Rob has thoroughly answered most of the question. I will answer whether "Upon excavating for the offices the Contractor encountered asbestos in the ground that no-one could have expected to have been there."
Under clause 60.1 (12) the unexpected physical conditions have to be within the Site for it to be a compensation event. It sounds as if the Contractor's offices are within the Working Areas - which the Contractor specifies in Contract Data part 2 as being the "The Site and >any other areas needed<", but not the 'Site' bit of the Working Areas.
Consequently, if I have read the question correctly, the answer is 'No, it's not a compensation event.'
Under clause 60.1 (12) the unexpected physical conditions have to be within the Site for it to be a compensation event. It sounds as if the Contractor's offices are within the Working Areas - which the Contractor specifies in Contract Data part 2 as being the "The Site and >any other areas needed<", but not the 'Site' bit of the Working Areas.
Consequently, if I have read the question correctly, the answer is 'No, it's not a compensation event.'