The Golden Highway remained closed in both directions on Tuesday afternoon as work to clean-up tens of thousands of litres of fuel continued.
About 7am Monday a B-double rolled onto its side near Elong Elong.
According to police, the driver escaped without any injuries. A roadside breath test was conducted and came back negative.
Fire and Rescue crews, the Environmental Protection Authority (EPA) and Rural Fire Service (RFS) helped secure the incident scene but the highway is still closed to motorists because authorities believe fuel has possibly contaminated soil.
"A diversion is still in place via Muronbung Road and Cobbora Road," a Transport for NSW spokesman advised.
"This diversion is suitable for all vehicles."
Police said investigations were ongoing.
Members of the public are encouraged to check the Live Traffic NSW website for updates about the status of the road closure and information about when the highway will be reopened.