another horizontal cylinder question

[gadwall]

Mr. Smart,
I have an interesting situation. I am working in a subdivision with very little elevation change. The outfall ditch that i am draining to is approximately 4 feet below the elevation of the adjacent lots. I want to model portions of the storm sewer system as horizontal clyinders. I want to install flap valves at the outfall locations (multiple storage facilities). How can I model this?

Thanks in advance.

 

[psmart]

You can model the pipe storage as a "pond", as long as there is a specific outlet control, such as a weir or orifice, in order to create a level pool across all the included storage volumes.

The pipe storage can be calculated using the "horizontal cylinder" option (with an optional slope.) For details see

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

If you have tailwater effects at the outfall, this can be handled with the dynamic storage-indication method. The flap values are easy, since reverse flows are automatically blocked unless you setup reverse outlets (which aren't required in this case.)