GroundwaterWater held in the ground below the site. The liner is there to protect it.
Clay linerCompacted clay on the bottom and sides of the pit.
GeomembraneA flexible plastic sheet laid over the clay. The two together make the composite liner.
Leachate pipeIt collects leachate for treatment. Leachate is rainwater that has filtered through the waste.
Compacted wasteWaste is spread and compacted in layers.
Daily coverA layer of soil spread over each day's waste.
Final cover (cap)The cover placed over a full landfill. It keeps rain out.
Gas wellIt draws landfill gas out of the waste.
FlareCollected gas that is not used for energy is burned here.
How this list was compiled: Every name checked on 2026-10-01 and kept only where two of these use it. (1) US Environmental Protection Agency, Municipal Solid Waste Landfills, https://www.epa.gov/landfills/municipal-solid-waste-landfills , and Basic Information about Landfills, https://www.epa.gov/landfills/basic-information-about-landfills : composite liners, a flexible membrane (geomembrane) over two feet of compacted clay soil lining the bottom and sides, to protect groundwater and the soil from leachate; leachate, formed when rainwater filters through wastes; leachate collection and removal systems on top of the liner; compacting and covering waste frequently with several inches of soil; daily cover; final cover and closure; groundwater monitoring wells. (2) US Environmental Protection Agency, Landfill Methane Outreach Program, Basic Information about Landfill Gas, https://www.epa.gov/lmop/basic-information-about-landfill-gas : landfill gas, roughly half methane and half carbon dioxide, is extracted using a series of wells and can be flared or used for energy. (3) Wikipedia, Landfill, Landfill liner, Daily cover, Leachate and Landfill gas, text only, https://en.wikipedia.org/wiki/Landfill and https://en.wikipedia.org/wiki/Landfill_liner : compacted clay overlaid by a geomembrane; waste compacted on the working face and covered daily; daily cover, a layer of compressed soil over a day's waste; the cap placed on a full landfill to keep out precipitation; gas wells and flaring. Licence: own work
The drawing: Own drawing from plain geometry; nothing traced. Not to scale. Licence: own work
How it works
An unlabeled landfill diagram to print and label by hand. Nine lines leave the drawing, each from a dot on one part to a blank end: four parts under the ground, three in the mound and two for the gas.
Read the full guide
Four names under the ground
The long line lying in the band of water at the bottom is for groundwater. The pit has two linings. The thick outer layer is the clay liner, and the thin sheet on its inside is the geomembrane; their lines leave from opposite walls. The slotted pipe on the floor of the pit is the leachate pipe.
Five names from the mound up
The large fill is compacted waste, and the thin level strips across it are daily cover: one line points to a strip. The grassy layer over the whole mound is the final cover, or cap. An upright pipe through the mound is a gas well, and the flame on the post is the flare.
Word bank: clay liner, compacted waste, daily cover, final cover, flare, gas well, geomembrane, groundwater, leachate pipe.
Questions and answers
Why is the waste in a landfill covered with soil?
It is one of the operating practices the US Environmental Protection Agency lists: waste is compacted and covered frequently with several inches of soil. That helps reduce odor and control litter, insects and rodents.
How thick is the clay liner of a landfill?
The federal criteria, as the Environmental Protection Agency sums them up, ask for two feet of compacted clay soil under the flexible membrane, on the bottom and the sides. The sheet is not to scale and draws the liner far thicker than that.
When does a landfill start to make gas?
Landfill gas is a natural byproduct of the decomposition of organic material. Freshly placed waste breaks down with oxygen at first and gives little methane. Typically within less than a year, methane-producing bacteria begin to break the waste down.
What is left off the unlabeled landfill diagram?
Groundwater monitoring wells, which the federal criteria require for testing whether waste materials have escaped. A real landfill also has many more layers and gas wells than the three strips and two pipes drawn here.
Does the unlabeled landfill diagram have an answer key?
Yes. The key is the same drawing with a name at the end of each of the nine lines. The top layer is written as Final cover (cap), so either name can be marked right.