@gbam, we are proposing bottomless culverts at a couple other locations but they are much more expensive. The nationwide permit allows for 300 lf of stream disturbance so we want to maximize this allowed disturbance to minimize costs.
Thanks for the reply, yes what you're saying makes sense as the velocities will increase in the culvert regardless of having a buried bottom or not. On top of that the topo on the project site is very steep; the longitudinal slopes of the streams are 2-4% at the crossings and the contributing...
I'm designing a couple culverts (one 8x4 box, one double 72") for stream crossings and here in the state of Georgia the culverts must be 20% buried in the stream bed. Is energy dissipation required with buried culverts? I considered designing a rip rap basin at each outfall but began to wonder...