said by Goober:Funny. The installer guy said the exact same thing in almost the exact same words when he was explaining it to us.
said by John Galt:You don't want to use a 'tamping' machine (presuming you do)...you want to use a vibrating plate compactor.
Two different beasties...! 
I agree. That's the correct terminology. I was just assuming that's what was meant. That's probably not a good thing to do since a person may go out and get the wrong thing.
Great advice guys! This is why this forum rocks ...