Introduction

To promote the efficient use of resources there is a recognised need to make best use of existing infrastructure. Whole Life Costing (WLC) in combination with computational optimisation techniques has been used to satisfy this need. WLC methodologies consider all the costs (private & social) that accrue to initiation, provision, operation, maintenance, servicing and decommissioning, over the useful life of a service facility. Application of WLC to (capital and operational) management of water distribution networks has been based on detailed consideration of holistic performance and explicit linking of costs to their drivers. Decision Modelling links the Costs and Performance frameworks via WLC Scenario Management Software called WiLCO. WiLCO incorporates an optimisation module to find the least Whole Life Cost management solution within the user defined performance/risk/cost scenario. All aspects of performance which impact on costs accruing to any party are considered resulting in the derivation of six integrated performance sub-modules; Leakage, Demand, Structural Performance, Customer Interruptions, Water Quality, Hydraulic Capacity. These sub-modules quantify current and future performance and the effect on performance of interventions, e.g. pipe replacements and changes in operational strategy, at given time horizons.

This two-centre project between the Centre for Water Systems (University of Exeter) and the Pennine Water Group (University of Sheffield) and has been carried out in close collaboration with the water industry. Collaborators included water companies (Yorkshire Water, United Utilities, South West Water, Thames Water, Lyonnaise des Eaux), a consultant (Ewan Group), and a software provider (Geodesys).