This may not do quite what you expect. Using an access value of permissive means that anyone is permitted to use that road, but that the permission may be revoked at any time.

If this is the service road for the waste water treatment works, then destination may be appropriate, or private if explicit permission is required in advance (or if there's a locked gate).

There's a full explanation of access tagging on the Wiki here:
https://wiki.openstreetmap.org/wiki/Key:access