Orifice calculations in Hydraflow Hydragraphs

[tjc4]

I can't seem to confirm the discharge table that hydraflow produces in hydraflow hydragraphs.  I think I understand the equation itself (it's been a while since I took hydraulics), but can't understand where I'm making my error (if I am).  Normally I trust the stage/discharge curve that hydraflow produces, but the City Engineer is asking me to confirm the values by hand and show them on the plans.  Is there a link to an detention pond example that shows how a curve (the outflow values) was generated (confirms the discharge table at various elevations)? The equation is on page 85 of the users manual.

[annw2]

Try going to the table tab under ponds and hit the little plus on the lower right to expand the table.  Print table.

What C value are you using in the manual calculations?  It is normally around 0.6 for orifices.

Are you taking into account the back water from the lower pipe?

Can you post a pdf of your pond outlet configuration?