Dynamic Prioritized System-wide Cleaning Schedule

The goal of this presentation is to describe the innovative approach developed by the City of Sacramento Department of Utilities (City) to clean their entire small diameter separated sewer system (30 centimeters and less) over a five year period. This presentation will focus on tools and business processes that were implemented to achieve the City’s goal of complying with their Consent Decree (CD) while simultaneously developing a plan that balances the economic viability of a system-wide cleaning program with the risk of a catastrophic SSO in the system.At the time the CD was adopted, less than 241 kilometers of the City’s nearly 1,450 kilometers of separated and combined system were on a cleaning schedule and this “hot-spot” cleaning occupied the entire City’s cleaning resources. It was essential for the City to evaluate their current schedule and to prioritize the assets to be cleaned to minimize the risk of a catastrophic failure. There were two major problems the City was facing as it implemented the requirements of the CD. First, cleaning had been historically only performed on approximately 20% of the system. This means that about 80% of the system’s maintenance condition was unknown. Second, the CD requirements pertained only to the separated system. This meant that with limited resources, there was a risk of neglecting the combined system in order to meet the requirements of the CD. The City needed a way to prioritize the maintenance activities to focus on the areas most likely to have an SSO, while simultaneously grouping work orders geographically to maximize crew production.