Should we be digging through landfills for cans and bottles?

Should we be digging through landfills for cans and bottles?

Should we be digging through landfills for cans and bottles?

Illuminating answers to environmental questions.
Nov. 13 2007 7:31 AM

Trash Mining

Should we be digging through landfills for cans and bottles?

I'm guessing there are lots of recyclables buried in our nation's overflowing landfills. So why don't we start digging through those colossal trash heaps in search of metal, glass, plastic, and cardboard?

Sounds like you're on the same wavelength as numerous waste-management entrepreneurs, who've long touted the potential of "landfill mining." Since at least the late 1980s, someone has come along every few years to declare that there's serious money to be made from excavating landfills, then shipping off the salvaged goods to recycling plants. (For example, check out thisNew York Times piece from 1993.) It's not an unreasonable idea: Only 32 percent of America's garbage is recycled, which means that plenty of plastic containers and aluminum cans are languishing in our landfills.

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But landfill mining has never lived up to the hype, and the Lantern must confess he's dubious about its prospects. Picking through landfills requires considerable effort and energy, and the payoffs are usually meager: There just isn't enough demand for, say, green glass to justify the cost associated with its recovery. And paper-based products are beyond salvation once they hit the landfill, due to contamination from organic waste such as food scraps and grass clippings.

Some proponents of landfill mining argue that the proliferation of high-tech waste will make the practice more viable, since the innards of computers and mobile phones contain valuable metals; as this article states, one ton of junked PCs contains more gold than 17 tons' worth of raw ore. But it's still prohibitively expensive to locate the right rubbish in a mammoth landfill, remove it using industrial machinery, and then leech out the few worthwhile scraps.

Until someone figures out how to extract those metals for a pittance, the most valuable commodity in a landfill may be something far less glamorous—dirt. Landfills need to be covered in soil on a regular basis, in order to deter rodents and squelch odors. But trucking in fresh soil can be expensive, so it can make sense to dig through the piles in search of old layers of dirt, which once formed the landfill's top but have long since been buried. That reclaimed soil is then poured over the landfill's current surface—sort of like scooping out a cake's middle layer of frosting and using it as icing instead. A decade ago, the Environmental Protection Agency analyzed the economics of soil reclamation at a landfill in Naples, Fla. It determined that mined soil cost the county $2.25 per ton, $1 less than trucking in soil from outside. The EPA also concluded that recycling mined copper, plastic, and aluminum wasn't worth the effort, since these materials "required substantial processing to upgrade their quality for sale."

Mining landfills for recyclable materials isn't just inefficient, it's also a potential waste of methane. When garbage molders in a landfill, it releases methane that gets trapped beneath the layers of rubbish; upsetting a landfill with excavating machines would release this potent greenhouse gas into the atmosphere. Many waste-management experts argue that it's better to leave landfills relatively undisturbed, so that the methane remains locked inside. The methane can then be captured in situ, using wells or vacuums inserted deep within a landfill's center. The gas can be used to generate electricity, or piped to nearby industrial operations that require natural gas. Morton A. Barlaz, an environmental engineering professor at North Carolina State University, points out that such methane-capture operations are currently in place at approximately 450 landfills nationwide. (As of 2005, there were 1,654 active landfills in the United States.) And the EPA is gung-ho to increase that number by partnering with local governments through its awkwardly named Landfill Methane Outreach Program.

Yet not everyone is thrilled about methane recovery. Some environmentalists contend that landfill methane contains trace amounts of toxic chemicals, which are then released into the atmosphere when the gas is burned. The Lantern isn't convinced by the case against recovered methane, but he does agree with the naysayers on one vital point: We'd be a lot better off diverting cans, bottles, and the like to recycling plants before they wind up in landfills, rather than trying to fix our landfill woes retroactively.

Is there an environmental quandary that's been keeping you up at night? Send it to ask.the.lantern@gmail.com, and check this space every Tuesday.