Pipe sizing using hydrocad.

fhl1 · Jul 23, 2006

I am having trouble sizing pipes using hydrocad. I am new to this software. Can hydrocad size a series of pipes? If I have subcatchment runoffs to cath basins through a pipe network with final dischage to a detention basin, how do I model this using hydrocad. I have it now were the tributary subcatments are linked to there respective ponds were I entered my data for the outlet pipes and inlets or grates. I clicked on the no storage check box to model catch basins. I entered the outlet culverts information as my primary and orifice/grate as primary also. I gave as the flood elevation the rim elevation of the inlet I have ponds linked to other ponds to represent the next pipes to be modeled and so on until the final pond for my detention basin. I did not use reaches for the pipes since I read that it is not advisable to do so. Anyway, I keep getting errors that I exceeded the previous pond devices by a certain elevation. Those that mean I need to increase my pipe sizes? I did not get these errors using Civil design for the same purpose. Can anyone please help without refering me to a website. I would appreciate a step by step simple instruction. Thank you very much.

FHL1

psmart · Jul 24, 2006

Please click the warning message for full details, and follow the links as needed. The warning messages will help you resolve 99.9% of all problems. Although you didn't indicate the exact message, I suspect it's a tailwater warning, indicating that you need to switch to a tailwater-sensitive routing procedure, such as dynamic Storage-Indication method. Regardless of the pipe size, your system probably has tailwater effects. For details see

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

If the catch basins are overflowing, you will also need to model the above-grade storage and/or use an overflow device. The overflow is usually a horizontal orifice. Set the routing to Primary if it is routed to the same location as the culvert. But if the flow is diverted for independent routing, they you should use secondary. For details see

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

fhl1 · Jul 29, 2006

Thank you very much. I will investigate.
FHL1

pinecreek · Jul 31, 2006

You may have to assume a downstream WSE in order to establish the potential energy avaible for pipe flow.
Also, I recommend using 6 ft/sec as the maximum avalable flow velocity before ponding drain inlets.
Also, do not use concentration time to determine rainfall duration. Rainfall duration will be independent from what is happening on the ground.

psmart · Jul 31, 2006

pinecreek: If you select a tailwater-sensitive routing procedure, such as DSI, HydroCAD will automatically calculate the downstream WSE for each culvert. This works better than a manual WSE setting, since the level is usually subject to significant change throughout the storm. For details, please see the links in the previous posts.

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Pipe sizing using hydrocad.

fhl1

Civil/Environmental

psmart

Active member

fhl1

Civil/Environmental

pinecreek

Civil/Environmental

psmart

Active member

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