What is a landfill?

Landfills are carefully engineered disposal facilities, designed to combat the problems you can expect if you just throw trash into a hole in the ground. So rather than dumps, which are just designated areas to leave garbage, landfills involve inbuilt solutions to leaching, leakage, off-gassing, and more.

In the USA, most landfills are municipal landfills that take non-hazardous waste, and a very small amount of particular types of hazardous wastes. A small number around the country handle dangerous or hazardous wastes, and landfills are “stitched in” as far as possible to a nationwide approach to disposal aimed at managing and reducing waste and mitigating its environmental and human impact.

How do landfills work?

Most landfills will have:

  • Leachate and filtration systems, to catch liquid and dissolved or suspended material that would otherwise leach out of the landfill into soil and water.
  • Subgrade and compacted soil, to reduce porosity and prevent groundwater contamination as well as to improve stability.
  • Geo-membrane liners that prevent buried solid waste from contacting soil and groundwater. It’s usually durable and puncture-resistant High-Density Poly-Eurethane (HDPE).
  • Gravel and rock filler.
  • Geotextile filter fabric, designed to prevent fine particulates from clogging the leachate filtration system.
  • Landfill gas collection well, to vent methane gas from the landfill. Landfills are closed and de-oxygenated, but materials — especially organic materials — inside them still break down, developing methane which is flammable and can cause explosions. Landfills use a system of pipes to safely vent methane to the surface, and some burn it for energy.
  • Closed cell or cover to close and permanently seal a landfill or landfill section when it is filled to capacity. These involve polyeurethane plastic to form a seal, compacted soil to form a cap, and a layer of topsoil that is usually seeded with vegetation to prevent erosion.
  • Groundwater monitoring well, used for direct access to groundwater for testing and monitoring.

Landfills are large, complex systems that rely on skilled operation and supervision. They’re also America’s primary form of waste disposal: just over half of all American waste goes into landfills.

where US waste goes pie chart

Source

How many landfills are there in the USA?

There are two main types of landfills in the USA: Municipal Solid Waste Landfills (MSWLFs), which accept solid waste deemed non-hazardous, and specialized hazardous waste landfills.

America has 1,908 MSWLs, spread unevenly across the USA, with a tendency to have more in the South and West than the North and East:

number of landfill in US by geographic region

Source

There are also hazardous waste landfills, regulated under subtitle C of RCRA, and they are much scarcer: just 21 in the USA.

The vast majority of American landfill space is non-hazardous, and much of it is organic waste:

US waste material breakdown pie chart

Source

What happens when landfills close?

When landfills are filled to capacity they’re closed, and topsoil and vegetation is placed on top of them to prevent soil erosion. Without this, the seal can quickly be exposed and then the landfill can leak.

Because landfills are being landscaped anyway, it’s common to turn them into parks or integrate them into wildlife or preservation areas.

For example, Freshkills, on Staten Island in New York, was converted to landfill from an area of marsh and bog in 1948. When the landfill approached capacity in 1991, it was capped and re-envisioned as a public park.

‘Because the site is so large and complex, the park is being developed from the outside in,’ says Eloise Hirsh, park administrator for NYC Parks. ‘Community-facing projects are opening first’, and these will gradually link up. The project is not yet complete, but it’s a common outcome for large landfills — even large and formerly busy ones like Freshkills.

The problem with landfills

Landfills come with several drawbacks: they reduce opportunities to reclaim waste, and they generate significant quantities of methane and carbon dioxide. Methane is a potent greenhouse gas that is also flammable and explosive. In addition, landfills contain liquids that can leach dangerous substances out of the trash. If they leak, these substances enter soil, groundwater and sometimes drinking water. There are often trace quantities of dangerous substances like heavy metals, dioxin and other toxins in landfilled trash, and leaching is unfortunately a great method of extracting and concentrating them.

Landfills can also suffer from subsidence and fail in other ways, though when they’re properly constructed, this is rare.

The biggest problem America faces with its landfills is that it’s running out of them.

The landfill crisis

The number of municipal landfills in the USA has fallen by more than nearly five-sixths since 1990:

Number of landfills in the US 1990 to 2018

Source

The Solid Waste Environmental Excellence Protocol (SWEEP) reported in 2018 that America faced a ‘landfill crisis.’ Waste was already beginning to pile up, triggered by China’s refusal to continue taking Western low-grade plastics, which are very hard to recycle. SWEEP updated their report in 2021, giving details showing landfills closing faster than they were being replaced.

In addition, the introduction of RCRA Subtitle D regulations bottlenecks landfills, forcing closure on noncompliant ones.

This table shows the rate of loss of landfill space across the USA and by region since 2015, using SWEEP’s figures in thousands of tons:

loss of landfill space across USA since 2015

America has lost over 15% of its landfill capacity since 2015, and 30% of the Northeast’s capacity.

How much time does this give the US to solve its landfill problem? In some areas, the issue will come to a head as soon as eight years from now.

Remaining United States landfill capacity 2021

(From SWEEP again.)

This effect is already being felt in some areas: in Massachusetts, two of the state’s nine solid-waste landfills closed in 2018 and two more are scheduled to be capped soon, leaving business owners spending large sums to ship waste out of state — and increasing pressure on other landfill capacity elsewhere.

To make matters worse, as is also true elsewhere, Massachusetts’ seven waste incinerators are running at or near capacity and are often closed for maintenance.

The Canadian province of Ontario is in a similar position, expected to run out of waste disposal capacity completely by 2032. Meantime, the dangers of waste are exacerbated by increasingly frequent and lengthy journeys as cities and counties ship their trash to remaining landfills.

However, some experts contend that there’s no landfill crisis at the national level. Bryan Staley, Ph.D., PE, president and chief executive officer of the Environmental Research & Education Foundation (EREF), argues that with reduced waste landfilling (Americans now send 7% less trash to landfill than in 2000) and improving technology, the US may have up to 62 years of landfill capacity.

Potential solutions to the landfill crisis

Assuming that pressure on American landfills does continue to grow, what can be done to alleviate it?

Reduce waste production

One option is to reduce waste production. The majority of waste sent to landfills is food, clothing and other organic materials; the FDA estimates food waste at around 30% to 40% of the food supply, though much of this takes place in the supply chain rather than the home. With efforts from both consumers and businesses, however, food waste can be reduced and with it pressure on landfill. Old clothing is also frequently landfilled and could be donated instead.

Improve recycling

One of the largest pressures on landfill is recycling. The Chinese companies that used to buy American recycling now charge a fee for contaminated loads and China refuses to handle much of the low-quality plastic it was once willing to buy. The result is a massively increased load on America’s already underpowered recycling capability, and landfill is handling the overspill.

Improvements in recycling sorting at the household level could reduce the number of loads rejected and change the economic calculus of recycling vs landfilling; at the same time, infrastructure and capacity could be improved to permit for recycling on a larger scale.

Improve reclamation

Reclamation, whether from the waste stream or from landfill after disposal, is a big issue in waste management at the moment. Repurposing trash doesn’t always mean re-using it in its original use or its current form. In Hampden, Maine, an $80 million waste converter intended to generate biogas, wood pulp and plastic construction materials remains under construction and facing setbacks.

Landfill mining

A more radical approach to landfills is to view them as mines, containing valuable metals and other resources which can be recovered using similar techniques to those used in ordinary mining.

The materials sought need not be conventional, however. Martin Ryan, vice president of engineering at Ocean County Landfill Corp says ‘we were looking at the lifespan of our facility and trying to figure out ways to squeeze a little more time out of their Manchester, New Jersey landfill, they discounted both horizontal and vertical expansion of the facility.

In the end, they decided to mine the oldest part of the site to reclaim, not metals, but soil to cap other sections of the landfill. In the process, they both created further space for landfill and saved the costs associated with importing about two million cubic yards of cover soil.

Landfill gas to energy projects

Landfills generate methane as a byproduct of organic matter decomposition. This poses a fire and explosion risk, so it’s collected and piped out to the surface. In most landfills, methane is simply vented. But it’s a greenhouse gas, and one that doesn’t smell great. It can also be used for fuel. So an increasing number of landfills are burning their methane.

Historically, only large landfills did this. Small landfills produce methane too, but it wasn’t considered economically viable to install Land Fill Gas To Energy (LFGTE) equipment at smaller sites.

That’s changing, as the price of LFGTE equipment falls. Additionally, many smaller landfills have scope to expand, meaning they’re a long-term bet for LFGTE. Collecting and burning the methane makes the landfill more pleasant for surrounding communities as well as generating power.

What kind of sums are involved? The Berkeley County landfill, in Martinsburg, West Virginia, closed in 1991 after 21 years’ operation. Its gas is burned off through a contract with a private developer that delivers Berkeley 12.5% of receipts from gas, with a floor of $10,000 per year. It’s not a large amount, but it takes a cost center and turns it into a modest profit center as well as extracting some residual value from waste.

Zero waste: the circular economy

The perfect solution would be to eliminate waste altogether, in a so-called circular economy that would view one entity’s waste streams as another’s supply chain. Governments and regulators around the world have echoed the idea, with varying degrees of enthusiasm, and tried to implement it with varying degrees of success.

Sweden notoriously burns its Nordic neighbors’ trash because its recycling-conscious businesses and citizens don’t produce enough to fuel its electricity-producing incinerators. The EU is developing a zero-waste plan that it hopes will generate revenue and jobs while practically eliminating the need for waste disposal. And President Joe Biden has signed off on a multibillion-dollar package of orders that look in the same direction, taking influence from the Green New Deal proposed by his Democratic colleagues.

If these initiatives come to fruition, maybe it won’t matter so much if we run out of landfill.

Conclusion

Modern landfills bear little resemblance to the open pits and leaking town dumps of the past. They’re complex entities that center safety, both for workers today and for communities tomorrow. But they’re also increasingly short of space.

Right now, they’re our main form of garbage disposal, and a shortage at the local level is translating to problems all over as businesses are forced to ship their garbage, sometimes across state lines. If things don’t change, the USA could run out of landfill space as early as 22 years, and pressure on remaining landfills will only increase as underserved regions reach capacity. That pressure might be alleviated by increased recycling rates and more infrastructure, as well as by different approaches to waste.


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