In 1960s Greenland during Project Iceworm the American government tried to create a nuclear ice base, aka Hoth Base
Discharging radioactive waste into ice used to be considered a viable method of waste storage.
With the half life it would basically be non-radioactive long before it ever exposed to anything other than ice.
With the current rate of ice melting it’s no longer viewed as a very reliable method. That being said it all depends on location. If the liquid was dumped in an area that isn’t going to melt for hundreds/thousands of years then it’s perfectly safe.
You can even put the waste into large concrete disposal tanks and set them on the surface of ice. The heat generated by the radioactive materials will melt the ice below the tank and it will slowly sink into the ice and soon be completely covered where it can finish it’s lifetime safely stored in a vault of concrete and ice. But like I said it depends on the rate of ice melting.
FUN FACT: The US also offered to buy Greenland for 100 million dollars.
A hypnotizing old documentary about the construction of the nuclear powered research center built by the US Army Corps of Engineers under the icy surface of Greenland