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

Storm Drain Inlet Blow-by

Storm Drain Inlet Blow-by

Storm Drain Inlet Blow-by

Does anyone know of a good source (book or software) that can calculate the volume of water which "blows by" the storm drain inlet?  I am interested in varying upstream gutter geometry and inlet opening geometry to optimize (minimize) that volume of water.

RE: Storm Drain Inlet Blow-by

Go to a couple of the 'curb inlet' manufacturers' websites and read and read and then watch water in the gutter. Then go to your largest local Public Works design group and ask how they do it. There are theories but they depend on perfectly placed and finished gutters. That never happens.

RE: Storm Drain Inlet Blow-by

FHWA's HEC-12, available for free download at


summarizes a method I have never seen rejected by any reviewing engineer.  Pages 22-35 details all equations you need to create a spreadsheet to do this.  Composite gutter cross sections are included, which I think is what you are looking at.

There is also a free software download available, but it had no tech manual with it when I looked at it (years ago, that may have changed); so I did not know where the numbers where coming from, so I didn't feel comfortable using it blindly.

RE: Storm Drain Inlet Blow-by

Visual Urban is a Freeware program that automates the HEC-12/22 from FHWA.  It can be downloaded from the FHWA Website.  I have compared results with the nomograghs and equations from hec-12 and it produces acceptable results. As stated above sreadsheet can be coded with the equations and easily viewed for your study.

Good Luck & Have Fun

RE: Storm Drain Inlet Blow-by

Neenah Foundry Co. has done actual tests on their frames and grates.  Try their web site or give them a call.

RE: Storm Drain Inlet Blow-by

Maury makes a good point.  A high-efficiency grate is probably going to help more than gutter geometry, and Neenah tends to be very responsive.  Make sure it meets bicycle-safe requirements...maybe fax a cutsheet to the reviewer and/or your DOT.

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