Abstract

Storm pipes are a major component of any municipal infrastructure system, however, poor attention is commonly paid to their management and replacement of pipes is typically guided by condition criteria. Pipes replacement also faces the issue that their capacity is not considered, and the proposed pipes replacements are of the same diameter as the previous ones. However, lagged replacements of storm pipes can compromise urban system ability to drain runoff-water from rainfall and this could lead into flooding. This research extents optimal condition-based allocation of pipes by considering demand-capacity ratios, in order to prevent flooding. The effects of urbanization and climate change are also incorporated. A general method for detecting the impacts of urbanization currently exist, however, a simplified approach due to the lack of data is suggested. A case study of the city of Kindersley in Saskatchewan is used to illustrate the application of the method. Hydrological models based on current and future land uses were used to estimate changes in demand-capacity ratios for each pipe in the system. Performance curves for capacity and condition were developed, and validated by change detection of observed historical land use cover for the past 25 years. An extra 18% rainfall intensity was used to model the impacts of climate change. It was found that CAN$40,000 were enough to sustain current levels of condition and capacity-demand ratios, however, condition was at unacceptable level. Budget was raised and weights were adjusted until a combination with 45% capacity and 55% condition with $100,000 was found to be the departure at which compliance begins to reach desirable point minimum levels of demand-capacity ratios and condition, possibly higher values of budget would be necessary as the municipality adjust such minimum requirements to the desired ones.