Chances of the drive having any readable data by now is about nil. They're not hermetically sealed so water and goodness knows what else will have heavilly contaminated it by now. Plus it's likely heen crushed several times by landfill vehicles by now too.
I am not an expert, but I have hired experts to do forensic data recovery. I have been amazed at some of the scenarios in which they have been able to recover data, wholly or in part, from hard drives that have gone through fire, flood and pestilence. From them, I have learned that if you want to ensure that your data cannot be retrieved, apparently the best bet is to physically smash, crush or grind the the hard drive such that all the platters are in little bits. This probably explains why so many of the IT guys I know, when we are disposing of computers at the hospitals, not only run the drives through a demagnitizer, but they then use them as targets at the local shooting pit. They only do that for the financial/business computers, though. Anything with patient information on it goes through a monitored and tracked destruction process.
