CP338 Mains Interventions – Improving Benefits Valuation
WRc has recently completed a two year Portfolio project to investigate the impacts of distribution mains rehabilitation on leakage and repair rates. This project built upon the data collection and analysis methodologies that had been developed under previous studies, which enabled nightlines for discrete areas of the distribution network to be estimated, following mains rehabilitation.
The project focused on three mains areas; the short term impact of rehabilitation at District Meter Area (DMA) level (1 year before to 1 year after), the longer term impact to DMAs (3 years pre- to 3 years post-rehabilitation) and also the impact on leakage on individual mains (site work).
DMA and site data were supplied by the nine contributors and collated into the Mains Rehabilitation Database and Graphical Viewing tool, prior to analysis. The study included a greater number of areas where the mains rehabilitation was undertaken to address high leakage and/ or burst rates, as water quality programmes have been completed. These data are more appropriate for understanding the impacts of current capital maintenance expenditure programmes.
The project has yielded statistically robust relationships to allow short term post-rehabilitation nightlines to be predicted and also demonstrated that nightline improvements can be maintained in the long term. The monitoring of isolated sections of the distribution network has shown that mains rehabilitation will have a positive impact on leakage, the majority of which can be attributed to the company pipes (mains and communication pipes).