Using SWMM 5 to Develop Wet Weather Operating Strategies in a Large Sewer System
The City of Columbus wastewater collection system includes separate sanitary and combined sewers, with interceptor sewers directing flow to two large wastewater treatment plants (WWTPs) through complex flow control structures. The potential benefits of modified system op-eration during wet weather, including potentially real time control (RTC), has been identified and is being investigated as a means to opti-mize performance of the collection and treatment facilities. Modeling of system performance helps engineers understand system constraints and simulate RTC operating strategies. SWMM 5 is being used to per-form these modeling assessments for the Columbus sewer system.
The City of Columbus is currently updating its system wide sewer model using PCSWMM with the U.S. Environmental Protection Agency’s Storm Water Management Model version 5 (USEPA SWMM 5) as the computational engine. SWMM 5 provides a number of advantages for modeling the operating strategies versus previous models of the Co-lumbus system that used SWMM 4.4. In particular, the ability to write control rules directly in SWMM 5 offers a significant advantage for modeling complex hydraulic structures and RTC strategies. One purpose of this study is to test the capability of SWMM 5 to simulate a large scale system with complex control rules and its potential to inform design of the real time control system.
The Interconnector sewer between the Jackson Pike WWTP and the Southerly WWTP is the central conduit that conveys flow from up-stream sewersheds to the WWTPs or to storage at the Whittier Street storm standby tanks (SSTs). In order to optimize wet weather flow cap-ture at the Whittier Street SSTs and at the two WWTPs, operating strategies for the Interconnector sewer were developed using SWMM 5.
In the study, SWMM 5 was applied as a fully dynamic hydraulic model with 1200 pipes, 11 pump stations, 28 orifices and 48 storage or wet wells. Control rules to operate the various gates and pump stations in the system were specified. The SWMM 5 model simulates flows in the Interconnector sewer; the control rules are being iteratively adjusted to achieve an optimal solution. This paper focuses on the effectiveness of SWMM 5 to perform the large scale complex modeling simulations through evaluation of the model representation and model verification.
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