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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]
Hydrogen sulphide attacks: (left) to the existing isolation penstocks, and (right) to the existing inlet channel walls - Courtesy of Morgan Sindall Infrastructure[/caption]
3D model of the existing and new structures – Courtesy of Arcadis[/caption]
3-D model showing all pipelines rising from ground and entering reception tank – Courtesy of Arcadis[/caption]
Installed reception chamber and rising mains - Courtesy of Morgan Sindall Infrastructure[/caption]
(left) DfMA installation of new inlet screens and chambers, (top right) the screenings skip canopy, and, (bottom right) internal photograph of bellmouth discharge points in reception tank - Courtesy of Morgan Sindall Infrastructure[/caption]
Overpumping manifold to isolate existing inlet works and grit plant - Courtesy of Morgan Sindall Infrastructure[/caption]
Activated sludge plant, interstage pumping station and blower building - Courtesy of United Utilities & Advance-plus[/caption]
BioMAg Magdrums - Courtesy of United Utilities & Advance-plus[/caption]
Burnley WwTW: ASP plant - Courtesy of United Utilities & Advance-plus[/caption]
Detention tank and pumping station - Courtesy of United Utilities & Advance-plus[/caption]
Sludge thickening area- Courtesy of United Utilities & Advance-plus[/caption]
Burnley STW: Chemical dosing area - Courtesy of United Utilities & Advance-plus[/caption]
Interstage pumping station and BioMag & blower buildings - Courtesy of United Utilities & Advance-plus[/caption]
Lindred Road detention tank during construction - Courtesy of United Utilities & Advance-plus[/caption]
Burnley WwTW: Odour control cover for PST4 from Corporate Engineering - Courtesy of United Utilities & Advance-plus[/caption]
Detention tank on water test - Courtesy of United Utilities & Advance-plus[/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]
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]
Odour model emission contours for selected solution - Google Maps[/caption]
Phase 1 odour control unit from ERG (Air Pollution Control) Ltd - Courtesy of Galliford Try[/caption]
(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).
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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]
View looking at Serpecon conveyors and pre-THP silo feed pumps - Courtesy of Galliford Try[/caption]
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.
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View looking north-east towards the Saxlund pre-THP cake silo - Courtesy of Galliford Try[/caption]
(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]
(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]