Main Contractor priced tender drawings which showed contradiction between construction sequence and design intent. After contract award design issues raised through EWN process. Design not amended by client. Design delivered by main Contractor, is there grounds for compensation to make the design buildable?
This sounds like there is an ambiguity between two items within the Employers Works Information. Clause 17.1 states that either Party should notify each other when they become aware of an ambiguity or inconsistency between the contract documents. The Project Manager should then issue an instruction to resolve an ambiguity. Clause 63.8 states that an instruction to resolve an ambiguity is a compensation event which should be assessed for the interpretation most favourable to the Party which did not provide the Works Information.
If neither party had spotted this ambiguity before it was installed them it would seem as though this would be a valid compensation event to the Contractor IF you require the design intent to be met.
There is also the question as to whether there are any Z clause amendments specific to your project that may change what we have stated here.