What happens when an old landfill closes?

landfill diagram -- old landfill, landfill closure

Diagram of a landfill

Landfills eventually fill up. Then they have to close.

Sometimes a landfill closure happens for political reasons before it’s full.

What happens to the old landfill site then?

Before the answer can make any sense, we have to understand what a landfill is.

Americans generate more than four and a half pounds of trash per capita every day. That’s almost twice as much as people anywhere else in developed countries.

Some gets recycled or composted, and some goes to waste-to-energy incinerators. Most goes to landfills.

In a landfill, technology and design isolate trash from the rest of the environment. A daily covering of soil minimizes contact between it and the air. It minimizes the amount of rain that falls on it.

Still, water percolating through the landfill mixes with the various chemical compounds buried there to produce leachate. A liner prevents the leachate from getting into the groundwater.

The trash remains as dry as possible and has minimal contact with air. Therefore, it decomposes slowly. Sometimes it’s necessary to excavate or sample an old landfill. Decades-old newspapers are still as readable as the day they were buried.

Landfills must have a drainage system to collect storm water, a system to collect and treat leachate, and a system to control the buildup of methane gas. It’s possible to collect the gas and use it as fuel. Usually, however, the landfill will simply flare it off and burn it.

We talk about the weight of trash, but the space it occupies matters more in determining the useful life of a landfill. Landfill operators compact the trash to make it take as little space as possible. Less trash also helps the landfill last longer.

Two looming landfill closures

Hawaii

Waste transfer station -- old landfill, landfill closure

Waste transfer station. Next stop, a distant landfill

The landfill that serves Hilo and the eastern part of the island of Hawaii will have to close in one to three years. It has accepted between 175 and 220 tons of trash every day.

Implementing an environmentally satisfactory landfill closure plan will cost about $10 million. Hilo will then have to truck its trash to the other side of the island.

It’s possible to extend the life of an old landfill. Owners can make it bigger—either converting adjacent land to landfill or redesigning the slope to make it taller. Better still, the public can send less trash there. Recycling and composting both reduce the volume of landfilled trash.

Hawaii County planned to build a composting facility for organic waste. Neighbors of the proposed site want nothing to do with it. They complain that the government signed a contract with a company to build and operate the facility without consulting with them. They express concern about traffic and smell.

The site is close to the old landfill and was once considered as a place to expand it. The neighbors would certainly have objected to that, and probably even more vigorously. As it is, the nearest occupied farm lot is less than 1,000 feet away. The county is investigating the availability of other suitable sites.

Massachusetts

Waste to energy plant

Waste to energy plant

Massachusetts doesn’t face landfill closure as soon, but it’s using landfills more than some residents realize.

Nearly all municipal solid waste from Cape Cod used to go to an incinerator in Rochester, Massachusetts, where it was burned to make energy.

The contract came up for renewal a couple of years ago.

Seven towns decided to sign up with a different company, with the understanding that it, too, was a waste-to-energy facility.

As it turns out, that company hadn’t finished building its plant, so it hauled trash to a landfill instead. Then it filed for bankruptcy.

Of nine landfills in Massachusetts, three will have to close before the end of the decade. No new landfill has been built there for about 20 years. No new waste-to-energy plants have come online, either. In fact, the state had a moratorium on building new incinerators between 1990 and 2010.

What if the state’s landfills all close and there are no new ones or new incinerators by that time? It will have no choice but to ship trash out of state for disposal. And not necessarily neighboring states, either. It’s even looking at landfills in Ohio and South Carolina.

Closing an old landfill: stalling off the inevitable

recycling dropoff center -- old landfill, landfill closure

Recycling dropoff center, Kansas City, Missouri

Lincoln, Nebraska has buried 19,000 tons of cardboard every year. A proposed ordinance bans it from the landfill effective April 2018.

Although it doesn’t directly require people to recycle it, it leaves little choice.

Most, but not all, of the city’s private trash haulers offer curbside recycling. The rest will have to start.City residents will have a choice of signing up for it or taking cardboard to recycling drop-off locations.

The city plans to add 17 new sites, which is greater than the number of existing sites. Since the ordinance also applies to trash from outside the city, county residents will face the same choices.

What happens if someone puts cardboard in the trash, anyway? The ordinance requires haulers or city employees to separate it out at the landfill. Without the cardboard ban, the landfill is expected to reach capacity and close in 2032. The ban will extend its life. Unfortunately, if many residents resist recycling, it could increase the incidence of litter and illegal dumping.

Why ban cardboard in particular?

Unlike some other recyclables, waste cardboard makes a profit for waste haulers. That is, if people put it in the recycling can and not the trash can. They count on that profit to offset their operational costs so they can keep their prices low.

Commodity prices vary over time, but cardboard can fetch $100-200 per ton. It’s valuable enough that criminals make good money stealing it. People take it from recycling containers provided by waste haulers. They get the money instead of the haulers.

After the end

Although trash decomposes slowly, it continues to decompose after the landfill runs out of room. If the old landfill operators didn’t effectively compact it, it will settle quickly.

A well-compacted one will settle more slowly. About 90% of settlement takes place within five years after landfill closure, but it can continue at a slower rate for another 25 years.

Therefore, groundwater monitoring, leachate collection, and methane control must continue for 30 years. Which means that expenses continue long after the income from tipping fees ceases. When the old landfill site has settled enough, the land can be reclaimed for other use.

 

Sources:
Cardboard theft in California is ‘big, big money’ for someone / Amy Taxin, Business Insider. February 12, 2015.
City will ban cardboard at landfill / Nancy Hicks, Lincoln Journal Star. January 20, 2017
How landfills work / Craig Freudenrich, How Stuff Works.
Landfill closure and long-term care / Philip O’Leary and Patrick Walsh, Biblioteca virtual de desarrollo sostenible y salud ambiental. 1991-92.
Landfill nears capacity; Hilo dump could be full in a year; options ‘limited’ / Tom Callis, Hawaii Tribune Herald. January 24, 2017
Where will Cape Cod put its trash with Mass. Landfills fill up? /Elsa Partan, WGBH News. July 5, 2016

Photo credits:
Landfill diagram. Source unknown
Transfer station. Some rights reserved by ACE Solid Waste
Waste to energy plant. Some rights reserved by
Recycling drop-off center. Kansas City, Missouri Public Works


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