South West Water
South West Water provides water and sewerage services across the south west of the UK, in Devon, Cornwall and parts of Dorset and Somerset. Two million residents and eight million tourists rely on them to deliver a safe and clean water supply and keep the region’s beaches and sewerage systems in line with stringent UK and European Union standards. Their assets include 29 water treatment works, 645 wastewater treatment works, 1,001 combined sewer overflows, 1,111 water and sewage pumping stations, 15,000 km of water mains and 14,000 km of sewers.
South West Water are utilising AIM for their extensive above-ground assets, water treatment works, sewage treatment works, pumping stations, and reservoirs, to inform the level of investment required to maintain and improve water quality, minimise and prevent taste, odour and discolouration and ensure wastewater leaving treatment works is no threat to the environment.
The challenge the UK water regulator Ofwat put to all water and wastewater companies was to understand their
customers’ needs and wants and reflect these in their business plans.
SWW was one of two UK water companies fast-tracked by OFWAT through its 2014 price review for the next regulatory period. Ofwat Chief Regulation Officer Sonia Brown said: “The plans submitted by South West Water and Affinity Water stand out. These companies have achieved plans of particularly high quality, with a consistent focus on listening and responding to what their customers want.”
Equipment failure models were developed for all equipment items and were validated and calibrated using engineering knowledge to ensure that the predicted results
were credible and intuitive to the business.
To appreciate the relative importance of equipment failures, the business needed to understand how they ultimately impact upon the service delivered to customers and other stakeholders. To do this required an understanding of how equipment items perform together as a system and how equipment failures impact upon the availability of the process within which they operate (e.g. levels of redundancy). Reliability block diagrams (RBDs) were built for each process in order to achieve this.
The unavailability of different processes can impact upon different types of service and to differing extents. Service impact modelling provided an elicited, rules-based approach for articulating the service impacts associated which the unavailability of each process type, i.e. likelihood and size of the service impact.
In calculating the type and extent of the service impact associated with the unavailability of a process, the time to restore the process to working order, the time it would take to experience a service failure and the availability of an alternative to the unavailable process were all taken into consideration.
South West Water talked extensively to their customers to ascertain what levels of service really mattered to them.
Results from these surveys were then used as risk nodes within AIM, where each risk node represents a service that an asset provides.
To derive costs and benefits of investment the various components, equipment failure, system reliability and service were brought together in an economic model.
This was done using a risk map, where the relationships between the assets, their propensity to fail, the impact of those failures on service, and the cost and value associated with those failures are represented in an intuitive and graphical manner.
AIM provided the basis for understanding how much the asset base would cost to own over a 40 year planning period and how service would change both in terms of dealing on a purely reactive basis and understanding the cost and benefits associated with being proactive in the way the asset base is managed.
Various scenarios were generated to optimize investment to meet multiple customer service requirements and submitted as part of the regulatory investment submission.
The ability to link assets to service to customers in a transparent and repeatable manner resulted in the investment plan being fast-tracked by the regulator. Delivering service for less resulted in more value for customers and shareholders.