"Gravity sub-network does not have downstream wet-well or outfall"

Question

I'm getting this error when I click on the compute button even though I do have a downstream outfall: "Gravity sub-network does not have downstream wet-well or outfall." It seems to only happen when I create a diversion link (however, the program won't run unless I create the diversion link). If I delete all the "diversion" pipes, the program runs fine. What could be causing this?

Jesse Dringoli · Accepted Answer

Hi Joe, 
 Thanks for providing the model files. 
 The issue is due to the setup of the diversions. It appears you've used a diversion on both of the downstream pipes in each of the two cases where flow is splitting. You only need to specify "Is Diversion?" on all but one of the outgoing pipes, and the remainder of the flow will pass through the other pipe. This is explained in the below article: 
 Modeling split flows in SewerCAD , StormCAD , or SewerGEMS/CivilStorm using the GVF convex or GVF rational solvers 
 So for example when flow splits into two downstream pipes, you only need to set the diversion on one of the pipes. For a given upstream flow, the flow specified in the Diverted Flow column of the diversion rating table will pass down that pipe and the rest will pass down the other pipe. 
 So, to overcome the error in question, remove one diversion from each of your flow splits, for example conduits "GC-DC-160.4-160.2" and "GC-110.1-110". Once you do this, you will also need to fix up a few other issues in the model, mostly related to wetwell/pump settings. Use Validate under the Analysis menu to see the list.

Scott Kampa · Answer

Hello Joe, 
 
Does the diversion pipe end in an outfall or wet well? If not, one will need to be added. 
 
If this doesn't help, we will need to see a copy of the model. There are two options for sharing your model files on Communities. If you would like the files to be visible to other members, compress the files into a zip file and upload them as an attachment using the ‘Advanced Reply editor’ before posting. If your data is confidential, you can follow the instructions in the link below to send it to us via Bentley Sharefile. Files uploaded to Sharefile can only be viewed by Bentley. 
 
 communities.bentley.com/.../7079.be-communities-secure-file-upload 
 
If you upload the model to Sharefile, please post here with the name of the model file so we know it is available. 
 
Regards, 
Scott

Jesse Dringoli · Answer

Additionally, here is a link to a related Support Solution: 
 How to resolve the user notification: Gravity sub-network has more than one outfall or wet-well

Scott Kampa · Answer

Hello, 
 
In the model you provided, there are currently no diversion links. However, junction GC-DC-160.4 and GC-110.1 should have one. Both of this loop back into the main network, so an extra outfall would not be needed in this case. However, if the diverted flow were to branch off and not loop back into the main network, then another outfall would be needed. 
 
In addition to the missing diversions, the pump data has not been included with the model. 
 
Regards, 
Scott