Innovative Solutions for Reducing Flooding in Sewer Systems
Advanced Flood Modelling: A UK Utility’s Success Story
Project facts
- ClientA private water utility company
- LocationUnited Kingdom
- ChallengeReducing sewer flooding and demonstrating regulatory compliance
- SolutionReducing sewer flooding and demonstrating regulatory compliance
- ImpactEnhanced sewer systems, improved customer service and strengthened regulatory compliance.
Sewer flooding is when sewage or foul water leaks from the sewerage system (through pipes, drains or manholes) or floods up through toilets, sinks or showers inside a building. According to the performance data for water and sewerage companies in England and Wales on Discover Water, in 2022-23: 47,176 areas were externally flooded by sewage; and 4,794 properties were internally flooded by sewage.
The challenge
A private utility company responsible for wastewater collection and treatment across several UK counties, as well as water supply and distribution in part of this area, faced a significant challenge: reducing sewer flooding. This task required advanced technical analysis and innovative solutions to better serve customers at risk of flooding and demonstrate proactive measures to authorities, ensuring compliance with performance expectations and regulations.To address this, the company embarked on a two-year flood reduction project, making substantial investments to mitigate sewer flooding inside properties and prevent future occurrences.
The solution
The utility company partnered with Twinn (formerly Ambiental), leveraging their expertise in GIS and flood modelling. Twinn’s team of GIS specialists conducted a comprehensive analysis of the company’s entire network using advanced flood modelling software. This process, known as integrated modelling, involves simulating water movement within sub-surface drains and sewers, alongside rainfall inputs and surcharge flooding on the ground surface.The project required high-resolution modelling at a 2m scale, presenting a significant challenge due to the hundreds of thousands of simulations needed. Twinn’s sophisticated data management and automation capabilities were crucial in handling this complex task efficiently and accurately.
From left to right: image 1 - example of sewer flooding depths for a 50-year storm event; image 2 - example of sewer flooding velocities for a 50-year flood event; image 3 - example of flood hazard for a 50-year storm event, classifying the risk posed to people by specific flood conditions calculated from depth, velocity and debris information.
Our sewer models now offer an all-round improvement in accuracy and precision, shifting from general assumptions to identifying specific properties at risk during flooding return periods.
The impact
The project delivered two key outcomes:
- Precise Risk Identification: Twinn’s modelling provided a detailed understanding of which roads and properties were at risk of surcharging sewer flooding. This high-resolution data allowed the utility company to prioritise future improvements effectively.
- Enhanced Reporting and Compliance: The precise risk assessments enabled the company to present accurate measurements of improvement to customers and regulators, down to specific addresses. This marked a significant advancement from previous generalized risk estimates, offering a more transparent and reliable view of flood risk management.
By partnering with Twinn, the utility company not only improved its sewer systems but also strengthened its commitment to customer service and regulatory compliance.
