Highway Ditch Storm Sewer / Storage Node Connection - SSA

[ncullen12]

I have a highway that drains to a ditch. This ditch has 4-Beehive Inlets that are in series with an underground 24" storm sewer. This ditch also acts as a storage facility in major events when the 24" storm line is unable to handle the higher flows and then exits up and out of the beehive and "builds up" within the pond/ditch. I have been unable to find a way to model this type of scenario. I do not want to use "ponding" above each of the beehives either due to the fact that all 4 beehives "flood" into the same pond. I would like to use a storage node, but have no way of connecting the inlet/storage node properly. Suggestions/help please and thank you!

[rdbrennan48]

The way I have usually split my storage into several section and divided up the storage area accordingly. eash storage node, inyour case there would be 4, would have an orifice outlet into a junction. The orifice would be horizontal and have an area equal to that of the grate on the structure. All of you junctions should have a rim elevation equal to that of your storage area. to model the cross connection between the storage nodes (ditch) I would use a channel link. See attached image.

[ncullen12]

Thank you rdbrennan48. Are you getting correct/expected results from your model by doing this, because I have considered this option as well. However, what concerns me is the warning that the SSA User's Guide gave me about orifices on page 315 - "Flow Reversals" . It states that if I have flow reversal, not to use an orifice and to use a pipe. However, when I use a vertical pipe, I get very incorrect results. May I ask, why you would use a "horizontal orifice" instead of a "vertical orifice" (as shown on page 313) if an orifice still does work correctly under flow reversal? Thanks!

[rdbrennan48]

Sorry I meant a vertical orifice. 

I have used a short lenght of pipe instead of an orifice and didn't have any issues.