LESSON 3	Activity 3

Grades:

4th - 7th

Objective:

Students learn how groundwater moves through the soil. They will also be able to see how the pollution from a source, such as a leaking septic tank, disperses and travels underground.

Method:

Students will work in groups to try to predict the path that pollution will travel, and how far the plume will spread. They will also see how a well works, and see how it is affect by underground pollution in the area.

Materials:

Two large, preferably clear, pan-like containers, sand, two clear plastic straws, cheesecloth to function as a filter for the end of each straw, food coloring, masking tape, two syringes, two watering cans or spray bottles, water.

Time:

Preparation Time: 20 minutes
Class Time: 30 minutes

Procedure:

1. Prior to the lesson in class, you must prepare two groundwater models in the clear containers. To do this, place a filter on one end of a straw. Tape the straw, vertically, to one end of the container, with the filter at the bottom, allowing 1/8" of space from bottom. Now simply pour three to four inches of sand into each container.

2. Pour water on the sand until a two inch high water table is reached. See if the water in the straw, now a piezometer (an instrument used to measure water table depth), is at the same level as the water table.

3. After you have prepared the groundwater models, and given an introduction to groundwater to the class, have the students break into four groups, with two groups at each model.

4. Explain that for this activity, one group will secretly bury the food coloring somewhere in the model. This represents pollution from a leaky storage tank. Once the group has buried it, the other group will try to determine its location and how it moves. They cannot dig it up. The groups will later trade roles.

5. Now have one group from each model secretly dig a little hole, put several drops of food dye in the hole, and cover it back up.

6. The group responsible for finding the pollution plume is now instructed to draw water out of the well using the syringe which acts as the pump. Meanwhile, another group member should create rain by spraying water on the surface to expedite groundwater flow.

7. The students continue to draw water out until the food dye begins to show up in their well water.

8. Once they have discovered that the pollution exists, they must now determine where it has spread. There are two options: 1. If the container is clear, they can pick it up and look on the bottom to see the plume that has formed. 2. If the container is opaque, students should use their fingers to dig at least five holes in the sand. In some holes, and not in others, they should see the pollution. Students explain what they observed about where the pollution began and how it reached their well.

9. This group should now sketch the model and draw in the plume of pollution that occurred.

10. Have the students spray the model and pump the well until the color is gone. Then fill the model back up with two inches of water, reverse the group roles, and repeat the activity.

Assessment:

1. Through which type of ground layer, sand or pebbles, would polluted groundwater flow more quickly? How might the topography of the land change the pollution travel time?

2. Once the groundwater has been polluted, what is the best way to clean it up? Is there really a possible solution for clean-up?

3. What is the best method to prevent groundwater pollution from sources such as leaky septic and underground storage tanks?
   

NYS Learning Standards:

Math, Science, and Technology
Standard 1 - Analysis, Inquiry, and Design: Scientific Inquiry
Standard 4 - Science: Physical Setting 2; The Living Environment 7
Standard 6 - Interconnectedness: Models

Source: Activity devloped by Nathan Chronister and Aaron Bennett.