Hello we have a place at that we recently installed and would like to install are you retention wall around it

In order to do that we need to:

1. Dig 2 additional feet into the side of the hill on one side of the play set  in order to expand the leveled area around the play set. We will dump the dirt on other side to create a platform
2. Dig a trench about 6-12 inches deep around all sides of play set. 
3. If interested, help build the wall (we plan to do this but would love some help.