AWWA ACE61660

In order to develop the most cost-effective infrastructure program to meet projected growth in the western portion of the City of Ottawa's water supply system, the City embarked on a significant study of outdoor water use. It was generally felt that by reducing peak demand usage, major infrastructure could be downsized, deferred or even eliminated, and therefore reduce capital and operating expenditures in the short and long term. Thus, determining the true impact of outdoor use on the peak flows was essential for assessing the potential benefits associated with an outdoor water use reduction program. The study involved a detailed analysis of the peak demands for a primarily residential area, which considered overall daily summer demands as well as diurnal water use patterns. This involved an evaluation of individual sprinkler usage, in terms of duration, flow rates and time of day. The analysis resulted in a separation of outdoor uses from the daily norms and provided a clear understanding of the actual outdoor water usage and its impact on maximum daily demands and the diurnal usage pattern. Both these factors affect major infrastructure needs. A statistical analysis was then undertaken to develop a predictive modelling tool, based on climatological factors and land use, to refine projections for peak water demands on the system in the future. This model will be used to provide confidence in assessing the impacts of any reduction strategy on the peak demand rates, resulting in a quantifiable evaluation of the program effectiveness. Includes tables, figures.