If a contractor prepares an excavation (including provision of support to maintain integrity) and is contracted to reinstate excavation following completion of Third Party works, where does responsibility rest to inspect for structural integrity during the periods when others are working within excavation?

Is it with Civils Contractor with a view to maintaining integrity of their support, or with TP employer who is required to provide a safe place of work. Contract is silent on this point other than to suggest excavation works are compliant with law.

Any thoughts would be appreciated.