Thursday, February 17, 2011

Inlet Mistake

This week I’m taking the State of California required Qualified SWPPP Developer course. In the parking lot of the facility 100_1329I noticed an inlet that just didn’t look correct. It appears that the top of grate is a little below to a little above the adjacent curb. The grate inlet was part of a retention basin to treat water. It appears that the water from the parking lot is supposed to flow into the basin and fill up. There is a low flow inlet at the bottom of the inlet to allow the water to meter out of the basin. If the basin fills up the water is supposed to exit the basin through the grate. The flow into the grated inlet should exhibit weir flow. Unfortunately it takes some available elevation above the grate to allow an adequate amount of water to flow out, which as shown in the images below, it doesn’t have. Water is going to exit the site over the curb instead of exiting through the inlet.

Today’s post is interactive, in that I want your opinion on if Civil 3D should include a basin design feature to help prevent these type of mistakes. Now this is just for my personal curiosity and has nothing to do with Autodesk.



Unknown said...

We have started modeling all structures in 3d as well.
My guess is pond was on a different sheet, so it wasn't part of the overall design.

JaysonE said...

It looks like to me that one corner of the inlet is only slightly lower then the top of curb. And since the the parking lot/curb flows in that direction, water will build up and flow into it. But it does look like the curb should be at least 6" higher then the weir/inlet. Probably some bureaucratic reading construction plans told the engineer to do it that way.


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