This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Chief Engineer Hinderweir wants you to swim down to the base of the dam, locate the powder keg and stir in the Disarming Mixture to prevent an explosion.
Earlier today I spotted some Dark Iron Insurgents swimming toward the Dam with a large keg. No Mountaineers were on hand to stop them! I'm afraid they've planted the Seaforium at the base of the Dam and it could blow at any minute!
Now I need you to take this mixture and stir it into the keg before it's too late! Hurry!