Burnley WwTW Catchment Strategy (2022)

Burnley WwTW: integration of new works into constrained site including earth bund of excavated material - Courtesy of United Utilities & Advance-plus

The Burnley Integrated Catchment Scheme is one of United Utilities largest AMP7 projects with a value of over £60m which commenced in 2020. The project is being delivered by Advance-plus, a joint venture between MWH Treatment, J Murphy & Sons and Stantec UK; United Utilities’ framework construction delivery partner (CDP). In UK Water Projects 2021 a case study was published that provided an insight into the project, focussing on the solution and design development. The focus of this case study, is to provide an update now that construction is in full swing and on course to complete ahead of the December 2024 regulatory completion date.

Burnley WwTW Growth & River Quality Improvement Scheme

Burnley Wastewater Treatment Works (WwTW) serves a domestic population equivalent (PE) of 107,115 plus trade load. A requirement for capital investment at Burnley WwTW had been identified to improve treatment capabilities and to achieve compliance with new tightened regulatory standards plus deliver the Environmental Agency (EA), Water Industry National Environmental Programme 3 (WINEP3) outputs for future population growth based on a 2035 design horizon.

These drivers are to achieve a ‘good status’ in the defined reaches of Pendle Water and the River Calder. The project will also include management of storm overflows to achieve a compliance with the WFD 99%ile wet weather intermittent standards.

Scope of catchment solution

Complex network modelling was undertaken to optimise the river water quality and levels of service in the catchment area to ensure no detriment. The model determined the lowest whole life cost solution:

• Upgrade Burnley WwTW comprising design, construction and commissioning of new 12,000m³ detention tank with associated pumping station, additional primary settlement tank (PST), activated sludge plant (ASP), BioMag process, final settlement tank (FST) refurbishment, surplus activated sludge thickening, ferric and caustic dosing, motor control centres, SCADA upgrade, and power upgrade.
• Construction of an online 1,950m³ detention tank with associated pumping at Lindred Road CSO (PEN0056).
• Actuated flow control penstock and upsizing of manhole at Altham Outfall Fennyfold CSO (BUR0026).
• New storm return pumping station at Hyndburn WwTW.

Caustic dosing system design with insulated stainless steel bulk tanks – Courtesy of United Utilities & Advance-plus

Process innovation

The BioMag System enhances conventional biological wastewater treatment by using magnetite (Fe3O4) to ballast floc allowing an increase in MLSS in the ASP and enhanced performance in the FSTs. The Evoqua Water Technologies detailed design has been finalised and the building layout confirmed. The main equipment including, 4 (No.) Magdrums and 2 (No.) shear mills, process tanks, silo and pumps have been manufactured.

Hydraulic modelling

Extensive computer fluid dynamic (CFD) modelling has been carried out by CER Technologies Ltd to optimise the design for chemical dosing mixing and ensure no magnetite settlement in the ASP. Hydrotec Consultants Ltd built physical models of the ASP outlet and ASP distribution chamber which were analysed at all flow conditions to confirm compliance with United Utilities specifications.

HADES models were utilised to detail the hydraulic performance of the new and reused assets.

Physical model of ASP distribution chamber – Courtesy of United Utilities & Advance-plus

ASP blowers

Sulzer HST Turbo-compressors have been selected from a lowest whole life cost analysis and offer significant benefits compared with positive displacement units:

• High efficiency with integrated control & monitoring.
• Superior low noise operation with blow-down silencers.
• Magnetic bearings eliminate mechanical wear and vibration so require low maintenance.
• Compact footprint.
• Air cooled & oil free.

The blowers will be housed in a prefabricated Saredon KITPAC building which has the advantage of a shorter installation programme. Acoustic louvres will be provided to minimise noise. The aeration FBDA system has been designed, manufactured, installed and commissioned by Suprafilt Ltd who have procured materials and manufactured air mains early to mitigate inflationary price increases. Each lane features four zones which are tapered to ensure maximum efficiency and optimise power consumption.

Odour risk mitigated

Due to the close proximity of the local residents, odour modelling was utilised to design a no detriment solution, which included covering the PST and providing an air extraction system. The PST will be fitted with a fixed bridge with rotating underwater scraper and a GRP cover. Ductwork will extract the air which will be dispersed via a 14m high vent stack.

PEN0056 detention tank

A 1,950m³ detention tank, of segmental shaft construction, will be provided at Lomeshaye Industrial Estate to reduce the storm discharges to Pendle Water to improve river water quality. This is a highly challenging build within a car park of one of the local businesses. An enormous amount of planning and stakeholder management has been required to get us started on site in July this year. The detail design identified that pipework could be connected to the existing CSO chamber which had the benefit of avoiding construction of a bifurcation chamber in the Lindred Road carriageway thus minimising disruption to local businesses.

PEN0056 site establishment – Courtesy of United Utilities & Advance-plus

BUR0026 modulating penstock solution

The constructability review of building a detention tank downstream of the BUR0026 CSO showed that it would not be possible to construct such a large underground tank due to the third party and environmental constraints. Therefore, it was agreed to move the required storage volume to the Burnley WwTW where the additional capacity could be accommodated. This has minimised the disruption to local residents, allotment users, Fennyfold playing fields, Padiham Cemetery, St John the Baptist RC Church and Primary School. At the BUR0026 site, a new real time control penstock will be installed to regulate and optimise flows in the downstream sewer to Hyndburn WwTW. Land has been purchased to site the new control kiosk with a new power supply also being required.

Hyndburn WwTW: New storm return pumping station

The network modelling identified that shortening the storm tank return time would improve the river water quality so an optioneering phase compared upgrading the existing 100l/s fixed speed pumping station to provision of a new system capable of returning flows through a range of 30-325 l/s. Due to the technical constraints and risks associated with the existing assets it was determined that a new pump station was the preferred solution as it would comply with the latest specifications and offer a more flexible and efficient pumping solution with a greater turndown capacity. A new submersible chamber will be constructed with 3 (No.) larger pumps, and 2 (No.) smaller pumps controlled with variable speed drives so that the flow can be controlled accurately to ensure flow to full treatment can be optimised. 2 (No.) Individual storm return mains will give resilience and ensure appropriate minimum velocity requirements.

The digital toolbox

4D digital rehearsals which link the 3D model to the programme have been used extensively by the site team to validate the constructability and sequencing of the works. Visualisation allows all parties to truly understand the construction sequence, interfaces and interdependencies which is relevant on such a congested work area with multiple subcontractors operating in close proximity. We have been able to identify high risk activities and plan mitigation measures. They help provide programme and cost certainty and facilitate stakeholder engagement.

Reduction of embedded and operational carbon

United Utilities projects require an estimate of the amount of embedded and operational carbon used. The project aims to reduce the carbon through the design and delivery phases.

Interstage PS wall shuttering – Courtesy of United Utilities & Advance-plus

Burnley WwTW Catchment Strategy: Supply chain – key participants

• Construction Delivery Partner: Advance-plus JV
  • MWH Treatment
  • J Murphy & Sons
  • Stantec UK
• Civil design detention tank: COWI UK Ltd
• CFD modelling: CER Technologies Ltd
• GPR & topo surveys: Atlantic Geomatics (UK) Ltd
• Flood risk assessment: Ambiental Environmental Assessment Ltd
• Physical modelling: Hydrotec Consultants Ltd
• Dewatering design: OGI Groundwater Specialists Ltd
• SCADA: Tata Consultancy Services
• Concrete construction: STAM Construction Ltd
• Concrete reinforcement: Capital Reinforcing Ltd
• Concrete supply: CEMEX
• Real-time concrete monitoring: Maturix
• Detention tank shaft: Joseph Gallagher Ltd
• Sheet piling: Sheet Piling (UK) Ltd
• Temporary works/shoring: MGF Ltd
• Precast post tensioned tanks: A-Consult Ltd
• Precast roof sections: Macrete (Ireland) Ltd
• Precast shaft segments: FP McCann
• Earthworks: D Morgan plc
• Blower building: Saredon Steel Buildings Ltd
• BioMag building: Gallaway Construction Ltd
• Tarmac surfacing: Multipave (NW) Ltd
• Dewatering: Alba Dewatering Services
• BioMag process: Evoqua Water Technologies
• BioMag mechanical installation: Alpha Plus Ltd
• Pumping station mechanical installation: Fluid Sealing & Engineering (FSE)
• PST fixed scraper bridge: EPS Water
• Epoxy coated carbon steel pipework & wall starters: Freeflow Pipesystems Ltd
• Dosing systems: Northern Pump Suppliers
• SAS drum thickeners: Huber Technology
• Odour control system: Air-Water Treatments Ltd
• PST odour covers: Corporate Engineering
• SAS glass coated steel tank: Stortec Engineering Ltd
• Ductile iron pipework: Saint Gobain PAM UK
• Ductile iron pipework: Electrosteel Castings (UK) Ltd
• FST scraper bridge refurbishment: Jacopa Ltd
• Blowers: Sulzer Water & Wastewater
• Aeration system: Suprafilt Ltd
• SAS tank air mixing system: Utile Engineering
• Submersible pumps: Xylem Water Solutions

Construction of the activated sludge plant, interstage pumping station and the primary settlement tank – Courtesy of United Utilities & Advance-plus

Progress update

The detailed design phase is substantially complete, and the catchment strategy solution accepted by the Environment Agency.

Three separate planning approvals have been granted for Burnley WwTW. The sheet piling operation was managed with a noise and vibration plan with monitoring equipment installed at the receptors which had to be revised and updated due to unexpectedly poor ground conditions which made pile driving harder. United Utilities and Advance-plus third party liaison teams communicated with the local residents to ensure they were informed of all works. The project has installed passing places on Woodend Road with electronic speed limit signs to minimise traffic disruption to local residents.

The earthworks phase has been successfully completed by D Morgan plc and J Murphy & Sons Ltd (JMS) with 38,000m³ of material being excavated and retained on site in a landscape bund, or stockpiled on local fields leased for the duration of the works.

Surplus made ground was removed from site and disposed of to a local tip in accordance with the Materials Management Plan (MMP). The dewatering system was designed by OGI Groundwater Specialists Ltd and installed by Alba De-Watering Services Ltd.

The civil FRC construction has been subcontracted to STAM Construction Ltd who have extensive experience in the water industry. The construction of the water retaining structures commenced in June 2022 and is progressing very well with a real focus on safety, production, and quality. The five ASP base pours are approximately 600m³ each and CEMEX are providing the concrete with 10 wagons on return from two batching plants at Burnley and Blackburn.

ASP construction: a well organised working area by STAM Construction Ltd – Courtesy of United Utilities & Advance-plus

Pour two had to be postponed due to the heatwave in July where we experienced excessive temperatures of 40 degrees in the cofferdam which exceeded the specification for concrete works and compromised the wellbeing of the operatives. Capital Reinforcing Ltd were due to source the rebar from Belarus but the Government Sanctions prevented this so an alternative supply came from Spain.

The civils team have trialled the Maturix Intelligent real-time concrete monitoring system to evidence the concrete curing and drying process with live data monitored directly inside the structure. Wireless devices send the data to the cloud and site engineers receive text messages with concrete temperature and strength data. The benefits include improved quality control, early striking of shutters, confirming readiness for crane loading, backfilling and water testing to shorten the programme.

The large diameter DI pipework has been manufactured by Saint Gobain PAM UK and will be installed by JMS direct labour and plant.

The detention tank and PST are being designed and constructed by A-Consult using precast panels which are post tensioned. Panels are in manufacture and have been factory inspected.

Detention tank panel manufacture at A-Consult – Courtesy of United Utilities & Advance-plus

The Xylem Water Solutions technical team have supported the project’s designers in providing efficient selections for the large submersible pumps and optimising the layouts of the pump chambers.

Mechanical installation of the pump stations will be by Fluid Sealing & Engineering (FSE) on the strength of recent successful delivery on other United Utilities schemes and outcome of the competitive tender process. PEN0056 planning permission has been granted and agreements in place with the businesses impacted by the construction works. Detailed design is complete and enabling works, including tree removal and service diversions, has been undertaken to facilitate the main construction starting on site in July 2022.

The shaft will be constructed by Joseph Gallagher Ltd using the jacking collar technique including base and benching, cover slab design, supply and install. Precast segments supplied by FP McCann and the precast roof sections manufactured by Macrete (Ireland) Ltd.

The project, like many others, has suffered from the current global environment and events such as Brexit, the Ukraine war and COVID-19 which are impacting on time and cost. Prices have soared across the supply chain with the unprecedented hyper-inflationary market conditions, especially in areas like steel and fuel. There has also been supplier shortages in areas such as instrumentation and PLC’s which have seen delivery durations go from 20 to 56 weeks in some instances putting real pressure on the programme.

Detention tank base, steelwork and outlet sump – Courtesy of United Utilities & Advance-plus

Challenges and recognition

In summer 2021 as COVID-19 restrictions started to be relaxed we launched a team-building event and programme of workshops to support the development of a strong collaborative working environment as the start on site at Burnley approached.

One of the outputs from this was a Project Charter, developed by the team, which sets out the culture and behaviours adopted and lived by all to help us deliver a successful project. All team members are task focussed and understand their roles and responsibilities to ensure a successful execution. Daily short interval monitoring of the programme activities keeps the team on track with achieving the project deliverables and enhances inter discipline communication.

A project of this type, across several sites, brings an enormous amount of challenges. These include health and safety management of large scale, complex construction in constrained working areas, on live operational sites and in 3rd party and public areas, working in environmentally sensitive areas and interfacing with customers on a daily basis. A lot of careful planning goes into this by the project teams with continual monitoring, regular auditing and reviewing to ensure the highest standards are maintained.

Project Charter

United Utilities’ construction supervisor recently nominated the team for a COMMEND award:

“The Advance-plus team achieved the milestone of working for their first year without an accident or lost time injury, which equates to 95,614 hours worked. Furthermore, the project team have received 5 recent WOW nominations for their efforts with managing the concerns of the local residents. Therefore, I feel that the whole ADV+ site team (management and operatives) deserve the COMMEND nomination for collectively delivering the last 12 months without injury whilst effectively managing the third party interfaces on the project.”

The team celebrated with a Greek lunch where delicious gyros and kebabs were enjoyed by all the workforce on site.

United Utilities operate a scheme known as WOW awards. This is where customers can recognise great service provided by an individual or team. The Burnley project team have really engaged with the local residents to minimise the nuisance caused by a major construction project on their doorstep and have received five WOW’s to date:

“I’m really pleased the project team have decided to repair potholes on the un-adopted road which I use to access my home. I understand they are not responsible or obliged to do anything, but the gesture is greatly appreciated and has made a hell of a difference to the road surface and journey I make several times a day, very happy. Well done team.”

ASP base pour No.2 – Courtesy of United Utilities & Advance-plus

Looking ahead

The main civils construction will continue to run through 2022 and into 2023. This will be followed by the mechanical and electrical installation and commissioning in 2023, through to performance testing in 2024.