Designing Environmental Solutions

Corel

Figure 1-4: People have some concerns about using landfills as a place to store garbage. In this activity, you will learn more about those concerns.

As you saw in the Explore activity, people have been throwing trash away for a long time. Landfills, like the one in figure 1-4, are one way communities dispose of their trash today. Other communities burn their trash. Both of these methods of garbage disposal have advantages and limitations. In this Explain activity, What Happens to Our Garbage?, you will find out more about the concerns related to garbage disposal. Materials

1. Write the following focus questions in your technology notebook. Draw a colored box around them. Then begin a list to show your best answers to the questions.

   If people have been throwing things away for so long, why is there concern in some places now? What are some problems that exist today that did not exist in the past? Hint

2. In the next few steps, you will conduct an investigation to learn more about landfills. Different teams will test soils at different sites. Watch as your teacher demonstrates the procedure.

3. With your classmates, discuss how to do your investigation. In particular, think about the controls each team needs to use. Hint

4. Get the materials you need for your investigation.

5. Pump the spray bottle a few times to make sure that the water is spraying. Remember that you are doing a controlled experiment, so do not continue pumping once it sprays. Hint

6. If the soil is not already in the box, put a 2.5 cm layer into the plastic box.

7. Follow the Landfill Box Protocol to conduct the investigation.

Landfill Box Protocol

1. Use a straw to dig a hole. Make sure the hole is the size and depth that the class agreed on.
2. Pour all of the powdered drink mix into the hole.
3. Cover the drink mix with soil. This will be the landfill site.
4. Place the block under one end of the box to tilt it. See the setup in figure 1-5.

Figure 1-5: Set up your landfill box like this one. The landfill site is the hole where you put the powdered drink mix. Use the wooden block to raise the landfill end of the box.
5. Decide which of your teammates will take each of the following roles:
   • Sprayer: This team member will spray the water when told.
   • Observer: This team member will carefully observe, measure, and take notes about what happens in the box.
   • Tracker: This team member will keep track of time and say when to start and stop adding water.
6. When the Tracker says “go,” the Sprayer should begin adding water at the rate the class agreed on. The Observer should begin his or her work.
7. Continue adding water and observing the results for the amount of time the class decided on.
8. Clean up your materials as instructed.


From “Movement of Groundwater and Contaminants,” in Groundwater Quality Protection in Oakland County: A Sourcebook for Teachers, pp. 22–26. Copyright © 1984 by East Michigan Environmental Action Council, Bloomfield Township, Michigan. Adapted with permission.

8. Copy the analogy map in figure 1-6 into your technology notebook. Then fill out the blank parts of the table to help you make sense of the model you used.

   

   Figure 1-6: An analogy map to help you understand the landfill model. Fill out the blank parts of the table.

9. Participate in a class discussion about the results of your investigation.

10. What lesson do you think people who build landfills could take from your investigation?

11. Add the information you discovered in your investigation to the answer you started in Step 1.

12. To learn more about other concerns people have about disposing of trash, read What We Do with Garbage. As you read, remember the focus questions from Step 1 and take notes that will help you answer them. Also, do the tasks found within the reading.

    What We Do with Garbage

    People today have more to throw away than they did hundreds of years, and even just decades, ago. Not only has the amount of trash increased, but there are different kinds of trash today. For example, if plastic bottles did not exist, you could not throw them away. The ancestral Puebloans and the people of the 1500s did not have plastic bottles. Today, you might not think that throwing away a plastic bottle is important. But Americans buy almost 30 billion plastic water bottles each year. That works out to 3.4 million bottles bought each hour of every day. What if all of those bottles were thrown in the garbage? Where do they go? Task

    

    Environmental Protection Agency

    Figure 1-7: Total waste generation by material. What makes up most of the garbage people produce?

    Plastic bottles are just one example of something we throw away. If you are like most Americans, about half of your garbage is paper and plastic. The rest of your garbage is probably food scraps, glass, metal, and lawn trash. (See figure 1-7.) A lot of the trash is put into plastic bags. Garbage collectors then haul the garbage to a landfill and dump it. A landfill is most often a large hole in the ground, unless it becomes so large that it becomes a mound. Layers of garbage are covered with dirt to keep the garbage from blowing away. This also keeps rats and other pests away from the garbage. In the United States, 73 percent of our garbage goes to landfills.

    The challenge with landfills is that they fill up. This is particularly true in areas with large populations. As landfills fill up, the garbage near the bottom that is not exposed to air breaks down very slowly. It can take 30 years for food and newspaper to break down when it is deeply buried. Other items such as Styrofoam® are not easily broken down. When trash takes a long time to decompose, landfills can fill up quickly.

    Some cities choose to have their garbage hauled to distant landfills. This can cause problems as well. Transporting garbage for long distances is expensive. Sometimes the managers of the distant landfills do not accept the garbage shipment. If the garbage is not accepted, the chances increase that the haulers will dump the trash illegally, either on land or in the ocean. It would be expensive to haul it back home, and there probably is no room for the garbage there.

    One answer might seem to be to dig more and deeper landfills. However, many people do not want landfills located near their homes. Also, landfills often cannot be dug much deeper than they are already because hard rock lies just beneath the top layer of soil. Cost is another concern-landfills cost about $20 million to build and millions to operate each year.

    To make the problem worse, as you saw in your investigation, many landfills can leak. When people first began digging landfills, they were not concerned about leaks. But through the years, rain soaking into landfills can become contaminated with materials such as paint thinner, motor oil, cleaning solutions, chemicals, and decaying matter from the garbage. Water does not stay in one place unless it is held by something watertight, so eventually water from old landfills has moved farther into the underground water supply, or groundwater, and into lakes and streams. This polluted water may make its way into someone's drinking water supply.

    Some of the first people to learn about the dangers of landfills lived in the Love Canal area of New York. In the 1970s, the people living near Love Canal had unusually high rates of cancer. Their children had higher than usual rates of birth defects. Many people felt sick for no obvious reason.

    It turned out that the residents were living on top of a landfill where harmful chemicals had been dumped in the 1950s. Medical experts were called in who determined that some of the materials in the landfill were causing the illnesses. Eventually, the area's residents filed a lawsuit, hoping that the company that originally dumped the chemicals would help pay for some of the damages.

    Since that time, people have taken steps to prevent chemicals from leaking into groundwater below landfills. Landfills built since the 1980s have plastic liners or 2-foot layers of clay at the bottom. The plastic, or clay, traps any water that might leak through. Task

    Tanks are used to hold the trapped water. Landfill workers treat the trapped water to remove anything that is polluting it. Sometimes the workers circulate the water back through the landfill, which speeds up the decomposition of materials in the landfill because moist materials decay faster. Some water probably still gets through to the ground after many years. However, it is a tiny quantity compared to leaks from old landfills.

    Because of the concerns about landfills, some city officials have looked for other solutions. One possible solution is to burn garbage. In 1885, a new technology was designed. Cities began building incinerators to burn garbage. Figures 1-8 and 1-9 show the outside and the inside of incinerators. People stopped using incinerators during the 1960s because the burning garbage produced a lot of smoke. People wanted to reduce air pollution.

    

    DOE Photo

    Figure 1-8: An incinerator used by a city. Garbage is burned inside and the ash is caught by the chimney.

    

    Ole Poulsen

    Figure 1-9: Garbage being burned in incinerators. This type of incinerator can burn several tons of waste each hour.

    In the late 1980s, new incinerators became available intended to reduce the problem of air pollution. These incinerators are able to burn large amounts of garbage, leaving only a small amount of ash. They burn garbage at very high temperatures, and their chimneys filter out the ash so it does not go into the air. The result is less visible smoke, but not necessarily less air pollution-the particles are simply too small for people to see.

    Incinerators have other problems. They are expensive to build and operate. In one city, the proposed cost to build an incinerator was $350 million. It would cost another $28 million per year to run. Some cities have paid hundreds of thousands of dollars to hire experts who know how to run the incinerators the right way. But even with experts, the incinerators can break down, which would then leave the city with no way to dispose of garbage.

    When incinerators do work and they are used to burn all kinds of trash, another problem arises. Toxic chemicals become concentrated in the ash. This ash is trapped in the chimney and the ash settles to the bottom of the furnace. Although the liquids evaporate during burning and the papers burn, some metals are left behind. This metal can be toxic and has to be disposed of in a special landfill that allows hazardous waste. Although it is a small amount compared to all of the garbage that might normally go into a landfill, the ash requires special handling.

    Using incinerators does have benefits. First, when cities use incinerators, less garbage goes to landfills. Second, engineers think that they can build incinerators that release almost no toxins. In addition, the heat from a certain type of incinerator can be used to generate electricity. This electricity can then be used in homes in the city.

13. Use what you learned in the reading to add to your answer to the focus question from Step 1. Hint