Cleaning Up the Cold War’s Nuclear Legacy at Hanford https://spectrum.ieee.org/aerospace/military/a-glass-nightma...

"During Hanford’s plutonium-production heyday, workers discharged some 1.7 trillion liters of waste liquids into soil disposal sites, which developed into vast underground plumes of toxic chemicals, including the carcinogens hexavalent chromium and carbon tetrachloride [PDF], that infiltrated aquifers."

No active reactor but 53 million US gallons (200,000 m3) of high-level radioactive waste stored within 177 storage tanks, an additional 25 million cubic feet (710,000 m3) of solid radioactive waste, and areas of heavy Technetium-99 and uranium contaminated groundwater beneath three tank farms.

https://en.m.wikipedia.org/wiki/Hanford_Site

Federal government promised to clean up but failed.

Hanford predates commercial nuclear power this is manhatten project era site. they made the plutonium for trinnity Nagasaki and they really didn't know much about how to handle radio active materials back in the early 40's. Hanford the idea was hey this stuff is dangerous lets through it in the vat of other dangerous stuff* we need to get rid of.

* other dangerous stuff being fun things like mustard gas and nerve agents

This was supposed to be cleaned up purified put into safe modern radioactive waste containment vessels and stored deep in Yucca mountain until the NIMBY folks got involved.

That's how it should work, but there have been ~15 or so reactors built there, with many of them in the 40s and 50s before there was adequate safety.

There was also the issue of "waste" being removed from those reactors for processing into more than 60,000 weapons.

The waste is leftover from cold-war-era plutonium production for nuclear weapons.