You'll be able to tell when you're nearing this important dungeon in the Penumbra Plains because you'll start encountering more and more loan shark defense systems and scrap metal as you approach it. The direct area around it is even surrounded with Voltage Spires, which can prove to be very annoying. Also keep on the lookout for things like G-Pods and Drilling Digger machines. You should enter with a highly diverse and able force to rescue the President at the bottom of the dig site.