Getting Started
What kind of decomposition happens to food in landfills? How do other types of material decompose in landfills?

Procedure

1. Explain to the students the purpose of a landfill and how they are constructed.

2. Have the students, individually or in small groups, construct their own mini-landfill. Line a small aquarium or clear plastic box with a plastic bag and fill it half full of earth.

3. Have each student prepare two identical groups of trash. Place the trash from the first group in one of the small plastic bags and seal it, simulating what they do with their household waste. Do not place the second batch of trash in a bag. Bury the two groups of trash in adjacent rows, marking the location of each item with a cardboard label.

4. On the worksheet, each student or group should note the items placed in the landfill, along with the date. Have them add water to moisten the soil and place the mini-landfill in a sunny spot. The landfills should be watered regularly, keeping the soil moist but not wet, to simulate rain.

5. After 7 to 10 days, have the students carefully remove some of the waste items from each of the rows of trash and examine them. (A magnifying glass may be helpful at this point.) Students should complete the questions for Week One on the "Mini-Landfill" worksheet.

6. Wait another 7 to 10 days and repeat the procedure for the remaining trash in each row. Have the students complete the questions for Week Two on the worksheet.

7. Use the students' observations to discuss the results, comparing the condition of waste in the plastic bag with that which was buried directly in the soil. Address questions such as: Which items in the landfill decomposed the most? Were the decomposed items natural or manmade? Did the type of decomposition in the bag differ from the type that occurred in the soil? What characteristics are shared by the items that decomposed the quickest? Some items showed no signs of decomposition: Will they remain unchanged for a long time? Why?

Extensions

1. Have students replace the items removed in step 6 and cover the box or aquarium. Let it sit for at least 2 months to allow for leachate formation. (Leachate will collect in the bottom of the liner plastic bag.) Have students empty the contents of the landfill to determine which items decomposed and which did not. Also have them collect a sample of the leachate and test its acidity. (Note, the mini-landfill does not contain the kind of toxic materials that exist in real landfills. These toxics would have an effect on the acidity of the leachate, were they present.)

2. Have the students research why leachate needs to be controlled at landfills, addressing what kinds of materials are commonly found in leachate and whether or not they are harmful.

3. Items such as disposal diapers and plastic trash bags are being advertised as biodegradable. Discuss with the class the meaning of biodegradable and whether these products are indeed biodegradable and why.

Source: Adapted from Bell and Swartz, Oscar's Options with permission

BUILD A MINI-LANDFILL
Worksheet

1. List the items placed in the landfill and the date you buried them:

2. The items that decomposed the most are:

Week 1:

Week 2:

3. The following items decomposed a little:

Week 1:

Week 2:

4. These items did not change at all:

Week 1:

Week 2: