Detention Ponds w/ Leaching Basins 1

[MHMcLeod]

I am designing a detention pond that allows for infiltration. As an overflow outlet, I'm using leaching catch basins w/ inlets set above the bottom of the pond (2 basins per pond). The catch basins are surrounded by stone and linked together w/ a perforated pipe surrounded by stone. I've tried modeling these components as a single node, w/ the above ground storage as one volume, the catch basins & their stone surrounds as 2 addtl. volumes, and the pipe w/ its stone as the 4th & 5th volumes. It's not working, because the software starts storing runoff at the bottom of the catch basins or in the perforated pipe, & later the pond fills. If I try to model the pond w/ catch basins as outlets that lead to the perforated pipe as a 2nd pond, there's too much water in the pipe & stone pond for the model to run. Anyone else had success modeling this situation?

 

[psmart]

Whenever you include multiple storage volumes in a single pond, the volumes are assumes to be interconnected in such a way that the water surface elevation is the same is ALL the volumes. In other words, they must behave as a single level pool. For details see

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

But if I understand your case correctly, you have two separate ponds with separate elevations, so they must be modeled as two separate pond nodes: The first is the main pond, which eventually overflows into the leaching catch basins. You can use a double horizontal orifice for the overflow. This would be routed to secondary (to separate it from any primary outlets) and directed to a second pond node, which models the leaching system.



Peter Smart
HydroCAD Software

http://www.hydrocad.net