Originally Posted by jludwig
I would make upside "U" out of the culverts then fill the voids with smaller PVC to create a denser structure.

My idea was contemplating structure for LMB.

I also like jludwig's idea. I think his idea would be really good for fish lower down in the food chain. And you would get two structures out of each culvert. (I assume he means to cut each culvert in half.)