Quest: Rat Trapz (Karak 8 Peaks) ???

[Monteaux]

Does anybody knows how to finish this quest? I carry the Boom Barrel and the quest said i've to plant it in rat ridge. I walked over the bridge into the marked zone and found nothing to interact with to finish the quest.

[Nygardable]

I'm replying to this almost 4 years later because I was also struggling with this quest and this was the only post I saw about it so I figured I would post my solution here and hope it helps someone down the road.

To finish this quest you need to stand on Rat Ridge directly across the chasm from the quest giver and then click to use the barrel inside of your quest items.