what is a landfill
what are landfills

In brief –


Landfilling has been, but may not continue to be, the primary way that discards are managed in the U.S.

We no longer fill wetlands with trash, which is the origin of the word “land filling,” because of environmental concerns. Instead, our garbage is piled high like a pyramid on top of the land and wrapped with liners. The waste industry asserts this practice is the “state-of-the-art.”

Concerns over whether those barriers will deteriorate, along with even deeper concerns about fugitive emissions of methane, a potent greenhouse gas, has led communities to increase their efforts to divert recyclables and compostables from landfills.

If those efforts continue, in the future more of our discards will be recovered than will be landfilled.


Landfilling is the primary way we currently manage our discards

landfills recovery

Landfilling has been, but may not continue to be, the primary way that the United States copes with the approximately 240 million tons of garbage discarded from our homes, offices, stores, institutions and light industry each year, which is often referred to as “municipal solid waste” (or MSW). Cumulatively, since 1940 when these sorts of statistics began being collected, that adds up to 14 billion tons of trash [Annex 3.14, p. A-32 Table A-248] that has been buried in the ground, which is enough to stack up a pile a yard square that reaches to the moon – and back – 30 times.


Ironically, the common moniker “landfill” originally meant just that – filling the land (with trash), which has little to do with how today’s disposal sites are constructed. For the term actually derives from a common practice dating around 1920, and continuing through the 1960s. As growing cities looked for land on which to expand, they filled nearby lowlands and swamps with ash, rubble and other discards, which were periodically burned to make space for more fill.


The Great Gatsby

F. Scott Fitzgerald described “the valley of ashes,” which he had seen commuting on the train from Broadway out to Long Island –

landfills - The Great Gatsby

The image was so powerful in Fitzgerald’s mind that he originally had titled his masterpiece, Among the Ash-Heaps and Millionaires.

Perhaps the best known example of “land filling” is the debris that filled the swamps in Flushing, Queens, atop of which was erected the 1939 New York’s World Fair, as shown in the contrasting side-by-side photographs of the site. Some of the choicest real estate in almost every city near water rests uneasily on the buried remains of earlier generations’ rubbish, as immortalized by the writer, F. Scott Fitzgerald in The Great Gatsby (see SIDEBAR).

cholera outbreak in London

Artist’s depiction of mid-19th century cholera outbreak in London

Environmental concerns sidelined land filling

Although, like the obsolete QWERTYUIOP keyboard, the archaic word still persists today, actual “land filling,” in its original sense, is rarely pursued anymore in the developed world. With the rise of environmental awareness in the sixties, those swamps, which had been looked down upon as mosquito infested nuisances, came to be recognized as the valuable wetlands that they are. Now they are typically regulated against further dumping in order to protect recharge areas, drinking water supplies and wildlife.


Drinking water threat forced changes

Further fanning the flames of discontent over vanishing wetlands was the mounting list of horror stories [pp. 14-16] about leaking dumps contaminating the water people drank, along with dumps’ putrefying stench. That followed on the heels of the health scares in previous decades, before the time of open dumps when people just threw their slop into the street, about cholera epidemics from the miasma thought to emanate out of the rotting offal, which was left for foraging pigs and rag pickers, a practice that continued even in the nation’s capitol as late as the Civil War. For more about the history of landfills, which reveals a pattern of doing the least possible, and only that in response to each successive crisis, read here.


Love Canal SOURCE: Kenyon University

The straw that broke the camel’s back, and finally precipitated a full-throated rejection of open dumps, was the tragedy at Love Canal. That calamity burst into the headlines in 1978 when homes and a school near Niagra Falls were found to have been built along a trench containing hundreds of corroding barrels of dangerous chemicals, covered with only a thin layer of dirt.

Landfills shape in Pyramid

Typical mega-sized MSW landfill shaped into pyramid

Congress required EPA to issue landfill rules

Six years after Love Canal, in 1984, Congress enacted a new law that called upon the EPA to shut down all those open dumps and create the first national standards for the next generation disposal facility, called “sanitary landfills,” so that, “at a minimum ... there is no reasonable probability of adverse effects on health or the environment” [at §6944(a)].

Those groundwater protection rules were issued in 1991, and amendments to the Clean Air Act led to companion air rules for area sources like landfills, along with the traditional smokestack industries, in 1996.

In consequence, landfill operators today pile trash on the ground into giant mounds in the shape of a four sided pyramid [at p. 33-7]. These mounds of trash are encased in liners, and include extraction systems to remove leachate, from infiltrating rain that courses through the trash, and landfill gas, from rotting food scraps and yard trimmings, along with monitoring systems to detect some of the leaks. The accompanying chart illustrates the barrier systems involved, showing the bottom liner and the cover, along with the gas and leachate collection system, as well as the perimeter monitoring wells.


Summary of groundwater protection rule

EPA’s 1991 groundwater rule was intended to protect drinking water by regulating the location, design, operation, monitoring and closure of landfills.

Landfills were supposed to be designed and operated as dry tombs to minimize the mobility of the dangerous constituents, and also to include additional layers of defense–


Schematic of landfill design Credit: City of College Station

With the requirement to install costly protective barriers under the site, industry soon realized that they could dramatically drive down the cost per ton of trash reposing above the liners by building modern landfills higher and deeper, even as the total cost of the entire facility ran into the tens of millions of dollars. Because of those economies of scale, today’s dominant landfills are mega-sized features, forming man-made mountains several hundred feet high extending over several hundred acres, and as large as 100 or more football stadiums in volume, but with negative implications for their safe operation.


Actual impact of rules has been minimal

Torn liner of landfills

Torn liner

Compared to the open dumps of the past, landfill proponents claim, today’s sites are now “highly engineered” and “state-of-the-art,” and all of the oft-reported problems are now things of the past.

However, for one thing, the industry also tooted its own horn in regard to earlier types of landfills that it ballyhooed as state of the art. Unfortunately, those self-promotional claims were belied by succeeding events in which whole new failure modes cropped up, caused by the very patches that were intended to resolve the previous issues. Indeed, the intractability of problems at landfills suggests that the whole approach of land disposal may be misguided.


Succession of “state of the art” landfills

To address the mounting complaints with open dumps, first in 1937 near Fresno, California landfill engineers had experimented and found they were able to suppress odors and vermin by layering the trash in trenches, or in cells (the area needed to spread a day’s incoming loads to a depth of about 10-20 feet high). At the end of each day, the garbage would be covered with a few inches of dirt, and then be run over with bull dozers to compact it. Although temporarily interrupted by hostilities in Europe, by the end of WWII these new practices increasingly came into common use.

Unfortunately, the new way to manage waste, which Fresno’s legendary Public Works Commissioner Jean Vincenz, called “sanitary landfills,” had an unwelcome side effect that he had not anticipated. That rude surprise was one that later, in 1989, forced this once admired state-ofthe- art facility onto the Superfund list of closed sites which were a threat to people and the environment.

Explosions. Because the garbage was being capped and packed down deep in these sanitary landfills, the wastes were substantially sealed off from the air, unlike the situation in the shallow and porous, open dumps. Practically for the first time, a new environment was created deep inside the mountains of trash in which microbes that could live in an oxygen starved, or anaerobic, environment, took over.

These bacteria produced large volumes of methane – which then came to be feared only for the explosions it could cause – as the bugs broke down the discarded food, grass and paper deep in the ground away from oxygen. In a twin irony, the new covers not only created the very conditions that, for the first time, produced large volumes of methane, but also erected a barrier on the top face of the waste piles preventing the gas from diffusing into the atmosphere. As a result, in these days before low permeable liners, the easiest route that the newly created gas had to escape was laterally through fissures, pipes and culverts in the ground and into adjoining basements where methane concentrations built up – until a spark would cause an explosion.

Landfill gas explosion SOURCE : University of Tennessee

As early as 1957, technical journals noted the problem, but no reports have cropped up of any response by the industry to do something about it. Instead, nearly thirty years passed before the drama of that little boy in the Montebello subdivision being severely burned, when this unintended consequence of sanitary landfills actually began to be recognized by the industry. But, because of its deeply entrenched reluctance to incur any non-essential expenses, its engineers largely studied the issue and otherwise dithered over what to do until four years later, when events overtook the companies’ resistance to the addition of any costs.

In the early hours of September 26, 1969, twenty-five national guardsmen were injured, twelve of them severely burned, when the armory where they were at training in Winston-Salem, North Carolina, suddenly exploded in a giant ball of flames. Methane gas produced in a nearby landfill had migrated through a culvert into the building’s piping, and was ignited by a soldier’s lit cigarette.

For the years that followed, explosions all too regularly rocked adjoining buildings, threatening people’s lives. The annoying smells, vermin and smoke that previously afflicted open dumps – bad though that had been – were now replaced with this all too visible, and violent, threat to life and limb.

Possibly nowhere was the public relations nightmare of a greater concern than at the Los Angeles County Department of Public Works and the nearby Sanitation Districts of Los Angeles County (LACSD).

With funding from the Environmental Protection Agency (EPA), in the late 1960s Los Angeles County embarked upon a years’ long study of subsurface migration of methane. But, because of the industry’s implacable opposition to adding any new costs, their focus, too, was on a means to zone development at least 1,000 feet from landfills, rather than on, themselves, incurring the expense of controlling the migration of gas.

That cost-shifting strategy, failing to find enthusiastic support among developers, proved impractical, and meaningful efforts to prevent future explosions in neighboring buildings appear to have faded in importance as the months since the last tragedy turned into years. One would have thought that the drama of the explosion in that Winston-Salem Armory, which almost killed twenty-five American soldiers, would have finally impelled the industry, or at least the best actors, to proceed until it had resolved the problem. But the waste business’s deep seated resistance to incur any additional outlays proved more powerful – until things detonated, literally, at the District’s own doorstep.

For years, the LACSD had ignored the little old ladies who complained about their roses wilting near the agency’s Palos Verdes landfill in Rolling Hills Estates, a genteel equestrian community south of Los Angeles. Then, late in 1973 the District received a peremptory wake up call. The Covenant Church that adjoined the landfill was blown up. Again, methane was found to have migrated out of the site, eventually finding its way to the pilot light in the building’s water heater – by a divine stroke of luck, not when the pews were filled with parishioners.

Over the next two years, through trial and error, first with interception trenches, and, when that did not work, with extraction piping, the LACSD – which retained one of this report’s authors for the engineering – worked out the essentials for energy recovery from landfill gas collection.

However, EPA required no efforts that anything be done to prevent further tragedies. The agency took four years to officially corroborate that the cause of the Armory explosion laid with methane from the nearby landfill. Then, it did nothing to follow up on that disturbing fact by requiring changes to avoid anymore explosions. In fact, in 1979, a decade after those two dozen troops in North Carolina were almost killed, they blandly observed in passing, still without taking any action, how there appeared to be some sort of connection between its admonitions for landfills to use tighter covers in an effort to prevent infiltration of precipitation and an increase in reported explosions.

Like the long delay in getting disease-causing garbage off the streets, their prevarication also delayed action to stop the migration of gas into neighbor’s homes, even when that meant people were at risk of being blown up. Indeed, inaction was so pervasive that it is not at all abundantly clear the industry would have ever gotten serious had something else not pulled their chestnuts out of the fire. That something was an unexpected benefit from the next generation of landfills with composite liners, which EPA eventually required because a crisis took out of their hands the capacity for the agency to dither any longer.

Bottom Liners. By the 1950s, Jean Vincenz’s sanitary landfills – the ones that covered the top each day to control vermin, wind-born litter and odors – were increasingly becoming the standard for “best practices” in the industry. However, although these techniques largely succeeded in reducing those nuisances, by the 1960s, a new set of concerns arose.

Heralded by Rachel Carson’s Silent Spring, the cumulative impacts of decades of unfettered pollution intersected with a new sensibility among the first generation weaned on affluence. The heightened sensitivity ratcheted concern beyond killer diseases to nettlesome questions about whether leachate would leak out the bottom, contaminating the groundwater below the sites – the same aquifer that people often used for drinking water.

The industry brushed these concerns aside, claiming that the underlying soil possessed a capacity to bind with and hold onto contaminants passing through the saturation layer under the landfill. Since there was no shortage of dirt under most sites, this approach also attracted their interest because it did not cost much. Perhaps mindful that this disarmingly transparent story line might not be as cogent to others, it tailored a more elegant wording for the notion.

“Natural attenuation” was what doing nothing was now to be called. That may have been the same thing, but it certainly sounded much better put in this artful way. The turn of phrase was incorporated into landfills’ appellation, as in “natural attenuation sanitary landfills.” And, for good measure, in case there was any lurking doubt, these dumps covered with a layer of dirt were also designated as “state-of-the-art” facilities. This tact worked for a short while, but ran aground amidst rough shoals when homeowners’ wells adjoining the state-of-the-art, natural attenuation, sanitary landfills became contaminated, eventually forcing many of those state-of-the-art facilities onto the Superfund list.

Faced with the need to do something that sounded more substantial about protecting groundwater, by the late 1970s, the industry was hoping that siting future landfills in areas with clay rich soil, or barring that, by trucking in clay to lay down a lining at the bottom and on the sides, would protect the aquifers below. But, in 1984, the California Legislature demanded Solid Waste Assessment Tests to validate whether clay would really prevent leakage, and found that it did not. While the clay may have slowed the rate that garbage juices flowed, the leachate soon leaked through these liners too, just as anyone would know who had observed how soon water will eventually seep through a bowel made of a child’s clay.

Then in the 1980s, a few engineers began experimenting with a barrier that had a greater capacity to resist things flowing through it. These so-called composite liners involved adding the same sort of thin plastic sheet used on flat roofs of houses, placed above a compacted two-foot layer of clay. Serendipitously for those troublesome explosions, this wound up showing how the problem could be remedied quite simply. For the geomembrane, which lined the sides in order to reduce leakage of leachate out of landfills, also physically blocked gas’s subsurface movements into adjoining structures– at least for the short-to-mid-term.

This was fortunate because, unlike the covers just on top used to suppress odors (which had worsened the problem of explosions by forcing gas out the sides), the bottom liners (which were actually developed in an attempt to protect drinking water supplies), provided this unexpected ancillary benefit for explosions. It was doubly fortuitous for a tight fisted landfill owners because, if composite liners were to become separately required for groundwater protection, as they later did, no additional costs would need to be incurred to prevent subsurface gas migration.

However, were it not for continuing series of galvanizing events, no changes in the once claimed state of the art landfills would have been seriously considered.

What is landfills

Sunrise Landfill’s catastrophic cover failure

For another, if one looks beyond the length of the two sets of landfill regulations – one to protect groundwater and the other, air – the details are decidedly less than inspiring. The liners intended to protect drinking water only do so for a few decades at best before they deteriorate, while the threats persist for centuries. Pollution is only postponed, not prevented.

As for the atmosphere, the rules only required the bare minimum that was necessary for the industry to do to protect its investment, leaving the vast majority of the toxic and greenhouse emissions to escape.


Groundwater was not protected in the future

Even composite liners “will ultimately fail” within decades after the agency's post-closure care requirements have expired, they advised, and when the liners fail, “leachate will migrate out of the facility.” Yet, its staff recognized, the duration of a landfill’s hazardous loadings that need to be isolated may be “many thousands of years,” long after the time when discharges will occur.

Why did the EPA nonetheless proceed to rest safety on a flawed technology? The answer is not edifying. “EPA officials,” an investigation by the agency's Inspector General reported a decade later, made the decision “based on a compromise of these competing interests ... not based on specific scientific criteria or research studies.”

The atmosphere was never protected

In the anti-regulation fervor that existed at that time the air rules were adopted, EPA did not prioritize public health as contemplated in the statutes. Nor did the agency indicate that it gave any consideration to the risks to the neighbor’s health against the benefits to industry’s economic interests. Based on the record, EPA’s decision was controlled preternaturally by the desire to provide “flexibility,” which, apparently, has become the code word for de facto deregulation, without respect for the controlling statute.

Unlike the European Union where all landfills are covered by the air rule, in the United States, EPA’s singularly vague rule not only allowed the owner near complete discretion over the design of the system. In addition, the rule only covered the largest facilities, generally those designed for more than 2.76 million tons of waste. That extremely high threshold for coverage exempted 95% of landfills [p. 9914].

Most important, for the few landfills that were covered, by design, these vacuum-based systems only had the potential to be functional during the limited period of time when the site is sealed and little gas is generated. As described in the earlier discussion of the Oonk conundrum, before the cover is installed, and after postclosure care ends when the cover fails – which are the times when most gas is generated – those systems envisioned in the rule either are not installed or are no longer operational or, if in place, are not functional.

Blown out cover at large landfill without gas collection (14)

Not surprisingly in view of the political climate of those times, the only substantive thing that the rule did achieve was to codify what the large landfill owners had found was economically compelled anyway, regardless of whether there was a rule that required it to do so. For in those large landfills that were affected by the rule, after a geomembrane cover had been installed, so much pressure built up from the gas generated by the residual moisture that the pressure overwhelmed passive venting systems. Too often, in sites without active gas extraction, that pressure literally blew out the expensive final covers, as shown in the adjoining photograph.

The cost to replace a blown out cover is more than $100,000 per acre, which compares to only about $25,000 for an active gas well in that same area. This is the reason the owners of large sites were already motivated to chose the less expensive, bare bones gas extraction system to protect their investment.


Moreover, as a consequence of landfills built to outsized proportions, they became too big to fix the barrier structures as they deteriorate, tear or clog because they rest under tens of millions of tons of garbage. And, they became so big that whole new and much more costly failure mechanisms could occur, such as the massive garbalanche that occurred at the Cincinnati area Rumpke landfill in 1996 that could cost hundreds of millions of dollars to clean up.


Outsized landfills magnifies frequency and impact of failures

Other key groundwater safety systems are far more likely to fail, to fail sooner and to fail more catastrophically than the liners beneath the site. In particular, that is the cover above and the leachate collection pipes along the bottom, which are identified with red arrows in the preceding diagram.

Covers. The final cover that caps a closed landfill usually consists of a two foot dirt or clay foundation and a thin plastic sheet the thickness of a credit card. It is overlaid by a drainage layer and a foot or so of dirt for vegetation to protect the cover (and at other times, the cap consists of just a few feet of dirt). That cover is mission-critical for safety.

Rumpke garbalanche in 1996 near Cincinnati

If that cover is breached, rainfall will re-enter the site and re-ignite a second wave of decomposition in the organic wastes below, which can set cascading failures in motion. If the landfill fails catastrophically at one time from an extreme weather event, or over time from the accumulation of many tears, garbage may washout into adjoining waterways and massive landslides could shear off from the manmade mountain of trash.

Moreover, given landfills’ immense scale and the fact that they are largely built above ground, they can collapse catastrophically. These types of disasters have already occurred at the Acme and Keller Canyon Landfills in California, Paxton Landfill in Illinois, Meadowlands in New Jersey, Metro in Wisconsin, and disastrously at the Rumpke Landfill in Ohio on “March 9, 1996 – [t]hat’s the day a massive portion of the landfill – known to locals as Mount Rumpke – collapsed as employees literally ran for their lives.”

Leachate collection system being installed

Leachate collection. Leachate collection pipes at the bottom of the landfill to drain out and keep the site dry. However, they are prone to clogging, and when they do, according to pre-eminent landfill engineer Robert Koerner, the accumulating leachate head “is not only a concern with respect to leakage through the base liner system, but can also negatively impact the stability of the landfill. ... [T]he failure can be enormous [and] waste masses up to [two football stadiums] have failed and actually liquified [and] slid over a distance of [almost a mile] in a matter of minutes.”

Essentially, mega-fills can be too big to fix, even when their critical safety systems degrade, and that flaw magnifies the risk of major site failures.

discard patterns of landfills

In a textbook case of regulatory capture, EPA’s rules largely papered over the problems [pp. 101-102]. Only the least possible was done in order to minimize costs for landfilling, with the result that an obsolete waste management strategy was artificially able to appear less expensive than sustainable alternatives, such as recycling and composting.

waste hierarchy of landfills

Presumably, citizens have increasingly understood this because public pressure at the local level has expanded recovery efforts (see CHART). Even the EPA, which acquiesced to weak regulations, recommends that communities prioritize the “3-Rs,” reduce, reuse and recycle over landfilling (see GRAPHIC).

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