Cleaning up a spill, a huge contamination in particular, would be very expensive. Therefore, if you notice a leak, stop as soon as you possibly can and get off the road. Stay with your vehicle because of liability and safety issues and send someone else for help. You will need to send a large amount of vital information, including where you are, your direction of travel, the hazard class and ID numbers, your carrier's location and the cargo's destination. Make sure you write it all down for the person seeking help.