After a once in 20 year clearout I have about 20,000 A4 sheets of paper (2m stacked up) that needs shredding.
A test of about 5cm of this stack shows that the time taken, volume of "shred" and dust dont make it sensible proposition to use my fairly powerful 12 sheet home shredder.
I see a few commercial services, but they look more oriented at big commercial quantities. Im waiting for a response from one (dataex 4000).
For an occasional one-off (i.e. no strings attached ad hoc arrangement) secure document disposal I've used Reisswolf, albeit for our office use. They have a variety of different sized containers which they drop off then collect when you need them.
Costs about CHF 37 for their smallest container, which held about 30 lever-arch files worth of paper.
I don't have your quantities, but when I dispose of bulk documents, that is more than my shredder can sensibly take, I soak then overnight in soapy water then tear them and roll the bits into balls and put them into the normal household waste.
I have a company I can run the contract through. RW also recommended by another source; awaiting quote... reminds how backward CH can still be for this sort of thing... wheres the online shop to do that?
I don't have a contract with them, which is why they're great for one-off jobs.
They have a website and I normally just drop their main email address a quick line when I need a new container. They're pretty efficient and cost effective in my experience.
You can reduce the volume of shredded paper considerably by wetting it. The downside is that you increase the weight unless, that is, you are prepared to wait until it has all dried out.