Question for Borderlands 2 players

In the southern Highlands area there's a small industrial type facility by the water with a tower up on a cliff behind it. By the water there's a small building containing a loot chest but with entry blocked by a forcefield. Anyone know how to switch off that forcefield? I've climbed right up the tower on the cliff (that's where the wires lead) and can't find any switch up there. Haven't found anything in my Googlings or even on the (usually excellent) Borderlands Wiki. Maybe nobody has figured it out yet? If you have though, post it here! :)