I wonder what semi permanent structures we are building now that future generations will be looking at in 80+ years and wondering about our archaic technology.
Possibly a lot of traffic structures, since vehicles and transportation may be largely computer-controlled by then, which would re-shape any related infrastructure that has "just made sense" to us in recent history
The waste water storage tanks at the Fukushima nuclear plant will probably still be around and contaminated 80 years from now. Although I suspect that isn't exactly what you had in mind.
Just fill them with grain and have the birds eat it all. Problem gone.
If the problem was "How can I spread radiation throughout the environment?"
Release a large number of cats to catch and eat the birds. Solved once and for all. ONCE AND FOR ALL.