PORTLAND, Maine — It’s cliche, but University of Southern Maine professor Travis Wagner really does believe one man’s trash can be another’s treasure.
Wagner said that Maine’s — and America’s — landfills are the next frontier for the mining of precious metals. He conservatively predicts that there’s more than $114 billion in metals buried in the country’s trash dumps, just waiting to be mined.
The tip of that economic iceberg, as it turns out, is right in Wagner’s backyard. The academic is finishing work on a case study analysis of a metal mining operation taking place at ecomaine’s southern Maine landfill — the first successful trash-to-mine effort in North America.
“Would you take a $20 bill and bury it in your backyard? Well, that’s what you’re doing when you landfill something [that has value],” said ecomaine Communications Director Frank Gallagher. “It’s our mission to capture that value for our member communities.”
Representatives of ecomaine, which stylizes its company name with a lowercase first letter, estimate that since late 2011, nearly 27,000 tons of metal worth more than $2.3 million have been mined from its landfill, which exists on 240 acres over parts of Westbrook, Scarborough and South Portland.
The waste disposal company, which is owned and operated by 21 southern Maine municipalities, already puts its collected trash through an elaborate process to sort out recyclables, then burns whatever’s left at a power plant to generate nearly 100 megawatts of electricity each year.
And since 2012, ecomaine has used a powerful rare-earth magnet to pull out even more of the metals than its 2004 electromagnet did.
Yet, tons of pre-2012 ash still remain to be mined, with plenty of value to be extracted.
“Maine has done a lot to pull metals out of the waste, and yet it’s still lucrative,” Wagner said.
By the time just the ashfill part of the landfill facility is mined completely, Gallagher said he expects as much as 45,000 tons of metal to be pulled from the debris, worth approximately $3.9 million.
That estimate could balloon further if the mining operation continues to refine its ability to isolate more valuable nonferrous metals — such as aluminum, copper, gold and silver — from the mix, Wagner said.
The USM professor said the nonferrous metals are worth about 17 times as much as the more magnetic — and thus more easily mined — ferrous metals like iron when burned.
Ecomaine has a deal with cutting-edge Ohio firm Reserve Management Group to do the mining.
“They’re getting a higher value for the aluminum and copper. This is a private company that’s doing it, and there are some proprietary issues, but just looking at the market value, aluminum is getting like $1,400 or $1,500 per ton,” Wagner said, adding that the $3.9 million estimate “doesn’t take into account copper and aluminum.”
The process to mine at the ashfill starts with excavation by heavy equipment. Specialized equipment then pulverizes and sorts the resultant clumps by size, and then magnets are used to pull the remaining metals from the material.
As valuable as the metals are, Wagner said the landfill space is nearly as beneficial. Gallagher said the mining operation has removed 10,500 cubic yards of material from the ecomaine ashfill, which Wagner factored out to be worth more than $430,000 in cost avoidance, and those numbers will continue to grow as mining continues.
“By pulling these metals out, they’re significantly reducing the air space and can add more ash there. As much as ecomaine is getting for the metals, they’re saving money by not having to add more landfill space,” Wagner said. “That’s an important aspect that’s going to be equally prominent in decision making.”
The issue of space can be looked at a different way, as well.
“By mining landfills, you recover resources that you don’t have to go out and mine from the natural world,” Gallagher said. “These are metals that are right there. If you come up with a ton of nickel, that’s a ton of nickel you don’t have to pull out of virgin land somewhere.”
Currently, mining metals from what Wagner called “raw” — or the more visceral “wet” — garbage is a process still wrought with risk. Extracting metals from a volatile soup of dirty diapers and old mattresses, among other things, is more expensive, less precise and threatens to exacerbate methane and toxic leachate problems already plaguing many traditional landfills.
But Wagner said researchers are looking for ways to make mining of wet landfills profitable. For starters, he said, ferrous metals that can be captured without first having been burned into ash are worth approximately $170 per ton, about double what they’re worth charred.
“At some point, with basic economics, people are going to see the value in the return and they’re going to get into the wet areas,” he said.