I am trying to reduce the "overflow volume" in the model calculation summary.
I have achieved this partially by -
- Adding overflow links (link to outfall structure with boundary condition set to discharge at next downstream node)
- Adding surface storage at local low points
- Adding additional (dummy) manholes at low points along the sewer line to account for local ponding
This seems to be working locally, but ends up pushing the flooding issues to subsequent upstream or downstream nodes.
I understand that this means the existing system is undersized, but I want to make sure that the model is not losing flow.
Any suggestions to address this issue?
Thanks.
I wanted to update that I am somewhat confused about adding "overflow" conduits (trap. channels). Based on some results I was just looking over, it looks like the overflow link is continuing to increase in flow, even though the manhole only is surcharging for a short amount of time (see two graphs below).
Is this an error? I am going to try removing the "overflow" conduit so that I am not losing flow.
Thanks, Seth
Update:
Here is the result when I turned off the overflow. It looks like the manhole HGL dropped almost 1.5 ft from the previous graph. Am I missing something? It seems odd that the HGL dropped despite removing the overflow conduit. (Note that the manhole already discharges to two (non-overflow) conduits.
Sorry for flooding the Bentley community with posts. Thanks, Seth
Graphs with overflow conduit in place: