This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Stop Control Structure Adjacent to Outfall

I have a system I am modeling in SewerGEMS and have run across the following error: 

20448 "Base" "Conduit" "29" "CO-1" (N/A) "Conduit has a Stop control structure, but this is not supported next to the connected outfall element."

It appears the software will not let me have a stop control structure before an outfall. Is this always the case? I have tried different outfalls and different stop control structures and I keep getting the same error. 

Is there a simple way around this? Is there a reason the software wont allow this? I am looking to model a stop control structure on the conduit that would be right before where the system discharges to a stream. 

Thanks!

  • Hello,

    It is true that stop control structures are not allowed on conduits directly connected to an outfall. One thing you could try to work around this would be to model the stream directly. You would have your conduit connected to a cross section, which would define your channel. The channel would then be connected to the outfall. The following screenshot is one possible setup.

    You should be able to add the stop control structure to the conduit then.

    Regards,

    Scott Kampa

    Bentley Technical Support

    Answer Verified By: Sushma Choure 

  • Thanks for info.

    I should have been more clear about the end conditions here. This outfall is a perpendicular discharge to a large receiving body of water (probably should have called it a river).

    I am trying to model the affects of a flap gate and the stop control structure looks to have the options to do this (flow as a function of head across an orifice).

    I guess I could model the end of the culvert after the flap gate as a very short concrete channel as you have shown (similar to what you have shown). I have currently just thrown a manhole in the culvert towards the end that is the same size and material and put the outfall right after that. Is there any reason this wouldnt work? Any ways that serwerGEMS may handle the manhole that will add some confounding or wierd hydraulics?

    Thanks again

  • Hello Kobalt,

    Your workaround sounds reasonable. I would recommend using the "bolted" option in the manhole, or use a transition node instead, and make sure the downstream pipe next to the outfall isn't too short (recommended minimum length is 10 feet.)Aside from that, I do not anticipate any problems with this arrangement, aside from the usual refinement that might be necessary to ensure stable results. In other words, you may need to adjust calculation options such as the timestep, if introducing the control structure causes stability issues (as seen in the overall continuity error and/or graphs).

    You could still model the "river" if you wanted to, as discussed above, which may be helpful if you wanted to simulate river flooding conditions and their effect on the outfall discharge.

    Should you have any problems with the control structure in place, feel free to start up a new thread and include your model.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Sushma Choure