Recycle City has two landfills—a solid waste (or sanitary) landfill for safe disposal of regular household garbage, and a hazardous waste landfill outside of town that was built with extra safeguards to handle more dangerous industrial wastes.
When Recycle City was called Dumptown, everyone threw everything into the same big hole in the ground. The hole soon became a little mountain of trash. Hazardous material in the dump would seep into the soil and even into the groundwater under the earth's surface. The contamination was so bad, it required an expensive clean-up effort. But now, there's a much better way...
Old Landfill
The old Dumptown landfill is all covered over now. But because it was just a hole in the ground where residents and businesses threw away everything—including hazardous waste—it caused a big problem. Poisonous liquids seeped through the soil into the groundwater beneath the earth's surface and contaminated it. This underground plume of contamination started spreading toward even larger underground water supplies.
With some help from federal and state authorities, the new Recycle City government started cleaning up the problem. Using money from the businesses that had been most responsible for the contamination, a "pump-and-treat" plant was built to remove the contaminated groundwater and clean it up. This plant pumps water out of the ground, purifies it by filtering out all the pollutants, and sends it to nearby farms so it can be used to water crops.
The plant was very expensive to build and run, and it taught everyone a valuable lesson: It's much cheaper to prevent pollution in the first place than to clean it up later!
Unfortunately, there are many contaminated places in the United States. To help the country clean up these hazardous waste sites, Congress created Superfund. Superfund is a law that lets the government find those who are responsible for creating the hazardous waste and have them clean it up. Superfund is also a name for special money the U.S. Environmental Protection Agency can use to clean up pollution from hazardous waste if they can't find who caused the contamination, or if those responsible for it don't have enough money to pay for the expensive clean-up.
New Landfill
After reusable and recyclable materials have been removed at the Materials Recovery Facility, the remaining household waste is compacted and trucked here to the solid waste landfill.
This landfill is a large pit with a liner along the sides and bottom that keeps the waste from touching the earth. When it rains, water drips through the garbage in the landfill and dissolves various chemicals in the waste, producing contaminated water. The landfill liner holds the contaminated water (called leachate) and keeps it from seeping into the earth and eventually into rivers or drinking water wells.
The liner has five layers made of different kinds of materials:
1. The bottom layer next to the earth is made of at least two feet of clay that has been pounded until it is very compact.
2. Next is a layer of strong, flexible, very thick plastic, called high density polyethylene (HDPE).
3. On top of the plastic is a one-foot layer of gravel with pipes running through it. The leachate collects in these pipes and is pumped out of the landfill and filtered.
4. Above the gravel is a layer of very tough fabric, called geotextile fabric, to protect the pipes.
5. Finally, the top layer is about one foot of compacted soil to protect the entire liner system from the waste.
Each evening, large trucks roll over the landfill to crush the day's garbage and then cover it with six inches of soil so the waste doesn't smell or attract flies and rats.
When an area of the landfill is completely full, the workers cover it with more layers of clay and plastic and soil. This final landfill cover helps keep rainwater out of the waste and reduces the amount of lechate that forms.
