The quick answer
- A sanitary landfill is an engineered site for burying trash that keeps the waste walled off from groundwater, air and animals instead of just piling it in a hole.
- The key parts are a liner under the waste, pipes that collect the liquid that drains out, a layer of soil over the trash at the end of each working day, monitoring wells and a cap when it closes.
- In U.S. law it is the opposite of an open dump. Federal law calls any disposal site that falls short of EPA’s landfill criteria an open dump, and open dumping is banned.
- Most “dumps” people drive to today are sanitary landfills, or transfer stations that send trash to one.
What “sanitary” means here
The word does not mean clean or germ-free. It means the site is run to protect public health. Older dumps let trash sit in the open, where it drew rats and flies, caught fire, blew around and let polluted water soak into the ground. A sanitary landfill uses design and daily routines to stop each of those problems.
U.S. law has a short, formal version. The Resource Conservation and Recovery Act (RCRA) defines a sanitary landfill as a solid waste disposal facility that meets the criteria EPA publishes under the act. For landfills that take household trash, those criteria are in 40 CFR Part 258, and the industry and EPA usually call these sites municipal solid waste landfills (MSWLFs). In everyday use, “sanitary landfill,” “MSW landfill” and “the county landfill” mostly mean the same thing.
Sanitary landfill vs open dump
RCRA defines an open dump as a site where solid waste is disposed of that is not a sanitary landfill meeting EPA’s criteria, and not a hazardous waste facility. Disposal by open dumping is prohibited under the act, and states were told to close or upgrade old dumps. When RCRA became law on October 21, 1976, EPA described one of its goals as bringing open dumping across the country to an end by 1983.
The practical differences come down to a few things:
- Liner and leachate control: a sanitary landfill sits on an engineered liner with a drain system; an open dump has neither, so polluted water can reach groundwater.
- Cover: sanitary landfills bury each day’s trash under soil or an approved cover; open dumps leave it exposed.
- Burning: the federal rules ban open burning at municipal landfills, apart from narrow exceptions such as land-clearing debris, while burning trash was common at old dumps.
- Monitoring: sanitary landfills test groundwater and control gas; open dumps do not.
- Permits: sanitary landfills are permitted and inspected, usually by the state.
“Illegal dumping” on a roadside or vacant lot is a separate problem, but it is the same idea: waste disposed of somewhere with no controls at all.
Where the sanitary landfill came from
The Fresno Sanitary Landfill in California is widely credited as the first modern example in the United States. According to the City of Fresno, Jean Vincenz, the city’s public works commissioner in the 1930s, tested his method at a small site starting in 1934 and then opened a permanent 90-acre site in 1937. His approach dug trenches, spread trash in layers, compacted both the trash and the soil over it and covered the fill every day. The city calls it the first landfill to use the trench method and compaction, and it became a model for landfills nationwide.
The Fresno site closed in 1987 and was named a National Historic Landmark in 2001. It was also reviewed under the federal Superfund program, which shows how far standards have moved. The 1930s idea of “sanitary” controlled pests and litter, but it had none of the liners and groundwater monitoring a landfill needs today.
How a modern sanitary landfill is built
EPA groups the federal criteria for municipal solid waste landfills into a handful of areas: where they can be located, how they are designed, how they are operated, groundwater monitoring, cleanup of any releases, closure and post-closure care, and money set aside to pay for it. States run the permit programs and can be stricter. The main physical pieces:
- Location limits. New landfills have to stay clear of, or be specially designed for, places like floodplains, wetlands, fault zones, unstable ground and areas near airports.
- A composite liner. Under 40 CFR 258.40, the standard liner pairs a plastic sheet at least 30 mil thick, or 60 mil if it is high-density polyethylene, laid directly on at least 2 feet of compacted soil with very low permeability (no more than 1 × 10⁻⁷ cm per second).
- Leachate collection. Pipes and drainage stone on top of the liner gather the liquid that seeps through the trash, called leachate, and the rule says the system must hold the depth of liquid over the liner under 30 cm, roughly one foot. The leachate is pumped out for treatment.
- Groundwater wells. Monitoring wells around the site are sampled to catch any leak early.
- Gas control. Rotting waste makes methane, so landfills watch for gas moving underground and many collect it to burn or use for energy.
A working day at the landfill
Trash is not spread across the whole site at once. It goes into one active area, often called the working face, inside a lined section known as a cell. Heavy compactors drive back and forth over each load to crush it down and save space. At the end of each operating day, 40 CFR 258.21 requires at least six inches of earth over the exposed waste, or an alternative cover the state approves, such as tarps or foam. That daily cover is the core “sanitary” step: it keeps down odor, blowing litter, birds, rodents and fire risk.
Some smell is still normal near a working landfill, mostly from fresh trash and gas. Our guide on why landfills smell covers the causes and what helps.
After it closes
When a section or the whole landfill is full, it gets a final cover. Under 40 CFR 258.60 that means at least 18 inches of low-permeability earth to keep rain out, topped by a 6-inch or deeper layer of soil able to support plants, which holds the cap against erosion. Then comes post-closure care, normally 30 years under 40 CFR 258.61: fixing the cap as it settles, running the leachate system and keeping up groundwater and gas monitoring. For the full story, see what happens when a landfill is full.
Because the site is designed to stay dry and sealed, what goes in breaks down slowly. Food and yard waste go fastest, while plastic barely changes. Our guide to how long trash takes to decompose in a landfill has the details.
Sanitary landfills vs other kinds of landfills
- Municipal solid waste (sanitary) landfills take household trash plus some commercial and nonhazardous industrial waste under Part 258. EPA counted about 1,908 of them in the continental United States in 2009.
- Construction and demolition and industrial landfills take things like concrete, lumber and shingles or nonhazardous factory waste. Federally they fall under the older Part 257 criteria, and many states add their own rules.
- Hazardous waste landfills are regulated separately under RCRA Subtitle C, with standards EPA describes as generally stricter than those for municipal landfills.
Some areas send most trash to a waste-to-energy plant instead, but the ash from those plants still goes to a landfill.
Hauling your own load to one
If your county landfill takes residents, you will usually cross a scale at the entrance, pay by weight or by load and get directed to the working face or to a separate drop-off area for small loads. Rules differ by site, so look over our list of what you can take to the dump first. Paint, chemicals, batteries and similar items usually go to a separate household hazardous waste program. Not sure whether to use the landfill or a closer transfer station? Our transfer station vs landfill guide compares them, and landfill prices covers what a trip usually costs. To find the nearest site, open the Dumpmapper map or use dump near me.
Sanitary landfill FAQ
What is the difference between a landfill and a sanitary landfill?
In the U.S. today they are mostly the same thing. A sanitary landfill is a landfill that meets EPA's design and operating criteria, with a liner, leachate collection, daily cover and monitoring. Sites that fall short count as open dumps.
What is an open dump?
Under federal law, it is any place where solid waste is disposed of that does not meet EPA's landfill criteria and is not a hazardous waste facility. Open dumping is prohibited.
What was the first sanitary landfill?
The Fresno Sanitary Landfill in California, opened in 1937 under public works commissioner Jean Vincenz, is widely called the first modern sanitary landfill in the United States. It closed in 1987.
What is the purpose of a sanitary landfill?
To dispose of trash while protecting public health and the environment: keeping polluted liquid out of groundwater, controlling gas and odor and stopping pests, litter and fires.
What is a sanitary landfill liner made of?
The standard federal design is a composite liner: a plastic membrane at least 30 mil thick, or 60 mil if it is HDPE, laid on at least 2 feet of compacted soil with very low permeability.
How long is a sanitary landfill monitored after it closes?
The federal standard is 30 years of care after closing, covering cap repairs, leachate handling and groundwater and gas monitoring. A state with an approved program can lengthen or shorten that period.
The bottom line
A sanitary landfill is a dump built and run to keep trash contained: a liner and drains below, soil over each day’s waste, wells and gas controls around it and a cap with decades of care once it is full. That engineering is what separates it from an open dump, which U.S. law has banned since the late 1970s. When you haul trash to a county landfill today, this is almost always the kind of site you are visiting.