Following this simple schematic of a sanitary landfill, your class can learn about modern landfill construction and eat the results!
A landfill is carefully designed to protect groundwater and the environment. A liner system consisting of two feet of compacted clay goes on the bottom (graham cracker crust) and a synthetic geomembrane liner (fruit roll-up) is laid on the clay. Gravel (crushed graham crackers) with leachate collection lines (licorice) is then placed on the liner. Leachate is the liquid that percolates through the trash. It must be collected and removed from the landfill to protect groundwater.
Trash (pudding) is then taken in by the landfill in daily cells that are covered with 6 inches of soil cover (crushed Oreos). As the trash breaks down, gas (primarily methane and carbon dioxide) is generated that must be removed with gas collection lines (licorice). When a real landfill closes, a final cap consists of one foot of compacted clay, a second geomembrane liner and a vegetative layer that will support grass. For ease of eating, the edible landfill closed with just grass cover! Construct an edible landfill to understand the design of high-tech landfills.
- Pre-made pie crust in tin
- Graham crackers
- Shoestring licorice
- Fruit roll-ups
- Vanilla pudding
- Crushed Oreo cookies
- Coarse graham cracker crumbs
- M & M candies, nuts, raisins
- Green food coloring
Save all wrappings and packaging. While landfill is being set up, engage students in discussion on how much waste is generated during the activity (packaging, etc.). What can be recycled? How can you reduce waste?
- Use graham cracker crust in pie pan to represent the clay soil. Clay soils provide a watertight base.
- Line the crust with fruit roll-ups. These represent a high density plastic liner used to line the bottom for added protection.
- Add licorice to represent leaching tubes. These pipes are used to collect leachate that has percolated through the trash and channels it to a treatment center.
- Cover the licorice with graham cracker crumbs. This simulated gravel used to percolate liquids up through the tubes.
- Next comes the garbage and trash. Use a mixture of vanilla pudding, M & Ms, nuts, and raisins (or use your imagination) to depict this.
- Add crushed Oreo cookies to represent soil. This is often done on a daily basis to eliminate odors and discourage scavengers.
- Poke licorice down through mixture in two places to represent gas collection lines.
- (Dye coconut with green food coloring.) Top off your creation with green coconut. This simulates the sowing of a final grass cover to prevent erosion.
- Eat your creation!