

Clear the pests out (be wary of a tripwire attached to a Grenade Bouquet in the south-western corner of the dump) then get to looting.

The first area you should come across is Jalbert Brothers Disposal, which is infested with Mole Rats. You’re the General of this pathetically moribund operation, so you can do as you damn well please but it also gives you an excuse to explore further south and keeps you out of the more difficult areas to the south-east of Lexington for now, so fast-travel back to the Corvega Assembly Plant and make your way south-west. If not, you can still go and complete the quest there, with or without Preston telling you about it.

Preston may have told you to check out Graygarden, which is south of Drumlin Diner and south-west of the Corvega Assembly Plant.
