Supply Chain - Mapping & Modelling - Wastewater Quality Monitoring

The technical solutions considered during design included increasing the storm tank capacity and the hydraulic capacity of the wastewater treatment works (WwTW) to reduce the intermittent storm discharges, with UV irradiation or membranes being considered to achieve the disinfection requirements.

Details of the five sites are as follows:

The project drivers required a reduction of spill frequency at storm overflows for all the catchments that discharge into Southampton Shellfish Water. This impacted five separate wastewater treatment works catchments.

Early in the design, the Southern Water (SW) project team identified an efficiency opportunity of combining the FFT U_IMP5 (increase in flow to full treatment) Driver with the Shellfish Driver, which had a significant impact on reducing the volume of the storm storage tanks. SW held regular meetings and agreed the approach with the Environment Agency (EA) including alignment of Regulatory output dates to the end of the AMP period.

The assessment of storm storage is based on the agglomeration approach outlined in the EA PR19 shellfish guidance and methodology. The definition of a significant spill was agreed with the EA at the conceptual stage of the scheme. This assessment treated all the discharges as a single agglomeration.

In summary, the integrated combined driver approach provided the following benefits:

To develop the solutions required at each wastewater treatment works, the sewer network performance for the five catchments was designed using a 10-year rainfall dataset. The observed spill frequencies across the catchment had to be agglomerated to ensure that 10 significant spills or less per year was achieved over a long-term (10 year) average.

This meant the modelling was more complex and took a lot longer than a usual model build and verification exercise because of the need to assess all five catchments together.

Following subject matter guidance from across the industry, the project team used an innovative approach of using an extended rainfall series duration and a single rain gauge. In addition, the team targeted the storage volumes at sites where there was available capacity to arrive at the most efficient storage volumes that were significantly lower than the original estimates, all while complying with good industry practice. In summary, this included:

The project team considered the best location for increasing the capacity of storm storage considering the cost/benefit for reducing significant storm spills. For example, at Millbrook WwTW redundant storm tanks were utilised that provided a volume of 3,140m3. The increase in volume at Millbrook enabled the storage volumes to be optimised across the agglomeration of sites with volumes being offset against other more constrained sites.

The initial significant storm volumes at Woolston were extremely challenging given the location of the site within an urban environment and lack of available space. The project team identified an opportunity of increasing the FFT at Woolston, which provided a significant reduction in storage. The scope involved utilising hydraulic headroom within the works, and through the installation of additional MBR capacity and associated pump upgrades, enabled a 20% increase in FFT at Woolston WwTW (427 l/s to 534 l/s).

The programme to deliver the increase in FFT at Woolston was short and provided an early reduction in E. coli concentration discharging to the Solent. This early delivery reduced 20% of the total E. coli concentration across the agglomeration of sites and was fundamental in agreeing new regulatory dates for the SW_ND (storm storage) drivers. The combination of the integrated driver approach to reducing spills, the innovative modelling and optimisation of assets reduced storage volumes by circa 46,000m3.

The final volumes are as shown in Table 2:

In response to a number of drivers, the EA has recently revised its approach to design and permitting of UV irradiation systems for the disinfection of final effluent. The aim is to move away from the use of generic assumptions, to follow international best practise with an approach which employs the use of a site-specific data in conjunction with performance validated UV irradiation equipment. This revised approach enables development of a significantly better understanding of performance and limitations on a site-specific basis.

Understanding the variation and impact of key wastewater characteristics on parameters such as UV transmittance and the UV dose-response relationship enables selection of a representative design envelope and minimum target UV dose. This enables the capital solution to be optimised, minimises power usage, operational costs and carbon impact while securing environmental performance.

The steps undertaken for the development of the design parameters and permit conditions for the UV irradiation systems at Slowhill and Millbrook WwTWs can be summarised as follows:

The new UV irradiation systems have been in operation at both sites since Autumn 2023 and are consistently achieving concentrations of E. coli in the final effluent discharges that will maintain the concentration at the Shellfish Water Boundary below the post PR19 target value of 5 cfu/100ml as a geomean.

Due to the limited availability of operational land in Woolston, the new storm shaft is being constructed beneath a car park and green area own by Southampton City Council (SCC), the area also had a Multi-Use Games Area (MUGA). The project team and the representatives of the Council engaged in extensive discussions prior to submission of the planning application which ensured a positive outcome for both parties.

From those conversations the project team learnt that the Council had worked to create a low nutrient coastal grass environment in the zone affected by the project. The topsoil had been amended and sown with the current species in previous seasons. Therefore, the agreed approach was to retain the topsoil stored on site and reinstate it at the end of the project, enabling the green area to grow and cover the old disused carpark.

The first activity after site mobilisation was relocating the reptiles that naturally inhabit coastal grass biomes. All areas with long grass that were part of the construction compound had the grass cut in two passes to encourage reptiles to move to nearby unaffected zones. Additionally, the top 100mm of soil was hand excavated with an ecologist carefully moving those reptiles still on site.

SW, working closely with the local Council, has ensured that the pre-existing facilities not only are kept despite the new structures being built, but that they are also improved. The number of parking bays and EV charging points will be maintained with improved access arrangements to avoid unwanted camping vans. The MUGA will be improved so the excessive slope that the old court had is removed and the pedestrian access to an adjacent park is protected with bollards, as previously vans used to park using part of the footpath.

The storm tank at Millbrook WwTW and the increase in flow to treatment at Woolston WwTW were both commissioned in July 2022 while the projects to install UV irradiation at Slowhill and Millbrook WwTWs were commissioned in Autumn 2023. In combination, these improvements represent a reduction of 72,500 cfu/s of E. coli being discharged to the Southampton Shellfish Waters, which is more than 60% of the total E. coli concentration reduction when all the projects are completed.

Results from sampling carried out after commissioning have demonstrated that both UV irradiation systems at Slowhill and Millbrook have reliably achieved the target efficacy, with concentrations of E. coli in the effluent post disinfection regularly below 200 cfu/100ml. Additionally, concentrations of E. coli in the final effluent discharge from Woolston have been consistently below 35 cfu/100ml since July 2019, following commissioning of the MBR.

The next key milestones are 31 December 2024, when the new storm tank at Ashlett Creek WwTW will be commissioned, and 31 March 2025, when all the remaining storage and increase in flow to treatment drivers will be completed.

The maximum modelled flood extent from a drawdown of Hallington Reservoir is in agreement with the flow path identified by the Environment Agency in the long-term flood risk map and no communities are shown to be at risk due to the proposed drawdown. As periodic testing of the reservoir drawdown will occur during dry periods, it is not considered that a drawdown of West Hallington Reservoir at this location would increase flood risk elsewhere.

The location chosen is on the north-east extent of the existing Slyfield Industrial Estate and is on an area previously used as a landfill site. In August 2023 Water Projects published a case study which provided insight into the extensive pre-construction design for civil and process engineering elements of the project. This article delves into the construction of the project and provides an update on the significant progress made to date on site.

The site for the new STW is approximately 70,000m2 and was previously used as a landfill site. It had originally been used as sand and gravel quarries and then subsequently used as landfill from the 1960s to the 1980s.

The landfill material is generally domestic and light industrial. It consists of black bag waste, timber, plastics, fabrics but contains fragments of asbestos and other materials.

The site was capped off with a granular layer in the early 1980s and has laid dormant ever since. The landfill depth varies across the site from between 2m and 6m thick. This then overlies an alluvium layer, sands and gravels and London Clay. The depth of the London Clay is approximately 10m below existing ground level.

Typically, major structures within a sewage treatment works are built below or partially below ground level to maximise gravitational energy. The new Guildford STW differs in that the strategy is to deliberately design and build above ground as far as practicable.

This is to minimise the disturbance to, and removal of the existing landfill thereby reducing the impact on the environment and the cost of disposal.

After a period of Early Contractor Involvement, Thames Water awarded a contract to BAM-Enpure Joint Venture (BEJV) in 2021 to design, build and commission this significant new works and once operational, to de-commission the existing works.

BEJV is a non-integrated joint venture, formed specifically to combine the excellence of experienced civil engineering contractor Bam Nuttall Ltd and the process engineering/MEICA specialism of Enpure Ltd to deliver a turnkey solution for Thames Water. The workscope split is as follows:

Decommissioning of the existing STW will also be undertaken by BEJV, in addition to working collaboratively with TWUL operational and networks teams to integrate existing TWUL operational assets into the new sewage treatment works.

BEJV undertook a series of site trials in 2021/2022. The purpose of this was to investigate the proposed ground improvement techniques further in order to validate proposals and inform detailed design. There are a combination of techniques which interface with each other in a complex manner.

The trials also gave important information about potential effects to both leachate levels and ground gas within the existing landfill to ensure there would be no impact on environment, ecology and human health.

The three techniques tested, and subsequently used within the works were as follows.

1. Rapid impact compaction (RIC): RIC was undertaken to remove the risk of long-term settlement to the landfill. Whilst the main structures would be supported on piles, this was to remove the risk of long term ground settlement underneath and around the structures. RIC is a method of imparting energy to the ground using a repeated but relatively short drop-weight, where a base plate is in constant contact with the ground. It is undertaken on a pre-determined grid pattern. At Guildford a 9T hammer was chosen, fitted to a 35T base machine and working on a 2.5m x 2.5m grid. Each ‘pass’ of the technique used 40 blows at each point.

Within the trial areas the technique was tested with 1, 2 or 3 passes (ie, 40, 80 or 120 blows per location). Cone penetrometer tests were used to measure the extent of deep level ground compaction before and after the trials. The continuous monitoring from the boreholes demonstrated that at each ‘thump’ of the ground there was no discernible change in leachate levels or ground gas volumes, and that there was no dispersal of leachate happening throughout the landfill.

From the trials it was determined that all areas of the site that are being built on should receive either 1 or 2 passes of RIC for the permanent works.

3. Vertical rigid inclusions (VRI): VRIs are mass concrete piles which are used for lightly-loaded structures and areas such as roads and hardstandings. They are a displacement pile, with the surrounding soil pushed sideways by an auger. As the auger is withdrawn the resulting void is filled with concrete up to ground level. They therefore work by increasing the density of the ground. A granular layer is then installed above to remove any ‘hard spots’. Again, this technique does not bring landfill material to the surface. It was trialled in two areas and found to be suitable for use, without causing any effects to leachate levels or ground gases. It is therefore being used as part of the permanent works over the whole site wherever there are not piled structures.

The trials of all three techniques, together with the subsequent site testing proved that the design principles were correct, and gave information on how to refine the solutions further. It also demonstrated that the techniques would not cause any adverse environmental effects.

Enabling works took place during Spring 2023 and consisted of site clearance, setting up the site offices and welfare and establishing fencing. The whole site was then covered with a 100mm thick layer of imported granular material to provide further protection against the risk of asbestos within the existing capping layer.

A series of 20 further boreholes were installed around the perimeter of the site to enable daily monitoring of both leachate and ground gas within the landfill and to ensure that none was being mobilised by our works. Mobile monitoring stations for noise, dust, vibration and asbestos were all set up, which are monitored continuously throughout the works. Over half a million data points have already been captured.

The permanent works started in earnest in Summer 2023 and in August, rapid impact compaction was conducted over the site, with a combination of one or two passes, as informed by the results of the previous site trials. In total the ground was hit 360,000 times! Precast piles were then driven for the major structures and pipelines. These were all 250mm square piles and varied in length from 16m to 20m. A total number of 3,422 piles have been driven using three piling rigs.

Vertical rigid inclusion installation is currently underway, with a total of 1,700 out of 9,000 already completed. The works are sequenced to avoid clashes with other work areas, on what is a congested site. Following installation, each work area is left for the piles to cure for the following seven days, thus effectively sterilising large areas of the site at a time. This therefore requires detailed collaborative planning on all work fronts to ensure that the site can remain operational.

Of the 59 concrete structures, some are simple reinforced bases, however ‘the big 5’ are significant structures:

Due to the repetitive nature of their construction, BEJV chose to construct the PST and the ASP using precast concrete techniques, which are then stitched together on site. The four FSTs and two storm tanks are also being constructed using precast panels which are then post-tensioned.

The inlet works and TTP are complex, bespoke structures with very little repetition and so are more suited to traditional in situ concrete construction. The inlet works is a particularly complex structure, and is the tallest structure on site at 13m above ground level and being formed of five separate elements.

As of August 2024, the inlet works concrete structure is half complete and the TTP structure underway. The PST precast walls are mostly in place and stitched together, with roof beams now being installed. Works have also started on the ASP walls.

Pipework to the FSTs is underway, which will then allow the construction of the bases to follow on. To date (August 2024), 4,000m3 out 14,000m3 of concrete has been poured, and 205 out of 454 precast wall elements installed.

The flows to the existing STW enter at the southern end of the works. A new transfer tunnel has therefore been constructed to intercept this and transport the flows to the new STW. This tunnel is 1.4km long, 1.5m internal diameter and flows by gravity. It is formed at an invert depth of 10.6m to 15.7m below existing ground level, entirely within the London Clay.

To construct the tunnel a series of six shafts were sunk. The largest of these is 12.5m diameter and forms the inlet shaft in the new STW. The raw sewage will then be pumped from this to the inlet works, from where it will then flow by gravity through the new STW. The remaining five shafts were used to launch or receive the tunnel boring machine (TBM) and pipe-jack, as well as being used for auxiliary connections to sewers in the existing network which don’t get picked up by the main connection.

The tunnel was constructed using the pipe-jacked method using a tunnel boring machine. This was named ‘Daphne’ in a competition by Bisley Church of England School. Daphne Jackson was the first female physics professor in the UK and taught and researched in Guildford. The tunnel consists of four straight sections, one curved section and one short hand-dug section to connect to the existing network.

Current progress is that all of the shafts have been sunk, the main tunnel is complete and fit out the shafts has commenced.

The outlet for the new STW consists of a 750mm diameter pipe from the TTP and a 1050mm diameter pipe which acts as a storm overflow during extreme weather events. These pipes are laid across a floodplain to the River Wey, a distance of approximately 330m before discharging via a bespoke headwall into the River Wey. This has been designed in conjunction with Environment Agency to minimise erosion in what is classified as a salmon river.

Due to Environment Agency and Local Authority permitting requirements as well as practical requirements of working on a floodplain with underlying running sand, these works are practically restricted to a short duration in the summer. This is being undertaken during Summer 2024 and the works are on target for completion within this period.

The majority of underground assets in the new works are being constructed within the existing landfill. This brings plenty of challenges in both design and construction. Assets must be designed to withstand both differential settlement and potential degradation from existing contaminants in the land fill material.

A variety of ductile iron, carbon steel, and concrete pipes are being used with various protection methods. The work is being self- delivered by the BAM workforce and the installation of below-ground pipework is underway with a focus on where it interfaces with the new structures. This requires extensive temporary works solutions to provide a safe working environment for the workforce within the band of landfill material.

Steel sheet piles are being used to provide temporary ground support and excavated landfill material is being sorted in a material handling area on site. This is being done to reduce the amount of hazardous material being sent off site, halving the amount of excavation and disposal required using traditional open cut methods.

As well as the main connection taking flows form the existing works to the new, there are three other existing assets which are to be integrated into the new system, at various points along the length of the new tunnel. This involves extensive research and planning in an open and collaborative approach with TWUL networks teams.

Bowers Farm Main was successfully diverted in November 2023, and has been constructed such that the final connection and commissioning to the new system will be a more straightforward operation. Planning works are currently underway on both Stokes Road syphons and Abbotswood syphons in order to construct similar scenarios for future connection and commissioning.

The main connection to the existing Guildford Main at the head of the new scheme entails connecting into an existing 10m deep concrete and brick built chamber, which carries live flows 24/7. The site team have undertaken several successful drawdowns in conjunction with TWUL to ascertain the dimensions and condition of the chamber in order to plan the final breakthrough works in great detail. This design work is currently underway and the new tunnel hand drive has been stopped a few metres short of the final breakthrough and shored up, prior to the final connection to the existing network.

Construction works of the ‘Big Build’ are continuing at pace and the BEJV Team are now focusing on ensuring a safe, effective and efficient integration of civils and MEICA elements. This will start in late 2024 and continue throughout 2025.

Following successful completion of commissioning of the new sewage treatment works in 2026, the existing works will be de-commissioned making way for the next stage of the Weyside Urban Village, providing homes and leaving a true legacy for local people and businesses.

The WINEP Enabling Project undertook a review of the U_IMP5 methodology, identifying the proposed FFT to ensure compliance with the above objectives. As part of the permit revision for FFT, the respective values for P, G, IMAX, and E were used to bring the permitted DWF into alignment too. A capacity assessment of major process units was undertaken under the enabling project, to identify the investment required to ensure compliance with the driver due to the increased FFT and the change to DWF.

The final contract scope was to replace the PST and HST, as well as modify the storm tanks and inlet works.

Wark on Tyne STW consisted of a narrow inlet channel with storm overflow, which fed an inlet pumping station with two fixed speed pumps, installed as duty/standby. The pumping station pumped flows to two pyramidal primary tanks with distribution and collection chambers. The storm overflow was connected to the two storm tanks with combined volume of 34.6m3.

From the primary tanks, two biological filters were gravity fed, which in turn fed two pyramidal humus settlement tanks with humus sludge returns to the inlet pumping station. Primary sludge was stored within a dedicated sludge storage tank prior to tankering off site. There was an existing MCERTS UMON 3 storm tank spill flow meter at the inlet pumping station building with a local display and an FE flow meter on the outlet to the watercourse, again with local display. The required contracted scope of works to meet the drivers included:

The new consent figures are shown in the table below:

Wark was selected as a project to drive digital delivery. Due to Wark being a less complex scheme in comparison to others within the programme, it was perfect for the first implementation of intelligent piping and instrumentation diagrams (P&IDs), design acceptance and build from model. The funding for the digitalisation project was embedded within the original design budget with the reduction in drawing production outweighing the development costs to implement the new process.

Traditional delivery can be cumbersome; old information such as-built drawings can be difficult to find, necessitating additional survey work. Residual risks are not readily identified, and previous lessons learnt are lost. Furthermore, engagement from the supply chain and construction staff can also be limited as they focus on one aspect of site at a time. Additionally, site support from design teams can prove time consuming, particularly where significant rework through design stages and completion documentation is necessary.

The objective of using digital delivery on Wark was to bring together best practice from across the water sector and other industries to streamline delivery in design and on site. The project aimed to reduce programme and costs whilst increasing engagement and safety from construction, the supply chain, and operations staff.

Finally, from a client perspective, leaving a legacy with the handover of a digital shadow to streamline operations, maintenance, and future projects on site.

At the outset, a digital delivery plan was developed to identify which technologies and software were to be implemented. These included:

New processes to implement these major changes were agreed to identify the input and boundaries of the key stakeholders. The team researched across industries, drawing upon experience within oil and gas to develop internal quality assurance gateways to give confidence to the client and to implement their feedback.

Bringing all these digital delivery aspects together meant completely changing standard design practices with which the team and the client were familiar.

The use of Intelligent P&IDs is not yet established practice within much of the water industry, meaning that the procedures and workflow for this were still being developed during implementation. Senior mechanical, electrical and process engineers, external to this project, were engaged throughout to govern this, using their extensive experience.

BETA testing the intelligent P&IDs resulted in schedules being produced automatically, resulting in one source of the truth. This resulted in reduced errors, automated cross checking, and a greatly reduced programme. The same intelligence was also incorporated in the PFDs, again reducing design programme and error.

All suppliers on Wark were engaged early, with 3D models requested to make the model build as seamless as possible. Discussions with the suppliers revealed that many of them design in 3D by default, and issue drawings following the model build. Therefore, requesting model data reduced their own workload and resulted in a quicker design turnaround. The digital shadow built to enable the ease of design acceptance and handover for the client, also allows the client to progress to their end goal of forming a digital twin of their network. The intelligence embedded in the model allowed the checkers and approvers to access the periphery information (calculations, enquires, etc) more readily, resulting in greater coordination checks and technical reviews with wider scopes.

Constructing from model enabled a greater level of detail around hazards captured within the model. Giving immediate health and safety benefits in the form of warning triangles, visible on the Icon whilst setting out in that location on site. Buildability reviews were also regularly held with the site team, to review the model, and ensure the design could be built as safely as possible. Items such as steepness of ground around the construction area, are not always noticeable in 2D form, when the team has not yet got site presence. Another immediate safety benefit was realised from the 4D Rehearsal. By sequencing the build within the model, the site team were able to recognise a hazard relating to the proximity of existing chambers and responded by resequencing the works to reduce the number of plant movements in a congested area.

This collaboration was conducted with both the client’s project team and engineering department to bring about lasting change; utilising their long-standing relationships to help drive this innovation across all projects in the future. The savings gained from digital efficiency and reduced drawing production is currently 4% of design budget but forecast to increase with the reduction in as-built production. It is anticipated that these efficiencies could increase on future projects once the new processes are embedded as business as usual.

The new design processes are being rolled out in the other teams working with Northumbrian Water, including their other framework partners to share the processes and learnings. The ongoing roll out to all MMB teams will enable similar benefits for all clients.

The new Melton Mowbray STW is designed to cater for increased treatment flows equating to a design horizon population equivalent of 123,328 (82% growth), a tightening of the Phosphorus permit from 2mg/l to 0.2mg/l and a tightening of ammonia permit of 5/10mg/l to 4mg/l. A significant proportion of the influent is from trade waste.

The new works design comprises:

MWH Treatment Ltd was appointed as the main designer and contractor by Severn Trent. The scope of works for the project included the investigation, assessment, design, procurement, construction and commissioning of existing and new treatment facilities, thus providing capacity to treat increased volumes of sewage to meet discharge permit standards agreed with the Environment Agency (EA).

A collaborative solution efficiency process was followed to develop the most effective and affordable solution, Severn Trent and MWH Treatment workshopping scenarios and risk that reduced the initial optioneered solution through an Outline Design Early Contractor Involvement order.

A schedule of innovative solutions included:

To create a vision of how best to design and build the new plant, the positive step to involve all key stakeholders at the earliest point in delivery was taken. Engaging with the supply chain early in the process gave an opportunity to challenge, augment and create an innovative design and delivery strategy incorporating the supply chain’s input to optimise construction safety of the build e.g. during workshops and collaborative planning sessions, every new asset was evaluated for off-site build potential, access and maintenance challenges with the plant design and construction in the already tight working environment.

The MWH Treatment team undertook a collaborative approach aligning the Client Operations team, the in-house design skill set with the construction team specialism to ensure the plant was both functional and constructible, overcoming access, maintenance and operability challenges and elected to take as much construction off-site and to modularise, wherever possible, thus overcoming conventional construction mind-sets.

Reference to previous schemes was also taken and the use of repeat proven design solutions adapted as widely as possible to mitigate re-engineering.

Ground conditions at the ASP location presented an early challenge for the construction of the new ASP being both very poor and highly contaminated.

Excavation and removal of this material, together with the importation of suitable virgin stone to create a piling mat, was expected to incur a significant carbon footprint and many vehicle movements along the shared access drive with local residents.

The team developed a comprehensive Material Management Plan including innovative solutions such as SMR UK’s cementitious binder to stabilise the piling and crane mat in lieu of excavation of contaminated materials and imported Type 1 stone mats, which resulted in project carbon reductions, together with costs savings in excess of £2m. The reduction in materials being exported to landfill together with imports of suitable replacement materials saved over 1300 vehicle movements combining for a carbon reduction of 1272.64 tCO2e.

To facilitate the stabilisation of the ASP formation, crane mat and piling mat, known buried structures that would have prevented piling were removed and crushed on site to form material suitable for reuse as hardstanding.

Additional carbon reduction activities included altering the design of the ASP straight wall to a tapered wall, reduced the quantity of materials used. Reduction in concrete of 368m3 (or 61 wagons) and reduction in 52 tonnes of reinforcement and adopting a process design to include an ASP structure with 13% reduction in area also reduced the materials used.

The design details developed at Melton Mowbray STW were also shared and utilised on the Hartshill STW project which shared similarities in design. This provided efficiencies in the detailed design of the Hartshill project which is running approximately 6 months behind the Melton Mowbray STW programme.

The collaborative approach between MWH Treatment, their subcontractors and the Severn Trent design teams enabled a focussed, efficient and standardised design sign off process.

The project team optimised digital delivery, developing innovative digital engineering tools to increase efficiency at initiation, design development, assembly, commissioning and ultimately client operational stages in the project lifecycle.

MWH Treatment undertook a full digital survey of the site. This was used as the basis of the 3D model but additionally this digital information and imagery was also actively used in the induction process to develop visual awareness of both the works layout and the impact on access.

The existing two-screen installation with centre by-pass channel was designed to be replaced by three new screens and two new wash compactors. This was further complicated as the refurbishment had to fit the existing inlet works structure.

This was achieved by the provision of a new bypass pipe outside the inlet works structure and the use of the existing centre bypass channel to house the third screen.

Hydraulic modelling of the inlet works ensured proper flow presentation to the new screen layout through the construction of a scaled model at Hydrotec Consultants, which identified enhancements that ensured flow calming and screen flow presentation.

The project has used an electronic GDPR compliant induction system for all workers and visitors. This system of completion online prior to arrival allows the site induction to focus purely on the key site-specific dynamic issues enabling people to start work more promptly. Over 1200 people have used this system, typically saving over 1700 hours of site time. The digital induction includes a video of the access routes and access restrictions enabling drivers and delivery persons to clearly understand the access routes and restrictions before setting off for site.

The induction was translated into a number of languages representing the diverse workforce deployed to deliver Melton Mowbray STW ensuring easy understanding of the requirements by the workforce on site.

The complex scheme involves intrusive works across most of the existing work’s operations which required meticulous planning to ensure Severn Trent process operation stability and security risks were minimised as far as practical.

These interfaces included:

All the above key interfaces were conducted seamlessly with no loss of production.

The site construction period was optimised using digital design, DfMA and effective site planning including collaborative programme workshops, and bi-weekly planning updates to drive the Melton Mowbray project to a completion date in May 2024, allowing Severn Trent six months of optimisation before the new consent comes into force.

The collaborative effort between MWH Treatment and Severn Trent is driving project success for all parties.