erosion on downstream edge of road 4

[queque]

A road crossing a Desert wash (Apache Junction,Az) is eroding on the downstream edge of the road. The road has a 4 inch layer of asphalt on it. It has scoured 2 ft. below grade on the downstream side and has eroded
about 2 ft. into and underneath road. Is there a formal engineering solution to this problem? I cannot locate typical discussions on USACE procedures or USFS techniques.
I appreciate any comments.
queque

 

[cvg]

sounds like Gold Canyon, that would be a 25 - 50 year storm. That area always seems to get a lot of rain...