I'm considering a tapered retaining wall - L shaped. The 90 degree would be the highest point of approx 30" inches. The long side is about 50 feet long and the short end about 10 feet long. I plan to fill in the area and make it level for a slab that will wrap around an in-ground pool. I plan on doing cutbacks or deadman ties approx every 8 feet.

How long would this last? 40 years? I realize water run off plays a roll. I was going to fill with crushed concrete. The slab would be about 10 feet wide also L-shaped. Price is my concern so I selected pressure treated. Is that the best choice? The wall does not have to look pretty but functional. A foot would be very expensive for cinder blocks.

Any suggestions?