the contractor! Period.

I just wonder if there's a drainage pipe or any water pipe embedded in that area. Pipe might be damaged during compaction unknowingly and it's only now that the sign are visible.

Contractor is obligated to repair the damaged portion. This thing happens and somehow unforseen. Need to open the underground to determine the extent of the damage prior to repair. No superficial repair should be done without proper investigation of the subsoil and underground structures if there is!