Taking up The Challenge of CSO Monitoring: The City of Winnipeg Experience in Setting up an Ambitious Program

The City of Winnipeg Water and Waste Department initiated a Combined Sewer Overflow (CSO) Outfall Monitoring Program with the installation of fifteen full scale pilot monitoring sites between June 2009 and April 2010. The overall goal of the CSO Monitoring Program is to develop a permanent monitoring system to accurately detect and quantify CSO events. The system is also being provisioned to enable future real-time reporting of overflow events.During the project's two pilot phases, monitoring sites were instrumented with a combination of flowmeters, level meters, and inclinometers. Data analysis from these first installations determined the most efficient ways to monitor CSOs. Different monitoring strategies were developed and evaluated as part of a cost-benefit analysis for future site instrumentation. Based on this analysis, the recommendation for the ongoing monitoring program was to primarily rely on a combination of level meters and inclinometers. These have proven to be reliable instruments and will provide redundancy in detecting overflows. It was also recommended to use a calibrated hydraulic model to estimate overflow volume. A model can provide sufficient accuracy for reporting purposes and is an interesting and cost-effective alternative when compared to the use of flowmeters. Further, experience gained from the pilot phases has shown that hydraulic conditions were not, for the most part, conducive to accurate and reliable flow gauging. Using a real-time model application can be a reliable tool and has the added advantage of offering many other benefits to the City's operation and planning functions.Status of Completion: Phases 1 and 2 of the project are complete with 15 sites instrumented and operational. Design for the installation of ten additional sites (Phase 3) is currently underway. Commissioning of these sites and the development of an online data management, real time model, and reporting application is due at the end of 2012.