My wood burning stove has disposed of more sensitive documents than an FBI shredder. 20 pounds of paper is worth about $3.50 in heat. I continue the fire with wood for a few days so there is not a trace. What little ash is left is scattered to the wind in the forest. .
I really enjoy burning shredded stuff. The shreds lights off like a torch when moistened with a little used cooking oil. It makes great fire starter!
Find a friend with a wood burner. Do it in the winter when the stove is in use.

I was going to suggest either burning in a stove/fireplace/BBQ grill or get a cross-cut shredder; not just the one which does strips, but a cross cutter as well. That way you have zillions of little tiny squares. And it comes in handy if you ever need confetti for a celebration :)

Use a cross cut shredder and then a burn bag

Bonfire, don’t be suckered into paying 5 bucks for a couple paper bags, just throw it in a firepit.

Since you mentioned cost-effectiveness as a criterion, if you don’t have access to a burn facility (or woodstove, bonfire or other cheap method of burning), then I’d suggest the cross-cut shredder as well, followed by recycling the shredded paper. Burning is cheap if you’re already operating an incinerator, fireplace or other controlled burn, but if you’re in the city, that’s more problematic.

This might depend, though, on the volume of paper that you have to dispose. Individual sheets such as those that a person working an office job on a daily basis – maybe 50 – 100 pages per day or so – would be easily handled by any workstation-sized paper shredder. If you’re talking about disposing of millions of pages of documents – paper that would be measured “by the ton” instead of “by the page”, then the advice would change.

@Cruiser

I never even knew there was such a thing as a specifically designated “Burn Bag” (costing $2.50 apiece).

Other than the pretty stripe pattern, why on earth would anyone pay that much for what is basically a plain old paper bag? I really don’t get that.

Am I missing something significant here?

I am not that interesting, document-wise. So I cut up my documents with a scissors and recyle half of each batch in one trash bag and the other half in another trash bag. I take them to the transfer station on different days.

My banker and my broker know me well and my one credit card co. is aware that when I am going to spend an abberantly high amount, I call first.

I also sometimes burn the paper in my wood-burning stove but for the moment need young knees to empty the ashes. And I can certainly see clearning a little spot in the snow and just burning stuff there, surrounded by high snow walls.

If you want total disposal, yep, burn ‘em.
Ashes to ashes.

The age old, tried and tested method of FIRE.

Get a steel 5 gallon can, poke some holes in it around the bottom side, then burn the papers in the can.

If you decide to burn them and want to be sure of absolute and total destruction so even the ash is gone find someone with a newer reburner type stove. (like mine). The firebox gets so hot you can dispose of anything in there. Once it hits light-off temperature the stove hovers around 750 F. (400 C). If you open the air intake it will jump to 1100 F (600 C) in a couple of minutes.
The UN asked if they could dispose of Syria’s chemical weapons here. I told them “No. The neighbors might object.” :-)

According to this, permitted incinerators should operate at 1,800º Fahrenheit to insure complete combustion, and should use efficient filters to reduce harmful emissions.

My guess is that such a device or one that could pulverize paper might be impractically expensive, so perhaps there’s a secure service that do one or the other.

PQ edit: ”...can do one or the other.”

@Brian1946 At the top of my stove’s firebox are 3 secondary burn tubes which look like gas grill burners. When I start the stove I open a bypass passage which lets the exhaust go straight up the flue. Once the stove is up to operating temperature I close the bypass and the exhaust and smoke from the main firebox is routed into the tubes and mixed with air to burn a second time. Sometime the tubes glow red hot. I have not measured the temperature in those tubes but I do know that steel glows cherry red at 1500 F (800C). I would not be a bit surprised if the temp was over the 1800 F you mentioned. When the system is up to temperature there is no smoke – just heat waves. It is amazing!
And a little scary.

@LuckyGuy that sounds awesome!

@LuckyGuy ” When the system is up to temperature there is no smoke – just heat waves. It is amazing! And a little scary.” Yikes- I’m sure it fits both adjectives! I’d like to see a pic of it if that’s convenient.

@Brian1946 Sure. Here is the link. It is a Lopi Freedom insert. You can look around their site for pictures of how it works.
There are other stoves that have reburners. I selected this one because of size, quality, and made in US.