I would suggest that the benching detail is part of the Contractor’s design solution (to restrict the settlement) and therefore is not a CE in accordance with 60.1(1) which directs
"The following are compensation events.
(1) The Project Manager gives an instruction changing the Works Information except
.
................................
a change to the Works Information provided by the Contractor for his design which is made at his request or to comply with other Works Information provided by the Employer."
The PWDD should be assessed based on the contract drawings and I presume there is a Bill item for the Contractor design element.
"The following are compensation events.
(1) The Project Manager gives an instruction changing the Works Information except
.
................................
a change to the Works Information provided by the Contractor for his design which is made at his request or to comply with other Works Information provided by the Employer."
The PWDD should be assessed based on the contract drawings and I presume there is a Bill item for the Contractor design element.