The comment intrigued me, and reminded me of a reference in Green Mars by Kim Stanley Robinson to landfill mining. At the time it made quite an impression on me. The idea of mining landfills, of these vast dumps of that must hold incredible value which is currently unattainable. It is an amazing idea, and you wonder if you could recover it.
Then you spend years in the industry and learn the many, many reasons for why you can't recover the value. Perhaps the reasons are sound, though a Fast Company article in 2006 suggests that the economics are beginning to change.
So lets go back to Green Mars and see what was written.
Before its acquisition, he [Art Randolph] had been the co-founder and technical director of a small company called Dumpmines, which was in the business of digging up and processing old landfills, recovering the valuable materials that had been thrown away in a more wasteful age.
So when starting Dumpmines he had taken the technical directorship, and had done some good work on their Super-Rathjes, the giant robot vehicles that did the extraction and sorting at the landfills...
Robots digging out and sorting waste from landfills. Obviously not now, and maybe needs development in waste sorting technology to recover the most valuable components that then cover the cost of processing. The gold and so on that is in the waste.
But perhaps we are getting close. Perhaps if we look at landfills that occupy valuable land, we might manage to make it pay off. The gold might not be within the waste, but beneath it.
So thanks for the comment Ken, it reminded me of some inspirational memories.