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How do I model a gate valve opening and closing based on the level in an upstream manhole?Problem ID#: 80214
This must be done using the Explicit (SWMM) calculation engine selectedin your calculation options. Then, define a start control structure onyour downstream conduit such as an orifice and give it a SWMM label(such as OR). Next, Go to Components > SWMM Extensions > Controls sets.In here you will need to define two control rules; one to set thesetting of the orifice to 0 when the level reaches the point when thegate should close, and another to set the setting to 1 when the orificeshould be fully open. For example:RULE AIF NODE WW-1 DEPTH <= 0.1THEN ORIFICE OR SETTING = 0}RULE BIF NODE WW-1 DEPTH > 3THEN ORIFICE OR SETTING = 1- You can read more about SWMM control syntax in the Help or in theEPA-SWMM documentation- You may need to use a wetwell upstream instead of a manhole forstorage.- If using metric units, some versions of the program still require thedepths in the control sets to be entered in feet.- In at least one previous case, high continuity error was seen. Thecontinuity error was much better if the gate wasn't opened all the way(80% versus 100%). In this case, try enlarging the full orifice diameterto compensate. You may be able to further reduce the continuity error byreducing the routing timestep.