The 141-car Norfolk Southern train derailed Sunday, causing local authorities to evacuate nearly 4,000 residents from Farragut, Tenn., and the surrounding area.
Residents living farthest from the crash site were told Monday they could return home, while others closer to the leak are still waiting for the okay.
Knox County Sheriff Tim Hutchison said his department was waiting to hear from the railroad and the Environmental Protection Agency (EPA) if the remaining residents were allowed to return to their homes.
Emergency responders diluted the sulfuric acid with water, lime and soda ash. They said the chemical did not make it to nearby Fort Loudoun Lake and that none was detected in the air outside of the 1.3-mile evacuation area.
The National Transportation Safety Board, the Federal Railroad Agency and EPA are investigating.
