Landfills: How They Affect the Air

To catch up read: how they affect our land and water.


Landfill is the cheapest way of disposing MSW, but all efforts to get rid of waste pollute the environment to some extent. In landfills the disadvantages are that gases and chemicals are released into the air we breathe. Experiments show that the gases and chemicals released from landfill sites are harmful to animals which common sense would tell us, it’s harmful for us too.

Early landfills were put in convenient locations on the least expensive land. The waste was ‘out of sight out of mind.’ People did not realize that as the waste rots and decomposes, it can release toxic chemicals.

However, there is another problem with landfills, whether lined or not. Bacteria in the soil, break down organic matter in the landfill, such as vegetable peelings. As they do so, they release methane gas. Methane is not a poison, but it has two drawbacks. Firstly, it is a greenhouse gas. It contributes to the greenhouse effect that is causing global warming. Secondly it is explosive. If it seeps from the landfill and finds its way into a building, it can build up unnoticed.

Methane Collection System

Bacteria in the landfill break down the trash in the absence of oxygen (anaerobic) because the landfill is airtight. A byproduct of this anaerobic breakdown is landfill gas, which contains approximately 50 percent methane and 50 percent carbon dioxide with small amounts of nitrogen and oxygen. This presents a hazard because the methane can explode and/or burn. So, the landfill gas must be removed. To do this, a series of pipes are embedded within the landfill to collect the gas.

More recently, it has been recognized that this landfill gas represents a usable energy source. The methane can be extracted from the gas and used as fuel. The extraction system is a split system, meaning that methane gas can go to the boilers and/or the methane flares that burn the gas. The reason for the split system is that the landfill will increase its gas production over time and exceed the capacity of the boilers at the chemical company. Therefore, the excess gas will have to be burned. It is not cost-effective to compress the excess gas to liquid and sell it.

The U.S. Environmental Protection Agency (EPA) has endorsed landfill gas as an environmentally friendly energy resource that reduces our reliance on fossil fuels, such as coal and oil. Landfill gas-to-energy projects are most successful when partnered with mature MSW landfills, as opposed to new landfills or C&D landfills.

There are three basic types of landfill gas-to-energy facilities:

Electric – Landfill gas is used as a fuel to generate electricity at small power plants at the landfill, or at a nearby industry, with the generated electricity delivered to a utility company.

Alternative fuel – Landfill gas is piped to an industrial or commercial facility, where it is used for heating in place of, or in combination with, fossil fuels such as oil, coal or natural gas.

Processed gas – Landfill gas is processed and cleaned to natural gas quality and delivered to transmission pipelines, to be used in normal applications for natural gas.

Landfill gas is still a problem. The Greenhouse Effect is caused by so called ‘greenhouse gases’ in the atmosphere. These gases, such as carbon dioxide, methane, and water vapor have existed naturally for millions of years. The amount of these gases has gradually increased, causing the earth to get warmer.

Landfill are a lot nastier than I had previously thought. I can’t believe that people think all this work is easier than just recycling. Recycling may be harder in the short run, but it seems like something that will save us a lot of problems and time in the long run.

Landfills: How they Affect the Water

Yesterday, I talked about the structure and parts of a landfill and how it affects the Earth. If you haven’t already, read to catch up. Today I’ll be talking about how it affects our water supply. And stay tuned because tomorrow, I’ll be talking about it affects our air supply. Read how landfills affect our air for more information.

Landfills and Groundwater

All sanitary landfills should have systems for collecting and monitoring groundwater to ensure against contamination. They also have systems for collecting leachate, a liquid that filters down through the landfill with rainwater and could contain harmful chemicals. The water can become acidic and eat into the waste of containers. The system for collecting groundwater and leachate does not breach the lining systems of the landfill.  Engineers line the quarry with clay or synthetic materials and the leachate cannot as easily pass through those materials. Pipes then collect the leachate for storage in tanks and special treatment. Old landfills do not have a leachate collecting system, so it flows to pollute and contaminate the drinking water in the ground.

Storm Water Drainage

It is important to keep the landfill as dry as possible to reduce the amount of leachate. This can be done in two ways:

  • Exclude liquids from the solid waste. Solid waste must be tested for liquids before entering the landfill. This is done by passing samples of the waste through standard paint filters. If no liquid comes through the sample after 10 minutes, then the trash is accepted into the landfill.
  • Keep rainwater out of the landfill. To exclude rainwater, the landfill has a storm drainage system. Plastic drainage pipes and storm liners collect water from areas of the landfill and channel it to drainage ditches surrounding the landfill’s base.

The ditches are either concrete or gravel-lined and carry water to collection ponds to the side of the landfill. In the collection ponds, suspended soil particles are allowed to settle and the water is tested for leachate chemicals. Once settling has occurred and the water has passed tests, it is then pumped or allowed to flow off-site.

Leachate Collection System

No system to exclude water from the landfill is perfect and water does get into the landfill. The water percolates through the cells and soil in the landfill much as water percolates through ground coffee in a drip coffee maker. As the water percolates through the trash, it picks up contaminants (organic and inorganic chemicals, metals, biological waste products of decomposition) just as water picks up coffee in the coffee maker. This water with the dissolved contaminants is called leachate and is typically acidic.

To collect leachate, perforated pipes run throughout the landfill. These pipes then drain into a leachate pipe, which carries leachate to a leachate collection pond. Leachate can be pumped to the collection pond or flow to it by gravity, as it does in the North Wake County Landfill.

The leachate in the pond is tested for acceptable levels of various chemicals (biological and chemical oxygen demands, organic chemicals, pH, calcium, magnesium, iron, sulfate and chloride) and allowed to settle. After testing, the leachate must be treated like any other sewage/wastewater; the treatment may occur on-site or off-site. Some landfills recirculate the leachate and later treat it. This method reduces the volume of leachate from the landfill, but increases the concentrations of contaminants in the leachate.

Occasionally, leachate may seep through weak point in the covering and come out on to the surface. It appears black and bubbly. Later, it will stain the ground red. Leachate seepages are promptly repaired by excavating the area around the seepage and filling it with well-compacted soil to divert the flow of leachate back into the landfill.

Groundwater Monitoring

At many points surrounding the landfill are groundwater monitoring stations. These are pipes that are sunk into the groundwater so water can be sampled and tested for the presence of leachate chemicals. The temperature of the groundwater is measured. Because the temperature rises when solid waste decomposes, an increase in groundwater temperature could indicate that leachate is seeping into the groundwater. Also, if the pH of the groundwater becomes acidic, that could indicate seeping leachate.

Landfills: How They Affect the Land

Where is ‘away’ and how does the non-fanciful place really affect us? These are pretty forward questions which I hope to answer with the three posts. How they affect our land, how they effect our water, and how they effect our air.

The space that is dedicated to landfills results in odor and loss of habitat. In addition, landfills are expensive to build and maintain. Americans spend $7 billion a year on trash disposal. In the U.S. it is estimated that 4.6 pounds of trash is thrown away by each person (I have a hard time believing it’s not more than that) which translates to 251 million tons per year. This is almost twice as much trash per person as most other major countries. About 32.5 percent of the trash is recycled or composed, 12.5 percent is burned and 55 percent is buried in landfills. The amount of trash produced has nearly tripled and the amount of trash buried in landfill has nearly doubled since 1960.

 The United States ranks about in the middle of the major countries (United Kingdom, Canada, Germany, France and Japan) in landfill disposal. The United Kingdom ranks highest, burying about 90 percent of its solid waste in landfills.

So what are we actually throwing ‘away’?

And this per person.

And then there is the question of what ‘away’ really is.

The purpose of a landfill is to bury the trash in such a way that it will be isolated from groundwater, will be kept dry and will not be in contact with air. Under these conditions, trash will not decompose much. When old landfills have been excavated or sampled, 40-year-old newspapers have been found with easily readable print. Landfills are not designed to break down trash, merely to bury it. When a landfill closes, the site, especially the groundwater, must be monitored and maintained for up to 30 years! A landfill is not like a compost pile, where the purpose is to bury trash in such a way that it will decompose quickly.

There are two ways to bury trash:

  • Dump – an open hole in the ground where trash is buried and that has various animals (rats, mice, birds) swarming around.
  • Landfill – carefully designed structure built into or on top of the ground in which trash is isolated from the surrounding environment (groundwater, air, rain). This isolation is accomplished with a bottom liner and daily covering of soil. A sanitary landfill uses a clay liner to isolate the trash from the environment. A municipal solid waste (MSW) landfill uses a plastic liner to isolate the trash from the environment

Landfill Disposal

There are different types of landfills, each designed to handle particular waste streams. A RCRA Subtitle C landfill contains mostly hazardous waste. Municipal solid waste can be placed into a RCRA Subtitle D landfill. There are also, construction and demolition landfills and industrial landfills which contain non hazardous waste. It is estimated that 78,000,000 tons of trash is under Industrial Waste. Each landfill is permitted or licensed for particular kinds of waste and generally cannot accept waste that falls outside the scope of its permit. The owner or operator does not have to accept any waste even if it falls among things that are permitted there. Some wastes may need to be treated before being disposed of in a landfill. It is important to note that treatment options may generate their own wastes, which may also be disposed of in landfills, when appropriate. More information on landfills can be found on EPA’s Landfills/Land Disposal web page.

Bottom Liner System

A landfill’s major purpose and one of its biggest challenges is to contain the trash so that the trash doesn’t cause problems in the environment. The bottom liner prevents the trash from coming in contact with the outside soil, particularly the groundwater. In MSW landfills, the liner is usually some type of durable, puncture-resistant synthetic plastic (polyethylene, high-density polyethylene, polyvinylchloride). It is usually 30-100 mils thick. The plastic liner may be also combined with compacted clay soils as an additional liner. The plastic liner may also be surrounded on either side by a fabric mat (geotextile mat) that will help to keep the plastic liner from tearing or puncturing from the nearby rock and gravel layers.

When a section of the landfill is finished, it is covered permanently with a polyethylene cap (40 mil). The cap is then covered with a 2-foot layer of compacted soil. The soil is then planted with vegetation to prevent erosion of the soil by rainfall and wind. The vegetation consists of grass and kudzu. No trees, shrubs or plants with deep penetrating roots are used so that the plant roots do not contact the underlying trash and allow leachate out of the landfill.

Cells (Old and New)

Perhaps, the most precious commodity and overriding problem in a landfill is air space. The amount of space is directly related to the capacity and usable life of the landfill. If you can increase the air space, then you can extend the usable life of the landfill. To do this, trash is compacted into areas, called cells that contain only one day’s trash. In the North Wake County Landfill, a cell is approximately 50 feet long by 50 feet wide by 14 feet high. The amount of trash within the cell is 2,500 tons and is compressed at 1,500 pounds per cubic yard! This compression is done by heavy equipment that go over the mound of trash several times. Once the cell is made, it is covered with six inches of soil and compacted further. Cells are arranged in rows and layers of adjoining cells (lifts).

Pictures That Say a Thousand Words

I’m going to let these picture speak for themselves. Below each picture is the link where I got them if you want to find more information.

This guy inspired this post. I first saw him on a video and so after I found it and realized what I was looking at I was really disturbed by it. I hope that your as disgusted as I am by this problem as I am and it inspires you to think about what you throw away and work to reduce waste.