I'm in the early stages of planning for a small implement shed, 16X32, to be built adjacent to my barn. There is a 42" change in elevation between the barn and the front wall of the implement shed. I'm debating building a block wall at the back of the shed or using pressure treated lumber. Pressure treated will be a lot quicker and cheaper so its my first choice if it will be durable enough to last ~20 years.

Has anyone used pressure treated for this type of wall? How well did it work. I see a fair number of pressure treated retaining walls, but they're all relatively new so I'm not sure how well they hold up.