My County has been conducting an experimental landfill “mining” process that has actually been profitable. The County has been running a “waste to energy” trash burning plant for decades (never made money) and then trucking the ashes to a county owned landfill. Recently they began “Mining” the old landfill ash pits for metals and they’ve been making profits even considering the initial costs in startup equipment. Two positives from this are landfill longevity and lowering tipping fees to garbage companies which means a lower garbage bill to the end consumer.
This same idea is writ large as the feds look for rare earth metals in the tailings of old gold mines.