Use the Barrel of Dynamite (in your inventory) where you get the pop up text near the tunnel opening ( -1008, 522, 663 ) Copy/waypoint -1008, 522, 663. Do not fall into the hole or you will die.
Note: if you can invis, you can sneak around the "Overseer" to the left , then go behind the hole to activate the Dynamite.
Return to the Chief Strategist. ( -368, 375, 600 ) Copy/waypoint -368, 375, 600