Omit any parts of the project that you suspect are plagiarised, then assess the project as normal. In the general comments to the student, give your normal feedback, then state the parts you thought were plagiarised and where from.
Naturally if most of it is plagiarised then they will meet little to none of the criteria. After you’ve submitted your assessment, just sendAngusan email so he can note it.
The students have a right to appeal, which will be administered by BSA staff. Look here for more information on that process.