Web, unless it rained too much today, I'll assume you met with PB or PC today, so will cover 2 quick points.
1) I can't possibly say whether or not PB knew anything, what I was saying is that; if someone had walked down the slope to the deep end and turned around and looked at the shallow end (with their eye at ~ the plane of the shallow end floor), it would have been fairly obvious - however, i suppose there is a possibility that 'some wierd lighting' might have hidden the 'island'.
2) The pipes don't need sand under them, per se (the co I worked for in Va, did the liner pool plumbing the same way), but sand placed over them, before the other backfill material, should help to guarantee their safety from breaking. The sand will fill any voids under them (SCH 40 PVC is pretty hardy stuff and doesn't mind resting on concrete) and insulate them from rocks, etc, that might be in the backfill material.
Looking forward to seeing what pool dudes said/ did today.