Burn barrel only works if you stand there the whole time feeding only 1 page at a time. If you are trying to burn banker's boxes worth of files forget it. The paper bundles just char on the outside and inside all your documents will be perfectly readable and remain intact.
Look for a local company that does on site shredding using a self contained truck. They usually charge $20-40 per bankers box to shred at your site. These trucks have shredders that will shred complete phone book or encyclopedia sized items including all bindings like staples and paperclips.
Your wood chipper will handle wood but choke on paper and bindings. It won't chip the paper into little bits.
Look for a local company that does on site shredding using a self contained truck. They usually charge $20-40 per bankers box to shred at your site. These trucks have shredders that will shred complete phone book or encyclopedia sized items including all bindings like staples and paperclips.
Your wood chipper will handle wood but choke on paper and bindings. It won't chip the paper into little bits.