Today we were moving fill dirt around in the east Cobb area. King wall company is building a wall off of horseshoe knoll and we are hauling the dirt for them to backfill the wall with. Topsoil would not be a good fit in this area as the topsoil holds water and the weight would eventually cause the wall to fail. So what makes good fill dirt? Usually a red Georgia clay that is free of any roots is best. Different types of fill dirt can be used. On this particular job they have a soil engineer onsite testing the soil as it is bein placed.