TECHNICAL FEATURES


Håbo Municipality water utility Bålsta, Sweden


Digital trial reduces I&I wastewater costs


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


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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.


| October 2024 | www.draintraderltd.com


Sara Frid, water and wastewater strategist, Håbo Municipality


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


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