Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Outlet structure for Detention Pond

Outlet structure for Detention Pond

Outlet structure for Detention Pond

I am reviewing an engineer's drainage report, showing both current and proposed conditions for a housing addition. In the proposed design, a detention pond is designed, with an outlet structure. The details are shown in the accompanying file. To figure the discharge at the elevations, would I use the contracted rectangular weir equation for the 12' wide portion from elevation of 669.50 to 671.50, then use the suppressed rectangular weir equation from 671.50 upwards? If so, what length would I use for the suppressed rectangular weir equation - 10 or 22 feet?

Thank you in advance for any advice.

RE: Outlet structure for Detention Pond

There are a couple of ways to solve this, but the easiest it to use 12' for the lower weir and 10' feet for the upper. This avoids any overlap (double-counting) of the flow area.

You could allow for contraction in the upper weir (depending on the geometry), but the lower weir is more complex, because it will only contract up to 671.5, where the upper weir starts. The easiest solution is to omit the contractions.

Peter Smart
HydroCAD Software

RE: Outlet structure for Detention Pond

Thank you Peter, for your answer.

Much appreciated,

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close