sanitary analysis in SSA

[Hidden_Brain]

i am currently experimenting with SSA to perform sanitary sewer analysis. i have two pipes, 8" dia at 0.76% and 0.78% slopes. my question is where should i input the sanitary inflows for the system. i am currently adding flows to the structures (manholes) as external inflows>user defined (direct) inflows. i do not have any sanitary patterns yet, just want to test run this sytem for capacity to get a hang of it. i did manual calculations simultaneously to calculate the pipe flowing full flows, and i have 1.14 cfs (8" @ 0.76% and n=0.012) and 1.16 cfs (8" @ 0.78% and n=0.012). so in SSA, i user input 0.8 cfs (arbitrarily) at the upstream structure (STR #4), and to make the downstream pipe flow full, i add another 0.36 cfs (1.16-0.8 cfs) at the next downstream structure. for a flow of 0.8 cfs, the upstream pipe (8" @ 0.76%) should be about 63% full, which it seems like from the attached SSA profile plot, but then the HGL shoots up to the top of the next structure (STR #4A) as if that structure is completely filled! also, the next downstream pipe (8" @ 0.78% does not seems to be flowing full). am i missing any necessary steps here? can someone please shed some light? profile plot from SSA is attached.

[Hidden_Brain]

anyone? Matt?

[Joe-Bouza · Accepted solution]

Hi Y-EIT, I don't have SSA but when you try to run pipes at 100% full you are going to be under presure; I got an HGL climbing the middle structure in Storm sewers also. for design you should limit yourself to 90% full at the at the outfall 0.8 cfs. (.04 +0.4) and the hgl reads more realistic. 

[Matt.Anderson]

YoungEIT -

You may want to check your middle junction's starting water surface elevation or your entrance losses to the downstream pipe.

[Hidden_Brain]

you are spot on Joe! yes, if i have it flowing full capacity, it does show the structure completely filled! i deccreased the flows so that the downstream pipe is not flowing full (100% capacity) anymore, and the HGLs inside the upstream structure are more realistic. i wonder why it does that though.

Matt, i did not have any entrance/exit losses specified yet, they were all zero in my model. i wanted to test and see for pipes flowing full if i get expected results. i did notice that i can change the field WSEL Initial inside the structure properties, which seems like it defaults to the structure invert, but do i need to mess with it?

[Matt.Anderson]

No need to mess with the results and Joe is correct that a pipe flowing full will become pressurized.  SSA will need an appropriate Entrance / Exit Losses as Junction Losses are not calculated.

[Joe-Bouza]

Happy that helped. How bout one of them kudos it would be my first

Please select "accept solution" so other readers may be aware of your solution

[Hidden_Brain]

solution accepted, kudos given. thanks much Joe and Matt!

[Joe-Bouza]

My first kudos and coming from storm/ sewer is an exra kick for me - Yeah!

[hamid.akbari]

Hi
Can I ask you to let me have a sanitary sewer file as sampel.
Actually I am new at SSA and need to a sample file for sanitay and storm sewer.
Thanks in advance
Hamid

[hamid.akbari]

my email address is Hamid.akbari.ca@gmail.com

[hamid.akbari]

my email address is hamid.akbari.ca@gmail.com

[hamid.akbari]

Hi Matt,
could you please let me know ,how SSA or civil3d could contributed area for manholes?
Thanks

[Hidden_Brain]

see if this helps: http://bimontherocks.typepad.com/my_weblog/2010/09/sample-data-for-autodesk-storm-and-sanitary-analy...

[hamid.akbari]

Thanks for your reply but this link is not what I am looking for.

[hamid.akbari]

Any respond?

Actually I don't know why Autodesk is not active at SSA like other Autodesk comunities! you can find whatever you want for autocad-drafting,lisp files,...

I have asked several times for calculating contributed area for the manholes but I haven't received any thing yet.

I look forward to hearing from you.