Cliffside Railway - Follow the river all the way to the end on the west side and hit Route 66. Follow the road west until the first southward fork and follow it until it hits a cliff and then go in the entrance by the parking lot to the north. The crate can be found by following the edge of the cliff to the other end.
Wrecking Yard - (Colloquially known as the impound lot); from the spawn head southwest past the grocery store until you see an American flag; go down this passage and you'll hit the road. Go down the road until you see a gated impound lot. It'll be one of the first areas on the southeast side. The crate is in the last room of the southern building.
Location: Sitting in the middle of the diagonal stone and wood bridge, north of Jordan.
Objective: Salvage 10 salt
While on this quest, infected will have a chance to drop crab, which can be salvaged for a chance to get salt, and you can also fish in the nearby fishing spots for various fish. Talk to him again when done.