Extensive damage to your wall can occur from incorrect placement of fill behind your wall. Material should be PLACED not PUSHED behind the wall. Pushing can result in sleeper displacement, cracking and failure.
Compaction should never be carried out above a wall; a void should always be left between the wall and material being compacted. Machinery should NEVER drive directly above your wall or within 1.5 metres of the wall.
Retaining Wall Industries has standard backfill practice sheets available to you upon request to hand to contractors.