Tailwater

[JStephens]

I am attempting to model an existing storm drainage system in Hydrocad that has the following parameters:

I am given the elevation of the downstream tailwater at the beginning of the analysis at say Catch Basin "A". After that I am given the pipe and catch basin information (length, inverts, size, material) and peak flows entering each pipe section. Due to the tailwater the system is pressurized. Is Hydrocad capable of handling this analysis? If so, how would you go about setting up the model and which calculation procedure would you suggest using? I have attached the Hydrocad file of one of my many attempts, but the numbers are not making since (for example look at pond I-26 75+15 RT). Thanks in advance!

 

[psmart]

The file you posted is empty. This can happen if the file is open in HydroCAD when you upload, since this locks the file.

For general comments and suggestions about modeling storm sewers please see

http://www.hydrocad.net/sewers.htm

To handle the tailwater effects you can use the Dynamic Storage-Indication method. For details see

http://www.hydrocad.net/tailwater.htm

If the "numbers are not making sense", be sure you have reviewed and resolved all warning messages. The messages indicate problems in the model that must be resolved before you can draw any conclusions from the results.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[JStephens]

Peter-Here is the latest attempt. Sorry about the earlier trouble with the upload.

 

[psmart]

OK, I got the file.

I see that you're using links to introduce constant flows into the model, rather than using time-varying flows. You also have no available storage, so there are no retention or detention effects. In short, it looks like a steady-state HGL analysis. Although its possbile to handle this type of calcualtion with HydroCAD, it would be much easier to use a steady-state solution, or even a spreadsheet.

For details please see

http://www.hydrocad.net/sewers.htm

Peter Smart
HydroCAD Software

http://www.hydrocad.net