- Fact Sheet
- Parent Guide
After source reduction, recycling, and composting, a large portion of municipal solid waste (MSW) still goes to landfills. While disposal of waste to landfills has decreased, it remains the primary disposal option for MSW.
A municipal solid waste landfill is where household waste is deposited and buried. Properly managed landfills are an environmentally safe means of disposal, and are closely monitored for their environmental impact by the U.S. EPA, as well as state and local authorities.
The number of landfills in the U.S. has steadily declined over the past two decades, but has remained relatively constant since 2002. The average size of landfills, however, has increased. While landfill capacity is largely sufficient, it may be limited in some communities.
Modern landfills are well-engineered facilities that are located, designed, operated, and monitored to ensure compliance with federal regulations, and to protect the environment from contaminants which may be present in the solid waste stream.
Municipal solid waste landfills are regulated under Subtitle D of the Resource Conservation and Recovery Act passed by Congress in 1976. In 1991, the U.S. EPA published a supplemental set of Landfill Rules which now serve as the basis for state regulatory and permitting requirement.
Standards for municipal solid waste landfills include restrictions on location, requirements for liners, collection and removal systems for leachate, operating best practices, groundwater monitoring, and closure requirements. New landfills may also collect potentially harmful landfill gas emissions, such as methane, and convert them into energy.
Because today’s landfills need to operate with unquestioned safety and efficiency, it often can take five or more years from the time a site is selected until design, permit application, and public hearings are completed and the facility is built.
How a Landfill Works
A typical landfill is divided into a series of sections called “cells.” Solid waste is placed in what is called a “working face,” which is a portion of a landfill cell that is currently available to accept material. Limited sites in a landfill are exposed at any given time to minimize exposure to environmental elements like wind and rain. Because a landfill is filled so systematically, landfill operators may be able to pinpoint where a specific load of garbage was deposited days, weeks, or even months afterward.
At the conclusion of each day’s activity in a cell, a “daily cover” is spread across the compacted waste to minimize odor, prevent windblown litter, and deter insects and vermin. The daily cover may include a layer of dirt, clay, foam, tarps, sand, or sometimes finely crushed glass. The landfill operator moves from working face to working face, and from cell to cell as the landfill gradually reaches its capacity over a period of years, or even decades.
Modern landfills are constructed with a number of safeguards, including clay or plastic lining to contain leachate. Rain, snow, and liquids created by the compaction and decomposition of solid waste, which can seep through a landfill cell, is called “leachate.” Leachate is a potential pollutant of surface waters (lakes, rivers, streams, or oceans) or groundwater, which is the source of most drinking water.
A protective liner is used to prevent filtration of liquid from the landfill. Liners may be made of compacted clay or impermeable materials such as plastic, or both. When clay is used, the layer may be as much as ten feet thick. This site preparation is done so that any liquid entering the landfill can be controlled and treated externally, or retained inside the landfill, rather than being permitted to pass through.
Beyond protective liners, modern landfills include multiple safeguards to contain leachate and other waste and waste byproducts and isolate them from surrounding water and soil. To prevent leachate contamination, a network of drains is installed at the bottom of the landfill to collect the liquid that has percolated through the solid waste. Leachate is then pumped to waste water recovery points for treatment.
Groundwater monitoring wells are also installed around the perimeter of the landfill to ensure that surrounding groundwater is not contaminated with leachate. Should a liner system fail by breaking or deteriorating, leak detectors installed under the liners signal the presence of leachate, allowing corrective action to prevent any movement of leachate from the landfill toward nearby ground or surface waters.
Landfills and Gas Emissions
Gases emanating from the landfill are also monitored and controlled. As the organic portion of waste (e.g., food and yard wastes) decomposes, large amounts of methane, a greenhouse gas, and carbon dioxide are produced. Under the Resource Conservation and Recovery Act and the Clean Air Act, landfill operators are required to monitor gas both on the surface and around the boundaries of landfills.
As cells to the landfill are sealed off, venting systems are installed to prevent methane from diffusing into the ground, and to collect any gas released and burn it off. The gas can also be collected and used to generate electricity for use on site or to sell for residential or business use.
Closing a Landfill
When a landfill has reached its capacity, it is required to close consistent with U.S. EPA “final cap” environmental requirements. A final layer of plastic, clay and top soil cap the landfill. It is then re-landscaped according to closure plans drawn up in accordance with the community. This process is planned many years in advance. To be granted a license to operate, a landfill operator must have a complete plan for the site’s eventual closure. The operator is also required to set aside necessary financial resources for all closure, post-closure, and corrective activity which may be needed over the lifetime of the landfill.
Once a landfill is capped and closed, operators are obligated to monitor the site for gas and leachate for at least 30 years, and may be involved in ongoing efforts to reclaim the land for other uses. Landfills can end up as open space for communities to use as parks, or other recreational facilities. Building any permanent structure on landfills is less common because, as solid waste decomposes in the landfill, the entire landscape can settle. A structure on the site could break the “cap,” allowing water to percolate through the garbage and potentially allow the release of methane gas.
MSW—otherwise known as trash or garbage—consists of everyday items such as product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances, and batteries. Not included are materials that also may be disposed in landfills but are not generally considered MSW, such as construction and demolition materials, municipal wastewater treatment sludges, and non-hazardous industrial wastes. In the United States, we generated approximately 243 million tons of MSW in 2009. Over the last few decades, the MSW generation, recycling, and disposal of MSW have changed substantially. Annual MSW generation in 1960 was 88 million tons. The generation rate in 1960 was just 2.68 pounds per person per day; it grew to 3.66 pounds per person per day in 1980, reached 4.50 pounds per person per day in 1990, and increased to 4.65 pounds per person per day in 2000. Since 2000, MSW generation has remained fairly steady with the current generation rate at 4.34 pounds per person per day.
Over time, recycling rates have increased from just over 6 percent of MSW generated in 1960 to about 10 percent in 1980, to 16 percent in 1990, to 29 percent in 2000, and to over 33 percent in most recent reports. Disposal of waste to landfills has decreased from 94 percent of the amount generated in 1960 to 54 percent of the amount generated currently.
The U.S. Environmental Protection Agency (EPA) uses two methods to characterize the MSW generated. The first is by material (paper and paperboard, yard trimmings, food scraps, plastics, metals, glass, wood, rubber, leather and textiles, and other); the second is by several major product categories. The product-based categories are containers and packaging; nondurable goods (e.g., newspapers); durable goods (e.g., appliances); food scraps; and other materials.
- Determine “crust” to be used. If using cardboard cake circles, the next procedure is outlined in #2.
If using the alternative pizza “dough” before class, prepare a “Garbage Pizza” crust, using the following recipe:
- Mix 2 cups flour, 2 cups salt, and 1 cup water (adjusting water per altitude and/or humidity) until a stiff dough forms.
- Knead the mixture, as you would bread dough. Flatten the dough into a well greased, 12” round, deep dish pizza pan, pressing the edges up the inside of the pan until it looks like a pizza.
- Cut the pizza into the same slices or sections to look like the Municipal Solid Waste by Weight, pie chart template included in this lesson.
- Using a fork or knife, puncture each slice several times before baking to avoid expanding air pockets. Bake at 350° for 40-45 minutes, or until golden brown. Check the pizza every 10 minutes or so and re-cut the sections. Remove the pizza from the oven and let cool completely. The dough should be hard and dry.
- Label the underside of each pizza slice with the correct type of waste and the percent it represents. A permanent marker works well. This makes it easier for students to glue the proper waste on the proper slice.
- For “sauce,” mix approximately 4 oz. of white school glue with approximately 2 oz. of red food coloring (adding a drop of blue food coloring will darken the red, but is not necessary for a successful “sauce”) until you achieve the desired red tomato sauce look.
Optional: Apply sauce with a small paint brush (an apron is highly recommended). Allow to dry thoroughly.
- Ask students to define the words garbage and trash. Garbage refers to only the organic or food waste thrown away. Trash represents broken, discarded or worthless things (e.g., rubbish and other forms of refuse which are not food).
- Brainstorm with students and list on the board all the waste items thrown away at home or school. Use the following categories: paper, yard waste, plastics, metals, wood, food, glass and other. Introduce the concept of municipal solid waste (MSW). MSW is made up of trash and garbage from household, commercial, and institutional sources in a community. Ask the class if the items listed on the board would also be found in a community’s MSW.
- Draw a circle on the board. Have the students pretend that all the waste thrown away in the United States will fit into this circle. This circle is filled with waste from all the categories (paper, yard waste, plastics, metals, wood, food, glass and other). Show students how much paper is thrown away by drawing a slice for paper (see chart included in this lesson). Repeat this demonstration for all eight categories.
- Reinforce the fact that the biggest slice, marked “paper,” means that there is more paper by weight than any other item in MSW. The next largest slice by weight is yard waste, etc. Ask the students why it might be important to know the amount and kinds of waste thrown away. By understanding the solid waste stream (MSW), and local conditions, (distance from recycling centers, available space for landfills, etc.), communities can implement a responsible waste management plan.
- Announce that the class is going to make a garbage pizza (with garbage and trash). Show the students the pizza dough either cardboard cake circles, plate plates or the homemade dough. Divide the students in teams and ask them to collect materials and glue to the applicable slice of pizza.
Optional: You may do individual pizzas instead of team. Share the garbage pizza model with other classes or the entire school. Have students team-up and teach students in other grades about MSW using the garbage pizza model.
- For an added touch after the glue has dried, spray the garbage pizza with polyurethane or lacquer (in a well ventilated area), available at your local hardware store.
- Set up a table with items from the eight categories of MSW: paper, yard waste, plastics, metals, wood, food, glass and other. Make signs for each category, and have students separate the waste items into the appropriate piles.
- Students will be able to look at different MSW categories and discuss the ways these materials are handled in their community. Students may identify creative ways that can assist in changing how these materials are disposed of locally (for example, by recycling).
- Use internet to research the waste stream in their school, local community or state and make additional pizzas to compare to the national version.
- Create a PowerPoint presentation for decision makers regarding trends in waste collection and recycling rates for school and community.
- For more advanced students, discuss the difference(s) between MSW measured by weight and volume by making two pizzas: one using statistics for percent by weight (as used in this lesson), and one using statistic for percent by volume. Weight reflects total municipal solid waste generated; volume represents what’s left over after recovery for recycling and composting. Discuss the advantages associated with a reduction in the weight of garbage (less energy to transport, less expensive to deposit at a landfill) vs. reduction in volume (less landfill space required).
- Ask students to look through magazines for pictures of items from each MSW category. Have each student draw a garbage pizza on poster board and glue the pictures on the appropriate sections. Display the posters in the cafeteria.
- Discuss ways students can help better manage solid waste in school. For example:
- don’t waste paper, use both sides of paper, start a reuse box for all kinds of paper;
- start a paper recycling program, determine what materials your solid waste management company accepts;
- start a composting program;
- think of creative ways to reuse different products and materials.
- Create a pizza using disposal methods. Discuss options for disposal and differences between discard (landfill), recovery (recycling and composting) and combustion with energy. How does this compare with local rates? (see EPA MSW Report).
- Note: Keep America Beautiful, Inc. poster “Million Tons of Stuff” provides a visual picture of the waste management options available.
Young children are learning about their environment and ways to manage waste or trash in the classroom and at home through recycling, composting, and other means. They realize how much they can contribute to helping our world, even though they are young children. Here some activities that you and your child will enjoy.
Being a “helping hand” for helping the environment is enjoyable for young children. Begin with recycling plastics. Check with the recycling guidelines if possible in your community. Set up a place at home to collect all plastics used. Sort the plastics into the recycling number at the bottom of each item. Containers can be flattened to save storage space. Praise your child’s “helping” efforts. With daily practice, managing waste can become a life-long habit which will help our environment today and in the future.
Old Things Become New
Find a new way to use plastic containers. For example, a milk plastic jug can become a watering can for potted plants. With help from an adult, it can even be made into a “glove” for catching balls. Use your imagination and creativity!
Making a list (and checking it daily)
Help your child remember all the products around the home that can be recycled. Encourage drawings to help them remember, as well as the adults living at home. Recyclable items may include: paper, aluminum cans, steel cans, etc. Place the list in a visible place to remind everyone about what items can be recycled and to help with managing our waste.
- Tour your home and help your child identify ways to manage waste that the family can do together.
- Discuss how the family can recycle aluminum cans. Provide a place for putting rinsed aluminum cans. Your child will enjoy visiting a recycling center that accepts aluminum cans.
- Discuss how the family can recycle paper. Provide a place for putting “used” paper. Discuss how some products on paper may make them unacceptable such as: rubber bands, metal fasteners, paper clips, and food residue. Make certain that all recycled paper is clean and free of contaminants.
Take time daily to address waste management with your child, as well as modeling appropriate actions. They will soon understand how everyone can make a difference in helping our environment.
- Tell me what you know about waste management?
- What can you do to reduce waste management?
- How can you help your family reduce waste and management it?
Good books to read together
Children enjoy the special times you spend reading to them. Take a blanket or large towel outdoors with your child and read!
- Earth-Friendly Waste Management by Charlotte Wilcox, Lerner Publishing Group.
The book with real pictures address the many issues of waste management such as understanding the trash problem, sorting out trash, and finding new uses for old “stuff.”
- Reduce, Reuse, Recycle: Paper by Alexander Fix, Heinemann.
This book addresses ways to recycle paper.
- Reduce, Reuse, Recycle: Plastic by Alexander Fix, Heinemann.
This book addresses the issues related to plastics and recycling.
- Reduce, Reuse, Recycle: Metal by Alexander Fix, Heinemann.
This book addresses information about recycling metals.