Supply Chain - Security - CCTV Security

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.

Winchburgh is located five miles west of Edinburgh Airport and the existing wastewater treatment works lies to the south-east of the town, approximately 200m from the nearest residential street. The site access road runs adjacent to the main Glasgow to Edinburgh railway line, the top of the embankment being a couple of metres from the roadside, with the railway line sitting approximately 10m below. The existing works is a traditional biofiltration process, rated for 3,800PE. Due to Winchburgh being designated within the West Lothian Development Plan for significant housing development, there is a projected population increase to 16,389 PE by 2032.  To cope with this increase, Scottish Water have started construction of a new £35m Nereda® treatment plant.  Scottish Water’s Non-Infrastructure Alliance Partner, ESD, a joint venture of MWH Treatment, Binnies and Galliford Try, commenced construction in July 2021. Existing works process The existing works takes combined flows under gravity from upper and lower Winchburgh. The lower Winchburgh flows gravitate into an inlet pumping station and are transferred up to the inlet works, whereas the upper Winchburgh flows gravitate straight into the inlet works. Flows less than 9 DWF pass through screening and grit removal and flows less than 6 DWF (full flow to treatment (FFT)) pass through primary settlement. Thereafter, secondary treatment of FFT is carried out by biofilters, prior to final settlement and tertiary treatment. Primary sludges are removed to sludge storage prior to tankering off-site and the humus sludges are returned for co-settlement. Process selection As a result of the growth in the area there is a need to increase the size of the treatment works. The technology selected by Scottish Water to meet this need is Royal HaskoningDHV’s Nereda® process solution. This decision was based primarily on the following drivers: Reduced land take due to the smaller footprint for the Nereda® solution, compared to a conventional solution. Carbon reduction due to the power required to run a Nereda® plant being significantly lower than that required for a conventional works. The Nereda® process technology was developed by Royal HaskoningDHV (RHDHV) and offers sustainable wastewater treatment. The natural sewage treatment process purifies water, using few or no chemicals, through proprietary aerobic granular sludge (AGS) technology. [caption id="" align="alignnone" width="1200"] Nereda® process cycle - Courtesy of Royal HaskoningDHV[/caption] Within a Nereda® reactor, through a simple three-step cycle, the purifying biomass grows naturally as compact aerobic granular sludge, with superb settling properties. An important feature of granular sludge is that aerobic and anoxic/anaerobic zones co-exist. This enables a large variety of biological processes, including nitrification, denitrification and biological phosphate removal, to happen simultaneously. The alternating cycle steps are: Filling of wastewater at the reactor bottom and simultaneously displacing purified water from the previous cycle at the reactor top. Aeration, resulting in extensive simultaneous biological removal of organic, nitrogen and phosphorus components. Fast settling, to separate biomass from the purified effluent after which the Nereda® plant is ready for a new cycle. Overview of scope and process The annotated model below shows the site layout and highlights each of the key structures and process units. The new wastewater treatment works has an upper and lower catchment pumping station that will intercept the two existing sewers and pump a maximum of formula A flows to the new packaged inlet works. In the event that the incoming flows defeat the inlet pumps, each pumping station includes a CSO that provides screening prior to the flows gravitating to the watercourse. [caption id="" align="alignnone" width="1200"] Winchburgh site layout model - Courtesy of ESD JV[/caption] The pumped flows from the upper and lower inlet pumping station are combined within the inlet collection chamber at the head of the above ground inlet works and screened via two screens operating in a duty/standby configuration. Grit and FOG removal are also included within the packaged inlet works and the screenings and grit discharged into dedicated skips, positioned adjacent to the units. Full flow to treatment (FFT) gravitates to the Nereda® influent buffer tank and flows greater than FFT will spill over a weir, within the packaged inlet works, and gravitate to a storm tank. The storm tanks are automatically emptied after each storm event, and the storm water returned to the inlet works outlet chamber via storm return pumps. At the end of each individual storm tank return cycle, a cleaning system flushes any residual solids back to the inlet works outlet channel. From the influent buffer tank, the FFT is split between the three Nereda® reactors. Excess sludge from the Nereda® plant will gravitate to the sludge buffer tanks, the contents of which, after further settlement and supernatant return, will be transferred to the unthickened sludge tank before being pumped to two disc thickeners. Thereafter, the sludge is transferred to the thickened sludge tank. Liquors from the thickening process are pumped from the liquors return pumping station back to the influent buffer tank. [caption id="" align="alignnone" width="1200"] Precast retaining wall installation - Courtesy of ESD JV[/caption] Treated effluent from the Nereda® reactors gravitates to an effluent balance tank, which is required to attenuate the flows, prior to being passed to the tertiary solids removal plant, which is the final treatment prior to discharge to the water course. Also included within the scope is a ferric dosing plant. This was included within the scope of supply on the Winchburgh project as a result of the lessons learned on the Inverurie WwTW project, the only other operational Nereda® plant in Scotland. The limited dosing of ferric will better facilitate P removal to a lower concentration, if required. Winchburgh WwTW: Supply chain - key participants Client: Scottish Water Principal designer & contractor: ESD JV Binnies MWH Treatment Galliford Try Nereda® process: Royal HaskoningDHV Design/fabrication/installation of inlet works & Nereda® plant: EPS Water MCC/systems integration: MCS Control Systems Ltd Mechanical installation: Dustacco Engineering Electrical installation: Field Systems Design Ltd Steelwork, cladding & access metalwork: Archibald McAulay & Son Ltd Tertiary solids removal plant & CSOs: Eliquo Hydrok Sludge thickening plant: Huber Technology Building designer: Allen Gordon LLP Building fit out: B2 Projects Ltd Service water & FE booster sets: KGN Pillinger Pumps: Hidrostal Pumps: Xylem Water Solutions Pumps: Mono Pumps - (NOV Process & Flow Technologies) Air mixer: Landia UK Ltd Standby generator: DTGen Odour control plant: ERG (Air Pollution Control) Ltd Sludge tanks: Goodwin Tanks Ltd Chemical dosing: Lintott Control Systems Ltd Precast concrete: FP McCann Ltd Gabion walls: Maccaferri Ltd Shaft sinking: Fineturret Ltd [caption id="" align="alignnone" width="1200"] Extract from 4D Synchro animation – Courtesy of EPS Water[/caption] DfMA and collaborative design The strategy from the outset of the project was to maximise the use of Design for Manufacturing & Assembly (DfMA) and the use of the available digital delivery tools, with the primary aims being: Reduced programme: Most of the M&E construction can be completed off-site, reducing the amount of manpower required on-site and enabling fabrication and mechanical assembly to be completed in parallel with civil construction. Improved quality: Stringent quality control in fabrication facilities, coupled with the ability for the client to inspect and snag assemblies prior to delivery. Reduced HSE risk: A significant portion of the construction is completed in a controlled factory environment, rather than on site. Improved collaboration: The use of common data environments and design within the 3D world to aid communication of latest information. Design To help assist in delivering the project strategy, EPS Water was identified early in the project life-cycle as being a key subcontractor. EPS are the Nereda® license partner of RHDHV for Scotland and were a key partner of ESD in delivering the Inverurie STW project. EPS was engaged at the outline design phase to work alongside ESD to collaboratively design the Nereda® works for Winchburgh. The design was developed using Revit, a 3D modelling package, which was shared in Glue, a cloud-based BIM management and collaboration product. Using these tools allowed regular design reviews between the ESD and EPS design teams throughout the design process. This being of particular benefit as the design could be progressed without restriction during the COVID pandemic. [caption id="" align="alignnone" width="1200"] Winchburgh 3D model (lower pumping station area) with below ground services visible – Courtesy of ESD JV[/caption] In addition to the experience held within EPS of Nereda® treatment works they also have a strong background in the development of DfMA solutions, which combines in-house advanced digital engineering services with their substantial manufacturing capacity. The Winchburgh project was designed to be a DfMA solution, meaning that the large assemblies were designed to be broken down into modular transportable sections, taking into account the particular site delivery restrictions, that can be reassembled on site. The DfMA approach was also utilised within the civil design, where possible. The level differences across the site led to retaining walls in excess of 4m high, most of which were constructed from precast concrete, reducing site installation time from 3-4 weeks to 6 days. Furthermore, precast segments were used to construct the shafts required for the upper and lower catchment pumping stations, the biggest of which was 8m diameter by 8m deep. This again had programme savings, but crucially reduced the risk associated with an in situ concrete solution for such deep shafts. [caption id="" align="alignnone" width="1200"] (left) Upper catchment pumping station and (right) lower catchment pumping station - Courtesy of ESD JV[/caption] The 3D model has proved invaluable throughout the life-cycle of the project, from the early stages of the project being used to develop the design in conjunction with all stakeholders within Scottish Water, to facilitating discussions between the site team and design team during the construction phase. A consequence of the model providing such a clear picture of the design is that meaningful discussions can be held with people of all technical levels and minimises the risk of miscommunication. The use of digital tools was further extended to develop the programme. The construction programme and 3D model was used in conjunction with a 4D Synchro scheduling tool to develop a simulated programme of works. This assisted the site team in planning the works and identifying any clashes or pinch points in the programme whereby there may be too much activity within certain areas of the site that could lead to inefficient working, or prevent certain operations being completed in parallel. Status - June 2023 Construction work commenced on site in July 2021 and is due for completion in October 2023 at which point process commissioning will commence. At time of writing (June 2023), the civil construction works are nearing completion, with key remaining works being the construction of the new outfall and the installation of the deep pipework for the CSO overflow and lower catchment sewer tie in. [caption id="" align="alignnone" width="1200"] Winchburgh WwTW (May 2023) - Courtesy of ESD JV[/caption] The main process units/structures are installed, with the MCC planned for delivery at the end of May 2023, at which point the electrical installation can be completed, allowing dry, then wet commissioning to commence. The target date to start slowly turning the flows from the existing treatment process to the new Nereda® treatment process is October 2023, with handover to Scottish Water planned for June 2024, allowing the intervening time for process commissioning.

In 2019, Wessex Water launched a £51 million project to upgrade the Durleigh Water Treatment Centre (WTC) in Somerset, which had reached the end of its operational life. This project was crucial in maintaining the delivery of high-quality drinking water to a population of 44,500 and was part of the company’s long-term water supply strategy for the region. Led by Wessex Water’s Engineering & Sustainable Delivery (ESD) department, this was the largest single-value scheme ever undertaken by the company. This case study focuses on the commissioning of the works and follows on from those published in 2020 and 2021: 2020: Durleigh WTC: Wessex Water’s flagship clean water project 2021: Durleigh WTC: Project construction update Introduction Construction completed in autumn 2021 after which the 12 months planned period of commissioning began, during which all systems were rigorously tested to ensure that the upgraded water treatment centre met the necessary standards for quality and safety. In late summer 2022, water was supplied to the region and the project was completed within budget and ahead of schedule, providing a valuable additional water resource during the driest summer since 1976. This successful upgrade demonstrates Wessex Water’s commitment to providing reliable water supply of improved quality to its customers for years to come. Multi-barrier treatment for challenging source water Durleigh Impounding Reservoir, which provides the raw water for Durleigh Water Treatment Centre, is fed by two sources; Durleigh Brook which runs through agricultural land from the Quantock Hills, and the Bridgwater to Taunton Canal via the Albert Street Pumping Station. The combination of these sources, however, introduces high levels of nutrients and several significant contaminants, leading to highly variable quality source water. Given this variability and the need to remove all potential contaminants, a multi-stage treatment process was required alongside the construction of a new wetland at the head of the reservoir. [caption id="" align="alignnone" width="1200"] New Durleigh wetland - Courtesy of Wessex Water[/caption] The wetlands have been designed to filter silt and coarse sediment and reduce levels of nutrients, helping to improve the raw water quality entering the reservoir as well as boosting biodiversity by becoming home to a diverse array of wildlife. An existing wet woodland also acts as a final screening process before the water reaches the reservoir. The two new habitats, constructed to the west of the water treatment centre and reservoir, have brought about a near 75% reduction in the amount of ammonia present in the raw water, while phosphorus and sediments have dropped by around a third. Treatment processes The following treatment processes were then selected: Pre-treatment with sulphuric acid and aluminium sulphate. Dissolved air filtration (3 x 10 Ml/d streams). pH adjustment (sodium hydroxide dosing). 6 (No.) dual media rapid gravity filters. Oxidation and pH adjustment (sodium hypochlorite and sodium hydroxide dosing). Re-lift pumping by 3 (No.) variable speed end suction pumps (duty/assist/stand-by). 6 (No.) manganese removal pressure filters. 9 (No.) pressurised granular activated carbon adsorbers. Orthophosphoric acid dosing (plumbosolvency control). Disinfection using chlorine and sulphur dioxide gases (super-chlorination and de-chlorination). pH adjustment (sodium hydroxide dosing). High lift pumping 3 (No.) variable speed end suction pumps (duty/assist/stand-by). Cryptosporidium inactivation using duty/assist UV treatment. Duty/duty lamella clarifiers for wastewater treatment. The combination of the wetland with the multi-barrier treatment process ensures that all potential contaminants are removed from the raw water, providing safe, high-quality drinking water. [caption id="" align="alignnone" width="1200"] Process flow - Courtesy of Project Support Systems[/caption] Risk based approach to commissioning The project team recognised that early consideration of the commissioning process would be critical to ensuring successful project delivery. To achieve this, a risk-based approach was adopted throughout the project starting with the design phase. In-house ESD commissioning staff were embedded in the design team and using the digital data available through the schemes BIM360 delivery mechanism undertook a detailed risk assessment of each commissioning activity to identify areas where the design could be revised to increase the efficiency of the commissioning process. By incorporating these changes into the final design, the team was able to expedite process commissioning and reduce testing time by implementing concurrent commissioning of parts of the treatment process. To ensure that the design of the control software met the company’s specifications and aligned with the delivery program, the project team took early ownership of this aspect of the project. The Functional Design Specification (FDS) was produced in-house by staff from the ESD Commissioning & Automation teams, as well as staff from Operations and the scheme designers AECOM. The FDS detailed the software requirements for normal and abnormal operation, setpoints, alarms, and interlocks. By constructing the control in a modular and standardised way, the team was able to achieve flexibility for future operations while reducing delivery and testing time through a simple logical code structure. [caption id="" align="alignnone" width="1200"] Instillation of 14/25 sand media into manganese removal filters - Courtesy of Wessex Water[/caption] The risk-based approach continued through the construction and commissioning phases of the project. Critical plant that had been identified during the design phase were subject to enhanced testing and inspection procedures to mitigate the risks and prevent any cost or time impacts. The risk-based approach also ensured that where specialist activities were required the appropriate contractors could be engaged in a timely manner to ensure the installation was delivered to their testing requirements. By utilising this approach, early involvement in the commissioning process, and careful control design, the project team was able to achieve significant cost and program reductions, while also ensuring that the final design met all project requirements. Collaboration in commissioning Wessex Water recognises that project outcomes rely not only on technical expertise but also on effective collaboration between engineering and operations teams. Collaboration between the Engineering Department and Operations Team within Wessex Water has played a pivotal role in the delivery of the Durleigh WTC refurbishment project. Key areas where joint efforts have contributed to project success are: Design specification collaboration: The engineering department and operations team within Wessex Water worked collaboratively from the project’s initiation to ensure that the design met both engineering standards and operational requirements. By leveraging their expertise, the teams combined engineering principles with operational insights to optimise the facility’s design for efficient water treatment processes. Ongoing involvement & secondment: To maintain a continuous exchange of knowledge and promote collaboration, members of the operations team were seconded into the engineering department throughout the project’s duration. This arrangement facilitated the sharing of operational insights and allowed the operations team to contribute valuable input during the project’s progress. On-site presence for commissioning: The operations team actively participated on-site several months prior to the completion date to observe and engage in commissioning activities. This early involvement enabled them to gain a comprehensive understanding of the plant’s operations, controls, and processes, ensuring a smooth transition from construction to operation. [caption id="" align="alignnone" width="1200"] Durleigh WTC main treatment building - Courtesy of Wessex Water[/caption] SCADA display optimisation: The operations team collaborated closely with the engineering department to optimise the Supervisory Control and Data Acquisition (SCADA) display. Leveraging their operational expertise, they worked together to customise the interface, aligning it with operational workflows and enhancing usability for the operators. Exposure to infrequent and abnormal operations: Through their presence during commissioning and early operation stages, the operations team had the opportunity to observe and gain experience with infrequent and abnormal operational scenarios. This exposure enabled them to develop strategies, protocols, and contingency plans to handle such situations effectively. Continuous training for operational excellence: Training was an ongoing process throughout the project, with formal training sessions scheduled after the operations team gained prior experience. This approach allowed operators to apply their knowledge and skills in practical settings, ensuring continual improvement and optimal performance. The collaboration between Wessex Water’s engineering department and operations team has played a vital role in the success of the project. Through joint efforts in design specification, ongoing involvement, on-site presence, SCADA display optimisation, exposure to infrequent operations, and continuous training, the teams have fostered effective collaboration and achieved project objectives. This collaborative approach serves as an example of how departments within an organisation can work together to drive success and optimise operational outcomes. [caption id="" align="alignnone" width="1200"] (left) High lift pump hall and (right) air saturation test of DAF lane - Courtesy of Wessex Water[/caption] Durleigh WTC: Supply chain - key participants Principal contractor: Wessex Water ESD Principal designer: AECOM Process design: Stantec UK CFD modelling: The Fluid Group Project and O&M documentation: Project Support Systems Temporary works & shoring: MGF Ltd End suction pumps: SPP Pumps Ltd Electrical installation: Field Systems Designs MDB/MCCs: GPS Group Lamella clarifier: Hydro International DAF saturation system: Quantum Engineering Developments Ltd Large bore pipework: Powerrun Pipe-Mech Large bore pipework: Berry & Escott Inlet screen air scour: Eliquo Hydrok Ltd UV treatment: Trojan Technologies Air blowers: Aerzen Machines Polyelectrolyte dosing: Richard Alan Engineering Sodium hypochlorite dosing: WES Ltd Chemical dosing: DMS Engineering Chemical dosing: MBH Engineering Access steelwork: Dan’s Engineering Tank & vessel manufacturing: Vessco Engineering Desiccant drying systems: Aggreko Ice pigging: Suez Water Technologies WQ monitors: SWAN Analytical UK Ltd WQ monitors: Malvern Panalytical WQ monitors: Yokogawa UK Ltd WQ monitors: ATi UK WQ monitors: Metrohm Durleigh WTC to Danesborough Service Reservoir Trunk Main The recommissioning of the trunk main connecting Durleigh WTC to Danesborough Service Reservoir presented unique challenges, and required meticulous planning. Assessing the condition & risks: The 1.7km long rising main, constructed from epoxy-lined ductile iron, served as the crucial link between Durleigh WTC and Danesborough Service Reservoir. However, the last 80m of the main were unlined and known to be a source of discolouration, with elevated levels of turbidity and iron. Although it had been flushed to a flow rate of 26 Ml/d prior to the old works’ removal from supply, it had been out of service for three years and it was essential to address the remaining risks and restore the main’s integrity. Ice pigging solution: Considering the limitations in delivering the required flow with Durleigh WTC still out of service, a decision was made to employ a technique known as ice pigging for the last 80m of the rising main. To execute this task, Wessex Water engaged the expertise of Suez Water Technologies, a specialist ice pigging team. The ice pigging involved the introduction of a 10m3 ice slug into the main, followed by a 90-minute flushing process. Effective turbidity reduction: The implementation of ice pigging, followed by flushing, proved highly effective in removing 21kg of solid material from within the last 80m of the rising main. This achievement was crucial in mitigating risks and guaranteeing the quality of the water to the Danesborough Service Reservoir. [caption id="" align="alignnone" width="1200"] Ice pigging flushing samples - Courtesy of Wessex Water[/caption] Comprehensive pressure testing & disinfection: To ensure the integrity and reliability of the entire rising main, Wessex Water’s in-house disinfection team carried out a comprehensive pressure testing and disinfection process. The main underwent rigorous testing over a 72-hour period, subjecting it to stringent protocols to confirm its ability to withstand operational demands and maintain water quality standards. Successful restoration & return to supply: Following clear sample results and meeting the required water quality standards, the recommissioning process was successfully completed, and the Durleigh WTC to Danesborough Service Reservoir rising main was returned to supply. This significant milestone was achieved in late September 2022, marking the successful completion of the project. Conclusion The successful completion of the Durleigh Water Treatment Centre upgrade project by Wessex Water represents a significant milestone in the company’s commitment to delivering high-quality drinking water to its customers. This ambitious project, the largest single-value scheme ever undertaken by Wessex Water, was executed with meticulous planning, collaboration, and a risk-based approach. Through the implementation of advanced treatment processes and a comprehensive control software design, the upgraded facility ensures the removal of potential contaminants, guaranteeing the provision of safe and reliable drinking water to its customers. [caption id="" align="alignnone" width="1200"] Low lift pumping area - Courtesy of Wessex Water[/caption] The project team’s focus on collaboration between the engineering department and operations team, along with their early involvement in the commissioning process, played a vital role in achieving remarkable results. By optimising the design specifications, streamlining the commissioning process, and fostering a culture of continuous learning, the team not only met project requirements but also set a new benchmark for water treatment engineering. This successful endeavour displays Wessex Water’s dedication to sustainable water management.

Goddards Green Wastewater Treatment Works (WwTW) is a Sludge Treatment Centre (STC) located near Burgess Hill in West Sussex. The catchment serves the towns of Burgess Hill, Hassocks, Hurstpierpoint and surrounding villages, providing for 54,789 people. The project implements an innovative approach to mitigate the likely odour from the processes at the WwTW to prevent any potential impact on the planned Northern Arc development in the surrounding area.  To enable the new development to proceed in the surroundings of the WwTW, there was a planning requirement for the odour of the WwTW to be limited to 1.5 OUE/m3 odour contour. Existing works The main components of the WwTW consist of inlet works (screening and grit removal), storm tanks, a primary settlement tank, anoxic tanks, oxidation ditches, returned activated sludge pumping station, final settlement tanks and disc filters. Treated final effluent is discharged into the River Adur East. Besides indigenous sludge, the STC also processes imported sludge (liquid and cake). The main components of the STC consist of sludge reception and storage facilities, screening and screened sludge storage, drum thickening, anaerobic digestion, digested sludge storage tanks, centrifuge dewatering and cake storage bays. Liquors from the sludge treatment process are treated in a cyclic activated sludge system (CASS) plant before being returned to the WwTW. Hot water for digester heating is produced by burning biogas either in hot water boilers or in the 800 kW CHP (combined heat and power) engine. Northern Arc development The Burgess Hill Northern Arc is a development in the southern part of the parish between Ansty and Burgess Hill. The project spans a period of over 15 years. Once complete it will provide 3500 houses with 30% affordable housing, four hectares of employment land, a community centre, two primary schools and a secondary school. The project is being run by a government agency, Homes England, and is a strategic development which is part of the Mid-Sussex District Council Development Plan. Southern Water’s project at Goddards Green WwTW aims to deliver a range of odour mitigation improvement measures; removing barriers to the housing development at the Northern Arc. Southern Water have committed to delivering a scheme that achieves a 1.5 OUE/m3 limit for a boundary as defined by the odour contour image (see below). [caption id="" align="alignnone" width="1200"] Odour model emission contours for selected solution - Google Maps[/caption] Project synopsis This scheme is being delivered in two phases. Phase 1 was delivered in May 2020 with the installation of a new odour control unit and odour covers to reduce odour emissions at the site. Phase 2 comprises the installation of a thermal hydrolysis plant (THP) with associated equipment, provision of a cake reception building to control odour during deliveries and a cake barn to protect the product from the weather. The THP will reduce odour emissions from the sludge treatment process, improve sludge quality and enhance gas yields from the digesters. The outcome will mean that new housing developments in the area will be better protected from odour emissions. Output of the THP process will provide enhanced treated sludge for farmers to spread to land as well as greater green energy production from the existing CHP engine, reducing the site’s need to draw power from the National Grid. Funding Mid Sussex District Council, in collaboration with Southern Water and West Sussex County Council, successfully secured government funding of £10.54m under the Local Enterprise Partnership (LEP) Growth Deal (Programme) and the Homes England Housing Infrastructure Fund. Southern Water has invested an additional £17m to deliver the odour and sludge treatment upgrade project. Phase 1 scope Phase 1 was delivered in May 2020 and comprised the installation of a new odour control unit and odour covers to reduce odour emissions. High odour emitting existing asset sources as identified from the odour model were covered. These assets included the primary settlement tanks, liquid sludge reception tank and oxidation ditch distribution chamber. [caption id="" align="alignnone" width="1200"] Phase 1 odour control unit from ERG (Air Pollution Control) Ltd - Courtesy of Galliford Try[/caption] Phase 2 scope The current practice of blending imported cake with indigenous liquid sludge has been retained. The blended sludge is then screened using existing strain presses and thickened using existing drum thickeners. New centrifuge feed pumps have been installed to feed thickened sludge to the existing centrifuges - these were previously used for digested sludge dewatering but have been repurposed to produce raw cake for the new THP process. Conveyors transfer the dewatered sludge to duty/standby cake hopper pumps which deliver raw cake to a 130m3 cake storage silo. Cake from the silo is discharged to duty/standby hopper pumps where dilution water is added to achieve a target dry solids content of 16.5% DS in the THP feed sludge. A single Cambi B2-4 THP stream is provided, capable of processing up to 24 tDS/d. The first vessel in the THP is the pulper which homogenises and pre-heats the sludge. Pre-heated sludge from the pulper is fed to the reactors in a sequential process that ensures sealed batches of sludge in each reactor. Steam is injected to raise the temperature of the sludge in the reactor to 165°C at a pressure of about 6 bar. At the end of the hydrolysis period, hydrolysed sludge is discharged from the reactor to the flash tank, which operates at about 0.2 bar. The sudden drop in pressure ruptures any remaining biological cells in the sludge. Flash steam generated by the pressure drop is returned to the pulper to preheat the incoming sludge. Thermal hydrolysis of sludge generates a highly odorous off-gas (referred to as ‘process gas’) which is continuously extracted from the pulper and passed through a cooler, with condensate from the cooler gravitating back into the pulper. Non-condensable gases pass from the cooler to the process gas unit where they are pressurised and injected into the digester feed lines (downstream of the sludge coolers). [caption id="" align="alignnone" width="1200"] (top & bottom left) BIM models showing the THP plant area and (bottom right) Phase 2 THP area looking north-west - Courtesy of Galliford Try[/caption] Digester feed pumps are used to pump hydrolysed sludge from the flash tank to the digesters. Disinfected process water is added to the suction side of the digester feed pumps to dilute the hydrolysed sludge to achieve the target digester feed sludge dry solids content. Diluted hydrolysed sludge is combined with recirculated digested sludge before being cooled while passing to the two existing digesters. The new digested sludge dewatering stage comprises new duty/standby centrifuges and an associated polymer preparation/dosing system. Enhanced treated cake is conveyed to the new cake barn. There is an existing 800 kW CHP engine. High grade waste heat from the CHP engine exhaust gas is recovered in a new composite steam boiler. Low grade heat is also recovered from the CHP engine jacket cooling water and used to pre-heat the boiler feed water. These heat recovery systems help to minimise the consumption of supplementary fuel (biogas or diesel) required to meet the THP steam demand. A new final effluent (FE) pumping station supplies cooling water to the sludge coolers. All applications requiring dilution or carrier water are supplied with filtered FE that has been UV-disinfected, ensuring that an enhanced treated cake is produced. The schematic diagram below shows the process stages with the additional odour reduction measures undertaken in Phase 1 (in green) and the main changes to the sludge treatment process for Phase 2 (in orange). [caption id="" align="alignnone" width="1200"] Schematic showing the process stages - Phase 1: Additional odour reduction measures (green) and, Phase 2: The main changes to the sludge treatment process (orange)[/caption] Design Galliford Try’s (GT) inhouse engineering team based in Stafford, have undertaken and coordinated the detailed design process, supplemented by specialist suppliers. Atkins were also contracted to undertake the civil engineering design on behalf of Galliford Try. Southern Water carried out the process design. Regular design coordination meetings have been held between all parties to ensure a coordinated approach to the design. 3D and Building Information Modelling (BIM) modelling has been used throughout the scheme to coordinate and manage the design process. Viewpoint for Projects was used as the project’s cloud-based collaboration tool throughout. The use of 3D modelling was particularly useful in spotting clashes and to enable early process plant operator involvement and feedback. This has been beneficial in highlighting access and maintenance issues, prior to construction work beginning. [caption id="" align="alignnone" width="1200"] View looking at Serpecon conveyors and pre-THP silo feed pumps - Courtesy of Galliford Try[/caption] Goddards Green WwTW - Supply chain: key participants Client: Southern Water Main contractor: Galliford Try Outline design: Stantec UK Detailed design: Atkins THP plant: Cambi AS Cake reception building/cake barn: APT Engineering Ltd Imported cake reception silo: Saxlund International Ltd Steam boiler package: Dunphy Combustion Ltd Groundworks drainage: TC Jones Groundworks Concrete cutting/diamond drilling: Castle & Pryor Ltd Workforce supply: Hercules Site Services Workforce supply: Fortel Group Kiosks: Morgan Marine UV Treatment: Xylem Water Solutions - Wedeco FE booster set & portable water booster set: KGN Pillinger Pre-THP centrifuge screw conveyors: Serpecon Ltd Vehicle exhaust: Air Technology Systems CHP exhaust flue: Rung Heating CHP pipework modifications: Edina UK Ltd MCCs: Blackburn Starling Ltd LV Switchboard/MCC 10: MCS Control Systems Ltd Final dewatering units & access platform: Alfa Laval Biogas booster system: DSL Building Services Final dewatering polymer system (powder): Richard Alan Engineering Mechanical/electrical installation: Field Systems Design Ltd Submersible centrifugal pumps: Xylem Water Solutions - Flygt Pumps Concrete: Hanson Aggregates Muck-away: Hesus UK Ltd Sub-base materials: Day Group Ltd Drainage materials: Jewson Civils Frazer Heat exchangers: HRS Heat Exchangers Ltd Reinforcement: Hy-ten Ltd Pumps: P&M Pumps Ltd Draeger control units: Draeger Safety UK Ltd DS monitors: Flow Technology Services Ltd Valves & instruments: ABB Ltd Valves & instruments: Siemens Valves & instruments: Glenfield Invicta Ltd Valves & instruments: Xylem Water Solutions Instrumentation: IFM Electronic Ltd Performance monitoring & operational support: PBJ Engineering Services Ltd Supply of steam boiler water treatment chemicals: EB Critical Engineering Services Ltd Construction Construction of the Phase 2 works commenced in the spring of 2021 with the clearing of existing cake bays and the construction of new openings to the existing structure. Castle & Pryor Ltd undertook the work to create new openings, utilising track saws and robotic demolition techniques. The decision for this technique was taken to minimise the health and safety risks associated with more traditional demolition methods. Once the new openings were formed, Galliford Try went on to construct new foundations to accommodate the new process units. Hercules Site Services and Fortel Group were engaged to supply the necessary skilled workforce to work directly under Galliford Try’s own control. [caption id="" align="alignnone" width="1200"] THP area looking north east - Courtesy of Galliford Try[/caption] This approach has proved successful throughout the first three years of the current programming AMP7 period (2020-2025) as it affords greater flexibility and control. Wherever possible the existing structure was retained and re-purposed to speed up the construction, and to reduce overall costs and the carbon footprint of the scheme. Before reusing the foundations, detailed in situ and pull-out testing was undertaken. The Cambi B2 unit and associated ancillary equipment are all located within the original cake drying beds. In parallel to the cake bay works, construction was undertaken within the existing plant to facilitate the installation of the other process units. This required close collaborative working between the contractor and the onsite operations team, to minimise disruption to day-to-day activities and the running of the treatment plant. Throughout the scheme, this close cooperation has continued, ensuring all stakeholders are kept up to date with activities and progress. Field Systems Design Ltd was engaged by Galliford Try to undertake the detailed design and installation of the complex interconnecting cabling and mechanical piping systems throughout the scheme. This included high voltage cabling and transformer upgrade works, low voltage power cables, signal cables and fibre optic networks. The scope of the mechanical supply included all piping and access arrangements, steam lines and pressure networks. In total, 48 kilometres of cable, 2.5 kilometres of pipes and associated support systems have been installed. These systems are predominantly placed above ground for ease of future maintenance, and to mitigate the risks of burying equipment within an already congested plant. Collaborative planning and design management have been undertaken between the site team and Galliford Try, to ensure the smooth flow of the mechanical and electrical phase of the works. Overall, the scheme is now (June 2023) approaching 200,000 hours worked without any lost time or other significant incidents. [caption id="" align="alignnone" width="1200"] View looking north-east towards the Saxlund pre-THP cake silo - Courtesy of Galliford Try[/caption] Risk management De-risking of the construction phase was considered key to the delivery of project. To achieve this, regular risk reviews and workshops have been undertaken throughout with significant benefits being realised. For example, the project team identified early on that Southern Water were best placed to deliver the improvements to the existing on site gas storage facility and flaring arrangement in advance of the main Phase 2 works starting. It also identified the need to procure longer lead-in items in advance of the main contract award being in place. This meant that the Cambi B2 unit, Dunphy boiler building, and Saxlund pre-THP silo were all procured under an early works agreement. This joined up approach to risk management meant that the scheme was able to rapidly adapt to the challenges posed by the worldwide semi-conductor shortage. The shortage affected the project, due to the multiple control panels and complex equipment being procured. The team agreed to utilise refurbished parts within the panels to enable off-site fabrication and factory testing to take place. These refurbished parts will then be replaced on site once the delayed components become available, which has saved many weeks of further delay. Stakeholder management As Southern Water had obtained funding from Homes England to undertake the odour reduction scheme at Goddards Green, they were identified by the project team as key stakeholders. It was therefore essential that they were kept informed of progress throughout the delivery phase. To achieve this, the project team held regular site tours and liaison meetings with the representatives of Homes England and the local council members, fielding questions and explaining the process and progress on site. [caption id="" align="alignnone" width="1200"] (top left) BIM model showing the steam boiler system, (top right) the rear of the steam boiler building and emissions stack, (bottom left) the front of the steam boiler building and emissions stack, and (bottom right) the Dunpy boiler package - Courtesy of Galliford Try[/caption] DfMA - Design for Manufacture and Assembly Design collaboration from the earliest stages of the project has provided tangible benefits in terms of costs, speed, sustainability of the project, and health and safety benefits. These small but practical examples are a core part of Galliford Try’s sustainable growth strategy. Galliford Try’s installation of the steam boiler at Goddards Green WwTW using an off-site solution, has reduced construction time on site as well as bringing health, safety, carbon, and community benefits. Manufactured and installed by Dunphy, the modularised plant room was fully fired and tested off site before delivery in two days using DfMA to allow modular construction of the building and plant, reducing the amount of time spent on site during the installation. The reduction of time spent working on site also has health and safety benefits, as more work is completed in a safer factory setting, and many of the hazards of a live site can be reduced or avoided. Conclusion At the time of writing (June 2023) the Goddards Green WwTW project’s construction phase is nearing completion and commissioning works have commenced on ancillary equipment. Beneficial use is currently forecast for the end of 2023. The use of THP is the first of its kind within Southern Water. Therefore, despite being utilised to manage odour, it will also alter the way the sludge is managed on site, contributing to several economic and environmental benefits.

Potters Way, located in the Fengate area of Peterborough, is a recent housing development next to the A1139. The development was built on the grounds of the former Fengate Water Recycling Centre (WRC) which closed in 1988 following the construction of the Flag Fen WRC. In early December 2018, Anglian Water became aware of the collapse of a section of 1500mm diameter concrete sewer pipe in Potters Way when a small hole was found after a customer used a ride-on lawn mower over the area. Temporary repair works were undertaken by the Integrated Operational Solutions (IOS) Alliance - a partnership between Anglian Water, Kier, Barhale and Morrison Utility Services - while a permanent fix could be designed and implemented. Background By the end of December, the IOS Alliance had installed a temporary repair using a vacuum excavator to safely clear the collapsed pipe before using half-pipe and canvas to seal the collapse. The area was also fenced off to prevent pedestrian access and ensure site safety. During this period, Anglian Water received several complaints from customers over the odour created by the collapse. Following meetings with the residents, Anglian Water’s Water Recycling Networks (WRN) team further sealed the excavation and installed carbon filters to the air valves. At the same time, the team repaired holes found in the rising main pipework at the nearby tower. The site was then handed over to the Anglian Water @one Alliance to implement their repair solution with @one partner company Barhale engaged as principal contractor. [caption id="" align="alignnone" width="1200"] Installation of the overhead diversion - Courtesy of @one Alliance[/caption] Finding a solution One of the challenges presented in finding a solution for this project was the high flow rate of the pipework, with modelling of Potters Way showing flow rates of 3,700 litres per second in the event of a 1 in 30-year storm. Downstream of Potters Way, this rises to 4,000 litres per second. To make the matter even more complicated, the pipe featured several significant bends along the affected route that increased the difficulty of finding an adequate solution. An extensive survey of 2.8km of sewer identified 1.79km of concrete sewer pipework ranging in diameter from 1050mm to 1950mm had a condition grade of either 4 or 5. All these pipes were identified as having been subjected to a hydrogen sulphide (H2S) attack which had caused the significant deterioration. The @one Alliance set out to repair an area of the network by covering a key 500m of pipework which serves the majority of Peterborough. Potters Way Sewer Rehabilitation: Supply chain Project delivery: Anglian Water @one Alliance Temporary repairs: Integrated Operational Solutions (IOS) Alliance Principal contractor: Barhale Over pumping: Vanderkamp UK GRP pipe lining: Amiblu Norway AS Lining & manhole repair: OnSite Central Ltd Specialist CCTV Survey: Bright Innovations Group Foam concrete: GS Foam Concrete Diamond cutting: SCS Ltd Cover slabs: FP McCann Ltd Temporary works/shoring: Groundforce Pipe rehabilitation The @one Alliance solutions team opted for a multi-stage solution due to the complex nature of the pipework and the compact area the teams would be working in. In order to repair the sewer, it was decided that a mix of CIPP (cured in place pipe) and GRP (glass reinforced plastic) lining would be used. The majority of the rehabilitation was completed using CIPP lining which allows the lining to be inserted into the shell of the existing, damaged pipework where it is then pressurised and cured in place with ultraviolet (UV) lights. The CIPP relining was split into eight sections covering approximately 360m of the repaired pipeline. At 1375mm in diameter, this installation was the largest diameter CIPP liner that the @one Alliance had ever installed. Six of the eight lengths of CIPP were installed under the A1139. Over pumping In order to fit the CIPP liners, the team utilised an over pumping set up capable of 250 litres per second (l/s). By using bungs at split manholes on the nearby Bourges Boulevard, the team could redirect the flow and use the pumping set up to divert the rest of the flow. The over pumping solution was provided by Vanderkamp UK who had remote monitoring capabilities from the Netherlands and provided the site teams with a mobile app allowing them to see real time data giving them advanced warning of increased flows which would require the removal of the bungs. Without this passive flow management, the over pumping setup would have needed to be able to cope with an excess of 2,000 l/s. The set up was made up of two pipe bridges 350mm in diameter and 5.5m high to allow clearance for high-sided vehicles. GRP lining Alongside the CIPP lining, the team also used GRP lining on a 48m section of 1500mm diameter sewer executing the rehabilitation in live flow conditions of approximately 850 litres per second; the first time the @one Alliance had installed GRP lining in live flow conditions. [caption id="" align="alignnone" width="1200"] (left) Live flow conditions and (right) inserting a new section of Amiblu Norway AS GRP pipe - Courtesy of @one Alliance[/caption] Operating in live flow removed the necessity to install an additional over pumping solution that would have dealt with 95% of Peterborough’s sewage as it combined into one flow towards Flag Fen WRC. In order to commence the GRP lining, the crown of the pipe was removed on a bend and concrete platforms were constructed on either side ensuring a safe working area. A pipe pusher attachment was then used to insert segments upstream and downstream from the bend location. Finally, a prefabricated GRP bend section was installed and connected to straight sections. To safely cut the existing mains the team needed to excavate an area of 6m x 4.5m with a depth of 3.5m. While having to excavate in an urban area is an option the team would have liked to have avoided, the next best solution to the live flow repair would have included installing a temporary pumping station that would have taken up all of Potters Way’s parking and grass area requiring 10 pumps and a 10m x 7m x 7m temporary wet well to complete the required repair. This would have been a major inconvenience for residents and would have seen an increase in the overall cost of the project of 200%. Manhole rehabilitation As part of the pre-work checks, it was identified that eleven manholes along the section of pipework required rehabilitation of various levels with the most severely affected requiring structural repair as a result of H2S attacks. Core samples were taken from one manhole which identified that in some places, more than 150mm of concrete had been lost to H2S attacks with no rebar remaining in any of the samples. To repair the manhole, the team used a concrete spray to bring the walls back to their original 250mm thickness, once this had cured a primary and finishing layer were added to ensure full protection against H2S attacks in the future. A new cover slab was also installed after the original was removed to provide access to the manhole, made of precast concrete the slab was also treated for H2S protection. [caption id="" align="alignnone" width="1200"] (left) H2S attack on a manhole and (right) inside a relined section of pipe - Courtesy of @one Alliance[/caption] Challenges Weather provided a significant challenge for the implementation of the solution as the site experienced an unusually heavy rainfall. Flow rate analysis for Flag Fen WRC shows that in the previous five years the average rainfall for the area fell between 35mm and 60mm. August 2020 saw average rainfall of 137mm. Because of the heavy rainfall several weather warnings were issued placing all CIPP lining activities on hold. The impact of the weather was so severe the flow of water increased from its usual 850l/s to 4,000 l/s in just 10 minutes. In order to reduce the risk of flooding outside the Magistrates Court the bungs were deflated, and the flow reverted. Due to the innovative combination of flow diversion and overpumping used in the CIPP lining the impact of the delay was significantly reduced compared to if the team had used the temporary pumping station solution. Rising mains issues During the repair of the sewer the @one Alliance became aware of complaints from the residents regarding the twin rising mains on Potters Way which used to feed into the old Peterborough STW and was diverted into the new gravity sewer discharging into Flag Fen WRC. The primary complaint from customers was the odour produced by the rising mains. The old Peterborough STW was sold for development and the rising mains tower was marked for removal. In early 2022 the @one Alliance returned to Potters Way removing the rising mains and installing a pumping station kiosk removing the odour and significantly reducing the visible profile in the area. Result Anglian Water invested £2.8m into the Potters Way project which will now allow customers across Peterborough to continue to use their taps and flush their toilets without second thought. The relining of the sewer network has ensured the network in the Potters Way area is now protected from H2S attacks for the next 50 years. Colin Handley, Construction Manager said:

“There was fantastic team collaboration between our Tier 2 Supply Chain Partners, the Principal Contractor (Barhale) and the @one Alliance, making it one team delivering the programme. The teams worked tirelessly to monitor the smells and reduce odours, whilst working in open excavations. They purchased additional fans and diverted rising mains to lower H2S and to allow the teams to work safely.”