The Metropolitan Sewer District of Greater Cincinnati (MSDGC) maintains a model of its sewer system to assist with planning, analysis and design related to stormwater runoff, combined and sanitary sewers and other drainage systems in its service area. The model is separated into multiple System Wide Models (SWMs), including the Mill Creek SWM that represents both sanitary and combined sewer areas in 19 subwatersheds. As the second largest stormwater management model (SWMM) in the world, the Mill Creek SWM is being enhanced by Wade Trim to reduce simulation run times, facilitate ease of functionality to make upgrades, and improve overall performance in simulating system flows.
The model’s massive size creates issues for reviewing and editing, and multiple problems for MSDGC and their consultants, including long simulation run times and difficulties managing ongoing work on various sub-watersheds. With 6,550 subcatchments, 28,000 junction nodes and 28,400 conduit links, the model will be reviewed to identify points in the system to break apart the overall Mill Creek SWM into smaller, more manageable sub-watershed models and an interceptor model. Portions of the system may also be impacted by receiving stream water levels during annual simulations, which will require development of boundary conditions at any impacted outfalls. A check-out and check-in system will be developed, and inter-submodel communication will be provided through the use of interface files.
The Mill Creek SWM enhancements are expected to be complete by the end of 2016 to support the MSDGC’s Wet Weather Improvement Program Phase 2 planning efforts. The model is currently being used to plan and design Phase 1 improvements on critical timelines.