When Kai Tak airport, Hong Kong was de-certified and the government wanted to sell it for housing and commercial use, the 'elf 'nd safety bods in the environment department said they better do some checks. 60 years of fuel and oil spills on the concrete had seeped into the subsoil and to bring it back to building standards they had to take two metres off the top of the airport and steam it clean. As I remember it took about six years. Two metres times the size of an airport is a lot of rubble.
So perhaps if you want to make sure that developers cannot economically re-develop your airport, keep killing the weeds with the fuel drains and remind them when they come round to buy it that they will have to clean up the entire airport.
