Scour Analysis for Open Bottom Arch Culvert 2

[debgallery]

I'm designing an 8'x4.2'' open bottom arch culvert to be used in a stream with a 100-year flow of 147-cfs. I'm using HY-8 for the culvert analysis - a HEC-RAS model is beyond the scope of this project. The footers for the culvert have to extend about 4.5-ft down to get below frost depth and there will be headwalls and wingwalls at both the inlet and outlet. How can I perform a scour analysis on this type of culvert to ensure the footers are deep enough? is this even a concern?

 

[cvg]

with maximum velocities of around 4 fps, I would not think that scour would be that big of a concern.

 

[gbam]

Live bed and contraction scour based on sediment fraction and velocity. Check out HEC-18. Make sure that your long term scour/bed change will not lower the channel bottom too much also. All are addative.