IBM has told Kodak that they can read original data up to 16 layers deep on hard drives even after thorough erasure.
Kodak implemented a policy of observed crushing of hard disk drives. Even if the drive is under warranty, if it is crushed and returned to the mfgr, the contract says that the warranty will be honored and the drive replaced.
Just FYI. Kodak takes security seriously and destroys all HDs.