This looks like prolongation of an operation on the programme, which is not on the 'critical path', and has resources allocated to it, whereby the compensation event uses 'programme float' or 'free float'.
The issue of cost reimbursement associated with prolongation of an operation depends upon the planned use of the associated resources and whether the operatives involvement on the project is extended due to the compensation event.
For example, if tunneling activities were delayed by a week, due to a compensation event, but this did not impact upon the 'critical path' then you would compensate for that extra week, provided these resources were not required for 'follow on' operations but were planned to be released upon completion of tunneling operations.
If the operatives' time could not be mitigated and they would still be paid, then any additional Defined Cost would be assessed and included in a quotation, including any relevant non-productive time.
You are effectively putting the Subcontractor back in the position they would have been had the compensation event not occurred, which is the philosophy of the compensation event procedure.
The issue of cost reimbursement associated with prolongation of an operation depends upon the planned use of the associated resources and whether the operatives involvement on the project is extended due to the compensation event.
For example, if tunneling activities were delayed by a week, due to a compensation event, but this did not impact upon the 'critical path' then you would compensate for that extra week, provided these resources were not required for 'follow on' operations but were planned to be released upon completion of tunneling operations.
If the operatives' time could not be mitigated and they would still be paid, then any additional Defined Cost would be assessed and included in a quotation, including any relevant non-productive time.
You are effectively putting the Subcontractor back in the position they would have been had the compensation event not occurred, which is the philosophy of the compensation event procedure.