I've had a read of sites explaining retaining walls however my project is slightly different. lve got a septic tank buried in my garden that required me to dig it out recently to be emptied. The tank is approximately 4-5ft deep, I've now dug out all around it and now look like it's at the bottom of a crater. My plan is to build a wall right round it and top it off with railway sleepers, then backfill to level everything off. As the wall will be square and 4 sided do I still need to beef it up to cope with backfilling, or will the 2 walls at 90deg to the other 2 create it's own support?
Length of walls will be 6ft x 4ft then around 4-5 ft in height. The sleepers will be placed internally to sit on a wooden ledge bolted onto the wall to lie flush with the top of the wall. Any advice appreciated.
