How do I construct a land bridge?
 

Good Day,
I have a 1/2 acre detention pond that I would like to split in half with a
land bridge down the center. The maximum depth is 4'. I need some advice on
what type of material to use and the proper layering of that material. The
end result should be a walking path that would be used on a regular basis.
Construction guidance is appreciated.
Thanks in advance,
Ted