Storm and Sanitary Sewer Analysis - Water Not Finding Its Level

[Anonymous]

Hi Everybody,

I'm trying to model a detention system in SSA because the evil plan checkers want a few hydrographs. It's a simple system, a 48" detention pipe flows into a drain box with an orifice but I can't seem to get it to model right. As shown in the picture below the drain box fills up and overflows but the 48" pipe is only filled to a depth of 2". Any idea why the 48" pipe is not filling up as the storage box is?

Thanks for your help,

Dan K

[wfberry]

Dan I wish I could help you but ever since Chris Meador left Autodesk several years ago SSA is like a ship with no Captain.  It is really sad.

Bill

[wfberry]

A little more background if you wish:

https://forums.autodesk.com/t5/civil-3d-forum/ssa-what-or-where-is-the-future/td-p/4694955

Bill

[BrianHailey]

Can you share your model? I'll take a look at it and see what I can find.

[Anonymous]

Here you go Brian. There's also a PDF of a detail of the detention system. I combined a couple pipe volumes into one big 48" pipe to make life easier on myself in SSA.

https://www.dropbox.com/sh/ko8u1mhc32d52qz/AAAIwW4VQ8FQFafsjT5GlUova?dl=0

It's not totally correct but when I've modeled the system with one giant storage vault with the total volume in my system I get results that might be close enough to the real thing that no one will notice.

Since SSA is pretty much unsupported these days does anyone know of a good program to do analysis like this?

[Hidden_Brain]

i did not open your model, two questions:

1. are you loading the influent drainage area to the drain box or to the node upstream of the 48"?

2. goes along with #1 above, are you running hydrodynamic? (Input>Project options>link routing method)  

[BrianHailey]

You have the analysis type set to "Kinematic Wave". This doesn't allow reverse flow in a pipe (you can think of the wave propagating along the pipe). If you change that to "Hydrodynamic", you'll get the results you want.

[Anonymous]

I knew there was some checkbox somewhere that I was missing. Thank's a million Brian!

[Anonymous]

As these things go the solution created another problem. When I had this set up for no reverse flow, basically with no detention, I had minimal overflow, 0.02 acre-in for 8 min.  Now that my 48" pipe is being used to store water I have a flooded volume of 417.6 ac-in for 202 minutes. This doesn't seem right. Is there another magic box I need to check?