Supply Chain - Asset Maintenance & Rehabilitation - Tank Maintenance & Repair

Anglian Water’s Toplers Hill Water Tower is situated just off the A1, south of Biggleswade, Bedfordshire, on a site which includes both the water tower and a water reservoir. The tower was constructed in June 1934 and its condition has started to deteriorate with age. Following Anglian Water’s internal inspection of the water tower, areas of concern were identified regarding the roof, internal coatings and some of the access ladders, which would require replacement or refurbishment before the tower could be returned back to service without compromising water quality to customers. Issues

The deterioration of the water tower was clearly identifiable, with there being several leaks in the roof of the tank and any sampling of the water would be insufficient to pass due to the interior surface corrosion. Also, the instrumentation and roof interface point were not sealed, with a noticeable build-up of debris/silt/carbon and corrosion across the walls. Another issue was the broken ladder which would cause a health and safety access issue moving forward.

The option of replacing the water tower with cellular units was considered, however, due to minimal site spacing, it was discounted and the solution was to modify the existing asset.

Due to the consequence of the tank’s condition, there was a risk of low-pressure events. Toplers Hill Water Tower also provides standby storage to the adjacent Toplers Hill Reservoir, which cannot be removed from service until the water tower has been returned back to service; therefore highlighting the importance of the solution being delivered in a timely manner.

It was evident that the roof needed replacing, which required considerations for the crane’s lifting ability, the crane’s positioning, lay down areas, the weather conditions and teamwork. It was also apparent that there would be the need to reposition a number of telecommunications aerials atop the tower to ensure the site team were not at risk of radiofrequency (RF) radiation whilst working the tower.

[caption id="attachment_13576" align="alignnone" width="1200"] Toplers Hill Water Tower - Courtesy of @one Alliance[/caption] Solution and construction

Anglian Water’s @one Alliance was tasked with developing a solution to the issues and the construction phase started in 2022.

Scaffolding: The team required safe access up the tower and around and inside the tank, so extensive scaffolding was put in place to allow this. The scaffolding works comprised the following:

An external scaffold tower supporting an electrically-powered hoist to the top of the water tank. Full external access scaffolding surrounding the tank. Full birdcage scaffolding inside the tank with several boarded levels to the sides of the tank. The birdcage scaffold would need to be altered throughout the installation whilst repairs were taking place to enable safe access to all internal faces of the tank.

Crane pad and lay down area: Whilst the scaffold was being installed, Claret Civil Engineering designed a crane pad to facilitate the old roof removal and new roof installation. A separate levelled roof dismantling/assembly area was created nearby and covered with track matting.

Tank internals: With the scaffolding installed, the internal walls and higher levels of pipework and support brackets were prepared by OnSite Central Ltd. This included lead paint removal by high pressure water jetting, abrasive grit blasting, and re-coating the tank interior with Acothane DW; a DWI approved, solvent free polyurethane coating for potable water tank lining. The new tank coating was tested for integrity and strength as it was installed then cleaned, disinfected and sampled ready for return to service.

Roof replacement: The leaking tank roof was removed by crane by Hayes GFS Ltd and dismantled this on site. This was replaced with a new glass lined steel structure provided by Permastore and installed by Hayes. The top section of the walls had been identified as heavily corroded, so was cut away and prepared to receive the new roof arrangement. Using a crane from Cadman Cranes Ltd, the new tank roof was lifted into position onto the existing structure.

[caption id="attachment_13580" align="alignnone" width="1200"] New roof ready to be lifted - Courtesy of @one Alliance[/caption]

Water tower access: The external tank ladder with two shorter ladder runs and an integral access platform for the existing side access hatch were replaced.

Instrumentation: Whilst the existing level instruments and cabling were re-used where practicable, a new ultrasonic level transducer and associated cable runs were also installed. The old and new instruments were mounted to purpose-made apertures in the replacement roof to monitor the ultrasonic levels within the water storage tank.

Toplers Hill Water Tower: Supply chain - key participants Client: Anglian Water Design & project delivery: @one Alliance Refurbishment of tank internals & re-coating: OnSite Central Ltd Old roof removal/new roof installation: Hayes GFS Ltd Civils works: Claret Civil Engineering Glass-lined steel roof: Permastore Ltd Polyurethane coating: Acothane UK Ltd Crane hire: Cadman Cranes Ltd Project challenges

Due to poor weather conditions, the crane lift date was delayed by several weeks. In addition, a last minute revision to the lifting plan caused delays to the lifting activities.

Having to apply the Acothane DW throughout both the winter and summer months, temperature and humidity extremes were experienced which was challenging during the preparation, application and curing of the coating.

Other challenges included nesting birds, tight site access, and several incidents of theft and on-site vandalism.

[caption id="attachment_13575" align="alignnone" width="1200"] The new roof being lifted into place - Courtesy of @one Alliance[/caption] Health & Safety

The @one Alliance, prides itself of ‘Deliberately Delivering Differently’ and with this scheme, several H&S opportunities presented themselves as it developed. Early on it was noted that there was some concrete spalling on the external tower wall, which was a concern as small clumps of falling concrete could occur at any time. The team decided to carry out some loose concrete removal at the start of the site phase to removed this hazard.

Another anticipated H&S improvement was the use of a remote-controlled robotic paint stripper and shot blaster to prepare the internal walls for the new coating. This meant that operatives did not have to be inside the tank to manually shotblast the exiting coating, but unfortunately, the team discovered that the device could not traverse the bolt heads or tank boiler plate joints well so was ineffective.

The team also found that the internal tank birdcage scaffolding could be rationalised down to one lower level deck for tank wall access and work could be undertaken from mobile tower scaffolds. This not only reduced H&S concerns, it also saved time in having to install and strip additional scaffolding which equated to a saving of approximately £40,000.

Project status

As the date of writing (July 2024), the team are finalising the last activities of the tank refurbishment.

Once the telecommunications aerials are repositioned to their original orientation the scaffolding will be fully removed and the water tower will be handed back to Anglian Water. It will then be returned to service and the year-long warranty period will start.

The challenge The South East Water contact tank has a constant output of 18.1 million litres per day, it contains water which is treated with Sodium Tripolyphosphate and sodium hypochlorite before entering the distribution network. The structure is of a ‘certain’ age and has a number of active leaks that have progressively worsened over time. As the tank is in constant use, it cannot be taken off-line and so a solution was required which could be undertaken against heavy flow of water with the tank still in use. The Xypex solution Xypex not only likes water, but the repair method requires a wet environment therefore an active leaking tank is not a problem. The cracks were chased out in accordance with the DWI Reg. 31 approved Instructions for Use Document i.e. a minimum of 37mm depth and 25mm wide, following the line of the crack. Either side of the crack was cleaned and the laitance removed to expose the capillary and pore network. [caption id="" align="alignnone" width="1200"] The Xypex solution; Concentrate and Patch'n Plug - Courtesy of SMR Projects Ltd - Xypex UK Distributors[/caption] A bleed pipe was installed and secured with Xypex Patch’n Plug at the lowest point of the crack where water flow was at its greatest. Then the base of the crack was plugged using Xypex Patch’n Plug to stop the flow of water. This was then left to see if there were any additional issues that manifested themselves over night. Once the flow was proven to have stopped, the repair was finished using Xypex Concentrate both as a dry pack and a slurry in line with the IFU and Xypex’s standard repair methodology. The results The Xypex methodology using Xypex Patch’n Plug stopped the flow of water instantly and allowed the repair to be undertaken. The crystalline chemistry within the Xypex Concentrate will migrate deep in to the concrete matrix around the repair, driving water out and increasing the life and durability of the tank in those areas. [caption id="" align="alignnone" width="1200"] Courtesy of SMR Projects Ltd - Xypex UK Distributors[/caption] As the original repairs were undertaken, additional pressure was transferred to other cracks that were visible, but not leaking, and these were all repaired using the same method. In all, only 2 materials were used on site and no specialist methods were used. SMR Projects Ltd attended and were on hand for technical help throughout the installation.   For more information: SMR Projects Ltd - XYPEX UK Distributors: +44 (0)1295 279747 | www.smrxypex.co.uk

 

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

 

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.