2 Continuous Model Simulations to Develop a Phased Approach for SSO

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 used to study how to reduce the frequency of the city’s SSO. The U.S. Envi-ronmental Protection Agency’s Storm Water Management Model (SWMM) version 5 built upon the city’s existing model and validated the model based on reported annual SSO activity using continuous simulations. The city’s collec-tion system includes 192 km sanitary sewers. The city’s wastewater treatment plant (WWTP) accepts an average flow of 175 L/s. Five-year continuous simu-lations were used to assess performance of an alternative that included an equalization (EQ) basin to store excess wet weather flows (WWFs) to greatly reduce SSO. The modeling identified existing system hydraulic capacity limita-tions and helped to optimize the EQ basin alternative. Optimization included using the model to identify an EQ basin location that uses gravity-in/gravity-out operation, minimizing infrastructure modifications. The continuous simulatio