The Northern Wasteland base is located under the "Second Chance" bar in Wellspring. It will become available after completing the quest "Liberate Captain Marshall"; Elizabeth Cadence will move down there and free the stairs so that Nicholas Raine can pass. It is also available during two Wasteland Legends co-op missions, "Water Service" and "Unwanted Guests". Since the Resistance mainly operates in the Eastern Wasteland, this location is considered the secondary base.