy Ireland[/caption] Conclusion Following commissioning, which took place throughout the first half of 2022, water went into supply in July 2022, and Cork now has a new, secure, modern, state-of-the-art water treatment facility that will serve the community for years to come. The flooding risk that pertained has now been removed and the new works at Lee Road is fully integrated with the City and County water reservoir storage system, offering huge flexibility in clean water provision.

Stithians is a village in Cornwall that lies in the middle of the triangle bounded by Redruth, Helston, and Falmouth. Stithians Reservoir (the largest inland lake in west Cornwall) is the raw water source that supplies a maximum of 27.7 ML/day to Stithians WTW, which in turn supplies a population equivalent of 276,741 in west and south Cornwall. The reservoir, formed in 1965, has an area of 1.08 km2 and a gross capacity of 5,415 ML. Stithians dam is recognised as the windiest inland water in the south-west due to the featureless surroundings and its geographic elevation. Project summary Galliford Try was contracted by South West Water to design and build a new Granular Activated Carbon (GAC) water treatment plant to target a 25% reduction in THMs (a group of volatile and potentially toxic chemicals formed during water treatment with disinfectants, such as chlorine), manganese removal, and improvements to taste and odour. The scheme was designed to maximise off-site build opportunities as this reduces error and waste and aligns with Galliford Try’s net zero carbon strategy, eliminating possible dangerous in situ site construction issues, thereby improving safety during construction. [caption id="" align="alignnone" width="1200"] Stithians WTW and Stithians Reservoir dam prior to the commencement of the works - Courtesy of Galliford Try[/caption] Design The new plant will be fed from the existing rapid gravity filters and pumped up to the new GAC contactors via the new interstage pumps and pipework. The design has utilised the site’s topography by siting the GAC contactors at the top of the hill, so the clean and waste flows can gravitate back down the hill, through the downstream processes (UV, contact tank, sludge plant) and then be transferred into the network via the existing pumps and main network pipelines. Galliford Try ensured that the design utilised the steep incline through the site. Over time, these subtle efficiencies will have a positive impact on the sites long term net operational costs. Project scope New interstage pumping station from the existing primary filters. Chlorine dosing system for manganese oxidation and lime dosing for pH correction with an in-line static mixer. GAC plant downstream of existing rapid gravity filters. Clean backwash pumps. Regeneration waste tank. UV plant downstream of new GAC plant. Chlorine contact tank. New sludge thickener to provide additional treatment capacity for site produced sludges. Modifications to existing contact tank and existing high lift pumps pipework. [caption id="" align="alignnone" width="1200"] Model extract showing the existing works on the left, the new process plant on the right, and the GAC at the top of the slope - Courtesy of Galliford Try[/caption] Preparation, planning and early engagement FLI Precast was engaged very early in the design stage and their programme was built into the main Galliford Try programme and weekly collaborative planning meetings were held with the site team as work progressed. FLI Precast and sub-contractor Freeflow Pipesystems were used to enable cast in wall couplers to be procured and sent to Ireland to allow early production of wall units to ensure a prompt start on site once the contract was signed for design to commence. The design also had to allow for three access roads which cross the construction area, all of which had to be always kept open for operations in order that they were able to receive delivery of process critical chemicals, on a regular basis. Construction Construction commenced in January 2022 with the GAC foundations being prepared for the delivery of the precast wall panels initially for the GAC and then the chlorine contact tank sitting lower down the slope. The GAC building is a critical element of the programme as the internal fit out is complicated and time consuming, comprising pipework, valves, dosing and sampling boards and electrical panels. Off-site build was chosen as the fastest way of erecting the building to contain all the pipework, control cabinets, valves and sampling panels which are contained within being installed quickly. [caption id="" align="alignnone" width="1200"] Stithians GAC steel frame prior to cladding - Courtesy Galliford Try[/caption] Off-site build was also the chosen methodology for the chlorine contact tank, the clean backwash storage tank and the rinse/regen tank, all of which were precast concrete panel system installations. The new sludge thickener tank was designed as glass coated steel, again off-site built with fast installation time. Precast concrete storage tanks were the next structures to be completed, at the same time as the underground pipework. All the structural elements have been linked together with process pipework and an extensive underground cabling network links them electrically back to the main South West Water control room. Stithians WTW: Supply chain - key participants Client: South West Water Main contractor: Galliford Try Civil engineering & process design: Arcadis Precast design & installation (GAC & chlorine contact tank): FLI Precast Solutions Ltd Wall couplers: Freeflow Pipesystems Ltd Precast design & installation (regen & clean backwash tanks): A-Consult Ltd UV disinfection: Wedeco Ltd Flow control valves/actuators: AFFCO Flow Control UK Ltd MCCs & LVDB: Galliford Try Electrical installation: Drew & Co Ltd GAC pipework & support steel: Alpha Plus Ltd GAC control valve actuators: Rotork Controls GAC steel frame & cladding: Hewaswater Engineering Ltd Standby generator: DTGen Sludge thickener: DD Engineering Ltd GAC launders & Leopold flooring: Xylem Water Solutions UK Ltd Media: Western Carbons Ltd Miscellaneous metalwork: Minear Engineering Ltd [caption id="" align="alignnone" width="1200"] Inside the GAC gallery: Upper level control valves and valve actuators from Rotork Controls - Courtesy of Galliford Try[/caption] Savings 300T of site-won material was re-purposed to construct gabion basket retaining walls, saving material being sent to landfill, and approximately 40 additional vehicle movements to and from site which equates to a saving of 51 tonnes of carbon and approximately £75k of capital cost. Local resources and materials were also utilised. Subcontract packages requiring a large site presence were all local and where local suppliers were not available, Galliford Try used off-site build solutions extensively to reduce carbon and minimise risk. Safety & environment A very experienced team of site operatives was key to service strike avoidance. Good early GPR (ground penetrating radar) scanning and existing client information was utilised by the designers. Project specific surveys incorporating Matterport scanning of existing buildings, boreholes, trial pits and topographic surveys, were also undertaken prior to the start of scheme. This allowed for the BIM model to be built containing location information for all the existing services to prevent clashes and provide the site team a comprehensive picture to help prevent service strikes, by allowing trial holes to be accurately and safely excavated. [caption id="" align="alignnone" width="1200"] UV building process pipework and support concrete for GRP kiosk - Courtesy of Galliford Try[/caption] Communication Regular letter drops were undertaken to local residents to keep them informed of busy delivery times and works progress. Client operations were involved in all monthly progress and programme meetings, alongside weekly updates of on-site activities. Status At the time of writing (July 2023) all the main civils structures have been constructed, GAC building, chlorine contact tank, UV building, chlorine contact tank, regen and clean backwash tanks, sludge thickener, and various concrete slabs for a standby generator, interstage pumps, sludge pumps and control kiosks. Cabling works are now underway along with final pipework connections, and commissioning works will take place in the coming months for completion in December 2023.

Wooler Water Treatment Works (WTW) is fed by four boreholes and supplies up to 160m3/hour of potable water to Wooler and surrounding areas, including several tourist and semi-residential holiday parks serving over 5,000 people. Seasonal fluctuation in demand can increase turbidity and increase iron and manganese concentrations in the borehole water, particularly when flows are high, interrupted or varied. The existing treatment facility was reaching the end of its asset life and did not have the treatment stages to remove the turbidity, causing flows to run to waste. Frequent power outages and varied seasonal populations led to regular manual operator intervention and a growing reliance on tankering from other sites to ensure the supply zone remained primed. Background/drivers In 2016, Northumbrian Water (NWG) awarded Mott MacDonald Bentley (MMB) an Investigate and Define contract to review potential solutions to improve treatment at Murton and Wooler WTWs. Following this, in April 2018, NWG issued MMB a NEC3 ECC Option C Design and Construction (D&C) contract to deliver the design, construction, testing and commissioning of the new treatment facilities. Design for Wooler commenced in June 2018, with construction works commencing in May 2020. The main build was completed in April 2021 and water brought into supply following testing and commissioning. The previous treatment site was set to run to waste until turbidity in the borehole water was suitable to be treated further. NWG experienced turbidity spikes on pump start-up and flowrate changes, exacerbated by frequent power outages. This resulted in time consuming, costly operator intervention, and wastage of borehole water to the environment. Disruptions in supply needed quick operator intervention to ensure no impact to the customer, often necessitating tankering to maintain supply. The rural setting of the WTW meant during winter, operators faced increased risk in accessing the site. The new WTW incorporates four large pressure filter vessels which are effective in removing turbidity, iron and manganese at higher levels. The reduction in run to waste occurrences provides a more sustainable use of water abstracted from the aquifer whilst improving water supply security to the Wooler area. Within the investigation phase MMB and NWG decided to relocate the works to a more urban setting to reduce the risk on operators and minimise risk of weather events affecting power supply and communications to the site, both of which are critical to maintaining supply to the local community. This is especially critical at Wooler, as the area benefits from a transient tourist population which puts additional strain on the water supply system. [caption id="" align="alignnone" width="1200"] Clockwise from top left - Dechlorination plant, wastewater tanks, chlorine contact tank and treatment building - Courtesy of MMB[/caption] Design development The design phase commenced during the latter phases of construction works at the nearby sister site, enabling the design team to capture positive and negative lessons from the construction and client operations team. Over 100 lessons were collated and assigned owners to incorporate into the Wooler design. The results were evident in the programming and sequencing of the project, which halved the workforce on site when compared to Murton. Several design efficiencies were identified that further reduced the construction duration, including, designing out thrust block requirement, simplification of a complex dechlorination system and pre-washing filter media prior to delivery to reduce commissioning and significantly reducing commissioning water wastage. The MMB project team successfully challenged client asset standards which would have required an additional filter, and as such specified filtration by four sand pressure filters. The filters consist of an anthracite cap, sand, and manganese dioxide (MnO2) media. The sand and anthracite layers capture larger solids particles during periods of poorer water quality whilst the MnO2 acts as a catalytic media and further promotes manganese and iron deposition onto the filter media. By removing iron and manganese over a single stage, the project team designed out a secondary treatment stage, saving on TOTEX, carbon and minimising site footprint. The filtration method selected also provides a higher level of robustness, reliability and low operational costs compared with other technologies. The notional solution proposed maintaining use of the borehole pumps to generate sufficient pressure to drive flow through the new treatment plant to the existing service reservoir served by the site. [caption id="" align="alignnone" width="1200"] Multiple supply chain interfaces were modelled to proactively reduce snagging - Courtesy of MMB[/caption] The additional pressure required would require replacement of the borehole pumps and over 4km of mains in serviceable condition. Instead, the pressure head was broken within the site, reducing operation and maintenance risks, and improving site control and resilience through installation of high efficiency booster pumps to supply the network. Pumping of waste flows was minimised through agreeing discharges into the local sewer and surface water network, with dechlorination included for treatment of non-compliant flows. Pumping of drainage flows was also avoided through minimising site access roads, maximising green space and incorporation of SuDS trench and lagoon within the site footprint. Digital delivery was preferred from the onset, and the site location was GPR and laser scanned to produce an accurate 3D model of the current land and subterranean utility infrastructure. This model was developed further with key suppliers and multidisciplinary designers to progress to a full site-wide model of the civil, electrical, mechanical and process elements. The pressure filter, chemical dosing and metalwork suppliers uploaded models of their discrete works packages into the selected Common Data Environment (CDE) BIM360. The packages were incorporated into the overall site model, produced in Revit. This enabled the MMB design team to accurately model surrounding road structures, interconnecting pipework, services and road infrastructure in both Revit and Civil 3D. The 3D model is earmarked for use as a digital twin, to improve asset management and aid with efficiency of the everyday site operation. The site was designed such that all key instrumentation is above ground, but transfer pipework between treatment stages is below ground, giving full access to all valves and dosing points. Through development of the 3D model, operators were able to fully review the site in advance of a spade being struck, leading to changes to further mitigate operational and site hazards. Rethinking of the operating pressures has reduced operator risk within the building and the new process utilises more resilient process units than previously, incorporating a sophisticated control philosophy which minimises unintended shutdowns and enables restart at the push of a button, rather than a complex series of manual valve operations. [caption id="" align="alignnone" width="1200"] Treatment process units being installed after off-site manufacture and testing - Courtesy of MMB[/caption] Off-site manufacture opportunities were identified to minimise personnel operating on a relatively small site. Chemical dosing facilities were manufactured and tested within kiosks and delivered to site as plug-and-play elements of the process, improving quality control through factory testing and commissioning. Vertical pressure filter units, associated pipework, and metalwork access gantry were all pre-assembled and tested prior to final offload and assembly on site. This approach was taken for the complex manifold pipework weaving between and connecting the site process plant. The 3D model was utilised by stainless steel pipework fabricators to design and detail the pipework for accurate off-site manufacture, eradicating cutting on site. Building on lessons learned from Murton, the contact tank design was changed from in-situ build to a semi pre-cast assembly, reducing the on-site build programme of the structure and reducing the trades and temporary works required. Covid19 hampered the ability to carry out informal meetings, though the digital delivery of the project meant that communication was not impacted during the critical latter stages of the design. The 3D model was utilised to facilitate key coordination meetings including ALM and HAZOP reviews, helping both MMB and NWG communicate proposals to non-technical colleagues. Enabling NWG to utilise the same model during design aided with design acceptances and operational reviews of proposed site processes. Fire and hazard reviews were carried out utilising third person perspective within the model. The integrated use of BIM360 brought more of the supply chain into the collaborative solution development allowing all stakeholders to visualise the final product in a way not possible with traditional 2D drawings. This allowed for greater clash detection prior to construction enabling designs to be tweaked at low cost in the office, reducing standing time on site. Key interfaces between each mechanical supplier were digitally inspected in advance of installation, reducing the likelihood of common avoidable defects in major treatment projects. [caption id="" align="alignnone" width="1200"] Complex subterranean service network required careful clash detection - Courtesy of MMB[/caption] Wooler WTW: Supply chain - key participants Design & build: MMB Hydraulic modelling: Mott MacDonald Ground investigation: Dunelm Geotechnical & Environmental Sheet piling: Van Elle Precast concrete: FLI Precast Solutions Blockwork: Gallaway Construction Structural steelwork design & build: Glendale Engineering (Milfield) Ltd Metalwork: JHT Fabrications Ltd Electrical/cabling: Dongard Mechanical & Electrical Ltd Scaffolding: Ingleford Scaffolding Ltd Shoring/temporary works: MGF Ltd Pressure vessels: ACWA Services Surge vessels: Quantum Engineering Developments Ltd Chemical dosing design & supply: Sheers Ltd Pumps: Grundfos Static mixers: Statiflo Intenational Major valves: AVK UK Ltd Steel pipework fabrication: JBF Group MCC: CEMA Ltd Systems integration: IDEC Technical Services Generator: WB Power Services Ltd Security systems: 2020 Vision Systems Ltd Roller shutter doors: Ascot Doors Ltd Security doors: Bradbury Group Construction Working within a D&C environment, constructability is considered at every stage. The Wooler construction team were identified early in the project, with regular reviews held to discuss the design, its buildability and associated temporary works requirements. These reviews, along with similar client meetings, were held to invite challenge and give the whole project team an opportunity to influence the design; reducing and controlling risk when total mitigation was not possible. Excavators with in-built GPS and intelligent machine control utilised the digital terrain model to excavate within 6mm accuracy, reducing over dig but also bringing wider programme and health and safety benefits. The programme was sequenced using the 3D model, with the order of build determined by service and structure depth. All below ground structures and pipework were set out utilising the model which, alongside excavation accuracy, ensured pipes were laid accurately with no clashes or diversions incurred despite the complex subterranean service network required. [caption id="" align="alignnone" width="1200"] (left) Precise installation of below ground infrastructure and slab penetrations prior to main slab pour and (right) treatment building slab cast prior to superstructure installation - Courtesy of MMB[/caption] The accuracy minimised soil disposal resulting from over dig and designing out thrust blocks through modifications to the pipework specification further reduced excavation. Under licensed exemptions, 1000t of excavated soils were diverted to local agricultural projects and 1000t of compound stone was re-purposed for an off-site access road. Similarly, 1000t of clay arisings from a nearby project were utilised within the Wooler site. Utilising CLIP (Collaborative Lean Improvement Programming) planning and careful sequencing halved the number of people working on site, compared to the sister project at Murton WTW, minimising the number of long journeys associated with rural working. Local suppliers and local staff were embedded within the delivery team, further reducing the embodied carbon impact. Accurate modelling of the proposal in advance of construction minimised material wastage in cut to suit elements of pipework, steelwork, and reinforcement. MMB utilised the local supply chain as much as possible. Major successes were brought about through engaging with a heavy steel fabricator based within a quarter of a mile of the site and an electrical installation contractor based in Northumberland, rather than usual supply chain partners. Utilising more local suppliers meant that the level of service and quality provided was high, with benefits of carbon reductions and reduced transport of major steel elements along busy rural single carriageways. Through inviting NWG, stakeholders and supply chain to CLIP planning sessions, MMB identified programme savings for all parties through sequencing of site tasks and identifying mutually beneficial opportunities, such as sharing plant to reduce vehicles on site. For example, bringing electrical and major steel subcontractors together identified opportunities for cable containment hangers to be installed within the fabrication works at no additional cost, reducing work at height risk and task time for cable installation teams. Construction sequencing, temporary works and site aesthetic were all modified to minimise impact on the local community. Installation of the permanent access point to the site was prioritised in the programme to minimise traffic management on Berwick Road, a main artery for the village. Moving treatment processes inside the main building negated the requirement for additional security fencing and the building itself was designed to resemble agricultural buildings in the area. The permanent site footprint was minimised as much as possible but in doing so, a larger temporary compound area was necessary. The project team worked with local landowners to identify the best location for the temporary works to reduce this impact, and temporary laydown areas were returned for use as soon as sequencing allowed. [caption id="" align="alignnone" width="1200"] Precast contact tank during construction - Courtesy of MMB[/caption] Health & Safety MMB’s positive safety culture was evidenced throughout construction, where in over 75,000 hours worked, over 5,500 proactive health and safety and environmental incidents were reported, resulting in no lost-time or reportable injuries. An added complication to this project has been the Covid19 pandemic, during which the site remained operational and avoided closure. The project was sequenced to minimise the number of people working on the site at any time and method statements were developed to ensure as much work as possible could be completed whilst maintaining strict social distancing. Conclusion Wooler WTW was built as part of a two-project batch. The two sites were built sequentially, which enabled MMB to derive multiple lessons from the Murton project and deliver a new greenfield treatment works within the client’s budget and with minimal impact to the local community. MMB’s long-term collaborative relationship with NWG, combined with the use of trusted local suppliers, off-site build techniques and regular planning sessions enabled multiple sequencing and material efficiencies to be realised, further driving down the carbon impact of the project. Through digital delivery, a significant number of supplier interfaces were carefully managed, avoiding the delays and defects commonly associated with multidisciplinary projects.

Littlehempston is a large complex potable water treatment works located near Totnes, South Devon, which has multiple river and reservoir sources. It supplies circa 78,000 properties to an area that includes Torbay, Newton Abbot and Kingsbridge. The original treatment works comprises flat bottom clarifiers (FBC) and rapid gravity filters (RGF), with an additional process stream added later, utilising dissolved oxygen flotation (DAF) and additional RGFs. The current £14.4 million, 2-year project involves intercepting the flows where the two treatment streams join and passing through a new granular activated carbon (GAC) process and ultraviolet (UV) treatment to the improve drinking water quality. Project drivers South West Water’s objective to employ granular activated carbon (GAC) has been to address the following: Ensure compliance with pesticide standards. Target a 25% reduction in total trihalomethanes (TTHMs)  in the final water leaving the treatment works. Target a reduction in average levels of TTHMs to less than the screening value of 50 µg/l. No detections of methyl-isoborneol (MIB) greater then 5 ng/l in final water and target a long-term reduction in taste and odour customer contacts. At the scoping stage, Galliford Try and Arcadis worked closely with South West Water to establish the most cost-efficient solution when considering both operational costs (OPEX) and capital expenditure (CAPEX) to ensure South West Water achieved the best whole life costs. [caption id="" align="alignnone" width="1200"] 21m diameter dirty back wash tank - Courtesy of Galliford Try[/caption] Project scope The project solution includes a new GAC treatment process. Six reinforced concrete contactors, were constructed in situ, and housed within a steel clad, portal frame building. ODEX piles were used to support the structure due to the encountered ground conditions. The new primary disinfection is to be via ultraviolet (UV) disinfection. The UV building containing the reactors is an in situ concrete structure, supporting a GRP (glass fibre reinforced plastics) kiosk. This kiosk also houses the new control panels for the GAC and UV processes being installed. Two new precast tanks are being installed, providing dual use as combined interstage pumping and clean backwash water storage. An off-site fabricated, precast solution was used which provided significant programme advantages, and reduced the health and safety risks. A four-pump arrangement provides duty/standby interstage pumping, clean backwash feed and a common standby which can support both interstage or backwash pumping as required. The duty pressure and flow characteristics of both systems was optimised to allow the same pump to be selected for both operations. This provides South West Water improved flexibility and resilience for future operation and maintenance. [caption id="" align="alignnone" width="1200"] Below ground large diameter pipework required to be installed around existing structures and services - Courtesy of Galliford Try[/caption] A further tank will be used for the collection of GAC backwash and rinse. The GAC backwash water is not being combined with the existing site waste and supernatant system, and instead will be returned via new pumps directly to the inlet works. Appropriate sampling is being installed to confirm it is of suitable quality to return and can be diverted into the existing wash water system if required. This sustainability driven solution improves the efficiency of the plant, reducing pressure on incoming water resources whilst avoiding discharges to the environment. During the outline design phase, an existing redundant structure on site was identified as being suitable for use as a collection tank for GAC regeneration wastewater. Re-using this structure provides improved value for money, whilst reducing the carbon consumption and the environmental impact of constructing a new concrete structure, as per the original concept. The re-purposing works will require some minor inlet and outlet pipework modifications, installation of new pumps and removing of the redundant equipment. Littlehempston WTW: Supply chain - key participants Delivery contractor: Galliford Try Design: Arcadis Consulting (UK) Ltd Piling: Roger Bullivant Ltd Reinforced concrete works: D Wall Construction Services Ltd Precast concrete tanks: A-Consult Ltd Steel frame building: Hewaswater Engineering Ltd Reinforcement: Hy-ten Ltd Aggregates & concrete: E & JW Glendinning Ltd Plant hire: Plantforce Rentals Ltd Ultraviolet reactors: Trojan Technologies Underfloor drains & launders: Xylem Water Solutions Underfloor drains & launders installation: Western Carbons Ltd Stainless steel pipework & galvanised mild steel structures: Alpha Plus Ltd Pipework: Freeflow Pipesystems Ltd Ductile pipework: Electrosteel Castings (UK) Ltd Flow control: Affco Flow Control UK Ltd GRP kiosk: Pro-Tect GRP Enclosures Ltd [caption id="" align="alignnone" width="1200"] FRC construction of GAC cells - Courtesy of Galliford Try[/caption] Project challenges As part of the scheme the site team have had to make pipework modifications to intercept flows between the existing RGF filters and primary contact tank. To achieve this, a series of seven independent site shutdowns were carried out weekly to facilitate the modifications needed. This area, affectionately known as the 'bear pit', required detailed planning to develop a suitable solution. The final arrangement includes branch connections to allow the existing flow paths to be kept on-line, the installation of new pipework, refurbishment of redundant pipework, temporary cross-connections to allow commissioning flows to be circulated, and also includes a new static mixer for the relocated dosing point for chlorine and orthophosphoric acid. The challenges were amplified further by the limited access to the area, meaning that pipework had to be fabricated in small sections that could be safely lifted in. A point-cloud survey of the original pipework was integrated into the BIM model which allowed the concept development. Exact measurements were then verified manually on site before fabrication. A 4D approach was implemented during the design development which allowed for the different phases to be visualised and support the buildability and planning discussions between the project delivery team, and South West Water operations. Access to site is also incredibly challenging, as the rural Devon location is only accessible with heavy goods vehicles (HGVS) via a narrow single-track road with infrequent passing places for HGVs for approximately 5 miles. This impacted multiple design and construction decisions, limiting the size of rebar, pipework, precast units and various types of plant and machinery that could be used such as piling rigs, excavators and cranes. The site team arranged suitable locations to hold vehicles allowing all HGVs movements to be managed through the narrow lanes. Surrounding business were updated weekly on HGV movements and in return made the site traffic management team aware of their movement so that they could also be coordinated. [caption id="" align="alignnone" width="1200"] GAC building pipework gallery - Courtesy of Galliford Try[/caption] Carbon savings and in-house capability Local resources and materials were used where possible including subcontractors which as a result provided a boost to the local economy during the construction phase. Where local suppliers were not available, Galliford Try endeavoured to use off site build solutions where possible to minimise commuting. The following in-house resources were utilised: Management. Electrical design. Process control. Commissioning. Workforce to undertake the following: Establish and demobilise site. Civils groundworks. Hard and soft landscaping. MECIA works. Stakeholder management At pre-construction phase, all third-party stakeholders were identified and entered onto a management plan. Galliford Try’s Customer Liaison Officer contacted all stakeholders prior to commencement to provide them with the appropriate project contacts should they have questions, queries, or complaints and to establish their requirements and desires throughout the construction phase of the works. As part of the management plan all communications where complaints or agreements are made are formally recorded, resolved, and closed out. [caption id="" align="alignnone" width="1200"] GAC & UV buildings with interconnecting pipework - Courtesy of Galliford Try[/caption] Noteworthy This job was aided by the useful wealth of archived drawings and pictures stored by South West Water on site. The documents gave Galliford Try a useful insight into the history of the water treatment site and proved to be invaluable in the process of locating services. Notably, Galliford Try discovered these documents were stored in a cold-war era bunker making the exercise of ploughing through documents not your average day on site! Summary Collaboration between client, contractor, designer and the wider supply chain has been a key factor in resolving significant challenges including establishing pipe routes for large diameter interconnecting pipework, suitable crane platforms for inaccessible areas of the existing operational site and the pipework modifications required during works shutdowns in the 'bear pit'. [caption id="" align="alignnone" width="1200"] Fit out of the contactor gallery prior to the erection of the steel clad portal frame building - Courtesy of Galliford Try[/caption] Currently (May 2023) all the structures are nearing completion, mechanical installations are well advanced with electrical fit outs to commence late summer 2023. Large diameter site-wide interconnecting pipework is currently being laid, with the vast majority programmed to be completed during the summer and early autumn months of 2023 to take advantage of more favourable ground conditions. Process Commissioning is to commence in late 2023 and is scheduled to be completed well in advance of the Drinking Water Inspectorate (DWI) Compliance Date 31 March 2025.