Deposit solid human waste in catholes dug 6 to 8 inches deep at least 200 feet from water, camp, and trails. Coer and - disguise the cathole when finished.
Under Mobutu Sese Seko's negligent and plunderous rule, much of the Belgian-built road system was buried under rainforest or destroyed by heavy lorries and lack of maintenance.
Two other techniques, called gasification and oxy-combustion, work by reacting coal with pure oxygen rather than air, and thus produce exhausts that require little treatment before burial.
Assuming a place is found, another challenge is figuring out how to warn distant future generations who may have a very different language system than ours that the nuclear burial site is not something they want to explore.
In the case of an eruption, the USA would be utterly devastated, with a good half of the American states getting buried in ash, and multiple knock-on effects would shatter much of the world's ecosystems and economies.