It relies upon whether you need it to be structural, for example, are you working over the wall, or whether it should drain.
For a draining area, sandy soil might be your smartest choice, or sandy gravel, since water goes through this material effectively, and it will, in general, reduced effectively as well. You can include a seepage pipe at the base of the holding divider to keep the water from moving through the solid, causing recoloring and flowering, as well.
For a retaining wall where a structure will be based on the fill, you need a more grounded soil mix, either sandy dirt, or silty sand that compacts to meet the auxiliary necessities. This should be dictated by a geotechnical engineer if the load is basic since settling can make shear and dynamic powers be made against the holding divider, and relying upon conditions, the holding divider could even be overwhelmed by these powers. In any case, it would be to your greatest advantage to fill and reduced the inlay in lifts with the goal that it doesn’t settle subsequent to filling.