The Winnipeg Combined Sewer Overflow Outfall Monitoring Program (Phases 1 to 4)

To comply with the recommendations of the Manitoba Clean Environment Commission regarding the instrumentation of CSO outfalls, the City of Winnipeg has implemented a city-wide comprehensive centralized CSO outfall monitoring program. This program consists of a permanent monitoring system and a data analysis and reporting tool, enabling real-time reporting of overflow events.

The new CSO Monitoring Program improves upon the existing overflow alert system by installing permanent meters combined with real-time data analysis and use of modeling in order to collect and report on the frequency, duration and volume of overflow conditions for all of the 79 overflow structures in the combined sewer network. The quality of the data, data validation, and redundancy in the monitoring will provide the City with a reliable means of reporting online discharge conditions, all with a better understanding of the existing overflow conditions and the impact of future work for CSO control.

As the prime consultant, Tetra Tech CSO led the preparation and implementation of the CSO Monitoring Program, in partnership with the local firm Stantec Consulting Inc. and sub-contractor SFE Global. The program was carried out in phases in order to meet the tight implementation schedule established by the City.

Phases 1 and 2 of the program began in 2008, and consisted in selecting and inspecting 15 overflow sites that were designated as pilot sites (over-equipped permanent facilities) to test the various measurement technologies that were identified as potentially suitable. The program selected 39 overflow sites as primary outfalls to be instrumented, while the remaining outfalls were considered secondary where the overflow conditions were estimated through model simulations. Phase 3 followed in 2012, consisting in implementing 15 additional permanent overflow monitoring sites, with a typical installation set-up based on experience gained through the pilot phases. This phase also included the development of an online data analysis and reporting tool, which included data validation and compilation processes to detect overflow conditions and a report on overflow event time, duration and volume. The tool control simulation runs in real time based on incoming rainfall, river levels, mix monitoring, and modeling data. A pilot project for water quality monitoring was also initiated in this phase. Detailed modeling of four CSO districts that include five secondary outfalls was performed and calibrated with temporary monitoring. Real-time modeling in conjunction with permanent monitoring of the primary outfalls provided reliable overflow conditions at these secondary outfalls. Phase 4 of the program began in September 2013 and will complete the permanent instrumentation of the remaining nine primary CSO sites.

Tetra Tech CSO assessed the hydraulic conditions, selected the monitoring technologies (measuring and telemetry), produced the preliminary and final plans and specifications, provided the City with assistance regarding procurement, the management of real-time data compilation, the analysis and validation for the production of weekly overflow reports, and technical assessments for defining and justifying the specifications of the CSO Monitoring Program. In Phase 3, Tetra Tech CSO also led the development of the online reporting tool, which incorporated the real time modeling of secondary outfalls.


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Diana Tao

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