Supply Chain - Asset Maintenance & Rehabilitation -

The existing large-diameter trunk main running from Nunhead Reservoir to Deptford is one of the key network assets supplying water to the Greenwich Peninsula. Tunnel sections of the pipeline had experienced failures in the past and the glass reinforced plastic pipes had deteriorated with extensive blistering, leading to concerns that the pipes are no longer serviceable and DWI compliant. Morrison Water Services (now M Group) was engaged by Thames Water Utilities Ltd to carry out site investigations, identify a cost-effective pipeline rehabilitation solution, and subsequently to deliver a £21m project to rehabilitate this trunk main using a hybrid lining system. Background

The Millennium Main is a large-diameter trunk main conveying potable water from Nunhead Reservoir to Deptford to support the Greenwich Peninsula and the Millennium Dome. The main is approximately 3km in length and it was built in 1999.

The water main is a combination of ductile iron (DI) and glass reinforced plastic (GRP) pipes; the latter being installed within concrete jacking pipes where trenchless methods were used to cross three railway lines and avoid open-cut trenching in some roads.

The existing GRP pipes sleeved in concrete jacking pipes (approximately 1.82km in length) can only be accessed through existing tunnel shafts deep below ground level; with access requiring extensive traffic management due to their locations.

In 2012, GRP pipes failed within one of the trenchless sections on two separate occasions. The site investigation revealed that the tunnel annulus grouting between the GRP pipes and the host concrete sleeve pipes at the failure locations was either entirely missing or incomplete, causing excessive tensile forces in the pipe wall and resulting in pipe failures. Subsequently, all the voids detected in this section were filled with grout. The GRP pipes within this trenchless section were relined with steel pipes (185m in length) and the main was returned to service.

In 2015, another failure occurred along another trenchless section. The post incident investigation again found that annulus grouting above the failed GRP pipe was incomplete, leaving air pockets between the GRP pipe and the concrete sleeve pipe. During AMP6, further investigation into the annulus voids and annulus grouting were carried out along the section that failed in 2015 and the adjoining trenchless section (total 270m in length). However, the main was not put back into service due to the risk of pipe failure that might occur along the remaining GRP pipe sections which had not been surveyed and repaired (approximately 1.36km).

[caption id="attachment_22364" align="alignnone" width="1200"] Existing tunnel shaft - Courtesy of Morrison Water Services (now M Group)[/caption] PPR survey & annulus grouting

In 2020, Thames Water appointed Morrison Water Services (now M Group) to carry out pipe penetrating radar (PPR) surveys to identify the locations of annular voids and grout the identified voids along the remaining GRP pipe sections (approximately 1.36km in length), in order to recommission the Millennium Main.

As part of the site investigations, pipe wall samples were taken from GRP pipes to test pipe strength and analyse their composition. The results indicated that the GRP pipes should have more than 30 years remaining asset life if the grout annulus were fully reinstated. The existing GRP pipes were first surveyed using PPR method to identify annular voids and the survey results were verified by an endoscope camera survey on targeted areas to confirm the highlighted voids.

On completion of the surveys, all the identified annular voids were filled with a special free-flowing grout to ensure complete void filling. The grouting work was completed in March 2022.

Osmotic blistering in GRP pipe internal surface

During the inspections of the GRP pipes, extensive osmotic blistering in the GRP gel coats was observed with many of the blisters ruptured, exposing the resin liner underneath. Further blisters were likely to form in the presence of water during operation and ruptures of the blisters was also expected.

[caption id="attachment_22327" align="alignnone" width="1200"] Osmotic blistering in GRP pipe internal surface - Courtesy of Morrison Water Services (now M Group)[/caption]

The exposed resin liner is not DWI Regulation 31 approved material, hence the ruptures of the osmotic blisters can cause potable water coming into contact with non-DWI approved resin which is a breach of DWI Regulations and Thames Water Standards.

In addition, the underneath GRP laminate would hydrolyse with time, weakening pipe structure and reducing the effective thickness of the pipe if this osmotic blistering issue were not addressed. Considering this, Thames Water made a decision to line all the GRP pipes within the trenchless sections.

Lining options investigated

Thames Water and Morrison Water Services (now M Group) reviewed a number of lining solutions including:

Steel liner. PE liner. Cementitious coating. Sprayed in place pipe (SIPP) liner. Cured in place pipe (CIPP) liner. Hybrid lining system.

Approximately 185m of a steel liner was installed within GRP pipes when GRP pipes failed in 2012. The steel liner option provides a robust solution, however, it was estimated that it would cost approximately £45m to reline the whole length of GRP pipe whereas the estimated cost for the hybrid liner option was approximately £17m.

Both steel liner and PE liner options require a longer installation period due to difficulties in installing pipes from restricted tunnel access shafts. The hydraulic modelling work also confirmed that the reduced pipe bore by these options would cause additional pipe head loss, affecting pressures in the downstream network.

Cementitious coating and SIPP options were discounted primarily due to the risk of the cementitious coating and spray lining not being able to properly adhere to the surface of the GRP pipes. CIPP liner option was also discounted due to the absence of DWI Regulation 31 approval at the time of optioneering.

Based on the results of the optioneering, Thames Water made a decision to reline the GRP pipes using a hybrid liner, considering the whole life cost, pipeline hydraulic performance, DWI approval, construction period and other risk factors.

Development of GRP pipe lining solution

Morrison Water Services (now M Group) partnered with VIP Polymers Ltd to develop a bespoke lining system, VIP-WECO hybrid liner, to line the internal surface of the GRP pipes for this project.

[caption id="attachment_22328" align="alignnone" width="1200"] VIP-WECO Hybrid Liner system - Courtesy of VIP Polymers Ltd/Thames Water[/caption]

Each hybrid liner is 1.7m long and comprises of one EPDM centre sleeve and two EPDM end seals. The EPDM rubber sections are then covered with stainless steel sheet and fixed to the GRP pipe, using stainless steel tensioned rings. The liners are butted up against each other to achieve full coverage of the GRP sections (approximately 1.63km).

The structural assessment of the hybrid liner confirmed that the lining system can withstand internal pressure and resist possible buckling when the GRP pipes are left empty and the liner is exposed to the full head of groundwater through cracks and voids in the GRP and host concrete pipes, in the worst case scenario.

The components of the hybrid liner system can provide durability for at least 50 years, which is longer than the remaining asset life of the GRP pipes. VIP Polymers Ltd obtained DWI Regulation 31(4)(a) approval for the hybrid liner they produced.

During the development of the hybrid liner, an above-ground mock-up of the lining system was built to refine the detailed arrangement of the hybrid liner, to test the installation of the lining system, and to check if the installation work could be carried out safely during the actual installation.

[caption id="attachment_22330" align="alignnone" width="1200"] Hybrid liner mock-up - Courtesy of Morrison Water Services (now M Group)[/caption] Millenium Main: Supply chain - key participants Main contractor: Morrison Water Services (now M Group) Designer: AECOM Subcontractor: DWG Infraco Key material supplier (hybrid liner): VIP Polymers Ltd Construction

Morrison Water Services (now M Group) commenced the installation of the hybrid liner in the GRP pipes in June 2023. The works within the GRP pipes and tunnel shafts were carried out by operatives who were qualified for high risk confined-space work with provisions of health, safety and rescue support, and periodic rescue training was conducted during the site investigation and construction phases.

A total of 973 hybrid liner units were installed in the GRP pipes and each unit was tested by air pressure to check leak tightness of the liner unit. The installation of the hybrid liner was successfully completed in October 2024.

Currently, existing DI pipe sections (approximately 1.2km) are being surveyed to check the conditions of the pipes and any identified defects are being repaired.

Progress

This project successfully restored the tunnel annulus grouting and the integrity of the internal pipe surface of the GRP pipes to comply with DWI regulations. It is currently planned to return the main to service in August 2025.

Potters Way, located in the Fengate area of Peterborough, is a recent housing development next to the A1139. The development was built on the grounds of the former Fengate Water Recycling Centre (WRC) which closed in 1988 following the construction of the Flag Fen WRC. In early December 2018, Anglian Water became aware of the collapse of a section of 1500mm diameter concrete sewer pipe in Potters Way when a small hole was found after a customer used a ride-on lawn mower over the area. Temporary repair works were undertaken by the Integrated Operational Solutions (IOS) Alliance - a partnership between Anglian Water, Kier, Barhale and Morrison Utility Services - while a permanent fix could be designed and implemented. Background By the end of December, the IOS Alliance had installed a temporary repair using a vacuum excavator to safely clear the collapsed pipe before using half-pipe and canvas to seal the collapse. The area was also fenced off to prevent pedestrian access and ensure site safety. During this period, Anglian Water received several complaints from customers over the odour created by the collapse. Following meetings with the residents, Anglian Water’s Water Recycling Networks (WRN) team further sealed the excavation and installed carbon filters to the air valves. At the same time, the team repaired holes found in the rising main pipework at the nearby tower. The site was then handed over to the Anglian Water @one Alliance to implement their repair solution with @one partner company Barhale engaged as principal contractor. [caption id="" align="alignnone" width="1200"] Installation of the overhead diversion - Courtesy of @one Alliance[/caption] Finding a solution One of the challenges presented in finding a solution for this project was the high flow rate of the pipework, with modelling of Potters Way showing flow rates of 3,700 litres per second in the event of a 1 in 30-year storm. Downstream of Potters Way, this rises to 4,000 litres per second. To make the matter even more complicated, the pipe featured several significant bends along the affected route that increased the difficulty of finding an adequate solution. An extensive survey of 2.8km of sewer identified 1.79km of concrete sewer pipework ranging in diameter from 1050mm to 1950mm had a condition grade of either 4 or 5. All these pipes were identified as having been subjected to a hydrogen sulphide (H2S) attack which had caused the significant deterioration. The @one Alliance set out to repair an area of the network by covering a key 500m of pipework which serves the majority of Peterborough. Potters Way Sewer Rehabilitation: Supply chain Project delivery: Anglian Water @one Alliance Temporary repairs: Integrated Operational Solutions (IOS) Alliance Principal contractor: Barhale Over pumping: Vanderkamp UK GRP pipe lining: Amiblu Norway AS Lining & manhole repair: OnSite Central Ltd Specialist CCTV Survey: Bright Innovations Group Foam concrete: GS Foam Concrete Diamond cutting: SCS Ltd Cover slabs: FP McCann Ltd Temporary works/shoring: Groundforce Pipe rehabilitation The @one Alliance solutions team opted for a multi-stage solution due to the complex nature of the pipework and the compact area the teams would be working in. In order to repair the sewer, it was decided that a mix of CIPP (cured in place pipe) and GRP (glass reinforced plastic) lining would be used. The majority of the rehabilitation was completed using CIPP lining which allows the lining to be inserted into the shell of the existing, damaged pipework where it is then pressurised and cured in place with ultraviolet (UV) lights. The CIPP relining was split into eight sections covering approximately 360m of the repaired pipeline. At 1375mm in diameter, this installation was the largest diameter CIPP liner that the @one Alliance had ever installed. Six of the eight lengths of CIPP were installed under the A1139. Over pumping In order to fit the CIPP liners, the team utilised an over pumping set up capable of 250 litres per second (l/s). By using bungs at split manholes on the nearby Bourges Boulevard, the team could redirect the flow and use the pumping set up to divert the rest of the flow. The over pumping solution was provided by Vanderkamp UK who had remote monitoring capabilities from the Netherlands and provided the site teams with a mobile app allowing them to see real time data giving them advanced warning of increased flows which would require the removal of the bungs. Without this passive flow management, the over pumping setup would have needed to be able to cope with an excess of 2,000 l/s. The set up was made up of two pipe bridges 350mm in diameter and 5.5m high to allow clearance for high-sided vehicles. GRP lining Alongside the CIPP lining, the team also used GRP lining on a 48m section of 1500mm diameter sewer executing the rehabilitation in live flow conditions of approximately 850 litres per second; the first time the @one Alliance had installed GRP lining in live flow conditions. [caption id="" align="alignnone" width="1200"] (left) Live flow conditions and (right) inserting a new section of Amiblu Norway AS GRP pipe - Courtesy of @one Alliance[/caption] Operating in live flow removed the necessity to install an additional over pumping solution that would have dealt with 95% of Peterborough’s sewage as it combined into one flow towards Flag Fen WRC. In order to commence the GRP lining, the crown of the pipe was removed on a bend and concrete platforms were constructed on either side ensuring a safe working area. A pipe pusher attachment was then used to insert segments upstream and downstream from the bend location. Finally, a prefabricated GRP bend section was installed and connected to straight sections. To safely cut the existing mains the team needed to excavate an area of 6m x 4.5m with a depth of 3.5m. While having to excavate in an urban area is an option the team would have liked to have avoided, the next best solution to the live flow repair would have included installing a temporary pumping station that would have taken up all of Potters Way’s parking and grass area requiring 10 pumps and a 10m x 7m x 7m temporary wet well to complete the required repair. This would have been a major inconvenience for residents and would have seen an increase in the overall cost of the project of 200%.

Amiblu relining pipes to protect sewer networks from H2S attacks - Courtesy of Amiblu Norway AS

Manhole rehabilitation As part of the pre-work checks, it was identified that eleven manholes along the section of pipework required rehabilitation of various levels with the most severely affected requiring structural repair as a result of H2S attacks. Core samples were taken from one manhole which identified that in some places, more than 150mm of concrete had been lost to H2S attacks with no rebar remaining in any of the samples. To repair the manhole, the team used a concrete spray to bring the walls back to their original 250mm thickness, once this had cured a primary and finishing layer were added to ensure full protection against H2S attacks in the future. A new cover slab was also installed after the original was removed to provide access to the manhole, made of precast concrete the slab was also treated for H2S protection. [caption id="" align="alignnone" width="1200"] (left) H2S attack on a manhole and (right) inside a relined section of pipe - Courtesy of @one Alliance[/caption] Challenges Weather provided a significant challenge for the implementation of the solution as the site experienced an unusually heavy rainfall. Flow rate analysis for Flag Fen WRC shows that in the previous five years the average rainfall for the area fell between 35mm and 60mm. August 2020 saw average rainfall of 137mm. Because of the heavy rainfall several weather warnings were issued placing all CIPP lining activities on hold. The impact of the weather was so severe the flow of water increased from its usual 850l/s to 4,000 l/s in just 10 minutes. In order to reduce the risk of flooding outside the Magistrates Court the bungs were deflated, and the flow reverted. Due to the innovative combination of flow diversion and overpumping used in the CIPP lining the impact of the delay was significantly reduced compared to if the team had used the temporary pumping station solution. Rising mains issues During the repair of the sewer the @one Alliance became aware of complaints from the residents regarding the twin rising mains on Potters Way which used to feed into the old Peterborough STW and was diverted into the new gravity sewer discharging into Flag Fen WRC. The primary complaint from customers was the odour produced by the rising mains. The old Peterborough STW was sold for development and the rising mains tower was marked for removal. In early 2022 the @one Alliance returned to Potters Way removing the rising mains and installing a pumping station kiosk removing the odour and significantly reducing the visible profile in the area. Result Anglian Water invested £2.8m into the Potters Way project which will now allow customers across Peterborough to continue to use their taps and flush their toilets without second thought. The relining of the sewer network has ensured the network in the Potters Way area is now protected from H2S attacks for the next 50 years. Colin Handley, Construction Manager said:

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

Leominster WwTW is a medium sized biofilter sludge works, treating a population equivalent of approximately 11,000. Welsh Water have invested £12.1m to deliver the process enhancements at the works as part of Welsh Waters’s commitment to deliver on improved water quality in the Wye River basin catchment. Other enhancement works were completed on existing sites including Eign, Rotherwas and Kingston & Madeley WwTWs. As part of the National Environmental Programme (NEP) commitments to meet the obligations of the Water Framework Directive in AMP7, new permit limits were put in place for 31 March 2025. The project exceeded this milestone by one year, achieving the tightened permit and Welsh Water’s annual commitment for river reach improvement. Existing works

In advance of the improvement scheme, the works comprised an inlet works, primary settlement tank (PST), seven mineral media biofilters, two humus settlement tanks (HSTs), ferric dosing, two storm tanks and sludge storage.

The works treated mainly domestic sewage from the catchment of Leominster, Herefordshire.

The planned improvement works

The upgraded Leominster WwTW is designed to cater for increased treatment flows equating to a design horizon population equivalent of 16,685 (46% growth) and a tightening of the phosphorus permit from 1mg/l to 0.5mg/l. The new works design included for the integration of the following process improvements into the existing treatment works infrastructure:

Four new tertiary nitrifying sand filters (including a tertiary lift pumping station and backwash returns system). New ferric sulphate dosing system for primary, secondary, and tertiary dosing points of application (including a new dosing equipment kiosk and safety shower). New sodium bicarbonate dosing system to supply additional alkalinity to the process for pH correction (including a chemical storage silo and dosing system). Inlet works refurbishment, upgrading the two existing escalator screens with two new 6mm screens, screenings trough, screenings transfer to two new compactors. New passive bypass screen with improved operation and maintenance access provision. New access platform around the screens to reduce the need for operator access into confined space areas. New potable water booster pumping station. New final effluent sampling system. New low voltage distribution board and inlet works MCC. New tertiary treatment MCC. Scope of works

As part of Welsh Water Capital Delivery Alliance (CDA), Morgan Sindall, in partnership with designers, Arcadis, was appointed as the main contractor by Welsh Water. The scope of works for the project included the investigation, assessment, design, procurement, construction, and commissioning of existing and new treatment facilities; thus providing capacity to treat increased sewage loadings to meet discharge permit standards agreed with the Environment Agency (EA).

[caption id="attachment_15336" align="alignnone" width="1200"] (top left) Construction of tertiary treatment system December 2022, (top right) construction of tertiary treatment system May 2023, (bottom left) Construction of tertiary treatment system July 2023, and (bottom right) Construction of tertiary treatment system November 2023 - Courtesy of Morgan Sindall Infrastructure[/caption] Innovative solution selection

Welsh Water, Arcadis and Morgan Sindall collaboratively assessed multiple options as part of the optioneering phase of the outline design, which included optioneering workshops for shortlisting, and risk and value assessments to select the most cost-effective solution based on whole life cost and risk. A schedule of innovative solutions included:

New nitrifying sand filter to combine the need for tertiary solids removal, to achieve the tightened phosphorus permit, and increase nitrification capacity to relieve pressure on the works to meet the existing ammonia permit.  Removed need for additional secondary treatment. Re-use of the inlet structure for the new 6mm screens, improving access and removing need to go in confined space during routine maintenance procedures. Re-use of the existing ferric sulphate storage tanks. Assessment of innovative alternative chemical to ferric sulphate (rare earth minerals). Use of BIM 3D modelling to ensure integration of mechanical design and location for the alkalinity silo and tertiary plant and avoid clashes with existing underground pipework. Gravity fed sampling system for final effluent monitoring. Design for Manufacture and Assembly (DfMA) MCC kiosk (used in the development of Welsh Water standard design). Re-assessed the need to refurbish existing sludge holding tanks through modification of sludge imports. Re-use of old Dortmund style rectangular/pyramidal standby PSTs. Re-purposing and re-establishment of area of works with abandoned process treatment assets– reducing the need for land purchase. Utilise existing static mixers on secondary ferric sulphate dosing. Ferric sulphate dosing flexibility (primary, secondary and tertiary). Project initiation and whole supply chain early engagement

The overall delivery programme for the treatment upgrade scheme at Leominster presented the Welsh Water CDA team a challenge to meet the NEP regulatory output dates for end of March 2025 and ODI date for 31 March 2024. To efficiently meet this milestone, the team developed a joint collaborative plan to work to with the key project stakeholders, including members from Welsh Water asset and operations teams and key supply chain members.

[caption id="attachment_15328" align="alignnone" width="1200"] Construction of tertiary treatment system February 2024 - Courtesy of Morgan Sindall Infrastructure[/caption]

The development of up-front outline design specifications and subsequent letting of Early Contractor Involvement (ECI) contracts with the supply chain allowed for all parties to truly work collaboratively in setting out and advancing the design strategy in an efficient manner. The ECI contracts enabled the supply chain and Arcadis to work together in an open and transparent manner through driving greater design efficiencies through sharing of ideas, skills, industry experiences, true value engineering opportunities, developing design and construction innovations, all resulting in a positive influence to the final scheme solution.

The successful working relationship was maintained through regular joint online progress meetings and workshops, where design efficiencies were discussed and implemented, and where any potential blockers were removed, to benefit design and construction. Other joint stakeholder meetings which assisted the advancement of the delivery programme included HAZOP’s, Access, Lifting and Maintenance (ALM) reviews, DSEAR meetings, referencing lesson learnt from previous schemes, progressing DfMA opportunities, production of outline commissioning plans early, and holding regular buildability review meetings as the design progressed. Having a common project management system, where all members of the joint delivery team shared information, was hugely beneficial, in addition to the open access to the scheme’s federated 3D BIM model.

Leominster WwTW: Supply chain - key participants Client: Welsh Water Principal contractor & civils: Morgan Sindall Infrastructure Designer & environmental consultants: Arcadis CFA piling rig: Foundation Piling Ltd Shaft installation: B&W Tunnelling Ltd Sheet piled interlocked cofferdam: Berryrange Ltd Mechanical installation: Industrial Pipework Services Ltd Electrical installation: PCS Ltd Earthing specialist subcontractor: BEST Services Ltd Tertiary nitrifying sand treatment: Brightwork BV Tertiary nitrifying sand treatment: Nijhuis Industries UK & Ireland Ferric dosing system: Colloide Alkalinity dosing system: Rospen Industries Ltd MCC & ICA controls: GPS Group Kiosks: Morgan Marine PLC network: Mitsubishi Below ground access chambers: Cubis Systems Pumps: Xylem Water Solutions Inlet screens and screening handling: SPIRAC Ltd Potable water booster system: Dutypoint Ltd Static mixer: Statiflo Ltd Temporary pump specialist: Hydrainer Pumps [caption id="attachment_15329" align="alignnone" width="1200"] Fully constructed tertiary treatment system integrated into existing treatment works - Courtesy of Morgan Sindall Infrastructure[/caption] Sustainable and efficient design and construction

The new tertiary treatment plant and associated pipework, utilities and control kiosks were installed in an area within the boundary of the existing treatment site, where disused sludge drying beds were previously located. Re-purposing this area led to a more sustainable solution as it avoided the associated expenditure, programme, and environmental requirements that land purchase would have involved.

Due to this area of the existing treatment site being near the final effluent pipework, it enabled the flow diversion to the new tertiary lift pumping station to be achieved via a short length of below ground gravity pipe at a shallow depth. This is also a more sustainable design as it avoided the increased excavation and carbon footprint requirements that additional manholes, longer/deeper pipe lengths and a pumped solution would have required.

Other examples included surveying existing duct runs and draw pits to review capacity and reuse, where possible, as well as refurbishing the existing ferric dosing system and containment bund, instead of installing new plant, thus providing efficiencies and cost savings to Welsh Water.

Another element of efficient design and construction was the civil bases associated with the three new MCC kiosks for the new plant and equipment being installed.

As the two larger kiosks were to be DfMA and hence delivered to site with the panels already installed within the kiosk, a support frame for the kiosk and floor was also provided. Due to the panels requiring man access below them for installation of cables, the support frame included for vertical legs and steps for access into the kiosk that was installed on a simple concrete flat slab with mesh reinforcement. This was a more sustainable solution as it minimised the excavation requirements and reduced the total volume of concrete and steel when compared with sitting the kiosk at ground level on a below ground concrete trench and base slab with more steel reinforcement. The solution led to a quicker installation and better from a Health & Safety perspective as the extent of confined space working was reduced due to the absence of a trench.

[caption id="attachment_15331" align="alignnone" width="1200"] Example of a Cubis Systems modular chamber and (inset) chamber being assembled at Leominster- Courtesy of Cubis Systems & Morgan Sindall[/caption] For the smaller alkalinity MCC kiosk (not DfMA), it was decided that the kiosk would sit at ground level but as it still required access under the panel for installation, a below ground trench was required. To make the construction process more efficient, the trench comprised of innovative and sustainable HDPE recycled plastic modular units from Cubis Systems, that were put together on site and built around with minimal concrete surround and base slab and backfill to support the kiosk. As well as the material of the modular solution being more sustainable, it also led to a reduced carbon footprint in delivery due to it being very light weight. This also made it a safer and quicker installation as the manual handling involved was minimal.

Cubis Systems products were also used for the draw pit construction where the rapid stack modular units were utilised to form the main structure saving man hours with additional safety benefits.

The existing layout of the inlet works presented increased risks to operations with the main components below ground level and within a confined space. The new design involved raising the working platform to ground level, around the new screens and creating a better working environment and removing the need for operations to enter the previous confined space areas.

  Design efficiencies

Working together with Welsh Water and the framework MCC subcontractor (GPS Group), the team were instrumental in the development of the standardised design for manufacture and assembly (DfMA) design for MCC kiosks within the Welsh Water business. The Leominster team delivered this standard product in the form of a new low voltage distribution board kiosk and a new tertiary filter MCC kiosk at the site.

The DfMA GRP kiosks are mounted on a raised steel frame floor to support the MCC and the access covers while giving ample space beneath the structure for cable connections and testing.

This kiosk design reduced health and safety risks associated with installation and commissioning and led to considerable reduction in installation time on site, as the kiosks were delivered to site, off loaded, and fixed down, all within a few hours. [caption id="attachment_15332" align="alignnone" width="1200"] Installation of DfMA low voltage distribution board MCC kiosk - Courtesy of Morgan Sindall Infrastructure[/caption]

The early engagement, with the electrical installation subcontractor, PCS Ltd, through an agreed Early Contractor Involvement contract arrangement, ensured that cable design and routes were agreed early in the design, to the new plant and equipment.

The standard designs for lighting, junction boxes and emergency stops were used where possible. In addition, the Welsh Water Capital Delivery Alliance team worked collaboratively with PCS Ltd and BEST Services Ltd, an earthing specialist subcontractor, to fully understand the earthing requirements for the site. Regular design review meetings were held to develop a workable earthing design, considering the impact of this deliverable with numerous site constraints.

Conversion of the existing Siemens PLCs to remote I/O, allowed for integration of all existing signals into the new schemes Mitsubishi PLC network. This minimised the number of telemetry outstations on the site, bringing all control associated with these MCCs into the new PLC network.

Hydraulic integration of new process scope into existing works

The new project scope required integrated into the existing treatment works hydraulic design and included the incorporation of two new SPIRAC Ltd escalator screens and storm bypass static screen within the existing civil structure, and the installation of new flow control weirs into the existing biofilter and humus tank distribution chambers.

[caption id="attachment_15337" align="alignnone" width="1200"] New Fineguard inlet screens from SPIRAC Ltd with improved safe access for operators – Courtesy of Morgan Sindall Infrastructure[/caption]

The new weir design was needed to achieve an appropriate flow distribution across the two sets of existing biofilters and the three existing humus tanks. To ensure seamless integration and maintain safe flow throughout the facility during the implementation of these changes, a comprehensive hydraulic assessment was conducted to verify the incorporation of new process assets within the treatment stream without negatively impacting on the existing asset structures.

To maximise the reuse of the existing works pipeline infrastructure and flow hydraulics, the team positioned the new tertiary treatment filters within the site layout to optimise the existing final effluent pipework arrangement by rerouting the flows from the existing humus tanks to the new tertiary treatment lift pumping station and then reintegrated the treated effluent from the tertiary filters back, by gravity, into the existing pipework to the final effluent lift pump station.

This approach reduced costs and construction time for the delivery of the project, reduced the impact of maintaining the existing works operation during the construction period and removed the need to agree a new final effluent sampling point location with the Environment Agency.

Digital delivery

To maximise the understanding and detail of the existing site arrangement and optimise the design process, a point cloud survey was undertaken, and a 3D Revit model produced. Along with existing as built drawings, asset and topographical survey information and historical as built drawings, the 3D model was developed further and then used to produce and develop a 3D model of the design proposals.

[caption id="attachment_15334" align="alignnone" width="1200"] (top left) Federated 3D model capture of sampling kiosk with tertiary filters - Courtesy of Arcadis, (bottom left) as built sampling kiosk with tertiary filters - Courtesy of Morgan Sindall Infrastructure, (top right) Federated 3D model capture of lift pumping station with tertiary filters - Courtesy of Arcadis, and (bottom right) As built tertiary filter lift pumping station pipework with duplex filter and tertiary filters - Courtesy of Morgan Sindall Infrastructure[/caption]

The 3D model was federated to include all the different design models (including those by the design subcontractors) and then used in internal meetings to agree on design proposals, by being marked up for updating. The federated model was also used to avoid underground clashes with existing pipework and produced the 2D drawings that informed the pricing and construction of the proposals and was also instrumental in getting acceptance from the stakeholders when used in project gateway approvals, HAZOP and ALM meetings.

This digital strategy for the project led to significant efficiencies in design as the federated model that contained the developed design proposals was uploaded to a BIM Docs page for the project, where all design deliverables were also kept, reviewed, and issued to the key stakeholders via the workflows and transmittals tools. The whole project team (designers, subcontractors, suppliers, stakeholders) were able to easily access and view the pertinent design information and subsequently design reviews and project decisions could be made easily which was instrumental in fostering a collaborative approach on this project.

Engineering challenges

Groundwater: As part of the overall design, a 3m diameter and 6m deep tertiary lift pumping station, was designed to lift and transfer influent flows, intercepted and diverted from an existing 450mm diameter final effluent gravity pipe, to the four new tertiary sand nitrifying filters.

During ground investigative works, it was identified that there was a high-water table present that would make construction of the shaft difficult. To fully understand the impact, pump tests were carried out to quantitate the expected groundwater influx during excavation and allow Arcadis to prepare and submit applications for abstraction and discharge (A&D) licences from the EA.

[caption id="attachment_15344" align="alignnone" width="1200"] Lift pumping station - Courtesy of Morgan Sindall Infrastructure[/caption]

However, due to the lengthy time-frame expected to obtain EA approval for an A&D licences, the team needed to reconsider the construction methodology of the lift pumping station in order to meet the consented target date of 31 March 2024.

B&W Tunnelling Ltd, who had been appointed to undertake the original caisson installation, jointly developed a solution with Morgan Sindall that would enable the pumping station to be constructed without the need to abstract any significant amount of groundwater. The agreed method was to drive interlocked sheet piles around the perimeter of the planned structure to a depth at which it will cut off any groundwater. With the groundwater under control, the caisson could then be installed under ‘dry’ conditions.

A 4.8m x 4.8m cofferdam was installed using 12m long GU27N sheet piles to penetrate the underlying mudstone formation. During construction the piles were required to stand as cantilevers. The temporary sheet piles were used for the construction period only, and were extracted once the caisson was complete. The Berryrange Ltd cofferdam allowed for safe construction of the shaft/lift pumping station and ensured the project kept on programme.

Network Rail: The location of the new tertiary plant on the site was in close proximity to the busy railway line that runs from South Wales to North Wales and Manchester. Network Rail were consulted, and mitigation measures agreed to ensure the safest method of constructing the new asset was followed.

A basic asset protection agreement (BAPA) was approved, which enabled Network Rail to review the safety documentation of lift plans (tandem lift method), method statements and temporary works design ahead of the planned work to install the filter tanks, sodium bicarbonate storage silo and associated high level stairs and working platform structures.

An appointed Network Rail Supervisor attended site to oversee the construction operations, which included the safe operation of piling rigs, multiple cranes, concrete pumps and the safe use of excavators in the vicinity of the operational railway line. This process was undertaken for over 20 separate operations through the programme period, all of which were undertaken safely and successfully.

[caption id="attachment_15335" align="alignnone" width="1200"] Installation of tertiary sand filters adjacent to railway line under agreed BAPA procedures - Courtesy of Morgan Sindall Infrastructure[/caption] Health & Safety

As always, during wastewater upgrades or extensions, the challenge and onus on the team is to integrate the new plant and processes, safely and efficiently, into the existing treatment works infrastructure, while ensuring that the existing process is not impacted or interrupted.

To formalise these crucial planning activities, Welsh Water required Morgan Sindall to work to their Business Continuity Plan (BCP) process. This BCP process encompasses the development and joint agreement of a detailed activity plan, initially, between Morgan Sindall and Welsh Water local operations teams, followed by presentation of the safe systems of work to Welsh Water senior managers for their final acceptance and approval.

As the integration of the new assets were built in and around the existing works, construction activities were proactively reviewed and agreed with Welsh Water to ensure minimal disruption to the operational site during the periods when these improvement works were being conducted.

Instances where the BCP process was followed included:

When temporary over pumping was needed to construct two intercepting manholes on the existing final effluent gravity pipeline. During over pumping of incoming sewage from the inlet works structure and during the installation of the new screening units. During construction of two flow meters on the feed pipes to the two sets of existing biological filters During the power upgrade to site and transfer of mains control to the new LVDB MCC unit from the old. [caption id="attachment_15333" align="alignnone" width="1200"] Leominster WwTW: Tertiary sand filters - Courtesy of Morgan Sindall Infrastructure[/caption]

In the case of the installation of the biological filter feed flow meters, a gravity solution was selected due to the hydraulic sensitivity of the biofilters and fluctuating flowrates of the incoming wastewater with the weather. The construction required several shutdowns and temporary storage of incoming flows as well as the installation of a network of above ground pipelines with flow control valves and flow meters over a 200m distance across the operational site.

Enhancing communities

During summer 2023, the Leominster team approached the local country park to enquire if there was any community-based volunteering work that the team could assist with. The Park Ranger highlighted an area of which they were planning on creating a community garden.

The Morgan Sindall and Welsh Water team assisted the local country park rangers with clearing a large area of brash and vegetation at Queenswood Park to open the space up. In addition, the team assisted in providing a new stone footpath and bridge to enhance access for the public. Several bird boxes were installed to encourage and enhance local bird populations in the area.

Another example where the team have helped and supported the local community was through the provision of food parcels to the local Food Bank. Staff from Welsh Water, Morgan Sindall and the project supply chain, all donated food parcels to the local charity to distribute.

To encourage and assist with the development of future engineers, the team invited two Year 11 students to undertake work experience on the site for a week and hosted a new graduate on the site as part of the Year in Industry placement scheme.

To celebrate British Science week, the Herefordshire Women’s Institute attended site during construction. The Leominster Town Clerk and numerous local councillors were also invited to site to explain the environmental benefits of the new enhancement works to the existing treatment works.

[caption id="attachment_15338" align="alignnone" width="1200"] Fully constructed tertiary treatment system integrated into existing treatment works - Courtesy of Morgan Sindall Infrastructure[/caption] Programme

Scheduled collaborative planning was undertaken at the design stage with all project stakeholders ensuring key deliverables were targeted and met to enable start on site. The collaborative planning sessions were also carried through to the construction phase where the main project programme was developed with all disciplines and key supply chain partners to achieve the milestones set.

Coupled with the regular planning sessions weekly site progress meetings were undertaken with all parties ensuring everyone was aware of the planned and forthcoming works with progress monitored throughout.

The main construction programme consisted of separate civil working areas ensuring the foundations and main structures were in place before mechanical and electrical supply chain partners were integrated into the programme to work alongside each safely to optimise the working time of the programme.

All parties worked together on site successfully with a standard daily safety brief to everyone ensuring all individuals were aware of the planned activities.

King George V Reservoir (KGV) is an operational raw water storage reservoir located in the Lea Valley at Walthamstow and is a Site of Special Scientific Interest (SSSI) with restricted access. It is controlled by Thames Water’s Lea Valley/North London Abstraction Group based at Coppermills AWTW. Seepage through the clay core at the north-east of the reservoir was identified by a Willowstick survey in 2020. MWH Treatment was awarded a contract to address the seepage issue, with the works taking place 1.4km north of the main entrance from Lea Valley Road to the north of the tidal break on the east side of the reservoir. History of the site The reservoir was conceived as part of an overall plan for the Lea Valley and was laid before the Royal Commission of Water supply in 1893. At this time, the responsible authority was the East London Waterworks Company. Construction took place between 1908 and 1912, and the reservoir was opened by Their Majesties, King George V and Queen Mary in March 1913. At the official opening there was a ceremonial guard of honour review, and The King signed a Grant of Arms to the Metropolitan Water Board (owners and operators at the time). [caption id="" align="alignnone" width="1200"] Google Maps - Location of King George V Reservoir[/caption] Description of the current facility The reservoir was formed by the construction of a continuous embankment on the floodplain of the River Lea. An earth embankment divides the reservoir into two compartments that are connected by three large diameter culverts. The external grassed embankment supports a central puddle clay core. The reservoir has a maximum capacity of 12,492 ML at its top water level (TWL) of 20.18m AOD. It is normally operated on a ‘put and take’ basis which at typical through‐flows of 60 to 100 MLD gives a theoretical retention period between 100‐150 days. The crest level is 22.50m AOD with a length of approximately 7km. The reservoir is operated in conjunction with other local reservoirs to provide a continuous supply of raw water to Coppermills AWTW and Hornsey WTW. The embankment, wave wall and clay core were raised between 1938 and 1941 to restore the 1.5m design freeboard that had been lost due to gradual consolidation settlement. The reservoir was, however, kept 1.5m below original top water level, as a wartime precaution, until February 1945. At the higher TWL leakage occurred at several points, being attributed to dryness of the very high plasticity alluvial clays within the core; consequently, the current TWL was established. A 4.5m deep grout screen was installed along an 800m length of the southwestern embankment in 1983 in an attempt to address the leakage. Access to the reservoir is located at its southeast corner from the Lea Valley Road. This access is shared with a sailing club and activities club. Sheep graze the embankments as an environmentally sustainable way of managing grass growth. Scope of works The key scope of works for the project was the provision of a sheet-pile cut‐off wall. The wall was designed as 15m deep; based on the pile toe being driven into the London Clay a minimum of 0.5m, and 165m long; being installed between crest chainages 1,715m and 1,880m. A low vibration technique of pile driving was promoted to minimise potential for stability issues within the embankment during construction. The scope also included provision of access to the crest and provision of temporary access road, strengthening of existing site roads and protection to existing pipework and services. [caption id="" align="alignnone" width="1200"] Google Maps - location of site compound and works area[/caption] Technical description A survey was carried out late 2019 to early 2020 in the area around chainage 1,750m as this had been identified as an area of interest in a previous survey. Willowstick surveying is a non-intrusive geophysical method used to map and model the subsurface water flow paths. The procedure involves energising the study area with a signature electric current between paired electrodes. The surveying equipment consists of GPS system and an instrument known as a Willowstick which measures the magnetic field response of an electric current. As the electric current flows through the survey area the preferential flow paths are identified, mapped, and modelled. The information gathered can be used in making informed, guided, and cost-effective decisions concerning how to further, monitor, intercept and mitigate seepage. The main findings from the survey were: A weakness zone of preferential flow identified between chainage 1,723m and chainage 1875m. The flow path shows the characteristics of uniform sheet flow and did not indicate a concentrated leakage path, rather a 150m zone where water was passing evenly through the core. The preferential flow was identified at elevation 12m AOD through the foundation underneath the embankment. The preferential flow path strongly correlated to the location of the original stream channel. Its characteristics indicated that seepage was concentrating in flood plain sediments deposited by the original river channel meandering through and beneath the survey area before the dam was built. The survey report recommended remediation works in this area within a short timeframe to reduce any movement or damage to the reservoir embankment. King George V Reservoir: Supply chain - key participants Principal contractor/designer: MWH Treatment Designer: Atkins Temporary works design: Noble Works Ltd UXO survey: 6 Alpha Associates Ground investigation, soil testing: Structural Soils GPR surveys: Technics Group Environmental surveys: Middlemarch Environmental Willowstick survey: Willowstick UK Noise & vibration monitors: RSK Acoustics Silent piling contractor: Sheet Piling (UK) Ltd Piling verticality survey: CMCS Ltd Civil works, labour/plant: Derryard Construction limited Electrical (site setup, gate works): SRS Electrical Ground maintenance: UK Landscapes Scaffolding/access: Clocktower Scaffolding General plant hire: GAP Group Ltd Welfare supply: Wernick Group Supply of Trakway Matting: Sunbelt Rentals Ductile iron pipework: Electrosteel Castings (UK) Ltd Valves: Glenfield Invicta CCTV, timelapse cameras: Wireless CCTV Ltd [caption id="" align="alignnone" width="1200"] Finished temporary road before track matting - Courtesy of MWH Treatment[/caption] Toe road and crane pad Atkins were instructed to advise on embankment loading constraints, construction methodology and the sheet pile solution. They developed the initially suggested remedial works to achieve a detailed solution which was then agreed with Thames Water. The existing track at the toe of the embankment was the only access route to the works area. The track had a loading capacity of 12t and the crest road a 5t weight limit; both limiting machinery and plant selection. A previous project adopted an 8t excavator and 6t tracked dumpers and Atkins used this information within their assessment to complete a slope stability analysis of the embankment. This confirmed that the use of an 8t excavator was acceptable for the works on the crest road. An existing 30” pre-stressed concrete (PSC) pipe main under the road at the toe of the embankment further constrained the size of vehicles to be used during construction and required enabling works. A disused section of pipe was recovered and tested to confirm dimensions and the material characteristics to be used in the loading analysis. Atkins confirmed that the pipe had sufficient capacity to support a maximum axle load of 12t. A temporary road was installed to minimise rutting and dynamic loading on the existing track. Trackway matting was installed from the sailing club ramp to the crane pad to disperse vehicular loading and mitigate impact on the pipe and vehicle speed was restricted to 5mph for all vehicle movements. An emergency plan was put in place to ensure the Thames Water Operations team were made aware of any incident and to cover the eventuality of a pipe burst. The temporary road was designed by Noble Works Ltd and installed by Derryard Construction Ltd over a period of 8 weeks. Over 1km of track matting was hired from Sunbelt Rentals and installed over a period of 2 weeks. Along with the temporary road, a crane pad was installed to facilitate the 200t crane used to lift the piling equipment and sheet piles from the toe to the crest of the embankment. The crane pad was designed by Noble Works Ltd and constructed in MOT Type 1 granular fill by Derryard Construction Ltd. A section of the adjacent aquifer recharge pipeline was dismantled to facilitate construction of the crane pad which also included a concrete protection slab above existing underground HV and telecommunications cables. [caption id="" align="alignnone" width="1200"] Finished installation of the track matting - Courtesy of MWH Treatment[/caption] Piling decision Following previous successful remediation works carried out at Sir William Girling, Staines South, and Island Barn Reservoirs, MWH Treatment selected Giken silent piling. This is a vibration free press-in method that allowed the pile installation to be virtually silent. This technique enables the piling plant to ‘walk’ over the tops of the driven piles. The initial press-in to install the dummy piles was carried out utilising a reaction platform. The Giken rig then used the previously installed piles to generate reaction to enable on-going pile installation. The sheet piling works (undertaken by Sheet Piling (UK) Ltd) commenced at chainage 1,880m which is the junction of the perimeter and the reservoir dividing embankments. A wider toe area had been identified as a turning and laydown area for the storage of equipment. It was also used for the reaction platform for the installation of the dummy piles. The first 100 piles were fed to the rig by the crane at the base of the embankment. Once the radius of this crane was exceeded, the ‘non-staging’ method was adopted utilising a clamp crane and pile runner to move the piles along the crest and to feed the piles to the Giken rig. A 15m long PU32 section pile was adopted being dependant on the chosen method of installation, length of pile and expected ground conditions. The pile clutches were lined with sealant to ensure low permeability through the wall joints. Press-in driving of the piles with the Giken rig was assessed as feasible with hard/difficult driving being a low risk when reaching the London Clay layer. Subject to the approval of the reservoir Qualified Civil Engineer (QCE) water jetting was an option to achieve required toe penetration. [caption id="" align="alignnone" width="1200"] Reaction stand setup excavation - Courtesy of MWH Treatment[/caption] Crest road works The Giken piling method minimised the access width requirement to work on the crest, however some excavation was still required. Using an 8T excavator the crest road was excavated to expose the clay core to allow the alignment of the sheet pile wall with the centre of the core. The base width of the trench was specified at 2m to allow the Giken rig to operate. The top of the core was covered with plastic sheeting to prevent desiccation and protect the clay core from being damaged. Following the completion of the sheet piling works, the trench and crest was reinstated. Site installation of the piles Sheet Piling (UK) Ltd commenced work on site at the end of October 2022, with a planned 10-12 week site duration. The 200T attendant crane was stripped of all non-essential weight in order to maintain the 12T per axle load weight restriction. Once in position on the crane pad a smaller 45T service crane off loaded the initial crane ballast and commenced rigging; once part rigged the remaining ballast was self-rigged. The reaction stand was lifted into position by the 200T crane to the 6m x 6m hardstanding area finished 600mm below the top pile design level. The Giken rig was then positioned onto the reaction stand followed by counterweights. The first pile was then driven utilising the weight of the rig and counterweight as reaction. After the first pile were installed, it became a reaction pile for subsequent piles to be installed. When the rig fully sat on the dummy piles, the reaction stand and counterweights were removed. Once a pile was sufficiently driven and stable the rig releases its clamps from the reaction piles and travels forwards. This ‘self-moving’ system eliminates the need for support by a crane during the piling operation. Following installation of the first 100 piles a clamp crane was utilised as the piling works had exceeded the working radius of the 200T crane. After the clamp crane had travelled along the piles as far as possible inside the 200T crane working radius a track, formed of a temporary pile welded along the completed wall, allowed a handling train to deliver the piles to the clamp crane. Pile verticality was critical as the piles must not exit the puddle clay before penetrating the underlying London clay. During piling verticality was monitored via spirit level. Once completed Sheet Piling (UK) Ltd employed CMCS Ltd to undertake a verticality survey. This included the first five 5 piles and then 10% thereafter, resulting in a total of 32 tests. CMCS Ltd utilised the lancing tubes on the piles that were welded prior to installation. The data reported the tilt of the pile and to what extent, whether leaning towards or away from the reservoir. [caption id="" align="alignnone" width="1200"] Train moving a pile to the clamp crane - Courtesy of MWH Treatment[/caption] Success of piling solution After the first week of initial set up and pressing of the 3 dummy piles, Sheet Piling (UK) Ltd installed 275 piles over the next 6 weeks. The site team completed the work in advance of programme despite difficult weather conditions. The crest of the embankment was very exposed; strong cross winds resulted in several days when piling was prevented, but the team were able to boost productivity to recover lost time. The Sheet Piling (UK) Ltd team de-mobilised mid-December; this was during the weekend of a severe snowstorm with over 6 inches falling over the Sunday night. The MWH Treatment team and subcontractors mobilised additional resources to clear the site of snow, including the 1km toe road, enabling several lorries and the 200T crane to safely leave site. Site demobilisation took place earlier than planned realising 3-weeks’ efficiency on the track matting hire period. After the Christmas shut down, the trench on the crest road was reinstated and an embankment survey was carried out by Derryard Construction to confirm the final ground levels were within tolerance. A post-installation Willowstick survey was conducted which reported that the previous flow path had been cut-of. The sheet pile wall appears to be working as designed by cutting-off the preferential flow of electric current through and beneath the northern half of the sheet pile wall; interpreted as cutting off the seepage flow. The post completion survey confirmed that the remediation works had been successful. Biodiversity The King George V Reservoir is a major wintering ground for wildfowl and wetland birds, including nationally important species. A total of 85 wetland species have been recorded and the reservoir also forms a moult refuge for a large population of wildfowl during the late summer months. Over the course of the project environmental consultants Middlemarch visited site monthly to monitor bird activity and to ensure site works were not affecting wildlife. The site compound took up the space of the sailing club/water sports club car park so MWH Treatment constructed a temporary car park providing sailing club patrons with continued safe parking. On project completion it was agreed with Thames Water that the car park should become a permanent overflow car park. A wildflower meadow is being planted to compensate for the biodiversity loss of the car park. Conclusion MWH Treatment have delivered a very successful project overcoming access, logistic, weather and environmental challenges. The sheet piling cut-off wall achieved the desired project outcome: mitigation of water seepage. The project was delivered early with an excellent safety and environmental performance. Thames Water additionally gained an upgraded toe road and improved protection for critical services. The project also fostered and maintained excellent relationships with neighbours at the sailing and activity clubs.

The challenge to improve environmental performance is common and topical across the industry, and Southern Water are no different; with considerable effort and headway being made to reduce said impact. A major transformational project is underway business-wide, which sees them moving from a reactive state to one that is more planned and proactive through the adoption of maintenance and reliability best practices. This case study sets out their challenges and how they have been tackled, including how they, in collaboration with consulting partners Binnies, embraced technology to provide an immersive and engaging training course to help embed the new ways of working with their field teams. Problem statement

Southern Water historically relied on reactive responses to maintenance issues, with day-to-day operations being driven by asset failure - approximately 70% of maintenance activities were reactive. Naturally, working this way impacts an organisations resilience for dealing with asset failures, meaning the impact is greater as an urgent response is required. Uncontrolled breakdowns often result in unconsented pollution events, water quality breaches, and loss of supply events, all of which attract financial penalties, and increased pressure from regulators and their customers for improved performance.

Some of the challenges which Southern Water wanted to resolve included a lack of accurate asset data, low completion rates of preventative maintenance activities, and the suitability of those  tasks, combined with an overall concern about the approach to asset health.

Project overview

The Planned Maintenance Project was developed to address maintenance challenges, focussed on improving asset health and reliability, and shifting the organisational culture. The project was designed to provide a refreshed operational maintenance strategy based on outputs from Failure Modes Effects & Criticality Analysis (FMECA), which would then be used to develop Standard Operating Procedures (SOPs) to provide a clear methodology for operators to follow. Additionally, operational staff needed to be trained on the new ways of working, so everyone impacted understood what was changing, why it was changing, and what it meant for them. Asset Management professionals will be aware of the P-F curve; the aim of the project was to get Southern Water on the journey to moving further up the curve, equipping them to easily identify asset health issues, and generate the required corrective actions to avoid a failure. The project was designed to ensure it was paced appropriately. Too many change initiatives become too big too quickly, and ultimately fail. The first step of this process wasn’t to get the teams working with predictive technology, CBM, or Machine Learning. Instead, the aim was to equip them to start utilising human senses, carrying out standardised and consistent inspections to recognise the early signs of asset deterioration and act appropriately in a planned manner.

[caption id="attachment_14634" align="alignnone" width="1200"] Image showing P-F failure curve - Courtesy of Binnies[/caption]

The original scope was focused on addressing the root cause of some of their largest financial penalties. This included 100 of the most critical wastewater pumping stations in the business, where sites had a history of pollution events or posed a significant risk to the environment or local community should there be a spill event. During the early stages of the project, Southern Water reviewed the business case and realised that expanding the scope was the right thing to do. This drove business-wide improvements and a consistent way of working, resulting in the scope being extended to cover the entirety of the Southern Water Operational estate.

Project deliverables

Asset register review: An effective maintenance programme requires an accurate asset register. Before any follow-on activities could be completed, Binnies were tasked with completing asset data capture surveys of the original 100 in-scope sites. The surveys captured all required asset attributes, plus a baseline condition report. Additionally, 3D photogrammetry was completed to create a digital twin model of the sites. The project led to 100,000 assets being surveyed, where the teams identified an additional 25% uplift in unregistered assets and corrected a 40% error margin in the data. This exercise put Southern Water in the best possible position for the next stages of the project. Companies struggle to accurately operate and maintain their equipment if they don’t know it exists, or the information held for it is incorrect.

Failure modes effects & criticality analysis: With the asset surveys complete, the next stage was to create network maps of the processes, which are used by field teams to support new starters and improve site familiarity. Within Binnies, the maps were used as part of the FMECA process as a guide to ensure all asset types within a process or site are captured within the analysis. The maps and FMECA were done on either a generic basis where common configurations had been identified, or site-specific/bespoke for higher criticality sites or those with a unique configuration.

Standard operating procedures: Completion of the FMECA exercise provided the maintenance task lists needed for each asset. The next stage was to use the tasks to populate the Standard Operating Procedures (SOPs) documents. Historically, teams would pass on their knowledge based on what they had been shown by their predecessors, or through their own understanding of a task instruction. Naturally, this brings inconsistencies with task completion, and the risk of misinterpretation. These documents provide operations with a clear set of job instructions to ensure tasks are completed consistently. Like the FMECA process, the SOPs were site-specific where needed, but used the common configurations allowing Binnies to produce templated documents in high volumes.

Through FMECA and the creation of Network Maps and SOPs, Southern Water gained over 20,000 operational documents which provided a standardised way of working and promoted asset health and reliability.

[caption id="attachment_14636" align="alignnone" width="1200"] Image showing example of Standard Operating Procedures - Courtesy of Binnies[/caption]

Dynamic risk model: To help support the internal deployment of effective, executable maintenance tasks, Binnies developed a Dynamic Risk Model for Southern Water. Understanding that risk is dynamic and not fixed, the model was developed to allow Southern Water to manage their assets based on real-time condition, understanding that time-based maintenance is not always the best solution. The model looked at fixed criticality but also took into consideration real time operating characteristics, telemetry data, and the condition data the field teams were submitting. The model was set up to enable Southern Water to schedule the right maintenance to the right assets, at the right time.

Project embedment

The final stages of the project involved training operational staff on the new tools and technology being implemented, and on-site embedment checks with the field teams to ensure the classroom learning could be applied in the operational environment. The course was designed to be interactive and immersive, reducing the passive learning time to promote engagement and interaction to ensure the operational teams were engaged throughout the sessions. The team designed a training programme which focussed around the newly created digital scans of the Southern Water sites. These scans were used to house the training content, in which the delegates were taken on a virtual tour of their sites. The course contained all key business messages along with foundational asset management knowledge to provide delegates with all of the information they need to understand what changes were being implemented, why the changes were needed, and what it meant in terms of new tools, and new ways of working. The second half of the training course was set up so the delegates could experience the practical requirements of the learning through using the 3D technology. Training scenarios were built into the models; these scenarios contained the job instructions from the SOPs, and a description of what was found when completing the inspection. The delegates discussed the consequence of the asset failing, and what the appropriate corrective action should be.

Following the classroom training, a 6-month Early Life Support (ELS) team was stood up to provide one-to-one coaching and assurance checks with the field teams to confirm they were able to put the classroom learning into action in the operational environment.

The training provided 67 face-to-face sessions, training over 500 of the Southern Water operational workforce. Additionally an eLearning course was created to be added to the Southern Water learning system. This was to be used for new starters and for anyone who needed refresher training following the ELS programme. The training received outstanding feedback from those trained. The trainers fed back to the project team that throughout the entire training deployment delegates remained highly engaged, and the use of 3D models promoted conversation in the room. Many of the delegates were familiar with the sites used to model the training which enabled them to discuss some of the issues they faced providing additional insight for the groups being trained. A temperature check was completed to gauge the delegates’ confidence in the new ways of working landing successfully, this scored 84%.

[caption id="attachment_14635" align="alignnone" width="1200"] Screen grab of 3D training model - Courtesy of Binnies[/caption] Next steps

To further support the embedment of the new ways of working, and to overcome some of the data challenges being faced by Southern Water, the company are currently in the process of implementing a new Enterprise Asset Management System, IBM Maximo.

This platform will provide an integrated solution to data management, ensuring all key information is stored in one system, breaking down some of the barriers they had previously experienced with data management. It will enable the field teams to effectively capture and feedback asset condition data and support central teams in monitoring and trending the information in parallel with the dynamic risk model, to ensure risk management is optimised and corrective actions driven at the right time.

The deployment of the system will be carried out in a phased approach, with the first pilot deployment due to go live on the Isle of Wight in July 2024.

Southern Water and Binnies continue to work closely together, with the asset data capture surveys now being deployed across the entire water supply estate to increase the baseline asset information standard. Additionally, Southern Water are investing further in their staff by increasing their problem-solving capability through the completion of Root Cause Analysis training provided by Binnies specialist trainers.

For Southern Water, proactive maintenance is not the end state, it is very much the start of an exciting journey.

Ise Valley, Wellingborough, is home to the £1bn Stanton Cross housing development just off the B571 in the east of England. In late 2022, parts of the development were struck with leaks in the underground rising mains, causing disruption to many new homeowners during the Christmas period. In November 2022, Anglian Water was made aware of several leaks on each of the 700mm ductile iron rising mains from Ise Valley Terminal Pumping Station (TPS), which pumps flows of up to 1500 l/s. Both rising mains are required for normal operation of the pumping station and to convey the maximum flow, however, surveys showed that both mains had reached the end of their asset life due to both internal and external corrosion, and further leaks would occur if no action was taken. Background

Once the team attended site, it became apparent that both the north and the south mains had leakage issues. Non-destructive testing confirmed external pitting and internal abrasion wearing in the upstream sections and an internal hydrogen sulphide (H2S) attack on the downstream section, which was determined to be the primary issue.

With two leaks occurring in close proximity, and previous leaks occurring over the last 10 years, there was a substantial risk of more. Anglian Water’s @one Alliance was engaged on 1 December 2022 with the immediate priority being to design, install and commission an temporary above-ground bypass to mitigate the impact of any further potential leaks while the permanent solution was identified.

The Stanton Cross housing development was recently constructed over the area along the route of the rising mains, with houses as close to the asset as 4m in places and leaving no clear route to bypass the flows. As an added complication, some residents located close to the rising mains reported feeling vibrations from the mains;  the cause of which needed to be investigated.

[caption id="attachment_13372" align="alignnone" width="1200"] Temporary pipeline ready for assembly - Courtesy of @one Alliance[/caption] Temporary solution

It was identified that the rising main leaving the building from the north could be isolated and cut into, to provide a temporary overland pipeline fed by the existing pumps, which would avoid the need for temporary pumping equipment over what would have been the Christmas period. Although the five pumps had recently been mechanically overhauled, the team found several electrical issues that required repairs. As such it was arranged for three temporary variable speed drives to be installed as a matter of urgency, to better manage pump performance and to help prevent further bursts before flows could be diverted.

Utilising contacts across @one Alliance’s supply chain, specialist overpumping contractor Vanderkamp UK was contracted to provide a temporary bypass in short order. The teams decided on a 1m diameter pipe to give the equivalent flow of the existing twin 700mm diameter pipes to avoid reducing pump capacity.

Working around the clock to find a suitable solution, Vanderkamp UK, the @one Alliance and Anglian Water’s Water Recycling Networks (WRN), allowed for a quick design and installation of the bypass. The whole team aided the process from construction design management documentation to hydraulic design, temporary works, customer and PR, supply chain and enabling.

Ise Valley Sewer Rehabilitation: Supply chain - key participants Project delivery: @one Alliance Bypass pipework: Vanderkamp UK Cured in place relining: OnSite Central Ltd CIPP liner supply: IMPREG GmBH [caption id="attachment_13369" align="alignnone" width="1200"] Road closures were necessary while installing the pipe bridges - Courtesy of @one Alliance[/caption] Overpumping bypass pipeline installation

In order to build the overpumping solution as quickly as possible, the @one Alliance team collaborated with the Integrated Operational Solutions (IOS) Alliance that provided provisional enabling works such as electrical isolation of services, excavation of the point of connection and temporary ground drainage/pollution avoidance provisions. With the initial works complete, the @one Alliance took full control of the site and initiated the installation of the pipeline.

Work of this scale required a coordinated customer strategy which was designed and implemented by the @one Alliance Customer Team who notified all affected customers of the planned works and continued to provide updates throughout the various stages of work making sure customers were informed and suffered the least impact possible over a busy Christmas period.

To make the connection to the bypass pipework, all flows were diverted to the south main and twin 600mm tee pieces were installed in the north main within the terminal pumping station compound. This arrangement allowed the south main to remain in service if required over Christmas. The connection was completed on 9 December with installation of the 1m diameter pipework commencing the following day.

Due to the new housing development, it was not possible to follow the route of the existing mains and care had to be taken to ensure the bypass pipework would not interfere with a permanent solution or the ongoing operation of the pumping station. A route along Driver Way and Irthlingborough Road was selected which included several pipe bridges in order to allow unrestricted customer access. Emergency road closures were agreed with both the local property developer and North Northamptonshire Highways to safely install the pipework.

[caption id="attachment_13373" align="alignnone" width="1200"] Installing the temporary overpumping solution - Courtesy of @one Alliance[/caption]

The pipework installation was completed in just 10 days during an extreme cold snap which saw Anglian Water’s @one Alliance and Vanderkamp UK operatives installing the overpumping pipeline in temperatures of -6°C. Nevertheless, the team worked two consecutive weekends to ensure the bypass was live and operational before Christmas. On 20 December 2022, the bypass was commissioned on time and to ensure there were no customer issues, inspections were carried out every day over the Christmas period.

Permanent solution

Testing and inspection of the mains showed that in the base of the pipe there were a series of what could be best described as wave patterns. The waves - the result of erosion of the pipe material - has been caused over many years by grit within the flow of sewerage. As the pipes rise steeply uphill the grit had settled at the base. Coupled with external and internal corrosion, susceptible areas of the ductile iron pipes have locally pin-holed, which had allowed leakage, and confirmed zero life span remaining in places.

Following the inspection and testing of the pipework, an accelerated Risk, Opportunity & Value sprint was held with all stakeholders to confirm the most suitable permanent solution. The team decided against the removal and replacement of the existing main due to the amount of time it would have taken to execute, additional disruption to customers and local traffic, and the small working space available to the team. It was then determined that the most effective solution was to use a structural liner.

The location of the trial holes, which had been used for examination and non-destructive testing of the mains, had been carefully selected as potential relining pits in the event this solution was to be used. This allowed for an accelerated programme to prepare for the relining works and a reduction in carbon and costs.

[caption id="attachment_13371" align="alignnone" width="1200"] Re-lining rig - Courtesy of @one Alliance[/caption] Rehabilitation of the existing mains using specialist pressure-rated cured in place pipe (CIPP) liners was selected. Framework supplier OnSite Central Ltd installed the liners using a combination of ultraviolet and water cure techniques to suit the challenging pipe conditions. Aware of the time constraints, OnSite Central Ltd worked with the project team to ensure the liners were delivered promptly from IMPREG GmBH in Germany, and that installation gangs were available to work extended shifts to ensure the challenging programme was delivered.

Once the relining was complete Vanderkamp UK  began dismantling the overpumping, all of which was removed by the end of May 2023. Pressure and vibration monitoring of the temporary bypass pipework identified a correlation between pressure spikes and vibrations. This resulted in a change to the pumping station regime and, along with the new variable speed drives and the liner acting as a barrier, resulted in a large reduction of vibrations felt along the route once flows had been returned to the rising mains. Post works vibration monitoring at a number of previously affected properties confirmed the vibration issues had been resolved.

Challenges

The team had to take into consideration a plethora of potential risks during the entire project lifecycle. From contaminated ground, congested buried services, extreme weather conditions, an construction challenges such as relining through 45° bends. The team had to sufficiently ensure a timely plan was in place, following many detailed impact plans created to overcome these issues to ensure efficiency in completion of the project, and reduce the disruption to customers over the festive period.

[caption id="attachment_13367" align="alignnone" width="1200"] Overpumping termination point - Courtesy of @one Alliance[/caption] Customer liaison

One of the big challenges for this scheme was the disruption to the customers during the festive period, with the scheme attracting significant nationwide media attention over the duration of the works from national and local newspapers, BBC television (“Look East”), BBC radio (Jeremy Vine), and news and social media websites.

While this work went on, the @one Alliance Customer Team kept residents up to date with the team’s progress while helping manage expectations as to how long the work would take, and how long the temporary structure would be in place. Communications to the local residents were consistent throughout the project lifecycle (from 2/12/2022 to 24/4/2023), ensuring constant updates, programme times, and responses to queries were included at all stages.

Outcome

Anglian Water’s £2.8m spend and proactive response to this issue enabled the successful relining of the existing pipe. The relining solution, which will give the pipe an expected 100 years of extra service, has been in service for over a year with no issues.

Since 1892, the Vyrnwy Aqueduct, which runs from Lake Vyrnwy through to Merseyside, has helped deliver clean wholesome drinking water to customers and communities across Cheshire, Merseyside and the North West region. However, the pipeline now requires maintenance work to ensure the quality of customers’ drinking water is resilient for generations to come. Vyrnwy Aqueduct comprises three parallel pipelines, referred to as Lines 1 and 2 (cast iron pipes) and Line 3 (steel pipe). Each line is 42 inches (over 1 metre) in diameter and has a combined distance of 139km in length between Malpas and Prescot. The challenge

Over time, deposits of iron and manganese have accumulated within the pipelines. While these minerals do not pose any health risks, they can result in discolouration of the water and be detrimental to the internal condition of the pipe. Due to the ages of the lines and the accumulation of minerals deposited, they now require cleaning and/or rehabilitating. To maintain the water supply, the refurbishment programme will be completed over a phased approach with work on the lines being carried out at different times.

[caption id="attachment_23853" align="alignnone" width="1200"] (left) Pipework set-up for vertical launch or air ‘pig’ and (right) launching the air 'pig' - Courtesy of Avove[/caption] The approach

Avove was chosen as the contractor for modernising the Vyrnwy Aqueduct pipelines, adopting innovative ways to inspecting, cleaning and relining the large-scale pipes throughout Cheshire. This includes designing, constructing, testing and commissioning the three pipelines in Phase 1 of the works between Malpas and Tarporley; a distance of approximately 18.75km per line. Avove’s approach will see a significant reduction in carbon emissions across the project.

Lines 1 & 2 - Cast iron pipe: A new slightly smaller diameter plastic pipe will be slip-lined into the old main, creating a brand-new pipe within the host main.

Line 3 - bitumen lined steel pipe: The original scope was using a traditional method of high-pressure jet washing, however, Avove’s design team reviewed the project and recommended the use of air pig technology working with specialist smart pigging partner iNPIPE PRODUCTS™. Air pigging has never been used before to clean this size and length of water pipeline, but after careful consideration, Avove and iNPIPE PRODUCTS™ designed and commissioned an effective, compliant and efficient process, that was approved within the United Utilities specification C05-i2-Spec document for large diameter bitumen lined mains.

[caption id="attachment_23855" align="alignnone" width="1200"] Launching the smart air 'pig' - Courtesy of Avove[/caption] Vyrnwy Aqueduct Maintenance Programme: Supply chain - key participants Main designer & contractor: Avove Air pigging designer & contractor: iNPIPE PRODUCTS™ CCTV: Ipsum Hydro demolition: Buxton Water Ltd Special steel fabrication: PMJ Mechanical Ltd AMEX 10 seals supply & installation: PMP Utilities Nova Siria pipe fittings: R2M Limited Special steel fabrications fittings: Water Engineering Services Ltd Manway installation: JOD Engineering Services Ltd Security covers: Technocover Ltd Site accommodation: Garic Specialist plant hire: Sunbelt Rentals Demarcation fencing: SP Environmental Demarcation fencing: GTS Haul road construction: Miles Macadam Haul road construction: Ecofill Group Ltd Air pigging system & its benefits

The air pigging system utilises an air-propelled cleaning tool, known as a ‘pig’, travelling through the 1m diameter pipes to remove any sediment that has built up from the natural minerals in the water.

The innovative process uses air to push a pig-train, containing a slug of water between two pigs down the host main to lift off and suspend waste deposits off the internal wall for removal at the receiver. Flow rates and pressures are carefully monitored at all times during the cleaning process and after each pigging run.  If required, brush pigs are used to remove hardened materials. These brush pigs have been designed to remove materials without damaging the existing bitumen lining. Following cleaning, a camera pig is run through the pipeline to ensure internal cleanliness is assured.

[caption id="attachment_23856" align="alignnone" width="1200"] Air 'pigs' - Courtesy of iNPIPE PRODUCTS™[/caption]

The ‘pigs’ are vertically launched to reduce the excavation size but can be launched horizontally when height is a concern. ‘Pigs’ are inserted into the pipe section at ground level to reduce working at height and the pipes will then be attached to the host main.

’Pigs’ are traditionally propelled by water, but by using air, the benefits for the Vyrnwy Aqueduct include:

Saving 15 million litres of water compared to using traditional techniques for the whole of this siphon. Saving 118.2 tonnes of CO2 across the whole project. Avoiding 1,104 water tanker journeys which has significantly reduced costs, time, carbon emissions and environmental impact. Saving 2,208 journeys and reducing the impact of traffic congestion and noise as well as supporting road safety. Achieving better results by using a close-fit, full contact, cleaning technique. The air pig technique cleans the pipes significantly faster, reducing the time from weeks to days. For example: 2,542m of Section 1 were completed in 4 days. Air pigging only requires a launch and reception pit for each section; reducing the number of access pits required from 37 to 12. The solution

For a large diameter main with manganese deposits, air pigging was a safer system to use and improved the quality cleaning method, due to the contact motion and flexible material of the bespoke cleaning air pig.

Avove designed the type of ‘pigs’ required for the project and worked with partner iNPIPE PRODUCTS™ to manufacture the type of cleaning tool; collaboratively agreeing on the frequency of the ‘pig’ run to ensure optimum cleanliness based upon more than 40 years of experience.

[caption id="attachment_23858" align="alignnone" width="1200"] The Avove and iNPIPE PRODUCTS™ teams - Courtesy of Avove[/caption]

Avove and iNPIPE PRODUCTS™ subsequently ran an integrated camera/data logging system which incorporated gyroscopes and a tracking module mounted within the ‘pig’. This system recorded high-definition quality footage of the water main as it passed through and allowed the team to analyse the pipeline.

The adopted method requires the ‘pig’ passing through the pipe six times:

Pass one: Prover camera ‘pig’. This also purged any standing water. Pass two: First cleaning train. Pass three: Second cleaning train. Pass four: Third cleaning train. Pass five: Fourth cleaning train. Pass six: Camera swab. The final camera ‘pig’ acts as a final clean with a bareback swabbing of the main to provide cleanliness and will be part of the Quality Assurance procedure. Progress

Avove is continuously striving to innovate and drive carbon reduction within the design and build aspects of the Vyrnwy Aqueduct Modernisation Project. By January 2025, all six sections in Siphon 1 Line 3 had been successfully cleaned and the aqueduct was commissioned and returned into service.

In 2020, a significant ground stabilisation project was initiated following the discovery of a sinkhole within the King George V Memorial Playing Fields. Investigations revealed that Clyde alluvial soils were being drawn into a collapsed section of pipework, resulting in void formation and settlement risk in the surrounding area. The Provost Driver Court Wastewater Pumping Station, located in Renfrew near the River Clyde in Glasgow, lies in a region notorious for challenging ground conditions, including soft Clyde alluvial soils and a high groundwater table. Due to the size, complexity, and risk associated with the works, George Leslie was appointed by Scottish Water, having previously delivered similar infrastructure projects under comparable conditions. The problem/issue

The area presented numerous geotechnical and environmental challenges. The soils were quasi-liquid and exhibited low cohesion, making them highly sensitive to disturbance.

The high groundwater table and ingress of fine silts had caused settlement and damage to the pumping station previously. This posed a risk not only to the infrastructure but also to nearby residential properties. Historical ground movement had already been observed, and further deformation could have had significant implications for the surrounding community and public green space.

In August 2020 a ground depression was located within the playing fields and after further investigation a section of the sewer had collapsed, which was drawing in silt, which led to ground settlement.

[caption id="attachment_22014" align="alignnone" width="1200"] (left) Ground depression (August 2020) - Courtesy of George Leslie and (right) image showing the damaged sewer - Courtesy of COWI[/caption] Ground settlement monitoring

In collaboration with COWI, principal contractor and designer George Leslie began an extensive monitoring regime during the design phase to ensure no further settlements within the area were recorded. This involved a team of engineers carry out daily monitoring for 18 months.

Early contractor involvement (ECI)

George Leslie was engaged early in the process to transition COWI’s concept design into a deliverable construction solution. The scope of the ECI contract comprised a detailed site investigation programme and production of a geotechnical baseline report which included:

Collation of historical site investigation. CPTs and boreholes. Ground penetration radar. Topographical surveys. Engineers monitoring data of natural water table.

The construction methodologies of all the appointed designers and contractors were considered during this stage of the ground stabilisation project, with COWI producing site specifications for each company.

[caption id="attachment_22016" align="alignnone" width="1200"] Ground stabilisation and sewer repair works underway - Courtesy of George Leslie[/caption] Provost Driver Court Sewer: Key designers Construction & planning: George Leslie Geotechnical: COWI Dewatering: WJUK Temporary works cofferdam: Mabey Hire Ltd Grouting: Geobear

Early procurement of long-lead items such as the steel sheet piles helped mitigate anticipated supply chain delays. George Leslie coordinated with the dewatering specialists, temporary works engineers, grouting experts, and geotechnical designers to collaboratively de-risk the scheme.

This integrated approach enabled a cost-effective and constructible design while allowing flexibility to adapt to findings from ongoing site investigations.

Provost Driver Court Sewer: Supply chain - key participants Pumps: Selwood Kowan Pile Press Still Worker: Watson & Hillhouse Ltd Diamond drilling: Core Drilling Specialists Ltd Sheet piles: ArcelorMittal Civils items: Keyline Civils Specialist Ltd Welfare buildings: Wernick Group HVO fuel: OilFast Ltd Crane & plant: George Leslie Aggregates: Paterson Quarries Ltd [caption id="attachment_22018" align="alignnone" width="1200"] Inside the cofferdam - Courtesy of George Leslie[/caption] The scope/solution

The primary aim of the works was to stabilize the soils and reinstate the wastewater infrastructure. Key elements of the scope included:

Compaction grouting was required to provide support to existing assets during the works, which may be susceptible to settlement. Grouting specialist Geobear was appointed for this stage of the works; utilising their own geopolymer grout to densify the ground around assets to mitigate movement. Installation of 16.5m long ZU sheet piles with sealed clutches, which toed into the underlying clay layer identified at -10mAOD. The sheet piles were installed utilising the hydraulic press still worker, supplied by specialist Watson & Hillhouse. Deployment of an internal dewatering system to lower the groundwater table and densify the soil allowing for safe excavation of soils. WJUK installed 24 deep wells within the in-pans of the cofferdam, which allowed the dewatering system to be phased and controlled depending on the activity that was being conducted on site. The system also comprised of a remote monitoring system based off wireless piezometers located within the site boundary. Application of permeation grouting installed by Geobear using their geopolymer grout which permeated the interstitial spacings within the soils to reduce the bulk permeability of the treated soils. Mabey Hire Ltd provided design works for a double-braced temporary works system that George Leslie installed. This provided lateral support to the cofferdam during the excavation stage. [caption id="attachment_22015" align="alignnone" width="1200"] (left) Cofferdam piling works underway and (right) Installation of the new sewer pipe - Courtesy of George Leslie[/caption] Community engagement

With this large-scale infrastructure project being delivered within community playing fields, George Leslie implement a number of focussed measures to ensure every resident was informed during each phase of the construction process.

In collaboration with Scottish Water, George Leslie led quarterly walk-in events which were held at the local high school, which allowed locals to meet with professionals involved with the construction. Scottish Water also delivered monthly emails and letters to the residents providing an update on the programme and how works were progressing.

A number of STEM events were held at the local school, providing children in the area the vital skills and knowledge to encourage them into STEM based careers.

Carbon savings

George Leslie completed the works whilst being connected the main energy grid. This powered the site welfare buildings, temporary sewer pumps and the dewatering system, saving thousands of litres of diesel in the process. The site’s construction plant was powered by hydro-treated vegetable oil (HVO) fuels helping to further reduce the project’s carbon output.

Scottish Water are committed to delivering net zero emissions by 2040 and beyond and every project we undertake is a step towards that aim.

Conclusion

The Provost Driver Court Ground Stabilisation & Sewer Rehabilitation Project has successfully implemented a multi-million pound, 18-month long project to bring resilience to the local sewer network in Renfrew. Despite the challenges of managing local residents, noise, vibration, ground movement and high water levels, the project team overcame these obstacles to deliver a low carbon approach to sewer infrastructure.

York city centre, with its dense network of restaurants, takeaways, pubs, and other commercial establishments, has long faced significant challenges relating to fats, oils and grease (FOG). These businesses contribute substantial FOG loads to the sewage system, leading to issues such as blockages, odour problems, pollution incidents, and infrastructure strain. In 2023, Yorkshire Water (YW) embarked on a groundbreaking initiative to address these FOG challenges. The trial leveraged Cobra Hydro UK’s innovative Cobra Bio Block technology, aiming to enhance wastewater management efficiency, reduce environmental risks, and improve overall network performance. This case study explores the objectives, deployment, technology, outcomes, and industry implications of the trial, showcasing a significant step forward for sustainable utility practices. Background & objectives

Before the trial, Yorkshire Water regularly encountered FOG discharge into the nearby River Ouse; presenting environmental hazards and regulatory compliance concerns.

The primary objective of the Cobra Bio Block trial was to mitigate FOG accumulation in York’s sewage network while exploring a cost-effective and environmentally friendly alternative to traditional FOG management methods. Specifically, the project sought to:

Achieve a measurable reduction in FOG levels within the network. Eliminate pollution incidents caused by FOG discharge. Improve operational efficiency by minimising maintenance requirements and infrastructure stress. Assess the financial and environmental benefits of deploying Cobra Bio Block technology. Project implementation

The trial commenced in September 2023 with the installation of Cobra Bio Blocks in over 40 key manholes across York city centre. The blocks were replaced every two months, ensuring consistent microbial and enzymatic activity. The final replacement occurred in August 2024, marking a full year of continuous operation.

YW provided a robust framework for monitoring the trial’s impact, utilising video footage, photographic evidence, and data collection to assess pre and post implementation conditions. These observations formed the basis for evaluating the effectiveness of the Bio Blocks.

[caption id="attachment_19284" align="alignnone" width="1200"] Bio Block - Courtesy of Cobra Hydro UK[/caption] Cobra Bio Block technology

The Cobra Bio Block represents a pioneering approach to wastewater management. Designed for durability and simplicity, the Bio Block is a semi-submersible solution engineered to reduce FOG and odours in wastewater systems. Its unique features and mechanisms include:

Innovative composition: The Bio Block consists of a slowly dissolving matrix enclosed within a durable, porous mesh sleeve. This design ensures gradual erosion and consistent release of active agents over time. Biological action: The block contains a blend of naturally occurring microbes and enzymes. As it dissolves, these microbes colonise surfaces within the sewage network, breaking down organic contaminants such as fats, oils, and grease. Ease of deployment: Suspended below the waterline in locations such as wet wells, pumping stations, or sewer lines, the Bio Block operates autonomously, requiring no electrical power, additional equipment, or extensive maintenance. Eco-friendly design: The non-toxic, environmentally safe composition ensures that the Bio Block poses no risk to aquatic ecosystems or surrounding environments. Benefits of the Cobra Bio Block

The Cobra Bio Block offers several advantages over traditional FOG management methods:

Continuous action: Unlike periodic dosing solutions, the Bio Block provides a steady release of microbes and enzymes, maintaining consistent effectiveness even during heavy rainfall or washout events. Odour and FOG reduction: By breaking down organic matter, the Bio Block significantly reduces unpleasant odours and FOG accumulation. Low maintenance: Operating 24/7 without the need for active intervention, the Bio Block minimises the operational burden on utility providers. Cost efficiency: The elimination of dosing equipment and associated infrastructure reduces both capital and operational expenditures. Environmental safety: The non-toxic formulation supports sustainable wastewater management practices, aligning with environmental regulations and corporate responsibility goals. Key findings from the trial

Yorkshire Water reported compelling results from the Cobra Bio Block trial, highlighting its effectiveness and transformative potential:

FOG reduction: The trial achieved a 90% reduction in FOG levels within the sewage network. This dramatic improvement alleviated blockages, enhanced flow capacity, and reduced infrastructure strain. Elimination of pollution incidents: Prior to the trial, six FOG-related pollution incidents were recoded between 2019 and 2023. During the trial period, no major pollution incidents were reported, marking a significant milestone in environmental protection. Improved network resilience: The absence of FOG-related flooding issues demonstrated the Bio Block’s role in enhancing system reliability and performance. Financial impacts: Although detailed cost analyses were not provided, YW acknowledged the potential for substantial savings through reduced maintenance requirements, lower risk of fines, and improved regulatory compliance. Stakeholder satisfaction: YW praised Cobra Hydro UK’s professionalism and the seamless execution of the trial, emphasising the collaborative effort’s success. [caption id="attachment_19285" align="alignnone" width="1200"] Examples of the results after Bio Block dosing – Courtesy of Cobra Hydro UK[/caption] Additional observations

The trial also uncovered secondary benefits that reinforced its value. Beyond the reduction of FOG and operational challenges, Yorkshire Water noted improvements in system cleanliness.

The microbial action facilitated by the Bio Blocks not only addresses fat and grease but also mitigated other organic contaminants. This broader impact on sewer line hygiene contributed to an overall reduction in maintenance costs and extended the lifecycle of infrastructure components. Additionally, the Bio Blocks’ low maintenance design allowed YW personnel to allocate resources more efficiently, focusing on proactive network management instead of reactive problem-solving.

The public’s perception of YW also benefited from the trial. By deploying environmentally friendly technology, the company demonstrated its commitment to sustainability and community well-being. This enhanced reputation is expected to yield long-term advantages in stakeholder trust and regulatory goodwill.

Implications for the utility industry

The success of the Cobra Bio Block trial offers valuable insights and opportunities for the utility sector:

Scalability: The simplicity and versatility of the Bio Block make it suitable for deployment across diverse wastewater systems, from urban centres to rural networks. Sustainability: By prioritising eco-friendly technology, utility providers can align their operations with global sustainability goals, reducing environmental footprints and fostering community trust. Cost management: The financial benefits of reduced maintenance, enhanced network performance, and regulatory compliance create a compelling case for wider adoption of Bio Block technology. Collaborative innovation: The partnership between YW and Cobra Hydro UK underscores the importance of collaboration in driving industry advancements and solving complex challenges. Testimonials

Kelly Burke, Network Protection Officer at Yorkshire Water, shared her perspective on the trial’s success:

“The trial of the dosing blocks in York has been very successful. The blocks have helped reduce incidents of fats, oils and grease causing blockages in the network and clogging up the pipes under the city to zero. In the last 12 months, we’ve had no pollution incidents linked to fats, oils and grease and no sewage escapes due to fat blockages.”

On 11 December 2024, the groundbreaking success of the product was featured on BBC Morning Live. During the segment, James Harrison, Head of Wastewater Asset Management at Yorkshire Water, highlighted its transformative impact on the utility’s sewer network:

“The thing that’s great about this product is that they’re easy to install, easy to replace. And they don’t just break down fat that is there, they can also prevent it’s built up as well, so it’s a really cost effective, practical, sustainable solution. The difference is incredibly noticeable if you look at the CCTV footage of the cameras down the sewer network, historically you would come back here to do an inspection and you’d see a coating round the pipe and it really starting to layer up, and the difference it has made is phenomenal.”

Clint Jackson, Business Development Director at Cobra Hydro UK, echoed these sentiments:

“Since we began this project in 2023, we have provided a cost-effective solution to reduce the fat, oil, and grease build-up within the sewers under the centre of York. We’re extremely pleased that our enzyme Bio Blocks have achieved the desired results.”

Conclusion

The Cobra Bio Block trial in York city centre represents a significant advancement in wastewater management. By addressing longstanding FOG challenges with an innovative, environmentally friendly solution, Yorkshire Water and Cobra Hydro UK demonstrated the power of technology and collaboration to achieve measurable improvements.

This case study serves as a model for the utility industry, illustrating how innovative solutions can enhance operational efficiency, protect the environment, and deliver tangible benefits to stakeholders. As the sector continues to navigate evolving challenges, the success of the Cobra Bio Block offers a roadmap for sustainable, effective wastewater management practices.

iNPIPE PRODUCTS™ Phoenix Debris Mapping Tool uses the latest hi-tech sensors to produce a highly accurate and detailed snapshot of a pipeline’s internal condition in real time. Unlike competing systems that often take weeks to deliver post-pigging results, the Phoenix Debris Mapping Tool generates comprehensive reports within minutes from the data collected and accuracy down to 0.1mm. The award-winning company believes this revolutionary technology has the potential to save clients hundreds of thousands of pounds. Barry Ritchie, General Manager of iNPIPE PRODUCTS™ Aberdeen Service Centre said:

"The Phoenix Debris Mapping Tool is a groundbreaking advancement, utilising the most advanced sensors in the industry. It captures up to 144,000 data points every second where required, delivering an unparalleled volume and precision of data across a pipeline network. This tool provides pipeline operators with a full 360-degree internal assessment, identifying everything from debris and damage to temperature fluctuations and internal joint measurements.

“The Phoenix Debris Mapping Tool truly gives both small and large, commercial pipes the ultimate MOT, ensuring you have the perfect pipeline picture that will provide businesses with peace-of-mind in knowing that money won’t be wasted during in-line pipeline inspections.”

Founded 40 years ago, iNPIPE PRODUCTS™ has established itself as a pioneering leader in pipeline pigging, maintenance, isolation, and testing products worldwide. The North Yorkshire-based company, with a service centre footprint based in Aberdeen  has developed a comprehensive suite of solutions for industries dependent on pipeline networks, from energy and petrochemicals to food and water. The Phoenix Debris Mapping Tool is expected to be particularly beneficial in sectors like water, where aging infrastructure presents unique challenges. Simon Bell, Managing Director of iNPIPE PRODUCTS™, said:

"The water industry has faced well-documented issues with leaks due to aging pipes made of materials like carbon steel, cast iron and even clay. Our technology enables us to map entire pipelines, providing vital data that can help locate and address problems before they become costly failures”.

As iNPIPE PRODUCTS™ continues to innovate, it remains dedicated to expanding its portfolio of cutting-edge solutions, ensuring clients benefit from a one-stop solution that enhances the performance and reliability of their pipeline assets.   Benefits of PHOENIX Debris Mapping Tool Debris location & pipeline route plotting Debris thickness measurement & visual inspection Internal joint measurement & visual inspection Damage/dent location, measurement & visual inspection Total volume debris calculation Temperature measurement Pre-commissioning visual & internal diameter datum study Pipeline cleaning regime validation & predictive calculation Scalable design accommodates 12” to 120” internal diameters Flow validation Immediate report availability     For more information on the Phoenix Debris Mapping Tool, visit https://www.inpipeproducts.com/     iNPIPE PRODUCTS™, Gatherley Road, Brompton on Swale, North Yorkshire, DL10 7JH | Tel: +44 (0)1748 813270    

Van Voskuilen, who act as SVI’s sole agent in the Netherlands, inserted 4.5km of 90mm PE into a 4” asbestos main in Hardenberg in the east of the country. To aid safety and efficiency during the project, the company used the SVI Mini Pipe Handler and the Hexi pipe coil Trailer. Reduced pipe wastage The Hexi Trailer is capable of dispensing coiled pipe with diameters of 63mm to 125mm. A major advantage of the trailer is that by taking a 500 metre coil (63 – 90mm) rather than the usual 100 or 120 metres, it allows operators to save money by reducing pipe wastage when used over several projects, as the quantity of unused ‘ends’ of pipe is minimised. With its hexagonal drum, which is raised and lowered hydraulically, the Hexi Trailer allows pipe to be pulled off smoothly, quickly and in a controlled manner. The trouble-free operation allows one operative to dispense the pipe compared with other trailers on the market which require two or even three people. With safety a key consideration in the design of the Hexi Trailer, all loading and dispensing procedures are carried out from ground level and both ends of the pipe are secured until the moment of dispensing to prevent the PE ‘springing away’ thus avoiding an injury hazard. Insertion controlled from digger cab To speed up the insertion process, Voskuilen used the Mini Pipe Handler. SVI’s range of Pipe Handlers attach to the quick hitch or standard bucket pins of most common hydraulic excavators to make the process of inserting plastic pipe easier, safer and faster. There are five models available to accommodate pipe diameters from 40mm right up to 630mm. Loading, manoeuvring and inserting operations are easily controlled from the safety of the excavator cab meaning that operators do not have to enter the trench. Asked why slip lining was chosen as the replacement method, Van Voskuilen Director, Albèr van Ee, said:

“There was considerable damage to the old main which needed to be replaced. As there were many trees on the course of the main there was insufficient space to lay a new pipe so insertion was the preferred option”.

Active throughout the Netherlands, Van Voskuilen designs, installs and maintains pipes, ducts and cables including gas and water mains and electricity cables. The company is the sole agent in the Netherlands for all SVI products and techniques for the trenchless repair, renovation and decommissioning of pipes. Vitens supplies 5.6 million customers and manages 49,000 km of water mains in the Netherlands.   For more information: Steve Vick International Ltd | +44 (0)1225 864864 | www.stevevick.com    

The challenge The reservoir had an estimated 180 meters of cracks that needed repair, as well as the main element of the concrete that required coating to waterproof and add durability to the concrete structure. The reservoir was taken out of commission but it needed to be returned to service as soon as possible. To do this, we looked at the order of the processes to ensure the tight time frames could be met. The Xypex Solution In accordance with the Reg. 31 IFU (Instructions For Use) all cracks were broken out to a minimum depth of 37mm and a width of 25mm. The walls were prepared by removing the laitance and the whole area was saturated. To stem the ingress of water, every crack that showed moisture was sealed with Xypex Patch’n Plug which sets in seconds stemming the flow. To meet the required time frame, the Xypex Concentrate coating work was then undertaken to allow it to air cure for the specified time. Once applied, the crystalline technology takes time to migrate deep into the concrete and become fixed within the concrete matrix as a permanent solution. When the curing is complete the coating could be removed if required, in this instance it remained. During the curing process of the coating, the crack repairs were then filled using Xypex Concentrate as a Dry Pack and then finally topped off with a thin layer of Xypex Patch’n Plug to enable the fast return to service. [caption id="" align="alignnone" width="1200"] The Xypex solution; Concentrate and Patch'n Plug - Courtesy of SMR Projects Ltd - Xypex UK Distributors[/caption] The results The allowed time frame meant undertaking the processes out of the normal sequence, but this allowed the repairs to be to be delivered on time. The coating was undertaken to increase the durability but also to pick up any minor unidentified cracks. The larger cracks were repaired and sealed using the standard Xypex repair methodology, however ultimately over 300 metres of crack repairs were completed.   For more information: SMR Projects Ltd - XYPEX UK Distributors: +44 (0)1295 279747 | www.smrxypex.co.uk

 

Kent County Council‘s programme of planned highways maintenance works to be carried out during 2019 – 2021 included strengthening works to structures such as the Raigersfeld Culvert situated beneath the A20 Ashford Road, Maidstone, Kent. Following on from previous culvert rehabilitation works for Kent County Council, Steadline Ltd. were once again commissioned to make the required improvements to an existing historical brick and steel beamed culvert which was showing signs of deterioration resulting the restriction of flow capacity. With the same project team comprising Steadline Ltd., BdR (Civil & Structural Engineering) Ltd. and Amiblu, a bespoke, non-circular GRP liner was designed with specific challenges to overcome, including: Steel cross sections to the soffit of the culvert Inconsistent shape Traffic loads Restricted access Environmental considerations [caption id="" align="alignnone" width="1200"] Existing Raigersfield culvert - Courtesy of Steadline Ltd[/caption] The result, 16m x 1m length sections, 1244mm x 754mm Eliptical shaped NC Line with a 27mm wall weighing just 175kg per metre with a push fit bell & spigot socket, was designed to maintain the required cross section and flow capacity. Steadline Ltd and BdR (Civil & Structural Engineering) Ltd worked in conjunction with Kent County Council, to ensure all works were carried out safely and efficiently whilst meeting the requirements set out by the client in respect of strength, durability and finished aesthetics. Forward planning of this scheme was critical as the culvert runs beneath the main A20 which is a major arterial route through Maidstone and a road closure was never an option, so the team at Steadline worked closely with park rangers within Mote Park to secure the downstream access and with residents of a gated housing estate for the upstream access. The stream was damned and over-pumped with precautions in place to ensure that no unwanted debris found its way into the natural water course. The 1m long NC Line sections were then craned onto the upstream landing area before being installed using a purpose built roller system to accommodate for the inconsistent internal condition of the existing culvert. Once all 16m of NC Line had been installed, grouting was carried out in stages as per Amiblu’s recommendations and the headwalls were finished in keeping with the original culvert construction. Amiblu relining pipes are particularly suitable for pipe and culvert rehabilitation, as they are light in weight, corrosion resistant, quality assured, easy to install and engineered to give 150 years’ service life, they are manufactured in a wide range of sizes in both circular and non-circular options and with varying strengths to cater for all locations and performance criteria. [caption id="" align="alignnone" width="1200"] NC Line example shape options[/caption] Amiblu NC Line pipes are produced to ISO16611. The non-circular cross-sections are ideal for relining and strengthening aging sewer networks, culverts and channels. Non-circular pipes are also used for open trench applications where capacity is required, but allowable depth to invert is limited. They can be customised according to project requirements and easily be adapted to different types of shapes and geometries. Project parameters Country: UK City: Maidstone Year of construction: 2021 Application: Storm sewer Installation: Trenchless Technology: Amiblu NC Line Total length of pipe: 16m Nominal diameter DN: 1244mm x 754mm Nominal pressure PN (bar): PN1 NC Line shape: Elliptical (1m lengths) Supply chain Client: Kent County Council Contractor: Steadline Ltd Engineer: BdR (Civil & Structural Engineering) Ltd NC Line relining pipe: Amiblu [caption id="" align="alignnone" width="1200"] (left & right) Finished Ragstone headwalls courtesy of Steadline Ltd and (middle) Amiblu NC Line Raigersfield design drawing - Courtesy of Amiblu[/caption] What was said Aaron Harber, Contracts Manager, Steadline Ltd.

” All in all the scheme was very successful and certainly improved the flow of the stream/small river and with the new rag stone head walls looked very pleasing to the eye.” 

  For more information: Amiblu UK | +44 (0)7786 013574 | www.amiblu.com    

iNPIPE PRODUCTS™ was commissioned to provide comprehensive pipeline pigging/cleaning services to a prominent civil construction firm, acting on behalf of a major client within the UK utility sector. Following a detailed review of project specifications and extensive consultation with the client, iNPIPE PRODUCTS™ executed a turnkey air pigging solution encompassing: Project management and engineering oversight. Development of pigging procedures and risk assessments. Provision of temporary launchers and receivers to facilitate seamless equipment. Manufacturing of bespoke pipeline cleaning pigs equipped with advanced tracking and internal camera recording capabilities. Supply of cutting-edge air pigging equipment. Due to the build up of manganese powder accumulated within the aged aqueduct, it became necessary to clean the pipeline. Air-propelled, tractable foam cleaning pigs were utilised to remove the sediment inside the pipe, ensuring the provision of cleaner, wholesome water for the area. The 17.5-kilometer-long, 42-inch diameter water pipeline was divided into six smaller 2 to 3 kilometer sections to manage water and air displacement. Each section was drained prior to equipment installation and pigging operations. The project required iNPIPE PRODUCTS™ to develop a specific foam cleaning pig that would remove debris from the pipe wall without damaging the internal lining or coating of the pipeline. Quality assurance was paramount throughout the operation. [caption id="attachment_17969" align="alignnone" width="1200"] 42" pigs during pipeline cleaning operations[/caption] To verify the cleanliness of the pipeline in real-time, a sophisticated camera pig equipped with video recording capabilities was deployed, providing the client with unequivocal confirmation of the pipeline's condition post cleaning. In addition to manufacturing bespoke cleaning equipment, iNPIPE PRODUCTS™ provided a comprehensive air pigging equipment spread, including air compressors, manifolds, and silencers. Launcher and receiver pods were particularly designed and fabricated to seamlessly integrate with the cleaning process. To ensure thorough pipeline cleaning, a series of specialised cleaning pigs were employed in succession, forming a pig train. The cleaning process began with a brush foam pig, accompanied by a 10m3 water slug, followed by a criss-cross foam pig propelled with air. Subsequently, a camera pig was utilized to meticulously verify the pipeline's cleanliness. Each pig was equipped with a transmitter for efficient pig tracking. Operational execution was carefully managed, with a dedicated onsite operations team, including the project manager, site supervisors, and pigging operators, overseeing every aspect of the operation. Mobilisation of personnel and equipment was executed promptly as per schedule, with meticulous coordination between our team, the client, and the asset owner. The project concluded successfully, surpassing expectations by completing ahead of schedule and budget, iNPIPE PRODUCTS™ commitment to excellence and expertise in pipeline cleaning delivered a pristine pipeline network, exceeding client expectations, and promoting environmental conservation and sustainability.   Air Pigging Project Benefits Air pigging is a safe, efficient and environmentally friendly method to clean water pipelines offering significant benefits compared to traditional methods. Considerable reduction in carbon emissions, costs, time, environmental impact, fuel, traffic congestion and noise as well as supporting road safety. The system significantly reduces water consumption from traditional water jetting together with a comparable reduction in the amount of contaminated water needed to be disposed of. Sustainably cleaning method of pipelines with air rather than water, minimal water wastage and minimum disruption to the environment. Camera-Integrated Pig provides visual cleaning result verification in real time PRODUCTS iNPIPE™. Savings: 1,104 tanker journeys. 15 million litres of water. 118.2 tonnes of CO2 across the whole project.     For more information on the iNPIPE PRODUCTS™ air pigging technology, visit https://www.inpipeproducts.com/     iNPIPE PRODUCTS™, Gatherley Road, Brompton on Swale, North Yorkshire, DL10 7JH | Tel: +44 (0)1748 813270    

The regional water and sewerage company, which serves 2.8 million customers across the south west of England, purchased six Hexi Trailers in 2013. The trailers have been put to good use ever since, and are currently employed on 70% of water main replacement projects. This recent project took place in Calne, Wiltshire and involved replacing 800m of cast iron water main originally laid in the 1920s. The main had reached the end of its life, and Wessex Water wanted to ensure that customers were provided with a reliable and clean water supply by replacing it with plastic pipe. The new plastic pipe was inserted into the old cast iron main using another SVI product – the Pipe Handler. By using this method, Wessex Water were able reduce the number of ground excavations and speed up the replacement process. 500m of pipe inserted in one push The high capacity Hexi Trailer, loaded with a 500 metre coil of 63mm diameter PE, allowed operatives to insert 800m of pipe in just two pushes, one of 500m and the second of 300m. The coils of pipe were manoeuvred on site and the pipe accurately inserted into the old water main by the SVI Pipe Handler attached to an excavator; an insertion rate of 300m per hour was achieved. Only one excavation was needed, leading to minimum disruption and reinstatement costs. Alternative methods of replacement would have involved digging down every 100m. Using a high capacity trailer and mechanised pipe handling equipment helped ensure this replacement project was completed within two days. New Design The Hexi trailer was a completely new design for SVI when it was introduced in 2012. It is capable of dispensing coiled pipe with diameters of 63mm-90mm and has a number of key advantages. Firstly, by taking a 500 metre coil rather than the usual 100 or 120 metres, it allows operators to save money by reducing pipe wastage. Secondly, due to the hydraulically powered raised hexagonal drum, the pipe is dispensed smoothly and quickly. The easy operation allows one operative to dispense the pipe compared with other trailers on the market which require two or even three people. Safety was a key consideration when developing the Hexi trailer, with the result that all loading and dispensing procedures are carried out from ground level and both ends of the pipe are secured until the moment of dispensing to prevent the PE ‘springing away’ thus avoiding an injury hazard. Insertion made faster and safer SVI developed their Pipe Handlers to make the process of inserting plastic pipe easier, safer and faster. There are five models in the range accommodating pipe diameters from 40mm to 630mm. All models attach to a quick hitch or standard bucket pins of most common hydraulic excavators. Loading, manoeuvring and inserting operations are easily controlled from the safety of the excavator cab.   For more information: Steve Vick International Ltd | +44 (0)1225 864864 | www.stevevick.com    

Under the DV2 Framework, Scottish Water appointed Morrison Construction as the Principal Contractor and Principal Designer to execute the Treated Water Storage (TWS) Programme. This ambitious programme spanning multiple years, focuses on refurbishing and enhancing the resilience of critical treated water storage infrastructure across Scotland. The programme aims to ensure the continued supply of high-quality drinking water while embracing sustainable and innovative engineering solutions. The Pitfodels Distribution Service Reservoir (DSR) Project exemplifies the success achieved under this framework, demonstrating how a proactive, collaborative approach can deliver significant cost, programme, and carbon savings. Through innovation and an intelligent engineering solution, the project not only extended the lifespan of a vital asset, but minimised network disruption, reduced embodied carbon, and improved resilience for future generations. Pitfodels DSR - Scope of work

Located in Aberdeen, Pitfodels DSR was construction in 2002 and serves a population of 225,000 people. Measuring 63m long x 44.5m wide x 6m high, it has a working storage volume of 14.55 ML. The primary issue was water ingress which could potentially lead to water quality risks, which require MorrisonConstruction to undertake a 19 week project valued at £1.6m, with the following scope:

External waterproof membrane installation (Fosroc Proofex 3000). Concrete repair works. Overburden removal and reinstatement. Drainage improvements. The Technocover Ltd access hatch resealing. Solar panel removal and reinstallation. [caption id="attachment_22128" align="alignnone" width="1200"] (left) Solar panels removed at start of works and (right) inside the reservoir at the start of the internal refurbishment works - Courtesy of Morrison Construction[/caption] Pitfodels DSR - Additional Scope An inspection upon entering the tank revealed severe deterioration of the roof structure, necessitating significant reinforcement measures. This £1.8m in additional work required an 85 week extension (from initial 19 weeks). A collaborative decision-making process involving Scottish Water, Morrison Construction, subcontractors, suppliers, and design professionals was undertaken to determine the optimal solution for addressing the structural deficiencies including innovative low-carbon reinforcement of the tank soffit and birdcage scaffolding for safe soffit access. Pitfodels DSR - Supply chain - key participants Project delivery: Morrison Construction Designer: Allen Gordon LLP Waterproofing, structural repairs specialist: Fraser Bruce Group Civil contractor: Macari Hill Civil Engineering External waterproofing: Fosroc Internal soffit/roof repairs: Sika Challenges The key challenges included: Limited site information: No as-built records, restricted surveys before tank decommissioning and project delivery. Structural failures: Bespoke beam and block construction deteriorated due to water ingress, freeze-thaw cycles, and block delamination, leading to falling debris. Environmental risks: Cold weather posed challenges for specialist waterproofing materials. [caption id="attachment_22127" align="alignnone" width="1200"] Scaffolding in place for the reservoir internal refurbishment - Courtesy of Morrison Construction[/caption] Engineering solution: Internal structural strengthening The solution ensured the existing beam and block construction functioned homogeneously. Concrete repairs: Hollow core blocks and precast beams repaired using Sika repair mortars. Carbon Fibre Reinforcement: Sika CarboDur Grid C System: Bi-directional carbon fibre grid (CarboDur 300 Grid) applied to the soffit. Encapsulated with two layers of Sika MonoTop-3200 Grid mortar. Total thickness: 6mm. Sika CarboDur S626 plates: Pultruded carbon fibre plates bonded to transverse beams using Sikadur-30 epoxy. Broadcast with kiln-dried quartz sand for enhanced adhesion. Surface protection: Sika MasterSeal 588 applied to encapsulate the strengthening systems. Engineering solution: External design enhancements Thermal protection: 100mm insulation to prevent freeze-thaw cycles. Load reduction: Overburden thickness reduced by 115mm, minimising roof stress. Waterproofing enhancements: 5mm Proofex 3000 membrane on Proofex primer. Two 8mm Proofex Sheetdrain 80 layers for improved drainage. 5mm self-levelling compound for surface refinement. [caption id="attachment_22126" align="alignnone" width="1200"] Refurbishment works underway - Courtesy of Morrison Construction[/caption] Stakeholder collaboration, community engagement & economic opportunities Regular communication with the local council facilitated necessary approvals and permissions. and early stakeholder engagement ensured the community were involved from concept until completion. A local Morrison Construction team was employed which included two trainee civil engineering graduate apprentices (the project provided invaluable experience) and the team utilised the local supply chain, with the overburden and drainage material being sourced from a local quarry. The project safeguarded the lifespan of this tank for the foreseeable future, mitigating future network disruption associated with a new roof or new tank construction. Environmental considerations No demolition waste: The works avoided significant construction debris that would have resulted from a full roof rebuild. Preserved natural surroundings: There was no requirement for large-scale excavation meaning no disruption to the local ecosystem. Mitigated water quality risks: By preventing roof deterioration and leakage, the project safeguarded local water quality and protected drinking water supply. Digital transformation: The project was managed using Fieldview, Viewpoint, and Hypervine, reducing 99% of paper usage. Sustainable site operations: HHVO (hydrotreated vegetable oil) fuel wasused across the project, cutting CO₂ emissions from on-site plant and machinery. Key Outcomes Significant cost & carbon savings: Instead of a costly £9 million roof rebuild, the tank was reinforced using lightweight carbon fibre, saving £5.6 million and preventing 300 tonnes of CO₂ emissions, compared with a roof rebuild also avoiding demolition and material wastage. Superior waterproofing extends asset lifespan: Drainage layers, insulation and waterproofing, reduce leakage risks, prevent future damage, safeguard water quality and reduce future maintenance. Lightweight, high-strength solution: Carbon fibre reinforcement enhanced structural integrity without excessive load. Minimal disruption: Existing structure strengthened without full roof reconstruction. Concurrent delivery: Initial works continued uninterrupted while soffit repairs were designed and implemented. Programme efficiency: 2.5 years saved compared to a full roof rebuild (4.15 years vs. 1.83 years for refurbishment) while maintaining water supply with minimal network impact. Mitigated network disruption: Strengthening works avoided a longer-term network-wide shutdown. [caption id="attachment_22125" align="alignnone" width="1200"] The internal works after project completion - Courtesy of Morrison Construction[/caption] Conclusion The Pitfodels DSR refurbishment stands as a resounding triumph within the TWS programme, underscoring the unwavering dedication of Morrison Construction and Scottish Water to delivering high-value, low-carbon infrastructure solutions. This project exemplifies the pinnacle of modern civil engineering – a cost-effective, sustainable, and technically advanced solution that fortifies public water infrastructure for decades to come. Morrison Construction, its delivery partners, supply chain, and Scottish Water have established an exemplary benchmark for asset resilience, low-carbon engineering, and innovation in water infrastructure delivery. This project serves as a paradigm for future treated water storage refurbishments, demonstrating that astute engineering can drive efficiency, sustainability, and long-term value.