Someone dumped gasoline into a drain on a septic system. How do I fix?

someone dumped gasoline into a drain on a septic system. How do I fix?
This will be difficult to answer since we weren't informed how much gas went in the tank. If it was a lot you could have Hazmat pump the tank and dispose of the fuel. If it were a small amount You could hope it would disperse itself in the 500 to a 1000 gallons of liquid inn the tank. How much was spilled and whoever was dumb enough to pour gasoline down a drain anyhow? The one thing I wouldn't do iis pop open a inspection port and light a match to look in to see. Good luck, Tom

Any idea how much gasoline?
If it is a small amount (quart or less) I don't see any reason to do anything about it. Drain pipe is either galvanized steel, cast iron or ABS plastic. Harmless to metal and the plastic pipe should be OK as well. This amount will evaporate through the vent pipes on your roof after a few days.
If we are talking about a gallon or more then that could be a problem. If you have a septic tank with a sump pump it would be bad for the gasoline to go through the pump as it could damage plastic seals and other parts.