Water & Wastewater Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/1062770
14 | JANUARY 2019 | WWT | www.wwtonline.co.uk The Works: Resilience • GETTING A MEASURE OF RESILIENCE W ith the new direction on resilience still at a formative stage, Ofwat outlined a "clear expectation" that companies implement their own forward- looking metrics on the issue as part of their PR19 business plans, with a brief that they should "focus on what matters to customers". In June 2017, United Utilities and global design and consultancy firm Arcadis published a report detailing a new metric that could assess resilience levels in a consistent manner, identifying areas of weakness and targets for improvement, and ultimately quantify the state of a company's system by 'households at risk'. The metric in the initial report focused on the resilience of water supply from treatment works, but it was designed to be adaptable to other single points of failure, such as aqueducts, trunk mains, service reservoirs and pumping stations. It encourages proactive interventions on the '4Rs of resilience' – resistance, reliability, redundancy, and response and recovery – which are lined up against four resilience risk assessments: the likelihood of hazards, vulnerability to those hazards, scale of impact and duration of impact. "The nature of resilience risks has changed and it's no longer about using traditional risk management tools to understand resilience," Olu EriOlu, UK risk and resilience lead at Arcadis, says. "We've developed a consequence-led methodology focusing on the impacts of resilience risks. It recognises that shocks can happen at any time because of our very complex and much more connected world, and that means that, when small events happen, the impacts will be greater." United Utilities had initially sought to develop the metric a"er determining that the performance commitments put forward by Ofwat were unable to fully assess certain aspects of resilience, in particular system resilience and single points of failure. "It came off the back of some of the incidents that we have had and the feeling that the metrics that were being put forward didn't really adequately cover those issues," Simon Boyland, head of asset systems and planning at United Utilities, says. "The failure of a single treatment works, or a number of treatment works, during an event like Storm Desmond for example – that's when our customers really notice an impact on their service." To make it applicable for wider use, it was designed to make risk assessments consistent between companies through a series of questions that would minimise individual interpretations of risk probabilities. "In theory it could be used to compare companies' levels of system resilience and ultimately potentially lead to targets being set across the industry to a minimum standard, or for Ofwat to put pressure on those companies that aren't delivering that level of resilience to customers," Boyland says. "It came a bit late in the day to be included as a mandatory measure for PR19, but we've developed it further and used it as a water service resilience metric in our plan to look at improving the resilience of the North West for PR19. There's a number of treatment works where we are building additional resilience in AMP7." The metric has since been utilised by other water companies and adapted to cover further single points of failure, while Southern Water has worked with Arcadis to adapt it to build in an understanding of wastewater. Using the resilience assessment methodology as the basis, Southern and Arcadis also worked in collaboration with infrastructure planning so"ware provider Optimatics to develop a pilot for a platform that could improve resilience through better informed strategic investment decisions. Optimatics' Optimizer so"ware is being used to assess the optimal mix of asset options for Southern Water's supply network, evaluating a series of inputs – business risks, cost of assets and network hydraulic performance – and then presenting an array of choices for the company to select from. "We were aiming to determine what the ideal balance between cost, performance and resilience looked like," Dr Bojana Jankovic-Nisic, Arcadis' digital lead for water engineering, says. "Planning and investment processes are generally manual, iterative exercises, so a plan is normally derived from a limited number of options and then the final one chosen based on what appears to be the best. "The Optimizer uses genetic algorithms to simulate hundreds of thousands of future water asset investment scenarios and then provides the most efficient set of options for you to look at further." The aim is that Southern will ultimately emerge with a financially optimised resilient plan that fits with its preferred approach. A visualisation of resilience (Arcadis)