SWMM56

The key problem discussed here is to keep the Force Mains full or d/D equal to 1 when the pumps turn on, it is sometimes difficult to get it to work like ICM or IWCS due to the fact that there is only one Q in the link of the SWMM 5 solution compared to the 4 or more flow points in the IWCS solution.  I have suggested in past that the user add a break node in the force main at the end so that the downstream end of the Force Main is full – however does not always work if there is a gravity main at the end of the rising force main.  The gravity main takes all of the flow coming down the long force main and the downstream node depth stays small so the Force Main is never full – this annoys the customers.    My suggestion is to increase the gravity main roughness to simulate the effect of the force main transitioning to the gravity main – this keeps the depth higher and the force main full most of the time and full when the pump turns on.   Here are eight sugge...