I am building a wood fence with 2" metal posts. I am going to backfill in front of the fence and am placing 2X6 pressure treated footer along the face of the posts to retain the fill. To insure that the wall remains in tact, I am placing additional short posts within the 8' fence spacing.
The largest height of the 2X6's face will be 30".

How many total posts over an 8 ft span should be required? The posts will be set at a depth of 2 1/2 feet.

Thanks!

I would think that every four feet (one post in the middle) should be sufficient but if it's in an area that gets a lot of water... that adds significant weight pushing the wall. If you want too... you can install "deadmen". A deadman is a piece of wood that runs perpendicular to the wall, under the soil with another piece at the back (buried) running horizontally to the wall. It acts like an anchor.