EJones

I'm glad you were able to get it worked out!! If you find the steps that make those problems that exiting the program will fix, send those into FHWA and we'll get them fixed. Thanks, --Eric

This question is a bit more involved and I'd like to be able to see the model that you are using and step through the calculations and compare them to the HEC-22 manual and your computations. I recommend that you contact technical support and they'll work with you to get the model transferred over and we can follow up from there. http://www.aquaveo.com/technical-support Thanks, --Eric

Thank you Dave for your question. There is no issue with the program. Nor would I characterize that you are doing anything wrong. But perhaps there's been an update in HEC-22 that you've missed. The latest version of HEC-22, is the 3rd edition, published September 2009. One of the main sections updated was the access hole procedures. On page 7-24 (page 234 of the pdf) there is this paragraph: In more simple words, inside an access hole, we can accurately determine what the HGL will be. So in HY-12, we assume the HGL to be the same as the EGL (as determining the velocity head is very difficult, even in controlled laboratory conditions). Does that answer your question and concern? Thanks, --Eric

The short answer to your question is that a riser has a vertical hole on the side of the pipe, where the standpipe has a horizontal pipe . To be sure that I'm clear I'll give the long answer. There are four discharge structures in the Hydraulic Toolbox Detention Basin Calculator: Weir, Standpipe, Riser, and known discharge. The Weir determines the flow that is available by using only Weir Flow. The Standpipe uses weir flow along the circumference of the pipe, until orifice dominates. The Riser uses weir flow across the submerged section of the hole (depending on shape and size) until orifice flow dominates. The top of the riser is closed. Known Discharge is where the user specifies a discharge for a depth and no discharge calculations are performed by the toolbox. Thanks for the question, --Eric