With regards to the SSCC and payment of the People costs element for people who are directly employed by the Contractor and whose normal place of working is not within the Working area but who are working in the working area - How should the contractor provide proof that an employee had been in the working area?
There are quite a few way to demonstrate this from sign in sheets/records to diary pages to a record of the work done by that person on site. The best answer however is to pro-actively ask the PM what is going to be acceptable to him. Why stumble about in the dark guessing if you can switch the light on and agree something.
Building on Rob’s answer, you use the word ‘proof’ which is a strong word to use and implies a requirement to prove ‘beyond reasonable doubt’ which is the level of proof needed to fid someone guilty under criminal law.
However, contracts are subject to civil law where it’s on ‘the balance of probability’. So what evidence with the burden of justification on you as the potential claimant. So it is more a question of (something like) ‘what information does the PM need to see that is sufficient to demonstrate these costs were, on the balance of probability, incurred within the WAs ?’ versus prove it.
As Rob says, the best thing to do is actually have a conversation with the PM about this and match up what he wants to see with what is easily available from you.