Science

Experimental Activities


The activities listed on this page are designed to provide students with process skills and background information specific to groundwater testing.

Outcomes:

  1. Students will collect and perform basic chemical analysis on groundwater samples.
  2. Students will map the flow of water through an aquifer using a groundwater flow model.
  3. Students will analyze data and determine environmental influences on groundwater quality.

Activites:

Table of Contents:


I. Permeability and Porosity

Brief Description:
Students will conduct simple experiments to determine pore space and permeability of gravel, sand, and clay.

Key Terms:
Porosity of a rock or rock material indicates how much of the total volume is air.
Permeability of a material is its ability to transmit water and or other liquid.

Materials:
Gravel, sand, clay, funnel, filter paper, glass-marking pen, graduated cylinder, small test tubes, glass bottles, ring stand, stopwatch.

Procedure:
A. Porosity

 

  1. Mark a bottle, beaker, or test tube about half way up the side.
  2. Fill the bottle with water to this mark and measure the volume using a graduated cylinder. This measurement will be the total volume.
  3. Dry the bottle and fill it to the mark with gravel.
  4. Using a graduated cylinder, slowly pour water into the gravel until the water reaches the top of the gravel.
  5. Note the volume of water added to the gravel. This measurement is the pore space.
  6. To determine the total % pore space in the gravel, divide the pore space volume by the total volume times 100. (% Pore Space=Pore Space/Total Volume x 100)
  7. Repeat with sand and clay.
B. Permeability
  1. Fold a piece of circular filter paper into quarters, open it so it is a cone, and place it in a funnel.
  2. Fill the cone with gravel to about half an inch from the top.
  3. Place the stem of the funnel in a bottle or graduated cylinder.
  4. Pour water into the gravel in the funnel and note how many seconds it takes to fill the glass bottle or graduated cylinder.
  5. This gives you a comparitive permeability rate.
  6. Repeat with sand and clay.
Variations/Extensions:
  1. Mix the sand, gravel and clay in various proportions and repeat the experiment.
  2. Collect soil samples from various locations and depths and repeat the experiment.

II. Groundwater Flow Model

The activities in this section are designed to used with a groundwater flow model. The flow model helps students to conceptualize the workings of an aquifer. Commercial models are available or inexpensive ones can be made. I have included instructions for constructing a flow model out of a two liter bottle as well as a picture of a typical commercial groundwater flow model.

 A typical goundwater flow model

 Concepts/Topics that can be demonstrated with a typical Groundwater Flow Model:

Inexpensive Groundwater Flow Model Plans
Materials:
2 liter clear plastic bottle, transparent straws, plastic syringe, washed pea gravel, sand, topsoil.

Procedure:

  1. Cut the top off the two liter bottle
  2. Place at least two inches of gravel on the bottom of the bottle.
  3. Position the two straws into the container and layer three inches of sand on top of the gravel. Make sure you hold the straws in place as you pour in the sand.
  4. Add two inches of top soil on top of the sand.
Please note that you can change the composition of the layers to make the ground flow model more consistent with your area.

Two liter groundwater flow model activity

 Procedure:

  1. Add water to the model slowly to saturate the sand and gravel layers.
  2. Ask students to predict what will happen if the water is drawn off (using a syringe) through one of the straws.
  3. Insert a syringe into one of the straws and withdraw some water. Observe what occurs.
  4. Move the syringe to the other straw and remove water through it. Note the effect on the level of the groundwater (cone of depression).
  5. Repeat the experiment.
Variations/Extensions:
  1. Inject food coloring into one of the wells (straws) to represent a contaminant. Observe how the contaminant enters the groundwater and how pumping form the other well affects its movement.
  2. Investigate how different soils influence the movement of contaminants.
Related Resources

III. How Soils Affect Water Movement

Brief Description:
Students will measure soil volume and make visual observations about water movement through soil.

Key Terms:
Percolation is the downward flow or seepage of water through the pores of rocks and soil.
A Zone of Saturation is an area where all pore spaces are filled (saturated) with water.

Materials:
The following is a list of materials that should be distributed to each lab group participating in this activity.
4 Large Paper cups, sand, topsoil, gravel,4 plastic coffee can lids or similar objects, cheesecloth or nylon stockings, rubber bands,four 250 ml beakers, thumbtacks, stopwatch.

Procedure:

  1. Students should use a paperclip to poke several holes in the bottom and lower portion of each. Each cup should have the same number of holes located approximately in the same spots.
  2. Put a piece of cheese cloth over the bottom of each cup so that the holes are covered, and secure the cheese cloth with a rubber band.
  3. Cut a hole in the coffee lid with a pair of scissors so the cup fits in the lid. Repeat with other lids and cups.
  4. Place the cups so they sit with the lid resting on the top of a beaker. (The bottom of the cup should be inside the mouth of the beaker.) Label the cups A, B, C, and D.
  5. Fill cup A half full with soil, cup B half full with sand, cup C half full with gravel, and cup D half full with equal amounts of soil, sand and gravel.
  6. Tell the students to predict which soil will percolate the fastest and ask them to predict how long it will take for this to occur.
  7. The students should measure 100 ml of water and pour it into cup A.
  8. Repeat the procedure for cups B, C, and D.
  9. Compare and discuss results.
Variations/Extensions:
  1. Have students calculate percolation rates and graph results. Students can also determine water retention for each sample.
  2. Use different soil types and mixtures.
  3. Compact the soil and repeat the experiment or ask the students to speculate how soil compaction might affect percolation.

IV. Groundwater Testing

Section Overview:
Students will test groundwater for pH, hardness, nitrates/nitrites, iron, and chlorides using water quality test strips. These strips can be purchased from most science supply companies or may be found locally. I have listed the brands that we use in the specific testing sections below. These tests can be easily performed by students. Check your area for local agencies that may be willing to perform other tests for you. The students will also interpret the results of their test to evaluate the quality of the groundwater samples, and learn how to create a well history.

Acids, Bases, and pH
I typically use a pre-activity to introduce acids, bases and the pH scale to my students. I have them test a variety of household products using litmus paper, pH paper, cabbage juice, and universal indicator. This helps my students to form a reference for the pH scale. Furthermore, it introduces them to indicators and that there are many different indicators that can be used for testing pH.

 

Collecting Techniques:

Collecting Techniques:
  1. Make sure you are collecting a representative sample of the true water quality. You can control this by doing the following:
  2. When collecting from a private well:
  3. When collecting from a public supply:

Measuring the pH:

Materials: Procedure:
  1. Wearing latex gloves, carefully dip the test strip into the water sample until all colored tabs are immersed.
  2. Remove the strip immediately.
  3. Match the color pad of the strip to the pH color chart on the test strip container.
  4. Record pH of the sample.

Testing Water Hardness:

Materials: Procedure:
  1. Wearing latex gloves, carefully dip the test strip into the water sample until all colored tabs are immersed.
  2. Remove the strip immediately.
  3. Match the color pad of the strip to the hardness color chart on the test strip container.
  4. Record hardness of the sample.

Testing for Nitrates and Nitrites:

Materials: Procedure:
  1. Wearing latex gloves, carefully dip the test strip into the water sample until all colored tabs are immersed.
  2. Remove the strip immediately and hold it level with the color pads facing up for 30 seconds. (If you are using a different brand check the directions they may vary.)
  3. Compare the nitrite color pad to the chart on the test strip container.
  4. At 60 seconds, compare the nitrate color pad to the chart on the test strip container.
  5. Record nitrate/nitrite levels of the sample.

Testing for Iron:

Materials: Procedure:
  1. Rinse the test cube in the kit with water to be tested. Fill to the mark with the water sample.
  2. Use the clippers to open the FerroVer Iron Reageant Powder Pillow.
  3. Add the contents of the pillow to the cube, cap the cube, and invert several times to mix.
  4. Allow 3 minutes and match the color of the sample to the closest color in the cube to obtain the mg/L of iron.
  5. Record the iron content for the sample.

Testing for Chlorides:

Materials: Procedure:
  1. Wearing latex gloves, carefully dip the test strip into the water sample for 1 second and remove. Do not shake.
  2. Hold the strip level for 30 seconds. (If you are using a different brand check the directions they may vary.)
  3. Redip the strip into the water sample and move it back and forth for 30 seconds.
  4. Compare the Chlorine pads to the color chart on the container.
  5. Record results of the sample.

Groundwater Testing Standards:

The following standards can help you and your students determine the quality of the samples you have collected.

 


V. Groundwater Projects

The following is a list of studies that we at Urbana Middle School have either conducted or will conduct.
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