The NW Disposal Systems was a pre-War company that specialized in nuclear waste disposal. Their flatbed trucks could be unmistakably identified by the characteristic atom-like logo on their cabs.
Three of their trucks were transporting nuclear waste throughout the Mojave on October 23, 2077. When the Great War took place, two of them were secured in the Searchlight fire station. Their two other trucks are found near the Junction 15 railway station and the Powder Ganger camp west.
NW Disposal Systems is only mentioned in Fallout: New Vegas.