Inflow of stormwater and infiltration of groundwater into wastewater systems is a constant operational challenge for managers. Now, Håbo municipality in Sweden is tackling the challenge head-on with an innovative digital approach, says Adam Wood, chief product officer at water analytics company Infotiles.

Water utility managers in Håbo, a small municipality north-west of the Swedish capital, Stockholm, began conversations with InfoTiles in 2023, when they suspected infiltration of wastewater and inflow of groundwater into wastewater networks (I&I) was adding massive volumes requiring transport and treatment.

Managers wanted to investigate I&I further and needed tangible evidence to demonstrate the need for investment but were facing budgetary and operational constraints. Using control system data together with weather data and analysis of wastewater networks using in situ sensors, the collaboration sought to determine when and where I&I was occurring and decide on the appropriate response.

Gathering evidence
Inflow is stormwater that flows into wastewater pipes through faults such as holes, cracks, joint failures, and broken connections. Infiltration occurs when groundwater enters the wastewater network through faults in pipes, compounding the flow.

Magne Eide, chief operating officer at Infotiles, said, “InfoTiles set out to show Håbo municipality what the cost of not maintaining its wastewater network to prevent I&I would be, versus investing money now. Water managers wanted to understand what the maintenance opportunities were, so they could create a wider business case to be put forward for funding during the 2025 budget process.”

Servicing a population of around 18,700, Håbo’s water utility treats about 4 million m3 of wastewater per year. InfoTiles discovered that 18% of that water is incurred through I&I, leading to SEK13 million (roughly €1.3 million) of extra operating costs annually equivalent to almost SEK700 per inhabitant (roughly €61).

Energy use is a significant part of the additional treatment and transportation costs involved in processing I&I, which means reducing energy consumption represents a potential saving on operational expenditure when I&I is remedied. Extra energy consumption also represents a higher carbon footprint, so accurately identifying and preventing I&I can help utilities meet carbon commitments, including net zero targets.

Compounded flow
For many utilities and municipalities, I&I can account for an average of 20-50% of the annual flow in sewers, but during snow melt and wet autumns, this figure is much higher.

It is widely acknowledged that most I&I is caused by ageing infrastructure that requires maintenance or replacement, but some is also caused by erroneous connections such as building drainage and rooftops connected to the wrong pipes. When this water penetrates the wastewater network, it can overload the system, which is a particular risk during periods of heavy rain or storm events.

In the worst cases, it can lead to the release of untreated wastewater into the environment and pollution of rivers and seas. It also increases the risk of cross-contamination of drinking water, where polluted water from the environment enters through faults in clean water pipes.

Increases in the frequency and intensity of rainfall as a result of a changing climate is exacerbating the problem, making wastewater networks ever more vulnerable to failure and putting the environment at greater risk. If left untreated, pipeline integrity will only deteriorate over time, increasing the volume of ingress water to be treated.

For Håbo municipality, the overall goal of the collaboration with InfoTiles is to gain a better understanding of the causes of inflow and infiltration into sewerage networks and to understand the options for remediation and impact reduction. The municipality hopes it will help policymakers gain a deeper understanding of decision-making around I&I and show how collaboration and digital solutions can be used as a catalyst for positive change.

Accurate pin-pointing
Inflow and infiltration compounds wastewater operating costs as excess water must be pumped, treated and discharged.

The InfoTiles platform uses SCADA control system data together with data from the Swedish Meteorological Institute to analyse historical rainfall and the dry and wet weather behaviour of wastewater networks. For example, how and when water hits the network and how it affects pump heights.

Sensor devices placed at critical points in the network can collect data such as precipitation, problematic thresholds of rain volume, or seasonally varied sensitivities. That feeds into a central dashboard and these detailed measurements can then be analysed by water managers.

By using information from pump stations in real-time, the model calculates the total and excessive volume transported, allowing managers to see not only weather-related trends but also the resulting costs both in terms of treatment and power expenditure.

Once problem areas have been identified, the search area can be narrowed down using compact internet-of-things (IoT) devices within the same platform. Some pump stations have multiple inputs or long upstream pipeline networks. By selectively measuring different branches, it is possible to identify exactly where the water inflows and infiltrates or exclude areas that are not problematic.

Positive proof
Håbo operates 38 pumping stations, in a network where several smaller pumping stations feed larger stations before the wastewater is ultimately transported to treatment.

InfoTiles and Håbo municipality determined that the pumps closest to the treatment stations were receiving the largest net volume of water, meaning that the largest influx was occurring in the parts of the network directly relating to the largest pumps.

With this information, managers from Håbo went searching for damage in the identified areas and were able to quickly confirm the findings of the analysis. Significant breaches of the pipe were found upon visual inspection. In one location, drained surface water from nearby farmlands was penetrating wastewater pipes at high pressure, causing large and continuous volumes of I&I.

Sara Frid, water and wastewater strategist, Håbo Municipality, said, “The new insight into ingress water, such as volumes, likely sources, and the resulting costs really sparked an interest among our operators to go on the hunt for it.

“Within the first couple of weeks, we had found damages to our wastewater pipelines that we could repair to reduce volumes and save treatment costs.”

Now, water managers can not only use data to identify the areas with the highest need of maintenance and repairs but also see the results of their work in reduced volumes of inflow and infiltration.

Continually reducing the total volumes of I&I remains a high focus for Håbo municipality.

With the InfoTiles solution, they have been able to prove that investments in wastewater maintenance are not only an issue of environmental risk and cost, but in fact, the reduction in volumes will ultimately lead to reduced treatment costs in the long term.

Regulations for hydrostatic pressure testing have taken a significant step forward with the release of Water UK’s Water Industry Standard for hydrostatic pressure testing of PE pipes, a move that will ensure the safety and reliability of the process, says Tony Kitchen of AHS Pipeline Innovation.

Water companies and contractors are adjusting to the requirements of the new Water Industry Standard 4-01-03, released in March 2024, which outlines the required standards for the hydrostatic pressure testing of polyethylene (PE) and polyethylene barrier pipes. The standard replaces previous guidelines from Information Guidance Notice 4-01-03.

The transition from an Industry Guidance Notice (IGN) to a Water Industry Standard (WIS) marks a shift towards more stringent and enforceable standards that aim to improve the safety and effectiveness of the pressure testing process.

WIS 4-01-03 specifies detailed procedures for pressure testing below-ground water supply pipelines and sewer rising mains comprised of PE and PE barrier pipes. It includes guidelines for testing entire systems as well as replacement sections and service connections.

The specifications emphasise the importance of considering the viscoelastic properties of PE, which exhibits what is known as creep behaviour – deformation that occurs when subjected to pressure over time.

Understanding the difference
It is important to understand the distinctions between WIS and IGN:

● An Information Guidance Notice serves as a set of recommendations or guidelines that offer advice on best practice but does not mandate specific actions or procedures.
● A Water Industry Standard is a more formal document that sets out mandatory requirements for products, materials or operational procedures. WIS documents are intended to ensure uniformity and compliance across the water industry, leading to more standardised and reliable outcomes.

Improving safety
The new WIS is designed to improve both the accuracy and safety of pressure testing which means there is now a zero-tolerance policy on pre-pressurisation. Key points are:

● The pipe must be at ambient pressure prior to testing
● If a test has failed, the operator must leave the pipe for four times the length of the ramp-up time before reattempting the test
● The operators must wait for two to three hours between filling and pressurising the pipeline. This takes into consideration the effects of thermal conditioning and allows the temperature of the pipe to stabilise once it has been filled.
● The allowable air content has now been reduced from 8 to 4 per cent
● The air content must also be accurately calculated during the ‘ramp-up’ stage as the pipeline is brought to system test pressure (STP). This means that the test can be immediately abandoned if it is over the acceptable limit.

What WIS means for contractors
There is no question that the new standard represents a significant step towards leak-free networks, but the new requirements potentially impose a greater burden on contractors. The stringent rules around correct preparation prior to testing, including pre-pressurisation, thermal conditioning, and calculating air content prior to starting the test, making it crucial to get the test right first time, to prevent wasting time and resources in retesting.

A reduction in the allowable air content means less margin for error, which highlights, from a compliance and cost perspective, the importance of contractors carefully managing their own and subcontracted pipeline pressure testing.

Due to the increasing complexity of hydrostatic pressure testing and varying levels of expertise among technicians and operators, some pressure testing providers may not meet the standards outlined in the WIS and could lack the knowledge or skills to correctly prepare the pipe for testing.

Contractors must ensure that all pressure testing activity is fully compliant with the new WIS specifications. Substandard testing potentially creates dangerous situations, with risk to life and limb, if air is not properly removed from the pipeline.

It is crucial for contractors to select subcontractors with proven compliance to ensure the safety and reliability of their projects if they are to maintain both contractual obligations and a good reputation in the industry.

Proven expertise
AHS Pipeline Innovation is recognised as an industry leader in hydrostatic pressure testing with over 20 years of experience and almost 50,000 tests completed. The proven expertise of AHS allowed the company to play a key role in the development of the new WIS as part of a multidisciplinary panel which included pipe manufacturers, water company representatives and trade organisations.

Careful consideration was given to onsite implementation of the new requirements, and how contractors can be supported in meeting the standard.

Pressure testing services at AHS are already fully compliant with WIS 4-01-03 and incorporate the latest technology and real-time assistance from the company’s in-house analyst teams to give contractors unrivalled support throughout the testing process, ensuring that testing is right first-time.

AHS is equipped to guide and support teams in adopting these new standards so that their pipeline operations meet the necessary requirements. Should water companies and contractors be unsure about how WIS 4-01-03 affects their operations, or require support to ensure compliance, AHS is available to provide the knowledge and tools necessary to navigate this transition smoothly and effectively.

WIS 4-01-03 not only mandates stricter controls over variables like air content, ambient pressure and temperature, it also effectively identifies and removes any activities undertaken onsite that can affect test performance. Importantly, it reintroduces rules that had been relaxed in previous guidance, restoring rigorous standards that are essential for maintaining the integrity of water systems and creating more defined regulatory expectations.

In addition, pressure tests carried out in accordance with the WIS are measured using sophisticated algorithms that deliver definitive test outcomes, ensuring clarity and reliability.

At a time when the water sector is experiencing reputational challenges, WIS 4-01-03 represents an opportunity for water companies and contractors to get it right from the start. By carefully navigating these changes, and ensuring that every test not only meets but exceeds the latest standards for safety and efficiency, they can mitigate risk to the public and their own teams altogether.

This article contains paid for content produced in collaboration with Winn & Coales (Denso) Ltd.. (Above) Densoclad 70 Tape is applied over the bitumen-based primer (inset) before the whole system is encapsulated with Denso Glass Outerwrap.

A bitumen tape wrap system from Winn & Coales (Denso) Ltd was utilised for the repair of damaged pipework at the new HS2 terminus at London Euston train station.

Following damage to the existing factory coating, corrosion had already begun to inflict damage upon the pipe and had propagated underneath the coating itself, causing it to delaminate. To eliminate further damage, the Denso Bitumen Tape Wrap System was applied to not only protect the pipe from the effects of further corrosion, but to provide a large degree of mechanical protection too.

Winn & Coales (Denso) Ltd are leading manufacturers and suppliers of corrosion prevention and sealing systems. The bitumen tape wrap system supplied for the project was comprised of a bitumen-based primer (Denso Primer D), a heavy-duty PVC-backed bitumen tape (Densoclad 70 Tape), and a protective outerwrap (Denso Glass Outerwrap). The protective outerwrap offers exceptional mechanical and impact strength for buried pipes exposed to aggressive backfill conditions. Once applied and fully cured, the whole system provides a long-term protective coating that is ready for immediate service.
www.denso.net

A ground-breaking project that is enabling continuous remote monitoring of a 16km trunk main has been recognised at the Water Industry Awards.

The Blairlinnans SoundPrint Acoustic Fibre Optic System, a joint project between Xylem and Scottish Water – and described as a European first, was named Asset Management Initiative of the Year at the awards ceremony on 4 July 2024.

The Blairlinnans water main is a 42 inch (1,067mm) pre-stressed concrete (PSC) pipeline that runs from the Blairlinnans Water Treatment Works to a service reservoir in West Dunbartonshire, Scotland. The pipeline was installed in 1974 and is critical to the ongoing operation of Scottish Water’s supply network.

Scottish Water identified the main as a high-risk asset, which prompted a complete engineering assessment to understand its true condition and prevent an unexpected burst.

Inspections using Xylem’s SmartBall and PipeDiver technologies provided the data necessary to conduct a thorough engineering analysis. The insights showed while most of the pipeline was in good condition, several sections had broken pre-stressed wires, which are critical to support operational pressures. If the wires break, a trunk main can lose its structural integrity, with a risk of failure.

In the first project of its kind in Europe, Scottish Water selected Xylem’s SoundPrint Acoustic Fibre Optic (AFO) system to continually monitor sections of the pipeline. SoundPrint AFO detects breaks in the pre-stressing wire that hold PSC pipelines together.

The system set-up comprises bundled, reinforced fibre-optic cable fed though the water main, which is connected to a data acquisition system to monitor the acoustic activity in near real-time. If a wire break occurs, it is detected by the AFO system, which is connected to Xylem’s AFO analysts via the cellular network.

Wire break events are investigated by the analysts and with the help of machine learning, the break location is pinpointed. An email notification is sent to the customer and the results posted on a cloud-based system, which displays the pipeline status on colour-coded dashboards.

The monitoring, combined with further analysis by Xylem’s engineering service, enables utilities to make proactive decisions about which sections of pipe need to be replaced or repaired as deterioration continues over time.

Ian Dunsmore, team leader – strategic water infrastructure at Scottish Water, said: “Replacement of major pipelines is often cost prohibitive, extremely complex and causes major disruption – however it is rare that the entire pipeline needs to be replaced.

“Leveraging Xylem’s AFO system and engineering experience enabled us to understand the true condition of the Blairlinnans water main at a single point in time and have confidence that the pipeline is being continuously monitored for any further deterioration. It is great news that the success of this joint initiative has been recognised by the sector.”

Andrew Welsh, water utility director at Xylem said: “Xylem is extremely proud that this innovative partnership with Scottish Water has been recognised by the Water Industry Awards.

“The AFO system has enabled Scottish Water to reduce the risk of failure by pre-emptively repairing areas known to be in poor condition, make significant cost savings by extending the life of remaining pipe sections and minimise disruptions to customers, while maintaining the utility’s reputation as a forward-thinking, reliable service provider.”

After less than a year in his job, a Scottish Water apprentice has clinched both Scottish and UK top awards for his innovative work and presentation on using the natural flow of water to generate electricity.

Inspired by an industry-leading hydropower scheme at his local site in Falkirk, Zac Mooney presented at the Pipeline Industries Guild Professional Development Network Competition. At just 22 years old and competing against industry professionals with far greater experience, Zac first won the Scottish award before then going onto to double his success at the UK-wide event held in Coventry.

Addressing an audience of over 100 industry experts, Zac described how a turbine installed on a critical clean water main at Carron Valve Chamber will provide nearly 20% of the energy needs for the nearby Dalderse Waste Water Treatment Works.

The innovative project, which is being developed by Scottish Water Horizons, Scottish Water’s commercial subsidiary, is set to be one of the first in Europe where a clean water supply powers a wastewater site.

Expressing his gratitude, Zac said: “I am thankful to have been given the opportunity to showcase my hydropower learnings so early in my Scottish Water career.

“We are committed to becoming a net zero organization by 2040, and Scottish Water Horizons is delivering many projects in line with this goal. My work has a strong focus on the environment which is something I am very passionate about.

“The support from Scottish Water Horizons has been instrumental in my development and has given me the confidence to compete at such a high level at Pipeline Industries Guild Competitions.”

Scottish Water Horizons Project Manager and Zac’s mentor, John Lenehan, highlighted Zac’s unique approach:

“Zac distinguished himself by using a prop on stage – a small pressure reducing valve to demonstrate the power-generating potential in our pipes and flows. His winning presentation attracted significant interest from attendees, who were impressed by the carbon reduction and cost saving aspects.

“Zac has had a busy first nine months with us but has taken all these new experiences which come from a Scottish Water apprenticeship in his stride and has done brilliantly.”

The publicly owned utility has 175 apprentices across the business with Zac’s achievements in the Horizons Hydropower Team highlighting the varied nature of opportunities available through its apprenticeship programmes.

Rachel Bridge, Chair of the Pipeline Industries Guild, said:

“The Guild is passionate about nurturing talent and the Professional Development Network Presentation Competition provides a platform for individuals to showcase innovation, share best practice and learn together. I was delighted to attend and sit on the panel of judges for the final round of this year’s competition, Zac Mooney’s winning presentation on Harnessing the Hydropower in Pipes was a creative presentation of a circular solution harnessing energy from one process to utilise in another. It was excellent and a worthy winner.

“Zac presented confidently with interactive elements to engage the audience. We are delighted that his idea has now been shared amongst the pipeline operators in the UK and look forward to seeing this idea progress across the water networks and wider pipeline industry sectors.”

A provider of innnovative drainage solutions, Jet Aire, has been named one of the winning partners in the Ofwat Breakthrough Innovation Challenge for its participation in a research project to develop the world’s first blockage clearing pipebots.

Working with Northumbrian Water Group, the University of Sheffield, as well as a number of other universities, WASC’s and suppliers, this project aims to find a way to proactively detect build-ups before they become a blockage, eradicating spills and sewer flooding and its devastating impact on customers.

The innovative technology will see a truly autonomous pipebot that will live in the sewer for 30 days at a stretch, patrolling to understand the network and detect blockage build-up, alerting maintenance teams.

There are over 40,000 incidents of internal and external sewer flooding in the UK every year which cause devastating damage to customers properties. A significant proportion of these are because of blockages in sewer pipes.

Dean Blackburn, North East Area Manager, Jet Aire said: “Current approaches using smart networks are reactive, based on detecting rising water levels in sewers to estimate where blockages might be. However, it is often too late to allow maintenance teams to locate and clear the blockage before flooding occurs. Pipebot makes this process proactive. We are very excited to be supporting this project which could be the first step in delivering the world’s first blockage clearing pipebots.”

Helen Campbell, Senior Director, Ofwat said: “There are big challenges in the water industry that must be solved, some are well known and others are less so. In our fourth Water Breakthrough Challenge we called for solutions with potential to deliver wide-scale, transformational change for customers, society and the environment – and that’s exactly what today’s winners have done. From raingardens to prevent flooding to green energy from treated sewage, innovations to cut the water sector’s carbon footprint to robots that patrol the pipe network, the winners are all helping shape a more sustainable and efficient water sector.”

The Water Breakthrough Challenge is part of a series of competitions from Ofwat, run by Challenge Works with Arup and Isle Utilities, designed to drive innovation and collaboration in the sector to benefit individuals, society and the environment.

It supports initiatives that help to tackle the biggest challenges facing the water sector, such as achieving net zero, protecting natural ecosystems and reducing leakage, as well as delivering value to society. 

For more information, visit: https://waterinnovation.challenges.org/breakthrough4/

This article contains paid for content produced in collaboration with Winn & Coales (Denso) Ltd.

On recent revisits to two Steelcoat 100/400 System applications in the Northeast of England, Winn & Coales (Denso) Ltd. were proud to confirm that both applications were performing as expected, providing exemplary protection from corrosion over a decade since their installations.

The Steelcoat 100/400 System consists of Denso Hi-Tack Primer, Denso Profiling Mastic, Denso Hi-Tack Tape, Denso Ultraseal Tape and Denso Acrylic Topcoat and offers an excellent long-term coating solution for exposed steel and pipework – particularly in areas faced with damp conditions. The system requires minimal surface preparation and is easy to apply, making it ideal for use in remote or difficult to access areas where preventing contamination of the surrounding environment is of the utmost importance.

Winn & Coales pride themselves on the longevity and effectiveness offered by the complete and correct applications of their innovative products and systems. The revisited Steelcoat systems – originally applied in 2008 and 2010 respectively – serve as demonstrable proof of their enviable track record of success and affirms their position as industry leaders.

Winn & Coales (Denso) Ltd are leading manufacturers and suppliers of corrosion prevention and sealing systems and celebrated 140 years of service to industry in 2023.

www.denso.net

This article contains paid for content produced in collaboration with iCenta Controls.

Instrument specialist iCenta Controls details a demonstration of its Metri Pro-Lite ultrasonic flowmeters on a 1260-mm mains water transmission pipe (see image, right) at a Southwest Water reservoir.

The pipe was in good condition, having been manufactured in the 1980s. Two sensor types were tested, both a large 0.5 MHz and a standard 1 MHz sensor (see images, below right). Firstly, 0.5 MHz sensors were installed on the pipe in Z mode using a bubble level and a ratchet strap.

The correct factor values were entered into the meter. One sensor measured flow, but it would only give a zero value. Although the signal looked good, the meter would not read the flow, indicated by the fact the signal was negative. The parameters that decide whether to let the unit read the flow needed to be adjusted in this case. The position of the sensor was adjusted to make sure the installation was the best available.

The 1MHz sensor was tested next, set up in Z mode. Good results were obtained.

The next test was in V mode. There was less signal this time, but enough to produce accurate results.

These tests prove that the meter will work on 1250-mm pipes that are in good condition and containing water, and it will work in both Z & V mode.

The device is fast to set up and we found that it compared favourably with the reference meter. There are also some video clips of this testing available. The device has exactly what you need to test the installation and log the data. It is intuitive to use.

www.icenta.co.uk

London Gatwick has created a new geospatial platform, said to be already making engineering and construction works safer at the airport by reducing accidental strikes on buried utilities and enabling better management of its biodiversity.

The platform uses Esri’s GIS (Geographic Information System) technology to support multiple operational areas at the airport, including engineering and environmental services.

The geospatial platform contains critical infrastructure information spanning the 70-year history of the airport, including BIM, CAD, utilities, environmental, aerial photography and legacy data. By integrating all spatial data into a single view, combined with advanced spatial analysis tools, mobile apps and dashboards, the Esri platform provides new insights to support better collaboration and decision-making across the airport. London Gatwick selected GIS from Esri UK following a competitive tender.

London Gatwick is using the geospatial platform to support its award-winning Biodiversity Action Plan, designed to deliver a biodiversity net gain at the airport by 2030. Within the airport boundaries are 75 hectares of woodlands, grasslands and wetlands, inhabited by hundreds of species of mammals, birds, insects and bees. Environmental data in the GIS includes environmental stewardship areas, notable birds, protected, rare or invasive alien species and bat box locations. The system also visualises the estimated embodied carbon of built assets.

Insights from the GIS allow London Gatwick to plan works around any environmentally sensitive sites to minimise impact and seek ways to bring additional benefits, such as improving biodiversity. The embodied carbon data allows users to see the carbon ‘price’ of assets, supporting sustainability decisions by showing the potential carbon emissions of demolitions or new construction.

“Being able to visualise and interrogate all spatial data from any discipline, on any device, is critical to the sustainable future of London Gatwick. Democratising spatial data in this way drives significantly more business and operational value from it,” explained Simon Richardson, Digital Information Lead, London Gatwick Airport. “The new GIS supports our Master Plan, which includes delivering efficiencies through new technologies and process improvements, while bringing passenger service benefits and protecting the environment we operate in. It provides an immediate understanding of operational infrastructure, supporting faster and more informed decisions, which are integral to the running of the airport.”

Previously, London Gatwick used Autodesk’s Infrastructure Map Server to manage spatial data but looked for another GIS software vendor when the product became unsupported. “We selected GIS from Esri UK because its Managed Cloud Service made it more accessible at lower cost than an on-premise approach,” continued Richardson. “It also removes the burden of system management and updates, which saves a significant amount of time, allowing more resource to focus on strategic projects. The new system is quicker and easier to use and the benefits far outweigh the cost.”

Future plans include using the geospatial system as a planning tool for estate-wide works, including runway maintenance and repairs and making the data available to local planning authorities bordering the airport to help streamline their planning process. The airport’s sustainability strategy is also set to benefit from the GIS, by helping to determine the optimal sites for solar panels, from potentially floating them in lakes or installing them on the most effective roof tops. London Gatwick’s ‘Decade of Change’ roadmap includes sourcing 50% of airport electricity from renewable sources with onsite generation part of the mix.

“Requests for new types of online maps are coming from across the business on a daily basis so the system is growing all the time. We expect the geospatial platform to grow significantly within the next 12 months,” said Richardson. “The Esri GIS has given us the foundation to create a digital twin. As a complex site with over 70 years of history, we are building a virtual representation of what has previously been built along with future plans, which helps manage the airport’s development.”

A specialist team from drainage and wastewater specialist Lanes Group plc has prevented the need to partially demolish three houses by using a water jet to remove concrete from a sewer pipe.

The ultra-high pressure (UHP) jetting system, which powers the water jet to over the speed of sound, was deployed after the foundation concrete in the pipe proved too tough for conventional robotic cutting.

The only practical alternative would have been to excavate and replace the pipe, buried three metres beneath extensions built behind the row of nine terraces homes in Ilford, north east London.

That would have involved the extensions for three of the homes being all but demolished, then reinstated, with the occupants placed in temporary accommodation while the work was done.

Lanes carried out the UHP jetting project on behalf of Thames Water and has now used the technique to complete other challenging concrete removal projects for the water company.

Lanes Operations Manager Calvin May said: “This was one of the toughest concrete removal projects we’ve ever tackled, and involved contamination of a 150mm-diameter sewer.

“We believe the concrete may have been linked to a nearby building project. Foundation concrete is particularly hard and, in this case, had time to set solid, completely filling the pipe for 11 metres.

“We didn’t make very fast headway with a robotic cutter, which works by grinding down the concrete, so we needed a different approach.

“UHP jetting turned out to be a gamechanger. It was over 20 times as fast as using robotic cutting and prevented the need for an alternative solution that would’ve been much more costly and disruptive.”

It meant the concrete could be removed in 15 shifts, equivalent to three weeks’ work.

Lanes, Thames Water’s wastewater network services maintenance partner, developed a business case for using UHP jetting to ensure it would work and be cost-effective.

This led to the initial hiring of a UHP jetting system to ensure the concrete removal process was effective – not least because a tanker was having to visit the site every day to remove sewage building up behind the blockage.

Lanes selected a Falch UHP pump combined with an IMS Robotics jetting system, capable of delivering a water jet at 2,500 bar (over 36,000 pounds per square inch).

Six Lanes wastewater operatives underwent Water Jetting Association hydrodemolition training and equipment supplier instruction to give them the knowledge and skills needed to operate the system.

The UHP jetting system has a jetting nozzle on the end of a hose encased in a flexible steel coil sheath. Once guided into the pipe, a packer is inflated with compressed air to hold the nozzle firmly in place inside the pipe.

A mini camera and powerful LED lights allowed the Lanes operative to then view the jetting operation, while controlling the nozzle with a joystick to direct it most effectively at the concrete.

The concrete was removed in one-metre sections, with the exposed pipe strengthened by installing a cured in place pipe (CIPP) point liner made from fiberglass matting, impregnated with resin.

Once the resin had cured, the liner created a durable new concrete-free pipe within a pipe, with a design life of at least 50 years.

Lanes Group: www.lanesfordrains.co.uk