I believe I can backfill to 14' with the Prescriptive method(no engineering). I've done 18' with buttress walls...engineered.
How many inches do you want 4,6,8,10,12,14,16? I've done 6" with 10' backfill.
I'd use Steel sheet or Ply/osb. Brick, stucco, stone anything is possible.
I most...