Continuous Simulation Hydraulic Modeling to Develop a Phased Approach for SSO Control in Piqua, Ohio

Ben Gamble, Derek Wride and Dave Burtner


The City of Piqua, Ohio initiated a study to develop an alternative for meeting regulatory requirements regarding an active Sanitary Sewer Overflow (SSO) in its wastewater collection system. Continuous hydraulic model simulations were utilized to study how to reduce the activity of one of the City’s SSO. The approach used hydrologic/hydraulic modeling built upon the City’s existing hydraulic model and validated based on reported annual SSO activity using continuous simulations. The City’s collection system includes approximately 120 miles of sanitary sewers and treats wastewater at a single Wastewater Treatment Plant (WWTP) in which the average daily flow is 4.1 MGD. Continuous model simulations (5-years and 56-years) were used to predict the performance of the alternative that included an equalization (EQ) basin to store excess wet weather flows (WWFs) to eliminate the SSO. The modeling process identified existing system hydraulic capacity limitations and helped to optimize the EQ basin alternative. Optimization included using the model to identify an EQ basin location that utilizes gravity-in/gravity-out operation that minimized improvements to existing infrastructure. The continuous model simulations resulted in a phased alternative and corresponding conceptual design that provided the City with flexibility in achieving the elimination of the SSO. This presentation presents the continuous simulation hydraulic modeling approach utilized to evaluate equalization storage to control SSO activity in the Piqua, Ohio wastewater collection system and the results.

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