It's ok to cover everything up with dirt if that's the look you're going for. It should not affect drainage too much. We did it only temporarily until...
If you have a slope that is need of a retaining wall and have access to railroad ties, this is the perfect project for you! We'll be showing you how we made a railroad tie retaining wall in between two of our shops. We had 18 inches of a hill that needed to be retained. This is how we made a basic retaining wall using railroad ties found on our farm.
Step 1: Level and tamp down the area
First, we leveled the area where to wall was going to be. Actually, it is slightly sloping down away from the building. We then tamped the dirt to make a nice, hard foundation. Tamping the dirt will also help to minimize settling and shifting of the wall. Although, it will settle and shift a bit no matter what you do.