1. Contract this out to a mining company and have it overseen by the EPA. There are plenty of mine-tailings lakes that could be immediately employed. Sure they will leak into tributaries of major rivers, but hey it's a national problem. Anyway the effects are unlikely to be much worse than leaded gasoline.
2. Guantanamo Bay. It is US territory, and the people who live there are already too dangerous to move. Could be the basis for a fascinating study into the effects on radiation on people. Better than using your own troops.
3. Ask Walmart to dump it off the coast of California. Will require some extra cost to employee marine biologists to identify any sites of the CA coast that haven't been dumped on - no point leaving a job half done.
4. Work with Trump: who needs a fence when you could build a moat, a giant moat filled with radiation. A modest and very intelligent idea. On the U.S. side this could be landscaped by Donald's wig maker who already specialises in things that look like irradiated desert plants.
5. Frack and Dump strategy. OPEC, and with it a dozen of America's least favourite countries are being crushed by U.S. oil. So why not crush the international black market in nuclear materials with US nuclear waste? It will then almost certainly be used in the Middle East or Europe (may as well wipe out Europe before it is totally overrun).
6. Just wait for Putin to nuke Estonia or Warsaw. There are two options here. One is to then dump it at ground zero, or (the best long term option) - fry Russia and dump it there. Hell this should have been done years ago.