![]() "Has anyone used storage nodes to represent a manhole before? Why does it seem to need less storage volume for underground storage when done like this?" There is a fundamental difference in how SWMM 5 calculates the depth for storage nodes and manholes when the water surface elevation is above the highest connecting crown of all connecting links which may account for your observation: Has anyone used storage nodes to represent a manhole before? Why does it seem to need less storage volume for underground storage when done like this? Note: for the scenario 2 each manhole (7 of them) is storing 3 m3 each for a total of 21 m3 according to the model. With my surcharge depth roughly the same in both scenarios, there seems to be a big discrepancy in the pipe storage that I need to provide (210 m3 and 127 m3) for each scenario. For each node that is representing a manhole, I have the storage curve as "FUNCTIONAL" with a coefficient of 1.167 to represent the same surface area as in scenario 1.Įverything else in both scenarios has been kept the same. Scenario 2 - I am using a 1050mm Concrete pipe for the entire 146.59m of pipe which gives me roughly 127 m3 of available storage in the pipes before it starts surcharging. Pipes are surcharging between 1.0m - 1.3m In "Simulation Options" I have left the minimum surface area at the default 0 to simulate a manhole junction with a surface area of 1.167 m2 (4 ft diameter manhole). Scenario 1 - I am using a 1350mm Concrete pipe for the entire 146.59m of pipe which gives me roughly 210 m3 of available storage in the pipes before it starts surcharging. Scenario 2 - Pipe segments with manholes (Modeled as storage units) ![]() I have run two scenarios: Scenario 1 - Pipe segments with manholes (Modeled as junctions) ![]() My pipe inverts are anywhere from 3.5 - 4.5m below the ground. I have 146.59m of pipe that I am using as pipe storage for both scenarios, and its ok if I surcharge the pipes, as long as it doesn't come to the surface. ![]() I have come across something that I can't seem to understand why it's happening. I have a very small discharge rate at the end of pipe, so the stormwater runoff is backing up into my oversized pipes using them as storage. In PCSWMM I am running a Dynamic Wave simulation using big pipes for underground storage. ![]()
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