Water companies across the world unite with a vision to cut carbon by 1m tonnes

Aarhus Vand (Denmark), Melbourne Water (Australia), and Severn Trent (UK) form a partnership to advance the future of environmentally friendly wastewater treatment. Partners will collaborate on developing technologies to reduce the carbon footprint of wastewater treatment sites to net-zero, sharing existing expertise, and establishing new international standards for measuring and reporting emissions.

A pioneering global collaboration of three major water companies is to be launched at the forthcoming World Water Congress & Exhibition in Copenhagen, setting out a mission to forge the next generation of sustainable wastewater management for customers, while reducing carbon emissions to net-zero by 2030.

Danish company Aarhus Vand, Australian water corporation Melbourne Water, and the UK’s Severn Trent, will join forces to co-create the development of technologies and innovations to make wastewater treatment greener, and begin to establish new international standards for measuring and reporting emissions, as the industry looks towards a carbon neutral future.

Together, the three companies have committed to work together to reduce their carbon emissions by around a million tonnes and aim to lead the green transformation of the sector. Through this worldleading collaboration the partners will build upon their experience, expertise, and innovation capacities on key complementary projects such as:

  • Transforming one of Severn Trent’s sewage treatment facilities in the UK into a Net Zero hub, dedicated to researching and testing the latest carbon neutral wastewater treatment technologies at an industrial scale.
  • Developing new techniques to measure and record nitrous oxide and methane releases from wastewater treatment sites, and establishing new, more accurate, international measurement standards based on this.
  • Identifying ways to enhance current wastewater treatment sites with green technology that optimises the performance and efficiency of facilities while reducing emissions to net zero.
  • Maximising the use of renewable, sustainable resources at treatment facilities.
  • Gathering and sharing information on the technical and economic feasibility of options to reduce emissions, creating a roadmap for the industry to achieve net zero most efficiently, at the best value for customers.
  • Exploring the potential for employment secondments between the three companies, so that talent and expertise can be shared and developed around the partnership and across the world - providing wellrounded international professional development and enabling the exchange of fresh ideas.

CSO Claus Homann, Aarhus Vand said:

“Aarhus Vand's purpose is to create health through clean water for people and the planet. The planet has a fever and many people are affected by too little and too much water in the wrong places. As water companies, we can both take local - and contribute to global - initiatives, and it is urgent to create climateneutral solutions.

Together we can create and implement solutions, motivate and challenge each other, but not least succeed faster and minimise risk. By focusing on climate neutrality, the water company of the future will be: energy producing, CO2 and nitrous oxide consuming and part of circular resource systems that make our activities truly sustainable. Radical innovation requires participants with great diversity, different expertise, curious, ambitious and trust-building precisely the characteristics of our partners in the UK and Australia.”

Nerina Di Lorenzo, Managing Director of Melbourne Water commented:

"We are in the decade that matters when the actions we take now will define our future. We must also adapt our operations to prepare for a changing climate which is why we are passionate about this international partnership with Aarhus Vand and Severn Trent.

At Melbourne Water we take a collaborative approach to the way we plan for and manage all elements of the water cycle: from providing clean drinking water, treating sewage so we can recover and re-use our valued resources, planning to prevent flooding, and keeping all 25,000km of Melbourne’s rivers, creeks and catchments healthy.

We are also at the forefront of a shift towards a circular economy, transforming our sewerage system, so we can recover Melbourne’s waste, turning it into water, nutrients and energy for re-use. Partnering with Aarhus Vand and Severn Trent will assist us in achieving this goal.”

Liv Garfield, CEO of Severn Trent said:

“The global water industry needs to come together and act now to take more responsibility for carbon emissions. This international partnership of water companies feels like one of the most exciting and important moment for the sector in decades. We share a vision and mission for the future - our pioneering collaboration will drive forward the net zero agenda, create green solutions for the worldwide industry, and protect our planet.

Together we will test and develop the wastewater treatment technology of tomorrow at industrial scale, enhance the efficiency and sustainability of our existing sites, and help set new standards for how carbon emissions are measured. We are so proud to be leading the way internationally alongside our partners in Australia and Denmark, and at the same time creating a new centre of innovation excellence in our region, which will attract new jobs and green skills to the UK’s Midlands region.”

Severn Trent has begun trials on ground-breaking technologies that monitor, capture, and break down nitrous oxide - the water industry’s most potent greenhouse gas — using the power of sunlight. Severn Trent will also progress the use of artificial intelligence and machine learning to optimise its treatment works, reducing emissions, chemicals, and power usage.

Melbourne Water has commenced a range of site-specific emission measurement initiatives to provide increased transparency of actual emissions and identify opportunities to reduce them. Sharing this knowhow across the industry will enable more utilities to better understand and reduce their emissions. Melbourne Water is also investigating how its wastewater treatment plants can be transformed to incorporate low emissions treatment technologies.

Aarhus Vand is currently developing a new sustainable sludge handling process, ‘digital twin’ technology (which uses simulation and machine learning to find the most optimal green processes), and Aarhus ReWater - a learning plan to determine where best to replace treatment technology with better, newer solutions.

Individually, the partners are already industry leaders in the field of environmental sustainability and renewable resources.

Severn Trent has invested in a Resource Recovery and Innovation Centre which explores technologies to reduce and remove emissions - including Europe’s largest anaerobic treatment process that uses less air and energy and has less embedded carbon. The UK company is also using drones to detect methane as part of sector-leading trials to measure process emissions.

Melbourne Water has a long history of onsite renewable electricity generation, including harnessing biogas from our wastewater treatment plants, the power of water and gravity via mini-hydro throughout our water supply network and the Australian sun via the commissioning of two large scale solar facilities. This combined with procurement of renewable electricity will support Melbourne Water being 100% renewable by 2025.

Aarhus Vand already focuses on turning wastewater into green energy, creating liveable cities through climate adaption, and the active reduction of nitrous oxide and methane emissions.

Aarhus Vand enters into close cooperation with Portuguese water company

Aarhus Vand has just signed a cooperation agreement with the Portuguese water company Águas do Tejo Atlântico. The collaboration must support the development and dissemination of sustainable solutions in the water area through knowledge sharing, training and exchange of employees.

From left Ambassador Maria Nilaus Tarp, Alexandra Serra, Director of Águas do Tejo Atlântico, and Claus Homann, COO of Aarhus Vand.

Published on March 29, 2022.

Back in 2017, Aarhus Vand signed a cooperation agreement with Águas de Portugal, the public umbrella organization for the water sector in Portugal. Aarhus Vand has now expanded its Portuguese cooperation with the signing of an agreement with the largest Portuguese wastewater company Águas do Tejo Atlântico, which serves 23 municipalities on the west coast, including Lisbon.

Águas do Tejo Atlântico are experts in digitization and reuse of water and are ambitious in terms of energy optimization and energy production. The company produces 18,000 MWh of energy per year from the wastewater from the 2.4 million inhabitants of the region. Aarhus Vand are experts in energy optimization and energy production at wastewater treatment plants and have also specialized in the utilization of other resources in the wastewater, such as struvite, which is a nutritious fertilizer product.

Claus Homann, COO of Aarhus Vand, signed the agreement on behalf of Aarhus Vand on 24 March with Alexandra Serra, director of Águas do Tejo Atlântico, at a ceremony at the Danish Embassy in Lisbon with the participation of Ambassador Maria Nilaus Tarp. Claus Homann says about the purpose of the agreement:

"We both have many activities internationally, and the purpose is to bring our common knowledge about sustainable water management out into the world and thus contribute actively to the UN's development goals. Together we will stand stronger internationally. Aarhus Vand's vision is that together with Águas do Tejo Atlântico we can develop solutions where we utilize resources in the wastewater to a degree not seen before. This must be done through knowledge sharing between the partners and through training and exchange of employees with special competencies. We must challenge each other and create joint innovation projects - preferably with EU support - which have great and long-term significance for both companies.”

The signing of the cooperation agreement was part of a multi-day event in Lisbon with a number of professional presentations and workshops from i.a. Per Overgaard Pedersen, Aarhus Vand, and Catia Martinho, Juan Vera and Laura Baillón from the global water alliance WTA EU, which the Danish Trade Council is behind.

Aarhus Rewater: Digitally mapping the resource recovery plant of the future

The Aarhus Rewater project will see a wastewater treatment plant developed near Marselisborg in Denmark. Once completed in 2028, this plant will not only include the world’s most advanced water treatment technologies, but also a technology development pathway that will keep us at the forefront of water treatment tech. To ensure both an economically and environmentally optimised wastewater infrastructure for the future, we are putting digital technology at the heart of its operation.

Published 22 October 2020

In the article 'Aarhus Rewater: Digitally mapping the resource recovery plant of the future' published by AquaTech chief digital information officer for Aarhus Vand, Jesper Kjelds, says that Aarhus ReWater, to his knowledge, is the most ambitious wastewater treatment plant. "But we’d rather call it resource recovery plant,” says Kjelds.

Read the article here.

Take It From The Top Series With… Claus Homann

Listen to Claus Homann, Aarhus Vand, discuss how the utility has shifted to activity based working, an approach that provides different physical work spaces that align with types of work, and how he envisions workplaces will change post-pandemic.

Published 22 October 2020

In this episode of 'Words of Water' - a podcast featuring conversations with influential and interesting people from the water sector - Claus Homann, Chief Operating Officer for Aarhus Vand, talks about the central place of water in the city of Aarhus and how that has resulted in clean water, a higher quality of life, and economic benefits.

He explains how Aarhus Vand as a water utility has shifted to activity based working, an approach that provides a variety of different physical work spaces that align with the type of work. Claus Homann also discusses how he envisions the workplace will change post-pandemic, including continuation of flexible work schedules and locations and use of technology to bring people together.

Listen to the podcast here (30 min.).

Claus Homann is a past member of the Board of Trustees for the Water Environment Federation (WEF).

Aarhus Vand goes all in on the UN's Global Goals

Aarhus Vand is taking sustainability to the next step and becomes the first water company in the world to be certified according to the UN’s Global Goals for Sustainable Development.

Lars Schrøder, CEO Aarhus Vand

Published 8 September 2020

Marselisborg Wastewater Treatment Plant - owned and operated by Aarhus Vand - is among the world's most sustainable wastewater treatment plants. Once a huge energy guzzler, the plant is now producing twice as much energy as is required to clean the wastewater from the city of Aarhus. This energy is returned to the consumers as green electricity and heating.

Aarhus Vand also extracts phosphorus from the wastewater, which is sold and used as a recycled fertiliser. In addition to producing drinking water and handling wastewater, the water company also focusses on groundwater protection, improvement of the aquatic environment and a wide range of climate adaptation projects in the municipality. Sustainability and circular economy play a major role in everything they do, and the company has an ambition to be completely energy and CO2-neutral by 2030.

Measured and weighed on sustainability efforts

This ambition requires intense focus on sustainability throughout the company and the entire production chain. This is why Aarhus Vand goes the whole length and becomes the first water company in the world to be certified according to the UN’s Goals for Sustainable Development. This means that the company will be measured and weighed on its sustainability efforts.

Aarhus Vand must prove that the UN's global goals are met in a number of areas that are central to its operation. This includes the SDGs 6 – Clean water and sanitation, 11 – Sustainable cities and communities, 13 – Climate action and 17 – Partnerships for the goals.

Requires action and continuous follow-up

For each of these four global goals, Aarhus Vand has set a number of milestones, all of which require action and continuous follow-up. Norwegian Veritas has been trawling the length and breadth of the organisation in search of evidence that Aarhus Vand means business. The result: a certification, which CEO of Aarhus Vand, Lars Schrøder, is very proud of:

“This certification means a lot to us. It shows that we work hard for the environment and want Aarhus to become an attractive municipality to live in. It’s proof we’re doing well in terms of the UN's global goals, and our ambition is to do even better. At the same time, it’s a quality stamp which will help attract new employees and partners. It’s also important to our international commitment, because the global goals have indeed been placed on the global agenda.”

Sustainability and the circular economy are important parameters in future projects

Lars Schrøder points out that the certification means that Aarhus Vand will demand of its partners and suppliers that they also work actively towards observing the UN's global goals and contribute to sustainable development. This means that sustainability and the circular economy are important parameters in the projects facing Aarhus Vand such as the establishment of a new domicile and Aarhus Rewater, which will replace Marselisborg Wastewater Treatment Plant in 2028.

Utilizing the Potential of Wastewater: From Energy Consumer to Energy Producer

Aarhus Vand have been working strategically to develop energy neutral utilities for decades. It all started with a challenge to save energy and become more efficient, and now, after years of continuous work, we're able to announce, that already now the GHG emissions are 77% lower than in 2008.

Published 24 July 2020

Read more about ours and our colleagues efforts to achieve energy neutral utilities in the article 'Utilizing the Potential of Wastewater: From Energy Consumer to Energy Producer' written by Frederikke Roervang Mikkelsen and Jens Enevoldsen.  

Cost-efficient capacity expansion of Viby wastewater treatment plant

Aarhus Vand had planned to increase the capacity of Viby wastewater treatment plant in order to ensure stable and efficient treatment performance. Due to the WWTP’s expected short lifetime (10–15 years), a cost-efficient capacity expansion should be achieved with minimum infrastructure interventions.The proposed solution is now implemented in full-scale operation at the WWTP with considerable improvements in operational stability.

Published 24 July 2020

In partnership with NIRAS, TechRas Miljø, EssDe and DHI we now have a solution relying on the optimisation of existing processes to achieve the desired increased capacity while minimising capital expenditures.

The result is:

  • 33% capacity expansion achieved through process optimisation and minimum infrastructure changes
  • Improved process stability under high influent loading conditions
  • Less than EUR 2 million invested in implementation of the capacity expansion

Flemming B. Møller, Project Manager at Aarhus Vand, says:

"The expansion of Viby WWTP during 2019-2020 has ensured improvements in effluent quality during peak loads and in the sludge quality. These outcomes have been achieved through a very constructive collaboration between the partners who provided the right solutions to achieve the desired end result."

Henning Larsen to design the world's most efficient wastewater treatment plant

The architectural firm Henning Larsen has been selected by Aarhus Vand to design Aarhus Rewater, a cutting-edge wastewater treatment plant and urban landmark. Henning Larsen, along with team members Klinges Tegnestue, Topotek 1, and artist Eva Koch, will lead the project.

Published 18 June 2020

The plant, which will replace the existing Marselisborg facility in 2028, will be a state-of-the-art treatment center and stand as a stunning landmark on the Aarhus harbor front. In just a few years, the existing plant will no longer have the capacity to purify the wastewater from the rapidly increasing population of Aarhus. With little room available to expand the existing facility, Aarhus Rewater is to be built with a new location in the area.

The selection was determined based largely on the strong strategy and vision for the development of the area in which the plant will be located. The agreement with Aarhus Vand means that Henning Larsen will prepare a master plan for the area, design the plant, make design manuals and incorporate the interaction between the plant, the city, the water and the surroundings. The architectural firm must ensure that the plant opens as far as possible to the surroundings and tells the story of water. And with a modular structure, the plant must be able to evolve in line with new needs - both in terms of technological development and capacity.

Upon completion, it is expected to be the world's most sustainable and innovative wastewater treatment plant, which, in addition to purifying wastewater, will produce surplus energy and utilize the resources in the wastewater to an extent not seen elsewhere. In the future, for example, it will be possible to produce nutrients, proteins, foods, chemicals and basic substances for the wastewater industry.

Signe Kongebro, a partner in Henning Larsen and responsible for the project, says about the project:

"We are very excited about the project, which we believe can express and shape possible solutions to some of our time's most pressing issues of community and urban planning in a sustainable world."

Signe Kongebro predicts that the facility will become as popular a destination in the city as the new Moesgaard Museum, which Henning Larsen also designed. She says:

"Aarhus ReWater will be a recreational destination in the city, where locals and visitors can gather about the water and learn about its social value and great importance for our common future."

Lars Schrøder, CEO of Aarhus Vand, agrees:

“I am sure that Aarhus Rewater with a unique architecture and with its location close to the city and the sea will be a beautiful landmark for all that we can in Aarhus in the water area. It becomes much more than a technical plant. Our ambition is to become a place of excursion that forms a hinge between the city and the port, and where you can see the city from a different angle and gain insight into the world of water and in an industry that many find exciting.”

Achieving 150% energy self-sufficiency at Marselisborg Wastewater Treatment Plant

Our biggest wastewater treatment plant Marselisborg WWTP produced 30% more electricity than the amount consumed by the plant itself as average between 2015-2019. At the same time the treatment plant produced 75% more heat than it consumed, resulting in a total net energy production of 150%.

Published 18 June 2020

Over the past five years, Aarhus Vand has put great focus on energy savings and energy production. At Marselisborg WWTP, we have implemented energy-saving technologies such as an advanced SCADA control system, a new turbo compressor, sludge liquor treatment based on the anammox process, as well as optimised the fine bubble aeration system.

This has resulted in a reduction in power consumption of approximately 1GWh/year which corresponds to about 25% in total savings. During the same time period, the energy production has been improved through implementation of new energy efficient biogas engines (CHP), resulting in an increase in electricity production of approximately 1 GWh/year. Furthermore, a new heat exchanger has been installed with the aim of selling surplus heat to the district heating grid, which represents approx. 2 GWh/year.

Between 2015 and 2019, Marselisborg WWTP had an average total energy production of 9,6 MWh/year and an energy consumption of 6,4 MWh/year, equivalent to a net energy production of 150%. Most of the installed technologies have a payback time of less than 5 years.

Rainwater for washing machines and toilets cut water consumption by 40 percent

Up to 10,000 households’ washing machines and toilets will soon use rainwater instead of drinking water in the Aarhus area. This is estimated to cut water consumption by as much as 40 percent.

Published 27 May 2020

Water resources worldwide are under strain. New solutions need to be tested and implemented to ensure that the next generation has better access to water. However, in the developed world water is being consumed indiscriminately. Therefore, in the newly constructed district Nye, which is a suburb of Aarhus, rainwater will be used for toilet flushing and laundry. Up to 10,000 homes are planned to be built in the new district.

Most commonly in the developed world, we are washing our clothes and flushing our toilets with clean drinking water. However, using rainwater instead could cut drinking water consumption by as much as 40 percent. It can also create a clear division between the essential drinking water and water used in everyday chores.

Purple pipes, an artificial lake and UV-disinfection

The solution is developed by Aarhus Vand in collaboration with Tækker, COWI, and Silhorko. The solution could be a vital part in the development of new sustainable districts throughout the world.

“We take the rainwater, which is collected in a lake that we have built, and clean it at the treatment plant. The treatment is done by a special ultrafilter and ultraviolet disinfection system, among other methods. We then send the water out into the homes via a separate pipe system we have developed for this purpose. The pipes are sized based on a calculation of the need for water for laundry and toilet flushing, and they are colored purple so that they are clearly different from the drinking water pipes. This will minimise the risk of malfunctioning,” explains Mariann Brun, Project Manager at Aarhus Vand.

The solution will also work in case of droughts. When there is insufficient rainwater available, the water supply is supplemented with wastewater from drains, which is also treated at the treatment plant. The entire infrastructure to direct the purified rainwater out to the residents of Nye has already been established. The purification plant itself is ready by the end of 2020.

Extreme rainfall and flood proof district

In addition to handling everyday rainfall, the district also deals with a rising threat of extreme rainfall due to climate change. Roads and paths are constructed to function as waterways, which should reduce the need for larger sewage pipes or delay pools during heavy rain.

“By using roads, paths and green areas to direct the water where it does the least damage, we handle extreme rain intelligently. We must not rely solely on laying pipes to alleviate extreme rain,” says Carsten Fjordback, Development Director at Cowi.

For example, roads direct the water to ball courts and parking lots designed to handle water in extreme quantities. Thereby, the solution combines water management with livability by using recreational spaces as flood protection.

Water companies develop joint data platform

Aarhus Vand and VandCenter Syd are developing a joint data platform together with software company Systematic. The platform will be used to gather data from across the water sector and to pave the way for the further development of a digital water sector.

Published 20 April 2020

Danish water companies collect and use huge volumes of data as part of their daily operations involving water supply, wastewater treatment and climate adaptation, and the volume of this data will see explosive growth in future. One of the biggest challenges for the water companies, however, is that the data is spread across various data islands, which makes it difficult to use the data effectively.

Two water companies – Aarhus Vand and VandCenter Syd – have set themselves the task of solving this problem in collaboration with the software company Systematic, and the work is already well under way. The three parties have just concluded a pilot project in which they have looked at how the water companies can join forces on establishing a data platform while at the same time keeping costs and raw data separate where necessary. The next step is to build a strong foundation with joint, documented standards and methods, so that future projects on the platform are run uniformly and efficiently.

Digitalisation paving the way for the development of new solutions

At VandCenter Syd in Odense on Funen, Anders Hansen, head of IT and digitalisation, is looking forward to water companies being able to work actively with data to a much greater extent in order to streamline further:

“The challenges faced by water companies across Denmark include increasing amounts of rain, groundwater pollution and working with the green transition. These are all areas where a joint data platform can play a decisive role and contribute to joint solutions. It will also enable us to create new services and solutions for our customers,” says Anders Hansen.

Jesper Kjelds, CDIO at Aarhus Vand in Jutland, also sees huge potential in making data available and sharable via the platform, which has been named OneWater – Water Informatics Platform.

“We’re continuously working to streamline our processes, and one of the keys to this is increased digitalisation. A joint data platform gives us the opportunity to easily access, share and process data, which can provide us with a data-based decision-making platform for e.g. servicing, maintaining and replacing our facilities. This will help us to cut costs and increase productivity,” he says.

Shared and open data creates value for more players

Cooperating with new parties is important for both Aarhus Vand and VandCenter Syd. Finding solutions to complex challenges calls for more knowledge than the two companies currently have at their disposal. Therefore, the idea in the long term is to invite other water companies, private companies, universities and start-ups to come on board the OneWater platform. OneWater is based on open and standardised data, which allows the parties to share the solutions that are being developed with each other. The more data they have to work with, the better the solutions which can be developed for the benefit of both customers and the water sector in Denmark and abroad.

To understand and exploit the potential of digitalisation and using technologies such as emerging artificial intelligence and machine learning, it is necessary to access the requisite experience, knowledge and inspiration. This is where Systematic comes in.

“When you start using data across the water companies, building joint solutions and taking advantage of big data for machine learning, artificial intelligence and everything else, then you are really getting closer towards running an efficient and reliable water and wastewater utility in Denmark. Systematic’s expertise lies, among other things, in collecting and collating data across systems and technologies and using this data to find solutions to complex problems, for example through machine learning and forecasts. We can help the water companies derive value from their data,” says Flemming Thomsen, Group Senior Vice President at Systematic.

Climate adaptation and rainwater management at the surface

Climate change involves more precipitation, more heavy rain and more cloudbursts. In Aarhus and all over Denmark, climate change poses quite distinct challenges in areas connected to a public sewer system.

By: Morten Østergaard Nielsen, Project Manager at Aarhus Vand

Published 3 September 2019


Increasing rainfall means that it will be difficult to meet the service level specified in the wastewater plan and observe the terms and conditions of the discharge authorisation of the wastewater treatment plants. Pipe capacity is already too small in many places, with excess water—a hazardous mixture of wastewater and rainwater—flowing into lakes, streams or the Bay of Aarhus untreated. The excess water also causes flooding of cellars, roads and green areas. In other words, we lack space in our sewer system, and at Aarhus Vand, we are doing something about this—in close cooperation with the municipality of Aarhus.

In Aarhus like in many other municipalities, we are hard at work on separating rainwater and wastewater in areas where this has not already been done. In some of these areas, rainwater is lead through new pipes. In other areas, we handle rainwater at ground level or through a combination of both methods.

In our attempt to adapt our city to climate change and avoid damage to properties or infrastructure following heavy rain, we treat everyday rain and 5-year rain events on the road surface and/or in drains. We do so because there is a potential for separating large areas for the same amount that it would cost to lay pipes. In addition, it offers a unique opportunity to use rainwater in a new way—for embellishment and recreational purposes. We make rainwater a visible element in the form of rainwater lakes, rainwater beds and rainwater drains. We also establish hollows and dams; we create entirely new urban spaces and find new ways to lay out green areas. The municipality of Aarhus has a vision of making Aarhus an even more attractive place to live, and Aarhus Vand should help support this ambition with our climate adaptation projects on the separation of rainwater and wastewater.

In Risvangen, Aarhus, rainwater is handled through a combination of surface handling and pipes.

Whether we choose to lead rainwater through new pipes to a stream or handle it on the terrain, we develop and prepare our sewer system for heavy rain—a direct consequence of climate change. Our choice of solution always depends on the local conditions. Furthermore, we keep measuring our efforts against the risk of flooding and the cost of the damage caused by flooding.

We've done it before

Aarhus Vand has carried out two major climate adaptation projects with rainwater being handled at the surface—one in Lystrup north of Aarhus and one in Risvangen in the northern end of Aarhus. In Lystrup all 12 climate adaptation solutions involved surface treatment. In Risvangen, rainwater is handled in a combination of surface handling and pipes. In both cases, vast resources were spent on citizen dialogue/involvement.

We become visible

At Aarhus Vand, we are faced with a new approach to rainwater treatment. Instead of two covers in the road, we establish visible water beds in the urban space in the form of rain beds, beds along roads, (wadis) and rainwater lakes. This gives rise to new expectations from citizens and landowners. We establish visible green drainage systems in the urban space. Since they are going to last for many years, we want them to add beauty to the urban space. This begs the question of what is beautiful/neat—a question to which there is no objective answer. It entails approaching the citizens who are going to live with these solutions to ask them what they think fits well into their area. This is no easy task. It is like asking people what good art is.

How do we succeed?

In addition to a new type of citizens involvement, this new reality calls for a new way of dealing with the stakeholders whom we often work together with: The road authorities the environmental authorities, road planners, urban planners, road operations, green upkeep, joint councils and homeowner’s associations. All very important stakeholders and key to our success.

In Risvangen, in Aarhus, rainwater is handled through a combination of surface handling and pipes.

Often there are other users who do not live in the area: kindergarten children, schoolchildren and the elderly. They also have to live with the new visible green drainage solutions. Therefore, it is just as important to get them involved and hear what they think. As a utility, we enter into a world in which citizen involvement processes become part of a drainage project.

The project manager will therefore contribute to a citizen process. We call it contributions, because as the manager of the climate adaptation and wastewater plan, it is the municipality of Aarhus who is responsible for carrying this process through. Success depends on close cooperation between municipality and utility. The municipality of Aarhus and the utility will see an increase in the entire information and citizen involvement efforts compared to earlier, and therefore the right resources must be allocated in order to succeed. We must make every effort to establish beautiful green solutions.

The added value of green drainage solutions may be further increased by integrating them with public benches, exercise tools and footpaths. However, this is not something the utility can finance. This is where the homeowners’ association and/or the municipality must pay, or where new sponsors must be found. This way, an active homeowners’ association or local council may prove to be important in ensuring a successful outcome.

Integration of rainwater beds - beds along roads with technical solutions to limit speed - is another example of added value creation. Either in combination with road bumps and/or split roadbeds. This must, of course, take place in close cooperation with the municipal road technicians, who must ultimately approve such projects.

A new reality—new challenges for the utility

Aarhus Vand may be said to be moving into unchartered territory, with the opportunities and risks this entails. We will inevitably make inappropriate solutions and even mistakes. Therefore, we must be prepared to fix the solutions we come up with. This could be in relation to a technical defect, say, a drain that does not works optimally. Where surface handling solutions are concerned, a drop that is merely a few centimetres off at the surface will cause the rainwater not to be led to the intended roadbed.

Citizens may also react to the plantation in which case we may have to make changes to our solutions. If the plantation is not maintained, then what? Do we then lose the support of the citizens?

In the long-term, cultivation and maintenance are very important aspects. What about roadbed plantation, rainwater drains or rainwater lakes? Who will maintain them and how? In Aarhus, the municipality is responsible for the upkeep of plantation, whereas the utility is responsible for the functionality. But what does that mean? Can operations and maintenance become a ticking bomb under the economy?

How do we register the new surface solutions? We know how to register rainwater pools, but what about roadbeds, drains, etc.?

How do we ensure that the laying of a new wearing surface or the establishment of new road bumps do not interfere with intended waterways, thereby obstructing the functionality of e.g. roadbeds or a climate adaptation solution?

What about private roads? And so on. The short answer is that we do not know. Therefore, it is important that we keep documenting the impact and the costs. We must learn along the way and we gladly share our experience with others.

Urban development

Aarhus is rapidly evolving, and the city is growing fast. Every year, 5,000 new citizens move to the municipality. This means an increasing demand for new housing. This demand will be met partly through urban densification, typically with high-rise building in the city centre, and partly through the establishment of new urban areas in the surrounding area with dense/low building. In the latter case, surface solutions may be introduced from the beginning. In Malling, a small town to the south of Aarhus, a new urban area has been planned to the south of the town, with the establishment of a drainage system for rainwater handling (everyday rain, 5-year rain events and cloudburst) based solely on a surface solution. It was the express will of the builder to go along with this solution, the rationale being better economy and the creation of added value to the area. For obvious reasons, citizen involvement has not been part of this project. From the very outset, the purchasers have known that this was about a different type of rain rainwater handling. The homeowners are responsible for the green maintenance whereas Aarhus Vand is responsible for the proper functioning. One of the challenges is whether the landowners manage to take the brunt of operations and maintenance. But if the outcome is successful, the perspective for future new urban areas is great.

Aarhus Vand in favour of surface solutions

There are many challenges to overcome in creating surface solutions in the form of visible drainage systems appearing as green features in the cityscape. At Aarhus Vand, we have taken up the challenge because we believe that handling of rainwater at the surface in the form of green solutions will provide significant added value to the citizens and support the municipality's vision of making the city a more attractive place to live. A good example of this is the Risvang project, where we separated rain and wastewater in a large area for less money compared to a pipe solution. And many of the residents have complimented us on having succeeded in creating great added value which makes it an even more attractive area to live in.