Utility Week

34 | NOVEMBER 2021 | UTILITY WEEK Analysis Can big data see off CSOs? Stuart Stone talks to Thames, Northumbrian, Wessex and Yorkshire about how they are harnessing data technology to prepare for looming industry-wide targets to end the use of CSOs. C ombined sewer overflows (CSOs) have been subject to increasingly intense public and political scrutiny for more than a year amid greater awareness of their existence and the potentially adverse envi- ronmental impact they have when they are used. Most recently, the Wildlife and Countryside Link (WCL) called for increased investment to be allocated at the next price review to render them obsolete. As reported by Utility Week, the alliance of environmental groups and stakeholders' Blueprint for Water report outlined the need for an effective enforcement regime as the first step in cutting pollution and stressed that a transparent, well-funded monitor- ing system would drive compliance up and pollution down. The group also urged gov- ernment to set a wastewater target in the upcoming Environment Bill to encourage water companies to phase out CSO usage. This news came off the back of a swirl- ing current of scrutiny and opposition that had been in motion for much of the past 12 months. In November 2020, for instance, Surfers Against Sewage demanded legally binding sewage emissions reduction targets and fur- ther transparency from water companies on discharges into rivers and bathing water. Its Water Quality Report identified 2,941 CSO discharge notifications between 1 Octo- ber 2019 and 30 September 2020. Although the number of notifications is falling year on year for most firms, the group said water companies were still "discharging sewage at alarming rates, polluting the environment, and risking our health". In the time since, a public outcry against the use of CSOs led to a private members' bill motioned by Philip Dunne, chair of the Environmental Audit Committee. Although it did not pass, several of its focal points were added to the Environment Bill, including water companies, the Environment Agency (EA) and the environment secretary being required to report on the use of overflows. More recently still, David Black – then interim chief executive of Ofwat – wrote to water and sewerage companies in June 2021 to underline the importance of monitoring storm overflows. He asked industry lead- ers to gather a "full and accurate picture" of performance and stressed the importance of actively considering the environmental impact of CSOs and implementing clear and timely strategy to address shortcomings. With this in mind, Utility Week Innovate asked a number of water companies to pro- vide updates on their CSO performance and policies over the past 12 to 18 months and outline what steps they are taking to protect the environment. The state of play: ongoing work and existing targets The EA has stressed that all overflows must be covered by event duration monitors (EDMs), to track how ošen and for how long they are used, by December 2023. Generally speaking, the water companies that provided updates on their CSO and net- work monitoring progress explained that existing regimes offered more than 95% cov- erage from sensors and EDMs. "We have invested heavily in reducing the impact of our CSOs and are continuing to work on further improvements," James Har- rison, head of wastewater asset management at Yorkshire Water says. "We have increased monitoring significantly, with 96% coverage and reporting in 2020 and an aim of 100% coverage by 2023. "Current monitoring provides 80 million data points and as a business our focus is on the reporting and validation of data to improve data quality, which will continue to improve as understanding of the data improves." James MacLean, technical policy man- ager at Northumbrian Water – whose net- work consists of nearly 30,000km of sewers – explains that the firm is in the midst of upgrading and deploying monitoring devices as it works toward a target of 100% CSO cov- erage in early 2022. "Our strategy since 2005 has been to install sewer level monitors at all our net- work CSOs for pollution prevention and operational reasons," he explains. "They are typically battery-operated monitors that communicate daily unless triggered by a warning level." Likewise, Wessex Water – which treats and supplies drinking water to roughly 1.2 million people and provides wastewater ser- vices to 2.5 million – is focused on upgrad- ing its network infrastructure. In fact, Jody Knight, asset technology manager at Wessex, explains that having installed 125 EDMs last year despite the Covid pandemic – 55 more than their target of 70 – the company is on course to provide 100% coverage of EDMs on storm overflows to the environment by March 2023. Fast facts: Northumbrian Water • 600m. The number of data points which have been collected by Northumbrian's monitoring systems since 2012. • 99%. The current level of monitoring cov- erage across Northumbrian's 1,520 CSOs. It is aiming for 100% in early 2022. • £80m. The amount being spent by North- umbrian between 2020-25 to investigate CSOs and reduce their use. Sense-checking monitoring technology Diving further into the technology at the heart of Northumbrian's approach, the firm explains that it is set on implement- ing the latest monitoring devices across its network as well as bolstering early warning capabilities. "Investment also continues in our opera- tional technology programme to replace telemetry equipment with new start-of-the- art technology with increased functionality and data availability," MacLean says. "This also includes increased visibility of wastewa- ter assets on our eSCADA telemetry system and new low-cost monitoring of sewers near to watercourses." What's more, off the back of a data hack led by Microsoš at its 2020 Digital Innovation Festival discussing how sewer-level monitor- ing data can help tackle environmental chal- lenges, delegates at Northumbrian's first

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