While it's easy and cheap to get your own shredding machines for normal circumstances, there may come times when you have a ton of paper to get rid of. You might just haul it off to the back corner of the lot and torch it, but that's irresponsible and may wind up costing you, big time — pollution damages, the fire getting away — you can imagine the maybes. Better to look into the use of a shredding service.
A Mobile shredding service truck
There are two kinds: those that will come to you and those that you'll have to ship to. If you have a compact bundle of stuff to dispose of, say up to a half-ton truckload, it's likely more economical to drop it off at a shredder central site. Otherwise, get a mobile service. They will either pick your stuff up or send a truck to your site. If there is a concern as to the ultimate destination of the paper — after all, a pickup service might just dump it somewhere out of site — then you'd be better off having someone come to you. Then you keep control of the ultimate disposal of the waste. Shredding companies make some of their money by selling the shredded material for packing; this isn't a major concern since your documents will be mixed in with everyone else's; but don't send out Top Secret stuff if you're worried about it.
There are shredding services in every metropolitan area; you can pick and choose. Iron Mountain, which also provides storage solutions, is a major provider. One of the largest services is the Shred-It subsidiary of Securit, of Oakville, Ontario. The company was founded in 1988 and now boasts of 150,000 customers, serviced from 130 locations, on five continents.
If you fancy getting into the business yourself, there are lots of options. Allegheny Paper Shredders, of Delmont, Pennsylvania, has been in the mobile shredder machinery business for over forty years, and there are many other providers.