HARD DRIVES?

I sure hope not...how the city of SF could have allowed this scenario to develop is beyond me. His manager and probably even the next fool up the chain should be out looking for other work. It's the manager's job to ensure that industry best practices are followed i.e. proper documentation, change management, cross training, config backup's, etc. It is the manager's job to run bureaucratic interference for technical staff, to ensure they have the support they need and the proper tools at their disposal. Managing a large network is a team effort and should never be a one man show.

There are ways to recover lost or forgotton passwords on network devices. I do not know the tech specs of the affected devices but the device vendors should be able to help recover the passwords if no one else can.

Maybe you're not aware of the "no service password-recovery" command for Cisco IOS devices:
e.g.
http://www.cisco.com/en/US/products/hw/routers/ps274/products_configuration_example09186a00801d8113.shtml

Cheers,
ahb.

Using router password recovery features is mildly annoying, because it wipes out the configuration for security reasons and you have to rebuild it. That's fine as long as you've got either a backup or decent network configuration documentation - if you don't, then you're hosed. If the city's network administrators don't have good documentation, or it's all in one place where one person can trash it, they've got serious management troubles, beyond whatever damage this guy may have done.