I am going to begin a small project in the next week and need a little advice. It consists of: Cross-tie (railroad tie) retaining wall. 2 1/2 ft tall at highest point and tapering to about 35 ft long. Backfilling will consist of about 10 tons of dirt. I think my main question would be... do I need to do a gravel footing for the ties to lay on or will well tamped dirt be OK? I am just unsure on a wall that short.