Unlocking the potential of sewerage analytics

Regulatory pressure to prevent sewer flooding and pollution events mean technology will play a bigger role in AMP7 than ever before. Ovarro's Technical Director, Marcus Fowler, reveals some of the advanced planning and analytics tools being applied. 

A lot of emphasis is placed on the importance of tackling leakage in the clean water network, but the UK's ageing sewerage network also poses significant risk to utilities and requires major investment. Blockages are the most common type of failure, but sewer collapses can have more severe consequences and are a problem for smaller clay sewers as well as Victorian brickwork.

The term fatberg has now moved into mainstream use, with sewer blockages caused by mammoth build-ups of fats, oils and grease and sanitary waste and wipes making newspaper headlines. At a local level, the misery and cost caused by blockages includes the flooding of homes and gardens with sewage, and pollution spills into rivers and waterways.

In AMP7 - the water industry's regulatory asset management period 2020-25 - Ofwat's expectations for sewerage focus on five outcome delivery incentives (ODIs) - external sewer flooding, internal sewer flooding, pollution incidents, blockages and sewer collapses. Companies in England and Wales face major penalties for flooding and pollution events on top of the cost of restoring the asset and redressing any damage. 

Typical ODI penalty costs combined with the cost of dealing with an internal flooding event, where the interior of a customer's home is directly affected, run into hundreds of thousands of pounds, and water companies are targeted with a tight score for the maximum number of breaches each year. The good news is that mitigating sewer flood and pollution events plays directly to the regulator's key themes for AMP7 - customer service, resilience, affordability and innovation - and the necessary technologies are already available. 

The squeeze on budgets and higher regulatory accountability than ever before means investment strategies need to be carefully targeted. A risk-based planning approach using probability and consequence models can ensure water utilities are investing cost-effectively.

Data Analytics in the UK Water Industry

Ovarro helped lay this out for the UK water industry as the lead contractor for the development of UKWIR's Common Framework for Capital Maintenance Planning. Investment planning feeds directly into water companies' Drainage & Wastewater Management Plans - the new way for stakeholders to work together to plan for future drainage, wastewater and environmental water quality improvements in England and Wales.

We have worked with 12 utilities on their asset management plans over four price reviews and have developed sewer models based on parameters such as age, diameter, depth, property densities, rain-fall, gradient and local features. Models can be calibrated against historical data, and data projections enable determination of the future risk profile.

The most advanced asset management planning software, like Ovarro's PIONEER, incorporates these models to produce optimal investment plans for future periods and analyse the trade-off between capital and operational expenditure. Utilities can decide how and when to survey, refurbish or replace assets at minimum overall cost, across a single asset group or an entire company network. The same software can be used to plan day-to-day operational activities effectively.

There is also great potential to make the daily management of sewer networks much more efficient through the use of real-time predictive analytics. In a dynamic real-world environment, where serious incidents can emerge rapidly due to storm weather and blockages, tools like Ovarro's Datective WasteSure detect the anomalies that warn of an emerging event. 

WasteSure is an automated online computing system that uses artificial neural networks and fuzzy logic to detect anomalous signals by correlating historical and current data. Rapid anomaly detection means events can be picked up early, averting more serious incidents, reducing customer contacts and avoiding regulatory penalties. 

Roll-out of real-time predictive analytic technologies means that even during extreme weather false alarms are less frequent, potential blockages can be identified earlier and operations teams can prioritise incidents more effectively. 

Being able to home-in rapidly on events is invaluable, but having a complete picture of the network means all assets can be operated at much higher levels of efficiency. 

Ovarro's MISER system can build a model of the physical network and the catchment that can be calibrated against historical data. One of many advantages of this kind of digital twin is that storage opportunities throughout the network can be put to work. By holding back dry weather flow, companies can capitalise on lower electricity tariffs for energy intensive pumping and treatment; maintenance work can also be scheduled more exactly. Under wet weather conditions, storage and other operating options can be used proactively to minimise sewer overflows. 

A further benefit is that the interaction of all components in the network can be modelled historically against the current situation to identify problems and faults. Mass balance checks can be used to test some assumptions, for example, if pump energy use is too high for the head, this might indicate a blockage or pump deterioration; if flow is too high for the size of population, this could indicate groundwater ingress or saline intrusion.

This valuable data - including information about flow, storage, pump operation, energy tariffs and population - can also be used to create 'what if?' scenarios and understand network bottlenecks. By simulating pump operations, problems in the network and ways to improve assets and capacity, engineering teams acquire deeper understanding of the whole system creating multiple opportunities for efficiencies. 

Data analytics has the potential to transform the way the sewerage assets are planned, managed and operated in AMP7 and beyond. By encouraging their teams to explore, trial and deploy the technologies available, water and wastewater companies can improve customer service, drive efficiency and build resilience into their networks.