Drop inlet model in hydrocad 1

[EvanEvie]

I want to make sure that I am appropriately modeling my drop inlet in Hydrocad. The drop inlet is a box structure w/ a 5.5' drop to a CMP w/ D = 36". What is the best way to model this in hydrocad? Thanks!

 

[psmart]

The most common approach is to use a zero-storage pond with a culvert outlet. If you expect the box to overflow, then you would add an overflow outlet at the rim elevation. Otherwise the dimensions of the box are not needing for the culvert routing and are not entered.

For details please see

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

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[EvanEvie]

Ok, so right now i have a zero storage catch basin with the following outlets: Primary CMP_Round 36" and Device 1 Top of drop inlet. I am uploading 2 pictures that show what I have entered for both outlets. Please tell me if what I have is correct and if not how to fix the errors.

What I hear you saying (or what I infer you saying from your reply) is that I don't need to put anything in for the box so long as I don't think it will overflow. Is that correct? If so, would my inlet elevation for the culvert be the elevation at the top of the drop structure and the outlet elevation be the elevation at the outlet of my culvert?

Thank you! Your response is much appreciated!

 

[psmart]

On the culvert screen, enter the inlet and outlet elevations for the culvert alone. The box is irrelevant when you are describing the culvert. When you're done the slope should reflect the actual slope of the pipe.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[psmart]

For the overflow device, this will usually be routed to secondary. Do not route the overflow back through the culvert! Your overflow outlet is for water that will discharge without passing through the culvert, so it must be routed for direct discharge (such as secondary) and not through another device.

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[EvanEvie]

Ok, I think i am almost clear on what to do. Just to clarify, the drop inlet is not what you are referring to when you say overflow device, correct? I don't plan to have an overflow device. The water is meant to discharge right from my drainage ditch into the drop structure which outlets with a culvert. The overflow, if there is any, can accumulate in the ditch. In that case, I don't need to give any information regarding the drop inlet itself and I can remove device 1 as i have it now? As it is now I am using device 1 to model the drop structure, but what I understand from what you are saying is that I don't need to add anything else for the drop structure other than to model it as a catch basin with zero storage?

Thank you for your patience. Your help is much appreciated.

 

[psmart]

The overflow device I'm referring to is the rim of the catch basin. When the WSE exceeds this point it will presumably flow overland, bypassing the normal culvert outlet.

If you're not expecting to have overflow, you can omit the overflow outlet, and all you need is the culvert.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[EvanEvie]

Wonderful! I finally understand (well enough, at least, to execute it in hydrocad). Thank you so much for your help!