The Value of Integrated Modeling for Predicting Bacteria and Dissolved Oxygen in Urban Streams

In 2012, Citizens Energy Group began the conversion of the legacy SWMM 4.4g & WASP 5.1 receiving stream water quality models to InfoWorks ICM, which is also used for the collection system model. Citizens sought to improve the efficiency of the modeling process by integrating the collection system hydraulics, receiving stream hydraulics, and receiving stream water quality into a single model. The legacy modeling framework of using modeled flows to develop pollutant loadings from SWMM and WASP was effectively maintained within the InfoWorks program.The integration was performed as a three-phase process:Phase 1: CSO and Stream Flow – Completed January 2013Phase 2: E. coli bacteria – Completed June 2013Phase 3: Dissolved Oxygen – Completed December 2014The integrated model has provided better labor efficiency for Citizens’ staff.An overview of Citizens’ new water quality modeling capabilities in this integrated framework is provided, including improving the overall efficiency of the Utility’s water quality modeling process, as well as future regulatory efforts the integrated framework can support. We believe that our lessons learned in the model integration process will be valuable for combined sewer communities that have water quality objectives to achieve.