As Alaska said, it's a case-by-case decision for me. Sometimes access has to be maintained for equipment, so a partial backfill is necessary, as long as I can see both sides, OK.
Going to a site and seeing the pole bases in place, and the parking lot sub-base down, now that causes an issue, start digging.
As to site wells, short lengths of PVC sitting on top of the conduit run and above grade may be acceptable, but on a case-by-case decision.
In any case, the EC should talk to the AHJ BEFORE hand to determine what is acceptable. Communications are cheaper then digging twice!