HydroCAD Infiltration Stormwater Planter Modeling

[GJ1970]

I am thinking I may have been modeling infiltration planters wrong. Let's say I have a soil infiltration rate of 5in/hr into the native soil (from a infiltration test). I design a planter, but have to limit the exfiltration through the growing medium to 2 in/hr. I create a pond node and input the storage layers to reflect the planter layers: Rock storage, Choker Rock Layer, Growing Medium, and then raw Storage. Since the growing medium exfiltration rate is lower than the native soil exfiltration, I use 2 in/hr exfiltration applied to the growing medium layer in the planter. Does HydroCAD then compute the ponding depth in the planter (i.e., above the growing medium) correctly, or does it just fill up the entire planter and not really think about the fact that the growing medium, which is the upper layer in the planter, is restricting flow down into the rock storage?

I'm concerned I'm not computing the ponding depth correctly.

Thanks!

 

[psmart]

At the water/media interface you would use an exfiltration outlet at 2 in/hr. Since the media is acting as an outlet control, the pond storage should include only the open space above the media. Any water below that point is not part of the same level-pool and ignored as far as the pond routing. For details see www.hydrocad.net/raingarden.htm