How to unlock: talk to the Caretaker after completing the Mercer Safehouse quest. He will come to the Red Rocket Trucker Shop (M1,4)
In order to obtain this quest, you must tell the faction password and then ask for any alarming matters when talking to the Caretaker. It's a very small quest during which you must clean a specific location. The location is the Federal Ration Stockpile - a warehouse taken over by thugs. Just get to the location and kill all enemies you find there (you will be informed about it).
Watch out for turrets at the entrance. The main location is the bunker's underground where you will face the largest number of enemies. However, if you're in the location for the first time, you can face an enemy in a power armor at the entrance. If you have been here previously and you've cleaned the location, it will be either repopulated or you will be able to immediately report completing the quest.
Quest rewards: experience, 3 Stimpaks, 150 bottlecaps