Knowledge transfer / Hivemind among site staff and getting it written down.
Our school site is byzantine in layout and configuration. We very recently had a fire alarm installer almost in tears of frustration because a) he was working from poor documentation from 1992 b) we've had lots of work done since then c) the original install is not logical at all.
The info is available if you ask, but you need to know who to ask, which itself requires asking people who to ask. Too often this is ending up as "Pete will know". As people retire, more knowledge is lost.
Has anyone managed to get their site staff to document things? How well did it go? While a wiki would be ideal, I think it'd be a barrier to entry in a few cases.