We are about to go into Phase 2 and 3 of design, which will include 8No. design work packages all interlinked. Phase 2 scope is detailed design for work packages 1 to 7, however package 8 requires further R&D and a preliminary design. The scope for packages 1 to 7 are well defined, but there are uncertainties around package 8 scope. Another added complication is the fact Phase 2 detailed design for packages 1 to 7 can not be finalised until package 8 Prelim design single option is known.
Phase 3 is simply detailed design of package 8.
Is an NEC 4 Option C suitable for the above for the entire Phase 2 and 3 scope, even though package 8 scope isn’t fully defined, albeit we have a good idea of what the final option could be, so we could make assumptions on scope and and key dates in the Scope?
Or is an Option E more suitable?
You could use Option A or C and in the Scope for package 8 state some assumptions about what is required to enable it to be priced accurately.
The Scope for package 8 could be limited to just phase 2 R&D and preliminary design with phase 3 detailed design being instructed as a change to Scope once you know what it is. This change would then be dealt with as a compensation event for cost and time. Alternatively you could include everything in the Scope with assumptions about the phase 3 detailed design etc then the compensation event would be just for the difference between what was assumed and what was ultimately required.
Another alternative would be to use Option G (NEC3 PSC but could easily be added to NEC4 PSC by Z clause) and call-off each phase / package as a Task Order.
The timing of the phase 3 R&D and preliminary design is irrelevant really, there’s nothing to stop it from being required before phase 2 can be completed, this just needs to be stated as a constraint in the Scope or possibly you could use X5 sectional Completion or Key Dates for each phase / package.