countersunk culverts 1

[kingpawn]

I am designing a subdivision road that crosses a drainage swale. In order for the roadway centerline to be at a reasonable elevation I will have to countersink my arch culverts. My question is...will the capacity in the culverts be same if I countersink them? The roadway is near the adjacent property so, I am trying not to minimize my headwater elevation. I am using the HY8 program.

Thanks for your time.......

 

[LCruiser]

Not sure what you mean by "countersink." Are you talking about depressing them below existing flow? If you create a bathtub you can have lots of problems including silt, mosquitos, etc. depending on where you are. Use more smaller pipes, run the outlets to a lower elevation, or raise the road.

 

[kingpawn]

Yes....The pipes will be below the flow line.....If I raise the road to much the lots will have to be filled. I was planning on a rip-rap basin on both sides of the culvert.

 

[LittleWheels]

That sounds a lot like the shape of Minimum Energy Loss culverts

http://eprint.uq.edu.au/archive/00002562/01/iahrss1.pdf

might be useful to you (from a quick Google search). I know how they are designed to work but have no actual experience with them. They are mostly used in flood plains and are dry most of the year. Some are grassed, most are concrete.

 

[Maury]

Follow LCruisers's suggestions. No good will come from setting the culvert in a hole, even if the hydraulic calculations say it will work. Riprap won't prevent standing water or keep the basin from silting in.

 

[proletariat]

Make it a wet crossing. Who needs a pipe? It will be a fancy "water feature" of the development hearking back to the days of yore, and should go nicely with the vinyl siding on the houses.

 

[ACtrafficengr]

Now that's thinking outside the box culvert! <grin>





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"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail."

Wm. Phelps Eno, ca. 1928

 

[proletariat]

In all seriousness though, how about a cattle grate crossing? Could you ever get that approved?

 

[LCruiser]

Or just a small box with a low flow on top...

 

[cvg]

if this is the access point for the subdivision, you are probably going to be required to maintain a dry crossing for emergency access. If that is the case, a bridge, more culverts (multiple pipes) or raising the road may be the best option.

 

[dicksewerrat]

Look at some low profile box culverts. Call Hansen Pipe for info. you don't say how much water goes through drainage area.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[trz]

My question is: How do you calculate the effective 'moment of inertia' of two steel beams ( one on top of the other ).

 

[LCruiser]

trz - I think you're in the wrong thread.