Pond Outlets not working correctly for Hydraflow Hydrograph Extension

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Pond Outlets not working correctly for Hydraflow Hydrograph Extension

Anonymous
Not applicable

I am having issues inputting my dry pond (sand filter pond with forebay) into the Hydrographs Extension. I have been told to input my forebay and sand filter pond as separate ponds and route the forebay outflow through my sand filter. Please see the attached profile of our proposed pond. The forebay's outlets include: 4 - 4" orifice pipes and a weir/berm @ 756. The sand filter/dry pond outlets include: exfiltration (through the sand @ 2 in/hr), a 6" orifice on the riser structure, a 5' weir located at the top of the riser structure and the emergency spillway. I was able to route my post-development conditions through the forebay and that hydrograph looks okay. However, when I go to route the forebay outflow through the sand filter pond - I keep getting the error: No Solution to Hydrograph 4..... Reservoir storage or discharge may be too small. I believe there is something wrong with how I am inputting my outlets for the sand filter pond. Please see screenshots. Can someone help me figure out what's going wrong? Thanks in advance!

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fcernst
Mentor
Mentor

Well first...you're pond outlet structure setups do not match your detail.

 

Forebay:

 

  • The berm should not be routed through the 4" PVC' pipes.

 

Sand Filter:

 

  • The 6" orifice should be routed through the 36"
  • The spillway should not be routed through the 36".

See what happens after making these changes?

 



Fred Ernst, PE
C3D 2025
Ernst Engineering
www.ernstengineering.com
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