Most managers struggle with the turnover of people and getting the new ones up to speed. Simple things work here.
Number 1 document your processes and procedures. Even the most simple ones such as vacation and email policies and the complex ones such as development and release processes.
Number 2 don’t make it perfect before you publish it. Better to have people use something that is 90% correct than nothing at all.
Number 3 you don’t need a fancy portal or knowledge base to do this. Simple stuff like open source wiki, joomla, and blogs work great for this.
The key thing with this philosophy is start doing it don’t wait for things to be perfect because they never will. Also by following this managers can spend time managing versus repeating themselves over and over again.