Chris Hogg posted
It could be dumped at sea, I suppose, that's a big enough pond, but FOE
would be up in arms, claiming it was killing the fish.

This certainly used to be done until the 1970s at least. One of my worst
ever jobs then was to carry asbestos lagging removed from old ships'
boilers and pipework, and tip it into the holds of other ships, which
then took it out into mid-Atlantic and dumped it.

--
Jack