Hmm. So at 2 seconds per shot thats 8500 seconds or 141 minutes. Thats doable.
Problem being that the abomination only has 800 health so will only eat about 200 arrows before dying on you.
So you will need about 21 abominations to pull this off.

Maybe you can get a bunch of shamans and harpoon them into a pit where they heal each other and you can plink away for hours.