Anyone who plans to stay in the area and wants to remediate their land should start thinking about working with the microbiology in the soil. Figure out what fungi/bacteria are best for remediation and transmuting toxic substances and start pumping that shit into their soils. Living soils are where it’s at for everything from growing food to cleaning up toxic brown sites. It’s not an overnight process but its tried, tested, and true.
https://fungiforthepeople.org/mushroom-info/myco-remediation/
https://www.researchgate.net/publication/328712018_Soil_Remediation_Through_Microbes
https://www.nature.com/articles/nrmicro2519
Phytoremediation is another option. Look for plants specifically bred for the process or those with naturally occurring abilities to clean up the soils.
https://www.resilience.org/stories/2017-09-26/use-plants-to-clean-up-toxic-waste/
https://www.iamcountryside.com/growing/phytoremediation-plants-clean-contaminated-soil/
https://www.isaaa.org/resources/publications/pocketk/25/default.asp