Coal ash in the US is not currently classified as hazardous material. Part of the issue is that some want to use it to do what the Aussies are doing, use it to make concrete. Classifying it as hazardous would preclude that in the US. The argument is that stabilizing the ash in concrete renders it nonhazardous.
Concrete replacement: The Melbourne invention turning toxic soil into bricks
https://www.smh.com.au/national/concrete-replacement-the-melbourne-invention-turning-toxic-soil-into-bricks-20240117-p5exvm.html