How Landfills Work

Materials Management Division

Portrait of Liz Browne, Materials Management Division Director.

Liz Browne, Materials Management Division Director

Michigan's Solid Waste Disposal Regulations

Michigan first enacted solid waste regulations in 1965, establishing operating standards to prevent nuisance conditions. Prior to that, places accepting  municipal solid waste  or garbage had no standards and were commonly called dumps. Dumps were often built in low-lying areas and wetlands without any precautions to protect public health and our natural resources. In 1978, the solid waste regulations were amended to establish siting, design, and monitoring requirements. Periodically thereafter, updates to the statute and rules have been made to provide for additional protections where needed and to encourage safe use of unwanted materials.

Today’s landfills are entirely different than the old dumps. They are engineered structures, built into or on the ground, designed to hold and isolate the waste from the environment and personal exposure. There are different kinds of landfills subject to different regulations administered by the Michigan Department of Environment, Great Lakes, and Energy (EGLE) and the United States Environmental Protection Agency (U.S. EPA). A few examples include hazardous waste, municipal solid waste, industrial waste, and construction and demolition landfills.

Although landfilling waste materials is the least preferred option in the  waste disposal hierarchy  (right), landfills are an important part of an  integrated waste management system . They are also the most common place for disposal of municipal solid waste.

Michigan's Disposal Statistics

In Michigan, about 80 to 85 percent of all municipal solid waste is  landfilled in the state’s 45 permitted and licensed municipal solid waste landfills.  Only about 20 percent is recycled. In 2021, 39,882,943 cubic yards or 13,294,314 tons of municipal solid waste generated in Michigan were disposed of in Michigan’s municipal solid waste landfills. ( 2021 Report of Solid Waste in Michigan ).

EGLE conducted a waste audit in 2019 and found that of the  solid waste landfilled in Michigan :

  • 38% was organic food, yard and compostable paper and packaging.
  • 26% was traditional curbside recyclables.
  • 20% was other recyclables like textiles, appliances, scrap metal, electronics, bulky plastics, and plastic films.
  • 16% was nonrecoverable waste materials.   

  

Reducing Climate Change Impacts by Composting More Food Waste and Other Organics

EGLE is talking trash in a new video series!  The “Talking Trash" video series focuses on waste management strategies such as recycling, composting, landfilling, and more.  Our first episode focuses on reducing climate change impacts by composting food waste and other organic materials instead of landfilling them.  Check out our  Talking Trash – Composting Video  to learn more about what compost is, how it’s made, and how the simple act of composting is a powerful tool to help protect our environment and fight climate change. 

Next up is a video on landfills which is coming soon!  

Michigan's Solid Waste Landfills

Michigan’s solid waste landfill map (right) shows both type II and III solid waste landfills in Michigan.  Type II landfills are municipal solid waste landfills that are used to dispose of all types of solid waste not subject to hazardous waste regulation.  Type III landfills are used to dispose industrial waste, low-hazard industrial waste, and/or construction and demolition waste that is not subject to hazardous waste regulation.  See our  Landfill Prohibited Materials Guide  to learn materials that are generally prohibited from being landfilled. Whole tires are one waste stream banned from being landfilled. To learn more about how tires are being recycled and used to make new products, check out this  Into the Outdoors tire recycling video  funded in part by an EGLE scrap tire grant.

Hazardous Waste 101 Video

EGLE Classroom - Hazardous Waste 101

A Deconstruction Story Video

An Alternative to Waste - A Deconstruction Story

From Your Home to the Landfill

When you think about garbage, you often think about a  garbage truck . Depending on the landfill’s size, as many as 300 trucks may come every day. Some come from up to 50 to 70 miles away. Why? Well, municipal solid waste landfills are difficult to site as well as expensive to build and operate. There are fewer municipal solid waste landfills today than in the past, but they are larger and accept waste from greater distances.

There are, of course, different types of garbage trucks that hold different amounts of municipal solid waste. The truck that comes through your neighborhood can hold anywhere from 12 to 14 tons of waste. How much is that? Well, on average, this type of garbage truck can pick up waste from about 800 to 850 homes. When the truck is full, it heads to the landfill. At the landfill, the truck drives onto a scale and is weighed on its way in, way out, or both. The truck carefully drives to a specific area of the landfill and dumps or “tips” its load. Then it leaves and drives to another neighborhood to repeat the process.

Cross Section of a Solid Waste Landfill

Landfill Basics

The solid waste regulations established siting and design criteria, as well as construction, operation, maintenance, closure, post closure, and financial assurance requirements for Michigan’s municipal solid waste landfills. Use the arrow on the right of the image below to view more pictures of the landfill parts.

Some basic parts of a landfill include:

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1. The Liner System

The  liner system  is designed to keep waste from getting into the environment – particularly groundwater that we often use for drinking water. From the bottom up, the liner system includes:

a)   A secondary (bottom) composite liner made of two feet of compacted clay or a manufactured equivalent liner and a 60-mil plastic liner (about the thickness of a penny). The secondary liner is not required if the site already has at least 10 feet of natural  low permeability clay .

b) A drainage layer if the site does not include at least 10 feet of natural low permeability clay. The drainage layer is part of the landfill’s leak detection system and is also called the secondary leachate collection system. It is designed to detect and remove any liquids that leak through the primary liner. The drainage layer resembles a plastic mesh and is a synthetic material called a geocomposite that is specifically designed for landfills.

c) A primary (top)  composite liner  made of two feet of clay or a manufactured equivalent and a 60-mil plastic liner.

d) A  leachate collection system  that collects and removes rainwater that contacts the waste and liquids released by the waste as it  decomposes .

e) A protective layer that prevents the liner and leachate collection system from being damaged. The layer is often made of 2 feet of sand.

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2. Cells

 Cells  are specific areas where the waste is placed in the landfill, then compacted or crushed.

3. Storm Water Drainage System

The  storm water drainage system  collects rainwater that falls on both final closed and temporarily covered parts of the landfill. The  storm water  drainage system may include plastic drainage pipes and ditches that collect and move the rainwater to a storm water storage pond for water that has not contacted the garbage.

4. Leachate Collection System

The  leachate collection system  collects liquids released from the decomposing waste and any rainwater that contacts the waste. Leachate forms when water in the waste works its way through the landfill much like water percolating through coffee grounds. As the water moves through the garbage, it picks up contaminants. So, leachate is collected, removed, treated, and discharged after treatment under a permit issued under the  Clean Water Act  and Michigan’s water resources protection statute and rules. Leachate levels in the landfill are routinely monitored to ensure the leachate collection system is working properly.

5. Gas Collection System

A  landfill gas collection system  collects landfill gas created naturally by the decomposing garbage. As bacteria in the landfill break down garbage, landfill gas is created.  Landfill gas  is about 50 percent methane, 50 percent carbon dioxide, and other trace gasses including hydrogen sulfide and mercaptans from sulfur reducing bacteria.  Hydrogen sulfide and mercaptans have very low odor thresholds.  That means people can smell them at very low levels.   Their odor thresholds are in the low parts per billion range.  That means that most people can smell it when there are around 10 parts of hydrogen sulfide or mercaptans in 999,999,990 parts of other gasses in the air.  More sensitive people may smell it even below that level.

The methane, without the hydrogen sulfide and mercaptans, is odorless, flammable, and can be explosive.  So, landfill gas is managed both for safety and odor control purposes.   

Landfill gas is actively collected from municipal solid waste landfills using a series of pipes installed throughout the landfill.  Some landfills vent the gas to the atmosphere or burn it through a flare.  A flare looks like a huge lighter. Many Michigan municipal solid waste landfills collect the gas and burn the methane in large engines to power a generator and produce electricity or they use it to replace natural gas for heating.  Permits for landfill gas collection systems and flares are issued under the  Clean Air Act  and Michigan’s air pollution control statute and rules.

6. Final Cover System (Or Cap)

The final cover system or cap is placed on the municipal solid waste landfill when it stops accepting waste and closes. From the bottom up, the final cover includes:

a) 18 inches of clay or a manufactured equivalent, such as a geocomposite clay layer, which has a layer of bentonite between two fabric liners that swells when in contact with liquid and prevents the liquid from moving through the liner.

b) A 40-mil plastic liner, about the thickness of a dime.

c) 2 feet of protective soil.

d) 6 inches or more of topsoil to support native shallow rooted plants such as grasses and wildflowers.

The cap seals the waste from air and reduces the amount of water getting into the landfill. It also prevents pests (birds, rats, mice, flying insects and so on) from getting into the waste.

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7. Environmental Monitoring System

The  environmental monitoring system  consists of monitoring points to monitor groundwater, storm water, and air.

a) A  groundwater monitoring program  is required to protect groundwater. Groundwater is evaluated to determine where it flows, and monitoring wells are installed upstream and downstream of the groundwater flow around the landfill. The wells are sampled on a regular basis for contaminants typical of landfill leachate like lead, cadmium, chromium, and common volatile organic compounds like benzene, methylene chloride, tetrachloroethylene, toluene, and xylene. These results are compared to previous results and other wells, then analyzed statistically to determine whether a release from the landfill has been detected.

b) A  storm water monitoring program  is required for storm water areas with the potential to be impacted by a release of leachate. The landfill’s storm water monitoring program designates specific locations in the drainage ditches and storm water ponds where samples are to be collected. Like groundwater, the surface water in these locations are sampled and tested on a regular basis for contaminants found in the leachate.

c)  Air monitoring is required for most sites that have a landfill gas collection system. A  landfill gas monitoring system  is used to evaluate the landfill gas collection and control system and ensure it is operating properly. Gas monitoring wells in the soil are also monitored around the landfill for methane to detect and prevent the migration of landfill gases below the ground.

Landfill Basics Recap

Check out our short videos that provide a recap of the landfill basics and provide additional details on how waste was managed historically, what causes landfill odors, and why it is important to manage the methane gas produced when waste materials decompose in a landfill.

EGLE Talking Trash Landfill Video

In this short video you will hear from EGLE landfill management staff, a geologist, an engineer, and a landfill gas specialist who explain how our landfills work.

Talking Trash - Landfills

EGLE Landfill and Recycling EnviroScape Video

In this video, you will hear about how landfills work from an EGLE landfill engineering specialist using a model that can be checked out from our  EGLE lending station .

EGLE Classroom - Landfill and Recycling Enviroscape

What Happens Every Day at a Landfill

Use the arrow on the right of the image below to view more pictures of the landfill parts.

Tipping

Waste is dumped (or tipped) into an open area of the constructed landfill called a cell. Municipal solid waste landfills almost always have one cell open at a time to accept waste. At the same time, another cell is being built so it is ready when the current cell becomes full. The daily operation at a municipal solid waste landfill includes the tipping of waste into a specific area of the landfill, called the  working face , followed by compaction or crushing of the waste and covering it with soil at day’s end.

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Compacting

Space is money. Garbage is compacted or crushed to save space. You may have seen the giant tractor with spiked wheels that goes back and forth over the garbage. Well, that’s a compactor. It weighs over 100,000 pounds. The compactor makes three to five passes over the garbage to crush as much garbage into the space as possible. On average, about 1,300 to 1,600 pounds of garbage can be compacted into one cubic yard (3 feet x 3 feet x 3 feet) of space. The landfill puts as much waste as possible into each cell, making them last longer and reducing the need for additional landfills to be built.

Cover

At the end of the day, the working face of the cell is covered with a layer of soil or other cover material to minimize odor and pests, as well as to prevent litter. This is called  daily cover . Rather than making a big pile of waste in the cell, waste is typically placed in 8 to 10 feet thick layers called  lifts . A lift will start at one end of the cell and, as days go by, will work its way across the cell to the other end. Much like the blocks in a pyramid, as each lift reaches the end of the cell, a new higher lift is filled in the other direction until the other end of the cell is reached. This process continues until the cell reaches its designed  grade  (slope) and height allowed under the permit issued by EGLE. The three-step process (tipping, compacting, covering) is repeated over and over until the cell is filled.

General Management

Each day, landfill workers perform housekeeping tasks to make sure the landfill continues to function properly. This includes items from inspections of wells, pumps, and flares, to watering onsite roads for dust control to sweeping interior roads to ensure mud and dirt are not tracked out of the facility.

Interim Cover

Lifts where waste will not be placed for 90 days or more or that will be part of the outer constructed edge of the landfill are covered by 1 foot of compacted soil or a flexible membrane liner to prevent storm water from contacting the waste. This is called  interim cover . Soil interim cover is covered with native shallow rooted plants such as grasses and wildflowers and maintained until the  final cover system  is installed over the area. The storm water that is shed from the interim cover is directed to storm water ponds which are monitored to ensure that no waste or leachate has impacted the storm water prior to it going off-site.

Oversight

EGLE is highly involved in the regulation of landfills. This oversight includes review and approval ( permitting  and  licensing ) of the landfill design, monitoring, and operations plans to ensure human health and the environment are protected as provided under our environmental regulations. It also includes inspections of the installation of monitoring systems and construction of landfill cells and pollution controls. EGLE also inspects each facility at least 4 times per year to ensure operational standards are followed. Each municipal solid waste landfill is required to submit environmental monitoring data. EGLE reviews the data and compares EGLE results with all historic data to ensure that the data is valid. EGLE staff also respond to complaints and concerns that members of the public submit.

The Life Expectancy of a Landfill

The life of a municipal solid waste landfill depends on the size of the facility, the disposal rate, and the compaction rate. All municipal solid waste landfills in Michigan are permitted to accept a specific volume of waste. Municipal solid waste landfill operators strive for the maximum compaction rate possible to save space and minimize cost of building new landfill cells. Given these considerations, the average life expectancy could be anywhere from 30 to 50 years.

When a Landfill Closes

When a municipal solid waste landfill is full, it is closed with a final cover that includes the clay layer, a plastic liner, and a soil layer discussed earlier. Even though the facility is closed, the responsibility of the landfill operator does not end. Municipal solid waste landfill owners must set aside money (called  financial assurance ) for the final cover system and ongoing maintenance of the landfill after closure. Operators must continue to pump the leachate, test the groundwater, inspect the cap, repair any erosion, fill low areas due to settlement, maintain vegetation and prevent trees from growing. Why no trees? Trees have roots and roots can tear the liner in the final cover system. Municipal solid waste landfills must be monitored for at least 30 years after they close.

Where to Learn More About Solid Waste Landfills

Visit  Michigan.gov/SolidWaste  to learn more about solid waste and materials management in Michigan.

Glossary of Terms

Municipal solid waste is everyday household items we use and then throw away, otherwise known as garbage. ( return to section )

An Integrated waste management system is a comprehensive waste prevention, recycling, composting, processing, and disposal program that considers how to manage unwanted materials in ways to best protect human health and the environment while supporting a vibrant economy. ( return to section )

The liner system is a system of layers of protection that must be installed to protect groundwater and keep waste and leachate in the landfill. ( return to section )

A composite liner is a combination of a clay component directly overlain by plastic liner to prevent the movement of leachate and liquids (leakage from the landfill). A composite liner is 1,000 times more resistant to leakage than either component used alone. ( return to section )

Low permeability clay is a type of clay soil with poor drainage used to prevent liquids from moving through the clay. ( return to section )

A leachate collection system is a series of pipes and pumps used to routinely remove leachate settling on top of the primary liner in a landfill. A drainage layer is a part of the leachate collection system. ( return to section )

Decompose means to break down into simpler substances through natural bacterial decay. ( return to section )

A cell is an open area in a landfill where waste is placed. Most landfills fill one cell at a time. When one cell is completely filled, a new cell is opened to accept incoming waste. Waste is placed and compacted in each cell in a manner that protects the landfill liner and the landfill gas and leachate collection systems. ( return to section )

The storm water drainage system is designed to collect rainwater that falls on parts of the landfill that have final and interim cover. The storm water drainage system may include plastic drainage pipes and ditches that collect and move the rainwater to a storm water storage pond. ( return to section )

Storm water is runoff that comes from rain or melting snow flowing across the land that does not come in contact with the waste. Generally, this includes stormwater from rain falling on areas of the landfill that have interim and final cover. ( return to section )

The leachate collection system is a series of pipes and pumps used to routinely remove leachate settling on top of the primary liner in a landfill. A drainage layer is a part of the leachate collection system. ( return to section )

The Clean Water Act is the federal law that regulates pollution entering waters across the United States and establishes water quality standards for rivers, lakes, streams, and wetlands. ( return to section )

The landfill gas collection system is a series of pipes and pumps used to collect and remove landfill gas from the landfill. ( return to section )

Landfill gas is naturally created from bacteria decomposing the waste. Landfill gas is made up of around 50% methane and 50% carbon dioxide. ( return to section )

The Clean Air Act is the federal law that regulates pollution entering air across the United States and establishes air pollution standards.  (  return to section )

The landfill environmental monitoring system consists of all of the groundwater, stormwater, and gas monitoring programs combined, along with the leak detection system. The purpose of the environmental monitoring system is to detect an unauthorized release from the landfill as early as possible. ( return to section )

The groundwater monitoring program includes all of the groundwater monitoring wells around the landfill that are routinely sampled and evaluated to detect a release from the landfill. ( return to section )

The storm water monitoring program designates specific locations in the drainage ditches and storm water ponds where samples are to be collected and routinely analyzed to detect a release from the landfill. ( return to section )

The landfill gas monitoring system includes all of the gas sampling wells around the landfill that are monitored for methane to detect and prevent methane from moving below ground, through the soil, outside of the landfill. For landfills that have a gas collection system, the pipes throughout the landfill used to collect the landfill gas are also monitored to ensure the landfill gas collection system is operating properly and methane is not escaping the landfill. ( return to section )

The landfill working face is an area in the landfill, within a specific cell, where waste is currently being placed and compacted. ( return to section )

Daily cover is typically a layer of soil placed on top of compacted waste at the working face at the end of each day. Daily cover functions to minimize odors, pests, and rodents. It also prevents waste from being blown out of the cell and reduces the amount of water that enters the cell. This reduces the amount of water that comes in contact with the waste and reduces leachate production. ( return to section )

A lift is an 8- to 10-foot-thick layer of waste within a landfill cell. ( return to section )

Grade means slope, angle, or incline. ( return to section )

Interim cover is one foot of compacted soil placed on top of lifts where waste will not be placed in the landfill for 90 days (or more) with the purpose of preventing stormwater from coming into contact with the waste in the landfill. ( return to section )

The final cover system is the system used to close a landfill or part of a landfill that is no longer accepting waste that is designed to keep waste in place and prevent water from entering the landfill. The final cover system includes a clay layer, a plastic liner, and a soil layer that is maintained with shallow rooted plants like such as grasses and wildflowers. ( return to section )

The landfill permitting process gives a person (property owner, individual, company, or organization) permission to construct a disposal facility meeting specific design requirements provided in the construction permit and solid waste regulations. ( return to section )

The landfill licensing process gives a person (property owner, individual, company, or organization) permission to operate a solid waste disposal facility that was constructed in accordance with the design requirements provided in the construction permit. The solid waste license includes the landfill’s operating, maintenance, closure post-closure, and financial assurance requirements. ( return to section )

Financial assurance is money that the disposal facility owner/operator sets aside to be accessed by the State of Michigan, should the State of Michigan need to perform activities required under the solid waste regulations at the landfill. ( return to section )

Liz Browne, Materials Management Division Director