It depends a bit on how far out the civilization is, since even what's now high-level waste will decay over time, but there do exist some speculative reactor designs intended to be powered by reprocessed waste - with output in the single-digit megawatt range, granted, but a megawatt just where you want it is nothing to sneer at.

The thought does appeal, on the whole: archaeologists and engineers working side by side, the former chronicling the deep and long-dead human past through its garbage, before the latter haul it away to melt down and rebuild into a new human future. There's a story in that, I think.