Researchers from the College of Engineering and Informatics at NUI Galway and the Galway-based civil engineering construction contractor Ward and Burke Construction Ltd, have completed a major sewer infrastructure project to tackle ongoing environmental issues associated with combined sewer overflows (CSOs).
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Scaled model of the combined sewer overflow interception structure at the NUI Galway Hydraulics and Aerodynamics Laboratory, College of Engineering and Informatics, NUI Galway. Photo: NUI Galway[/caption]
The partnership scooped the Technical Innovation of the Year Award at the Engineers Ireland Excellence Awards in late 2018.
The academic-industry partnership was established to design and validate novel structures to alleviate wastewater discharges from combined sewer overflows which is a major source of pollution in rivers and estuaries in Ireland and abroad.
This involved the design and build of a major new state-of-the-art model testing facility at NUI Galway, spanning the entire length of the laboratory, which is one of the largest in the country.
One of their super sewer designs is currently well under way on the Thames in London and is expected to reduce the overall project costs by about €3.4 million and project delivery time by 25 per cent. (Video of scaled model of combined sewer overflow structure at NUI Galway here: https://www.youtube.com/watch?v=GTH-Xe0171o&feature=youtu.be).
Environmental concerns
With populations set to grow by 30 per cent in the next 30 years and climate change resulting in warmer temperatures, more frequent rainfall events and sea level rise, challenges in the water and wastewater engineering sector are greater than ever.
Larger populations mean more water usage resulting in larger volumes of wastewater to treat, which in turn means greater costs for wastewater transport, storage and treatment.
In addition, increased surface water run-off from the development of new housing and urban areas is being further augmented by climate change impacts of more frequent and intense rainfall and flooding events.
Sandwiched between such irrepressible pressures is an already stressed and ageing water and wastewater infrastructure which is calling for innovative measures, leading-edge design and interdisciplinary collaborations between engineers in the field and engineers in research institutes to establish a climate resilient future for our infrastructure and economies.
A 150-year-old technology
One of the most pressing environmental concerns for existing wastewater collection systems is their pollution of receiving waterbodies such as rivers and estuaries.
One of the chief contributors to this problem is the combined sewer system, a 150-year-old technology which was designed to collect and convey both rain water and raw sewage in one pipe.
As these pipe systems fill with rain water running off houses and street pavements, these old systems tend to fill quickly and overflow to natural water bodies before reaching treatment plants.
In years gone by, this approach was efficient and perhaps even acceptable. However, with ageing infrastructure not designed to cope with the stresses of modern day urban activity, natural watercourses are more frequently experiencing the discharge of raw wastewater from combined sewer overflows after only short spells of rain.
Combined sewer overflows are considered by Patrick Decker (CEO of Xylem) to be one of the three major pain points currently in the water industry.
Combined sewer overflow structures
The solution to this problem is to build so-called combined sewer overflow interception structures. The interception structure functions by capturing the wastewater before it discharges from a combined sewer overflow to the environment and redirects it to a wastewater treatment plant often via deep tunnel conveyance systems.
Due to the complex patterns of urban growth combined with existing river systems, no interception structure site is the same and they therefore often require innovative design approaches.
Sean Mulligan, project manager and co-principal investigator from NUI Galway, said: “Unseen to the eyes of the public, raw sewage overflows occur continuously throughout the year.
"For example, 32 million tonnes of wastewater is released to the River Thames in London, while in the US, three billion tonnes of wastewater is released to rivers through combined sewer overflows annually.
"The effect is continuous significant damage to a river or estuary’s health, not to mention implications to public wellbeing. Given the ageing condition of these old sewer systems coupled with more stringent discharge regulation, the only solution is to intercept the overflows before discharge to the river and convey them to a treatment plant for cleaning.
'Massive impact on our day-to-day lives'
"The research on these structures that our team has undertaken at NUI Galway has a massive impact on our day-to-day lives, that’s what makes it very interesting, challenging and worthwhile.”
Michael Ward, director of Ward and Burke and a former NUI Galway graduate, said: “Civil engineering is an art and a science, contractors build infrastructure and train young engineers in the process, universities educate them, collaboration between the practitioners and academics is very productive for both parties.
"In the long run there is a residual when future students use the apparatus. Great engineers don’t stop learning in practice and smart construction continues to learn first and lasting principals.”
Colin O’Neill, a part-time master’s student at NUI Galway and design engineer at Ward and Burke Construction provided an essential link between academia and industry for this project being involved extensively in the model build and testing.
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Dr Sean Mulligan, NUI Galway, receives the Technical Innovation of the Year Award from Geraldine Larkin, CEO of NSAI, pictured with Stephen Nash from the College of Engineering and Informatics, NUI Galway, Colin O'Neill, NUI Galway master's student and Ward and Burke design engineer, and members from Ward and Burke Construction Ltd at the Engineers Ireland Excellence Awards 2018.[/caption]
He said: “Having an appreciation of the challenges involved in the construction of heavy civil projects from working in the industry, coupled with the skills I learnt from my master's, was essential for me to work on a research project such as this and help bridge the gap between the industry and research.”
With a growing economy and the growing emergence of the ‘smart city’ concept, it is more important than ever to bridge the gap that has developed between laboratory research and engineering in the field. Collaborations such as this between academia and industry are crucial to solving engineering challenges.
Eoghan Clifford, co-principal investigator of the project and senior lecturer at NUI Galway said: “This project and indeed, the success at the Engineers Ireland Excellence Awards, shows the need for novel solutions for challenges facing the water sector.
"In particular, with challenges such as climate change and demographics putting pressure on infrastructure, NUI Galway is delighted to work with innovative Irish companies such as Ward and Burke to design and test solutions to large infrastructural projects.
'Sustainable and cost-effective engineering solutions'
"The development of this large-scale model shows the way forward for how new, sustainable and cost-effective engineering solutions can be developed and tested against various scenarios that may occur in 50 to 100 years’ time.”
NUI Galway lecturer and co-principal investigator, Stephen Nash, added: “The project highlights the importance of having world-class laboratories and researchers.
"The expertise of our research group and technical support staff and space afforded by our hydraulics lab has led to a number of collaborations with engineering companies like Ward and Burke to assess new technology or test engineering solutions.
"This type of work helps NUI Galway to provide a first-class teaching experience to its students where they can learn from the real engineering projects that our staff are heavily engaged in.”