Supply Chain - Wastewater Treatment - Secondary Treatment
- The Woodlands Water Recycling Centre (2024)
- Horsham New WwTW (2024)
- Towcester WRC (2025)
- Lingfield WwTW (2024)
- Sleaford WRC (2024)
- Warrenpoint WwTW (2023)
- Ballygowan WwTW (2023)
- Guildford STW (2024)
- Winchburgh WwTW (2023)
- Ballyronan WwTW (2024)
- Beckton STW (2023)
- Boherbue Wastewater Treatment Plant (2024)
- Ards North Wastewater Improvement Scheme (2023)
- Lower Gornal STW (2024)
- Burnley WwTW Catchment Strategy (2023)
- Melton Mowbray STW (2024)
- Ballina Wastewater Treatment Plant (2024)
Rendered 3D model of The Woodlands WRC - Courtesy of EPS Water[/caption]
View of the main MBBR treatment block - Courtesy of EPS Water[/caption]
Noggerath® inlet fine screens at The Woodlands WRC - Courtesy of EPS Water[/caption]
View of the clarifier, sludge thickener & MCC kiosk - Courtesy of EPS Water[/caption]
Chemical dosing plant at The Woodlands WRC - Courtesy of EPS Water[/caption]
Tertiary solids removal plant - Courtesy of EPS Water[/caption]
New inlet screens supplied by Hydro International UK Wastewater Services division - Courtesy of CMDP JV[/caption]
The existing deep bed sand filter is being extended with three additional cells to enhance the tertiary treatment process - Courtesy of CMDP JV[/caption]
The two new Moving Bed Biofilm Reactors (MBBR) to remove ammonia from the final effluent returning to the River Arun - Courtesy of CMDP JV[/caption]
DN900 outlet pipework installed on one of the newly constructed MBBRs - Courtesy of CMDP JV[/caption]
(left) One of the two existing inlet screens being removed, (middle) one of the new 12.8m long Alpha Beta Escalator Screens being lifted carefully into place, and (right) the new inlet screens installed - Courtesy of CMDP JV[/caption]
Inside one of the new MBBRs as its installation approached completion - Courtesy of CMDP JV[/caption]
Setting out for piling works in alkalinity dosing area with sheet piling in place for bank stability - Courtesy of CMDP JV[/caption]
The new MBBR blowers are fitted with acoustic barriers to minimise any possible impact on nearby residential properties - Courtesy of CMDP JV[/caption]
(left) Garry Burgess, CMDP Construction Manager, receiving the award for the efforts of the Horsham New WwTW team and (right) CMDP JV and Southern Water staff pictured volunteering to support local charity, Ten Little Toes - Courtesy of CMDP JV[/caption]
Access platform above the ASP tanks - Courtesy of Anglian Water’s @one Alliance[/caption]
Final settlement tank construction - Courtesy of Anglian Water’s @one Alliance[/caption]
The new final settlement tanks with scraper bridges - Courtesy of Anglian Water’s @one Alliance[/caption]
Towcester WRC ASP - Courtesy of Anglian Water’s @one Alliance[/caption]
FST scraper bridge - Courtesy of Anglian Water’s @one Alliance[/caption]
Towcester WRC - Courtesy of Anglian Water’s @one Alliance[/caption]
(left) New trickling filter pumping station pipework and (right) chemical dosing facilities - Courtesy of CMDP[/caption]
Trickling filter tank precast panel installation - Courtesy of CMDP[/caption]
Trickling filter pipework - Courtesy of CMDP[/caption]
New Humus tank construction and temporary works access - Courtesy of CMDP[/caption]
Clean and dirty backwash tanks and the FilterClear tertiary package plant - Courtesy of CMDP[/caption]
Lingfield WwTW - Courtesy of CMDP[/caption]
Project Engineer Xenia Magdaleno-Tseng in front of the new trickling filter bed - Courtesy of CMDP[/caption]
Above-ground tricking filter - Courtesy of @one Alliance[/caption]
(top left) Preparing the reed beds, (top right) aeration pipework for the reed bed, (bottom left) the reeds, prior to planting, and (bottom right) reed bed planting - Courtesy of @one Alliance[/caption]
Construction work in progress (June 2021) - Courtesy of NI Water[/caption]
Construction progress (January 2022) - Courtesy of NI Water[/caption]
(left) Tertiary treatment unit being installed and (right) UV building and final settlement tanks - Courtesy of NI Water[/caption]
Sludge holding facilities under construction - Courtesy of NI Water[/caption]
The project team, and in particular the civil and MEICA contractor, worked hard to overcome supply chain issues. This involved developing a high degree of flexibility in the programme and delivery strategy to ensure that longer delivery times could be mitigated to ensure that the impact on the critical path could be minimised. NI Water also implemented measures to deal with the unprecedented levels of inflation that were being observed in the construction industry. This encouraged proactive discussion to mitigate the impact on price and programme and utilised an open-book approach to identify the real impact on projects and reimburse costs where required.
While Phase 1 was mainly constructed in areas of the site which were not in use, Phase 2 required the construction of a significant number of large structures in areas that contained the existing live treatment process, therefore careful phasing of the construction work was required. The main challenge involved the construction of the new final settlement tanks.
Two of the new final settlement tanks had to be built in a constrained area, where the redundant aeration tanks from the original works were located. Due to the depth of construction and the limited area, cofferdams were required to provide a safe excavation. During construction the existing settlement tanks, which were in close proximity to the new settlement tanks, had to be fully operational requiring careful demarcation of construction areas and NI Water operational areas.
The upgrades to the sludge handling facilities also required careful phasing as the new sludge holding tanks and sludge thickening facilities had to be constructed in the area where the existing sludge holding facilities were located. This required a detailed construction plan whereby the new facilities were constructed and brought online in stages, with new and existing facilities being used in different combinations during different stages of the process. The design had to account for the different pipework and valve configurations which would be required at each stage of the process, while ensuring that the final arrangement was as uncomplicated as possible.
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Phase 2 works nearing completion (November 2022) - Courtesy of NI Water[/caption]
As a result of the two-phase delivery, careful consideration had to be given to the electrical upgrade which was required at the site. A new motor control centre (MCC) was required for the upgraded works which would control the equipment provided in both Phases 1 and 2. The new MCC was installed during Phase 1.
Any assets from the existing MCC that had to be retained, until the Phase 2 works were complete, were transferred across. This required meticulous planning, communications and numerous shutdowns of existing plant and equipment and recommissioning to facilitate transitioning across to the new MCC.
Subsequently, Phase 2 plant and equipment had to be commissioned on the new MCC, which again required meticulous planning to complete without adversely affecting the ongoing operation of the works.
An unexpected challenge occurred during the construction of the final settlement tanks, when a bird nest was found in the cofferdam sheet piles. A specialist ecological consultant was brought to site to complete a survey and it was found that the nest was active and contained eggs. It was determined that work on the settlement tanks could continue, however, the sheet piles could not be removed until the birds had flown the nest, which did impact the delivery programme.
Warrenpoint WwTW - Courtesy of NI Water[/caption]
The objectives of the Warrenpoint upgrade met over the two-phase delivery are:
(left) Existing Ballygowan WwTW - Courtesy of NI Water and (right) demolition in progress: (top) the existing storm tank and (bottom) the existing CAS basin tank - Courtesy of GEDA Construction[/caption]
CAS basins - Courtesy of NI Water[/caption]
New storm tank being utilised during construction - Courtesy of GEDA Construction[/caption]
Ballygowan WwTW under construction (December 2021) - Courtesy of NI Water[/caption]
Interface between new and old works during construction
The majority of the new WwTW works was to be built on a greenfield site which allowed GEDA Construction to build most of the new structures without having to work around existing infrastructure.
However, in order to construct pipelines which would eventually take the flow into the new works, and to construct the new WwTW access road, it was necessary to demolish the existing storm tank in the old works prior to the new works becoming live. GEDA Construction carried these works out by utilising the newly-constructed storm tank and incorporating a carefully developed phasing plan.
A temporary 300mm gravity fed sewer was laid from the existing inlet works to the new storm tank, which in turn rendered the existing storm tank surplus to requirements, as all storm flows had been diverted away from it. GEDA Construction also had to lay a temporary 200mm pumped sewer from the new storm tank complete with temporary pumps to send the storm flows back to the existing pumping station in order for the influent to then go through the treatment process. This in turn allowed us to demolish the existing storm tank and construct the new permanent inlet sewers to the new works ahead of turning flows. This process had to be carefully managed both hydraulically and biologically to ensure the treatment process was optimised and effluent compliance was maintained at all times.
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New permanent high-level sewer under construction - Courtesy of GEDA Construction[/caption]
Turn of flows
Influent flows were successfully diverted into the new works in early May 2022. In order to bring the new biological treatment process online, several tanker loads of seeded sludge were brought to site from another treatment facility and were introduced into the new CAS basin tanks to promote bacteria growth. With flows diverted, and effective treatment established through a rigorous sampling regime, approval was received from NI Water to proceed with the demolition of the remainder of the existing treatment works. Once the existing works were decommissioned and demolished, the entire new WwTW site was able to be finished and access roads completed.
Demolition
Post turn of flows in early May 2022, the existing treatment works was decommissioned and then demolished. Reusable mechanical and electrical assets from the old treatment process were removed for future use by NI Water, while the effluent left in the old CAS basin and pumping station was removed from the site to allow demolition to commence. Effluent was filtered through the new treatment process to minimise unnecessary removal and disposal from site.
CAS basins in operation - Courtesy of NI Water[/caption]
Solmatix Renewables Ltd solar farm - Courtesy of NI Water[/caption]
Ballygowan WwTW nearing completion - Courtesy of NI Water[/caption]
A screenshot of the 3D model used for design and construction - Courtesy of Bam Nuttall Ltd[/caption]
Construction of the high level inlet works structure - Courtesy of Bam Nuttall Ltd[/caption]
(left) Rapid impact compaction underway and (right) a selection of site plant in use - Courtesy of Bam Nuttall Ltd[/caption]
(left) Driving precast concrete piles and (right) vertical rigid inclusion installation - Courtesy of Bam Nuttall Ltd[/caption]
2. Precast driven piling: The main structures and pipelines are founded on precast driven piles. These are end-bearing into the London Clay, approximately 10m below ground level. Precast driven piles were chosen as the solution as the operation does not bring any landfill to the surface. Various size piles were driven to various depths and tested with both dynamic and static tests. Borehole monitoring showed that there was no discernible change to leachate and ground gas levels and that there was no dispersal of leachate happening throughout the landfill.
(foreground) Ferric mixing and flocculation chambers and (background) concrete bases for sludge tanks - Courtesy of Bam Nuttall Ltd[/caption]
Piles and blinding concrete for the four final settlement tanks and (left) temporary ground support for pipelaying into the centre of the tanks - Courtesy of Bam Nuttall Ltd[/caption]
Activated sludge plant precast walls erected, prior to pouring base slab and concrete stitches - Courtesy of Bam Nuttall Ltd[/caption]
(foreground) PST precast walls with concrete stitches and bases and (background) ASP precast walls - Courtesy of Bam Nuttall Ltd[/caption]
Safdar Ali, Andrew Dawes and Izhar Ahmad from the BAM team at the completion of the tunnel - Courtesy of Bam Nuttall Ltd[/caption]
Threading buried process pipework between new structures requires extensive temporary works - Courtesy of Bam Nuttall Ltd[/caption]
(left) Concrete bases for the tertiary treatment plant, (top right) cross-sectional view through the primary settlement tank, showing the piles and gas dispersal layer beneath the base, and (bottom right) precast wall panels are joined with an in situ concrete stitch - Courtesy of Bam Nuttall Ltd[/caption]
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:
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.
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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.
Extract from 4D Synchro animation – Courtesy of EPS Water[/caption]
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.
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(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.
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.
(left) Existing site on western shores of Lough Neagh, (top right) existing PSTs, and (bottom right) existing percolating filters - Courtesy of NI Water[/caption]
Early excavation works with compound set up - Courtesy of NI Water[/caption]
The contract delivery team worked in a collaborative manner with NI Water, project managers RPS, and key suppliers and subcontractors to deliver a robust, effective and modern treatment solution which allows for future growth in the catchment area and protects the environment by adhering to a tighter discharge consent.
Excavation of FSTs to depth of 5m - Courtesy of NI Water[/caption]
Bottom section of FSTs installed - Courtesy of GEDA Construction[/caption]
Make up of the FSTs from KEE Process - Courtesy of GEDA Construction[/caption]
Installation of RBCs - Courtesy of GEDA Construction[/caption]
Construction of inlet works, sludge tank & storm tank - Courtesy of NI Water[/caption]
Completed Ballyronan WwTW - Courtesy of GEDA[/caption]
ASP4 South Tank twin wall under construction - Courtesy of Laing O’Rourke[/caption]
New inlet works under construction - Courtesy of Laing O’Rourke[/caption]
ASP4 extension and sludge improvements
ASP4 was installed under the last major upgrade at Beckton (by Laing O’Rourke), which completed in 2014 and currently treats up to 8m3/s. This project will provide two new aeration lates in separate tanks, referred to as the North and South Tank. Each are 85m long, 41m wide and 8.5m deep. Four new FSTs will be provided; each being 45m diameter and 5m deep.
A new aeration building is required to house blowers for the new aeration lanes with the aluminium clad structural steel building envelope installed by Galloway Construction Ltd. The aeration blowers are supplied by Howden, diffusers by Xylem Water Solutions and new transformers by Winder Power Group as part of a substantial upgrade to the existing electrical infrastructure for the new ASP.
The sludge improvements include new Huber Technology raw sludge screens to remove rags and improve resilience in the sludge treatment stream. Sludge treatment capacity improvements, surplus activated sludge (SAS) thickening, is by new gravity belt thickeners (GBTs), supplied by Kent Stainless Ltd in a new building. An extension to the existing sludge cake barn building to increase sludge cake storage capacity is required. The sludge steam has further resilience work by the provision of a polymer dosing facility, new electrical infrastructure, new sludge holding tanks from Stortec Engineering Ltd, and an upgrade to existing tanks.
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ASP4 North Tank completed and new blower building cladding underway - Courtesy of Laing O’Rourke[/caption]
Capital maintenance
There are a number of improvements to the existing site wide electrical infrastructure such as the refurbishment of existing LV panels. The other key element is replacing the outfall channel flap valves to prevent site flooding.
Fibre optic network upgrade
The site-wide fibre optic network will be replaced as it has reached its design limit and has no capacity to be extended to accommodate the growing operational and performance requirements. Laing O’Rourke and Atkins are working with Thames Water to develop a new network architecture based upon the utilisation of a ‘Layer 3’ backbone network. The design will incorporate four ‘Layer 2’ process networks with firewalls between each Layer 2 network and the backbone Layer 3 network. The updated network architecture will improve resilience and security of the network.
(left) 3D BIM model of new inlet works and (right) new inlet works under construction - Courtesy of Laing O’Rourke[/caption]
Another lesson learnt applied was to implement solutions with Engineered Safety in mind, both for temporary and permanent works. Engineered Safety is Laing O’Rourke’s approach, which aims to improve health and safety outcomes for those who design, construct, use, maintain and dismantle the assets (examples outlined later). This approach has helped to identify key hazards further to which simple but effective solutions have been implemented to eliminate or mitigate risks.
Notwithstanding the above implemented lessons, one of the key ethos of this project is capture and disseminate new lessons learnt during the design, construction, commissioning, and handover stages of the Beckton STW upgrade and future projects.
(left) Extract from 3D BIM model: raw sludge screens and (right) raw sludge screen civil works - Courtesy of Laing O’Rourke[/caption]
Digital build
Laing O'Rourke’s construction assurance procedure requires the use of digital build models prior to construction. Whilst the federated model aims to show the permanent works, the digital build process aims to incorporate both permanent and temporary works requirements by reconstructing the model using 2D outputs from detail design. This has allowed Laing O'Rourke to minimise health and safety risks by planning the build with better accuracy.
Drone deploy
To monitor progress in construction, drone technology has been used to capture photos and videos. Drone Deploy platform which utilises the rich data captured also allows superimposition of detail design drawings showing outline of permanent works. This tool has been used effectively in collaboration meetings to demonstrate progress or to resolve complex engineering problems, and to plan construction activities.
Point Cloud surveys
Point Cloud surveys have been used to inform the detail design. This method of survey that capture fine details of location of civil assets and MEICA plant and equipment in 3D format. Although, it requires careful treatment before incorporating into the 3D model. In particular, areas with high density of MEICA plant and equipment such as the sludge tanks, existing grit channel at the inlet works, and existing cake barn ventilation were surveyed using Point Cloud surveys.
Design challenges due to scale - constant velocity channel and grit bridges design
The scale of the works at Beckton STW created several design challenges around plant sizing, meeting performance requirements and space constraints. One example of this being the grit removal solution on the new inlet works. Conventional design methods for calculating grit channel lengths have been challenged. CFD modelling has been used to size the constant velocity grit channels and to demonstrate the proposed location of flow measurement devices are acceptable. This has reduced the length of the channel by 23m and hence the cost of civil infrastructure.
The pumps in the grit bridges are specified to remove up to 3.5kg/s and calls for an automatic system with level instrumentation to detect grit. This would make the classifiers ones of the largest in Europe. Borger Pumps and SAVECO Environmental Ltd are providing rotary lobe type pumps to achieve the specified rate. This design rate of removal is exceptionally high, taking into consideration the incoming grit from the Tideway Tunnel.
As detection systems in this scenario are not usually required in the UK, market research had to be undertaken to select the detection system in discussion with the supply chain with their experience from other industries to reach to a solution.
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(left) 3D BIM model of new inlet works screens and (right) new inlet works forebay with coarse and medium screens upstream of the constant velocity grit channels - Courtesy of Laing O’Rourke[/caption]
ASP4 North Tank under construction - Courtesy of Laing O’Rourke[/caption]
Sustainability
The project aims to minimise off-site landfill disposal by re-using spoil for engineering works or redistributing it on site through landscaping activities and creating additional biodiverse habitats. This has been the strategy included in the MMP from the inception of the project. This has been reviewed and updated with new information rising during the construction activities.
Any contaminated sections of the excavated materials were monitored with greater scrutiny, supported by chemical testing and analyses. Localised treatment has been implemented complying with environmental standards. For instance, the identification and safe method of disposal of soil contaminated with Japanese knotweed has been carefully selected with engagement from all stakeholders and planning requirements.
The above measures have assisted in ensuring construction activities are conducted in a sustainable manner.
Another area where sustainability has been considered is in concrete mix design. Due to the large volume of concrete required on site, the use of ground granulated blast furnace slag (GGBS) has been maximised in line within the parameters defined in the project specifications. This has assisted in reducing carbon footprint of the project.
Overcoming challenges - Cadent gas main diversion
An example how a complex engineering problem was solved in close collaboration with key stakeholders is the resolution of the crossing of the Cadent gas mains to enable the construction of the new inlet works channel. The new structure had to cross an intermediate pressure steel 600mm diameter gas main and a medium pressure 30” cast iron main which then split into two polyethylene (PE) mains. The mains then cross beneath the historical Victorian NOS brick barrels.
Engagement with Cadent instigated extensive and detailed assessments of the existing gas mains, this identified the need for the MP cast iron main to be replaced due to excessive ground settlement driven by changes in ground levels. The medium pressure gas main was replaced with a new 750mm steel main, which included a section inserted into a microtunnelled concrete sleeve underneath the NOS. In addition, pipe protection measures using polystyrene blocks and lightweight fill were required to minimise the loadings on the intermediate pressure mains.
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New 45m diameter FSTs under construction - Courtesy of Laing O’Rourke[/caption]
Engineered safety: (left) use of access hatch to internally access FST during precast wall installation and (right) use of RMD soldiers for aeration tank construction - Courtesy of Laing O’Rourke[/caption]
ASP4 tank walkway handrailing
The installation of walkway handrailing from Steelway Fensecure Ltd has been developed for this project and proven to reduce the site installation period and improved safety by reducing the working at height requirements. The lifting operations have benefitted from the site already having large lift capacity craneage and the construction logistics have enabled access into the working areas to align with the civil engineering works. Systemising pipework and cable containment onto the walkways for future projects are the next generation opportunities to be investigated.
Use of RMD soldiers for twin wall propping
A simple solution to negate the use of inclined props to create more workspace and reduce hazards is to use RMD soldiers. This required careful planning from the design of twin wall during temporary phase and ensuring appropriate measures are in place within the panels to allow safe fixing of the RMD soldiers in place.
Access hatch to FST walls
Another example of a simple solution to reduce safety risk is the provision of an access hatch to enable access during the erection of the precast panels, which was developed with the precast wall supplier A-Consult Ltd. This negated the need for providing high level access through temporary staircases and reduced risk of working from height.
The above examples emphasize the benefits of DfMA accrued at Beckton STW of an improved product, reduced installation period, and the on-going development opportunity that has made construction activity safer. The project has demonstrated how incremental innovation can be achieved on a relatively new and stable construction method using twin wall construction techniques.
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Precast construction of 45m diameter FST - Courtesy of Laing O’Rourke[/caption]
Use of non-piled solution
As old structures have been historically filled with mass concrete to significant depth, the reuse of these mass fill structures as foundation for new structures was explored as a safer and more sustainable solution. This enabled the project team to avoid the need for mobilising piling rigs, reduce lifting requirements and need for heavy plant and equipment. High-risk service diversions of were also avoided.
The SAS thickening system comprising the GBT building, polymer facility, potable water supply facility and the SAS storage tank all are founded on the existing mass concrete foundations. The choice of foundations was supported by structural analyses and further ground investigations.
Designer tours
To instill a culture of continuous improvement, designer tours encouraged the main designer and those from trade contractors to visit the site, inspect works being undertaken and provide feedback on how hazards are being mitigated on site. The aim being to capture feedback and consider them in future design work on Beckton STW and other projects.
New FSTs with backfilling underway - Courtesy of Laing O’Rourke[/caption]
Google Earth image of Boherbue[/caption]
Inlet works preliminary treatment - Courtesy of Glanua[/caption]
Secondary aeration treatment - Courtesy of Glanua[/caption]
Cloth filter tertiary treatment - Courtesy of Glanua[/caption]
Sludge drying reed beds to process wastewater sludge naturally - Courtesy of Glanua[/caption]
Solar panels for clean, renewable energy - Courtesy of Glanua[/caption]
(left) Precast concrete aeration tanks reduced construction time and safety risks and (right) view of final clarifiers and cloth filters - Courtesy of Glanua[/caption]
Off-site fabrication of steel building, fully assembled as works have been completed (April 2024) - Courtesy of Glanua[/caption]
Bulk excavation - Courtesy of BSG Civil Engineering Ltd[/caption]
Ards North WwTW - Inlet works overview - Courtesy of BSG Civil Engineering Ltd[/caption]
Inlet works side view - Courtesy of BSG Civil Engineering Ltd[/caption]
Screened raw sewage continues to the grit removal plant. The grit settles in a sump underneath the grit paddle. Any grit that settles in this sump is periodically aerated using the grit blower and then removed. From here the grit is transported out of the grit plant by the grit classifier and is deposited into the grit skip. From here it is removed off site for disposal.
After the wastewater has passed through the grit removal plant, flow continues to the FFT pumping station. Here influent is collected, and FFT of 48.2 l/s (summer) & 29.6 l/s (winter) is pumped to the PST flow splitting chamber.
(left) Ards North WwTW - Courtesy of NI Water, and (right) storm tanks tipping bucket installation - Courtesy of BSG Civil Engineering Ltd[/caption]
Aeration plant air manifold control valves and instrumentation - Courtesy of BSG Civil Engineering Ltd[/caption]
RAS/SAS pumping station - Courtesy of BSG Civil Engineering Ltd[/caption]
The thin sludge tank is equipped with an external mixer for the blending of the tank’s contents to feed the sludge thickening plant. A level ultrasonic with low and high-level floats are used in the control of the mixer.
Mixed sludge from the thin sludge tank is pumped to the sludge thickening plant via the two thickeners feed pumps. These pumps are progressive cavity pumps and are arranged in duty/standby configuration. The pumps are VSD controlled to allow the flow to the thickening plant to be controlled.
There are two sludge thickeners, with an individual throughput of 8.3 m3/hr @ 1.3% DS with a discharge of no more than 6%, based on a 5-hour day, 7-days per week operation at 100% of the maximum design load. The thickeners are arranged in a duty/standby configuration with two actuated isolation valves installed on the feed pipework allow this to be fully automated. If one thickener was to develop a fault, the standby thickener can resume operations without manual intervention.
Polyelectrolyte is made up on site to be added to the sludge fed to the sludge thickening plant. The addition of this chemical aids flocculation and makes thickening easier.
This plant is a liquid polymer set. The liquid poly is delivered within IBCs for the makeup process. The set mixes the poly from the IBC with water to a preset concentration rate and is then transferred to the poly storage tank. The duty poly dosing pump doses to the thickener’s sludge feed pipework from here.
Thickened sludge from the sludge thickening plant is transferred to the thick sludge tank. Here thickened sludge is stored for removal off site. A collection tanker removes the tank’s contents off site by coupling to the tank’s Bauer Coupler connector.
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PST No 1 & control building - Courtesy of BSG Civil Engineering Ltd[/caption]
The tank is equipped with a decant valve arrangement to facilitate settlement of the tank’s contents. The tank is also equipped with a level ultrasonic, low and high-level floats for level status and control of an externally fitted mixer for tank agitation.
The return liquors pumping station receives liquors from the following areas: inlet works drains, thin sludge tank decants and overflow, thick sludge tank decants and overflow, sludge thickening plant bund, FE and washwater drains and odour control plant drains. The station comprises of two fixed speed pumps, which are arranged in duty/standby arrangement. These return liquors to the activated PST splitting chamber.
Low level structures RC concrete installation - Courtesy of BSG Civil Engineering Ltd[/caption]
(left) Ballywhiskin TPS - Courtesy of NI Water, and (right) Carrowdore WwPS - Courtesy of BSG Civil Engineering Ltd[/caption]
(left) Sandycove WwPS and (right) Ballywalter Fowler Way TPS - Courtesy of NI Water[/caption]
NI Water, TetraTech, BSG Civil Engineering Ltd and Farrans along with local elected representatives to mark completion of the £18m Ards North Wastewater Improvement Scheme - Courtesy of NI Water[/caption]
Demolition of biofilter bank - Courtesy of MMB[/caption]
Construction progress (August 2023) - Courtesy of MMB[/caption]
MBBR tanks completed (June 2024) - Courtesy of MMB[/caption]
The MBBR plant was provided by FLI Water comprises two MBBR tanks, which operate in a lead/lag configuration. Flow is pumped to the MBBR plant from the tertiary feed pumping station, and passes into either MBBR Tank 1, or MBBR Tank 2; dependant on which tank is selected as the lead. Every day the tanks rotate the lead. This will be inhibited if the flow to the plant is too high (hydraulic safety), or if the ammonia monitored in between the MBBR tanks is too high (to protect the permit, if there is too much ammonia contained within the tank that would become the lag tank).
TSR plant (June 2024) - Courtesy of MMB[/caption]
Recirculation pumping station (June 2024) - Courtesy of MMB[/caption]
Completed plant (June 2024) - Courtesy of MMB[/caption]
ASP under construction - Courtesy of United Utilities[/caption]
Detention tank on water test - Courtesy of United Utilities[/caption]
Primary settlement tank
The new primary settlement tank (PST) civils construction is also complete, again undertaken by A-Consult Ltd using the precast concrete panel method of construction. It has also successfully passed its water test. Mechanical installation by EPS Water is now in progress on the ‘H’ frame steel structure which will support the scraper bridge. The design of the PST incorporates a fixed bridge arrangement with rotating scrapers beneath. This arrangement is necessary as the PST will eventually be covered with a GRP roof for odour mitigation. The odour control fans, ductwork and vent stack are scheduled to be installed in December.
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PST4 and ASP lane 1 on water test - Courtesy of United Utilities[/caption]
Interstage pumping station
Due to the topography and hydraulic levels across the site, a new interstage pumping station (IPS) is required to pump the effluent leaving the four PSTs up to the new activated sludge plant (ASP) distribution chamber.
Civils FRC works are being undertaken by STAM Construction Ltd and contain 94 tonnes of rebar and 900m3 of in situ poured concrete. The pumping station structure is complete and has undergone successful water testing.
The internal benching is complete and the next activities planned for the coming period will be the mechanical installation of the pumps and pipework. As the pumping station is vital to keep all flows passing through the treatment process, a standby generator will also be installed. The IPS is a two compartment design to facilitate future maintenance activities preventing the need to take it completely out of service. The new pumps have been supplied by Xylem Water Solutions who have supported the designers in providing efficient selections for the large submersible pumps and optimising the layouts of the pump chambers.
Activated sludge plant
The ASP distribution chamber is currently being constructed with all four concrete walls having now been poured. These are curing and the structure will undergo a water test in September 2023.
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ASP constructed and water tested - Courtesy of United Utilities[/caption]
In constructing the new ASP, STAM Construction Ltd have installed 650 tonnes of rebar and poured 4500m3 of concrete. The overall size of the ASP is 48m x 48m x 6.6m deep, has a capacity of 14,500m3 and comprises four lanes. Civils construction of the ASP is complete and fully water-tested with the mechanical installation of the internal pipework, aeration grids, diffusers and access platforms and walkways taking place over the next few months.
Suprafilt Ltd will be supplying and installing the internal pipework, aeration grids and diffusers. Mechanical installation of the pump stations and access steelwork etc will be undertaken by Fluid Sealing & Engineering (FSE).
BioMag®
The Evoqua Water Technologies detail design for the new BioMag® process has been finalised and the building layout confirmed. The main equipment including four Magdrums and two shear mills, process tanks, silo and pumps, which have been manufactured and are ready for delivery to site when required. The BioMag® building is currently under construction by Gallaway Construction.
The steel frame has been erected and the gantry crane and roof cladding have been installed. External wall cladding is in progress, after which attention will turn to the internal fit-out and installation of the BioMag® equipment.
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BioMag® building being erected - Courtesy of United Utilities[/caption]
Final settlement tanks (FST)
There are four existing final settlement tanks which required refurbishing to ensure adequate performance and asset life are achieved. The scope includes civils refurbishment of the tank walls which involves cutting approximately 300mm from the top of the walls before installing new reinforcement and re-casting concrete to the required coping levels.
Cutting works is being undertaken by Holemasters and FRC works self-delivered by JMS. The mechanical and electrical work is being delivered by Jacopa and comprises refurbishment of the bridge, scraper assemblies, and other ancillary equipment. Three of the four FSTs have now been refurbished with the final one due to be undertaken towards the end of the year.
Surplus activated sludge (SAS) thickening
Civils works has been ongoing in the SAS thickening process area for the last couple of months with the storage tank, drum thickener, poly plant and kiosk bases all constructed. Underground services, ducts and pipework have also been installed and tested. The filtrate return pumping station construction is in progress with the mechanical installation due to follow on.
Chemical dosing
The new ferric and caustic dosing plants comprise storage tanks, dosing rigs and dosing pipelines, all of which have been designed and well progressed in manufacture. These are being supplied by NPS Engineering Group. A new chemical delivery facility will also be provided with civils construction in this area commencing towards the end of the year and installation of the new dosing plants taking place early 2024.
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3D model of chemical dosing area - Courtesy of United Utilities[/caption]
HV works
A new, uprated HV cable has been installed from the off-site substation to the wastewater treatment works, a length of approximately 900m, passing through a number of fields and third-party land.
Motor control centres (MCCs)
To control all the new assets a number of new MCCs housed within kiosks are required around the site, along with a new site-wide SCADA system. The MCCs are all in various stages of manufacture and factory testing. The electrical installation and system integration works, including dry testing, will be undertaken in phases over a period of months as the programme for each of the new process areas dictates.
The MCCs are being built by Technical Control Systems Ltd, electrical installation will be by PICOW Engineering Group and system integration by Tata Consultancy Services.
Looking forward to commissioning
Commissioning of the new treatment process, and transitioning from the old process in a controlled staged approach, will be complex.
The existing treatment stream and process compliance cannot be put at risk or compromised and months of hard work and planning for commissioning has already taken place. Wet commissioning is due to start in April 2024, gradually increasing flows into the new treatment process over several months while the new biological process builds up and matures to a point where the improved treatment standards are being met. The forecast project in use date is October 2024.
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Aphex construction planning software map view - Courtesy of United Utilities[/caption]
Lindred Road detention tank during construction - Courtesy of United Utilities[/caption]
Work started on site in July 2022, with the first phase involving the diversion of numerous services, including gas, fibre, BT, water and power, to clear the area for the tank construction. Enabling works to provide safe access routes, segregation, and procurement of alternative car parking for the impacted business employees was also required before the main construction work could commence.
Ground was broken in August 2022 with the tank construction continuing through to December 2022 when full depth was reached. Construction of the pump sumps, inlet channel and complex benching arrangement followed.
The spring months of 2023 saw the mechanical works inside the tank take place with the installation of the pumps, pipework and access ladders and platforms. Once the internal works were complete, the roof beams were installed and the roof slabs placed on in May 2023.
The inlet and outlet pipework for the tank has now been installed, including associated manholes and chambers. To facilitate the connection of the 1200mm inlet pipe into the existing CSO chamber, a complex timber heading arrangement needed to be constructed in order to access beneath, and protect a myriad of services crossing the vicinity. All buried pipework, chambers and ducts etc have been completed and reinstatement of the area is in progress.
The civils and pipework has been undertaken by SGC Civil Engineering Ltd and the mechanical works by Fluid Sealing & Engineering (FSE).
A new motor control centre and power supply is being installed for this facility. The new control kiosk was delivered and installed in July 2023 and the electrical installation is currently ongoing with the new power supply due to be energised in October.
Testing and commissioning is scheduled to start in November, with the site achieving project in use in February 2024.
Lindred Road: Aerial view of detention tank - Courtesy of United Utilities[/caption]
Hyndburn WwTW - 3D model of storm return pumping station - Courtesy of United Utilities[/caption]
A new below-ground wet well type pumping station will be constructed with three high-flow pumps and two low-flow pumps which provides a more flexible and efficient system with greater turn down capability. A new single rising main will return the storm flows back to the head of the treatment works. A new kiosk and motor control centre will also be installed.
Planning permissions are in place and all pre-start surveys and investigations have been completed. Detailed design is nearing completion and the site has just been established. Construction is due to start in earnest in September on the new pumping station excavation. The winter months will see the civils works progress, with mechanical and electrical works due to start in spring. The project in use is forecast for July 2024.
Aphex construction planning software Gantt chart - Courtesy of United Utilities[/caption]
Melton Mowbray STW before the start of works - Google Earth image[/caption]
(top left) Groundworks underway, (right) SMR UK ASP area soil stabilisation, and (bottom left) stabilised ASP area with piling and ASP base construction ongoing - Courtesy of MWH Treatment[/caption]
The net carbon reduction profile of these activities[/caption]
(left) Inlet works physical model at Hydrotec and (right) inlet works screen baffles and dye test - Courtesy of MWH Treatment[/caption]
Refurbished inlet works with three screens & bypass pipework and (inset) the inlet works prior to the upgrade with two screens - Courtesy of MWH Treatment[/caption]
Refurbished inlet works with three screens & bypass pipework and (inset) the inlet works prior to the upgrade with two screens - Courtesy of MWH Treatment
Construction work underway at Ballina - Courtesy of Shay Murtagh Precast[/caption]
New inlet works under construction - Courtesy of Ward & Burke[/caption]
New final settlement tank under construction - Courtesy of Ward & Burke[/caption]
Scope of works (continued)
New storm water tank under construction - Courtesy of Ward & Burke[/caption]
New outfall under construction - Courtesy of Ward & Burke[/caption]
- Air Blower Retrofit at Wastewater Treatment Works
Air Blower Retrofit at Wastewater Tr...The issue: Energy efficiency has not been the focus so far
Operational efficiency and reliability should be priorities in wastewater treatment plants. Consequently, there has been a prominent focus on being more efficient and reducing carbon footprint. This WwTP treats wastewater for over eight million people. The company was working with three energy-intensive competitor blowers that no longer met today‘s standards, this is where AERZEN was consulted.
The solution: Turbo technology for efficient aeration
For this replacement a detailed calculation of profitability showed a potential energy saving. All three blower units were showing significant signs of wear. Therefore, instead of an extensive and costly refurbishment, it was decided that these old units should be replaced with three new efficient AERZEN Turbo Blowers.
- AERZEN consulted with the company Air Technology to determine the current load requirement. A detailed profitability calculation indicated energy savings of over 20%.
- AERZEN supplied 3 Turbo G5plus blowers (3 x AT150 0.8S DN250), which modernised the plant as they replaced the competitor’s aging blowers that were consuming a lot of energy.
- While these works were going on, the client involved AERZEN Rental to avoid downtime, who supplied the end user with 2 BVO 55000 skid mounted assemblies.
[caption id="attachment_8979" align="alignnone" width="1200"]Type of technology Turbo blower Overpressure 1,000 mbar Version Positive pressure Conveying media Air, neutral gases Volumenstrom 360 to 8,400 m3h Conveying oil-free 
Courtesy of AERZEN Machines[/caption]
The result: Modern technology used to reduce CO2 emissions
The space-saving installation of the new turbo technology from the G5plus series enables an efficiency gain of approx. 21% for the aeration of wastewater tanks which ultimately leads to savings in operating costs.
Additionally, in comparison to the earlier ventilation systems, the noise emissions were significantly decreased.
Summary
This wastewater treatment facility can save over £21.000 by utilising state-of-the-art technology, the AERZEN Turbo G5plus blower. AERZEN had a 4-week lead time. The calculation assumes an amortisation period of about three years. The cost and energy savings coincide with the customer‘s desire to reduce their carbon footprint.
Ian Moore, Technical Director, Air Technology, commented:
"It’s looking like a really good installation, and it is much quieter and more efficient than the old system."
For more information: AERZEN Machines | +44 (0)208 502 8100 | www.aerzen.com
- Goscote STW: IFAS Installation
- Finham STW: IFAS Installation
