Orifice, Weir or What?

If you’ve spent any time at all at this website (or any other site for that matter) you know that I don’t do a lot of public postings. So this is strange that I’ve made two posting in less than two weeks. This is pretty cool for a geeky engineer like me and thought it you might think so too. Last October (sorry it took me awhile to fugure out how to post the video) we had a huge rainstorm. I don’t know what the intensity was in technical terms (50-yr; 100-yr; etc). I do know it was a lot of water in a little time. This caused about 12″ of ponding at the inlets in the parking lot of our Chicago office.

Normally, when designing an inlet grate for flow capacity, it’s modeled as either a orifice with H set to the height of ponding or modeled as a weir with the length and other variables dependent on the grate geometry. Maybe I haven’t done enough designs, but I’ve never modeled an inlet the way this one was behaving.

Check out the video. Pretty cool. I really need to get out more….


  1. MAnderson says:

    Hmmmm… I don’t remember it raining last week! It snowed in the Chicago area. 😉

    About time you got the video up!

  2. You’re right Matt! Geesh this post is old! Its from October. I couldn’t figure out how to post the video so I had to settle on YouTube.

  3. MarkEvinger says:

    Normally I’d jump up to say “or firm designed that”, as we did most of the Hamilton business park there…

    However; that parking lot is most assuredly is *not* one of ours!


    Keep on sailing!