×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

pre and post developmed modified rational method

pre and post developmed modified rational method

pre and post developmed modified rational method

(OP)
I have to design a detention pond for a 10-acre development with the modified rational method. The detention pond catches 8 of the 10 acres and the remaining 2 acres bypass the pond. There is not any room within the 2 acres to put a detention pond.

To determine the post developed 2 acre bypass peak release rate what duration/intensity do you use?

You can't get the Tc for the bypass and add it to your pond release rate because then you're adding two watersheds together that are peaking at different times.

I would think that you could use the duration/intensity for the routed pond outflow rate to obtain the bypass peak runoff rate?
 
For example:
If the pond maximum storage requirement was determined to happen at a duration of 2 hrs you would get the intensity
rate for 2 hrs and use that to obtain the bypass peak rate?
Then you can combine the pond and the bypass rate to obtain the post developed flow????

Anybody have any thoughts on this?

RE: pre and post developmed modified rational method

Per VT/PSUHM, v6.2, by Kibler, Hodges, Smith and Thye:
"Several questions have been raised regarding combination of hydrographs.  A unique hydrograph results from a given time of concentration.  In the Rational Method the duration of the storm is set equal to the time of concentration (Tc).  By combining different time of concentration hydrographs, one is actually combining storms of different durations, which is incorrect.  The correct way to analyze such situations is to...analyze the longer storm routed through the basin, and then combine the latter hydrographs."

Dr. Seybert can answer your questions regarding VT/PSUHM methodology, or at least he has for me before:

Tom Seybert
Associate Professor of Civil Engineering in Surveying
Penn State Wilkes-Barre
123 Technology Center
P.O. Box PSU
Lehman, PA 18627-0217
Voice: 570-675-9139
Fax: 570-675-7713
http://surveying.wb.psu.edu/psu-surv/tombio.htm
mailto:tseybert@psu.edu


Engineering is the practice of the art of science - Steve

RE: pre and post developmed modified rational method

(OP)
Thanks for the information. From the response you sent me it appears that I am thinking correctly. I will contact
Dr. Seybert

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


Resources

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