Brother Staal wants 3 containers of sludge to make nuke grenades

Brother Staal wants 3 containers of sludge to make nuke grenades is a quest in Wasteland 2.

Overview
The Servants require radioactive sludge to make their nuke grenades. While that is the tribute the Rangers have to pay, Brother Staal will require another 3 containers

Walkthrough
Find another three barrels to collect sludge from and deliver them to good ol' Staal.

The locations of the barrels can are the same as in Pay tribute to enter the Temple of Titan quest