32_Porosity and Permeability
32
Investigating Porosity and Permeability
Investigating Porosity and Permeability Aquifer Study OBJECTIVE Students will test the porosity and permeability of several different substances and from the results draw conclusions about which substances make good aquifers and which make good confining beds, or aquitards. LEVEL Middle Grades: Earth Science
T E A C H E R
P A G E S
NATIONAL STANDARDS UPC.2, UPC.3, A.1, A.2, D.2, F.3 TEKS 6.2(B), 6.2(C), 6.2(D), 6.2(E), 6.14(B) 7.2(A), 7.2(B), 7.2(C), 7.2(D), 8.2(A) 8.2(B), 8.2(C), 8.2(D), 8.14(A) IPC 1(A), 2(A), 2(B), 2(C), 2(D), 3(A) CONNECTIONS TO AP AP Environmental Science: I. Interdependence of Earth’s Systems: Fundamental Principles and Concepts B. The Cycling of Matter 1. water II. Renewable and Nonrenewable Resources: Distribution, Ownership, Use, Degradation A. Water 1. fresh TIME FRAME 50 minutes MATERIALS (For a class of 28 working in groups of 4) 1 10 lb bag of sand 1 10 lb bag of clay 1 10 lb bag of gravel 1 10 lb bag course sand 7 100 mL graduated cylinders
7 rubber bands 7 ring stands 7 stop watches 1 or 0.5 liter carbonated beverage bottles with cap several pairs of old nylon stockings
TEACHER NOTES The sand and gravel can be purchased at a garden store. Regular art clay can be used for the clay sample. The pantyhose tend to break easily so have extra on hand and replace as needed. All of the empty bottles need to be the same size, but either 1 liter or 0.5 liter bottles will work, depending on the size of the rings you have for your ring stands. 610
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
Investigating Porosity and Permeability
32
After getting 7 same sized bottles the teacher should cut the bottom of the bottles off so they are open and easy to fill. The cap end of the bottom stays untouched so that the lid can be taken off and put back on during the lab. Use a permanent marker to draw a line around each bottle 10 centimeters from the cap end. The teacher needs to measure and draw a black line to the same level on each of the bottles so that each bottle will contain the exact same amount of material to be tested. For a 0.5 liter bottle measure from the bottom of the neck POSSIBLE ANSWERS TO THE CONCLUSION QUESTIONS AND SAMPLE DATA Answers will vary widely with the provided materials. A range of answers is given below. Porosity (mL) Flow time (min) Recovered water (mL) Permeability (mL/min) 45 - 65 2-5 190 - 200 100 - 40 40 - 60 2 - 10 150 - 190 95 - 15 30 - 55 8 - 11 145 - 185 23 - 13 0 0 0 0 porosity permeability
120
40
100 80
30
60 20
40
10
20
0
0
gravel
coarse sand
fine sand
millileters per second
50
P A G E S
millileters
Porosity and Permeability
clay
1. Which sample held the most water? Which held the least? • The gravel held the most water, clay held very little or no water. 2. Describe the amount of available pore space in the material that held more water? • The material that held the most water has the most porosity, or rather has the most space between particles to hold water. 3. Which sample was the most permeable? Which was the least permeable? • Gravel was the most permeable. Clay was the least permeable. 4. Why would gravel be a poor filter for water? Which material might make a good filter? • Gravel allowed the water to pass through too quickly to filter the water. Sand would be a much better filter. Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
T E A C H E R
Sample Gravel Coarse Sand Fine Sand Clay
611
32
Investigating Porosity and Permeability
5. Why would clay act as a confining layer (aquitard) for an aquifer? • Clay does not allow water to pass through and therefore is an excellent confining layer. 6. Aquifers must be permeable. List the samples which would be good aquifers. • Gravel and both types of sand would be good aquifers because they are both porous and permeable.
T E A C H E R
P A G E S
7. Discuss the truth of statement “What goes in, must come out.” How does your data support or refute this statement. • The volume of water that was recovered was less than the volume of water that was added. Some of the water remained in the material clinging to the particles. Therefore, only some of what goes in comes out!
612
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
Investigating Porosity and Permeability
32
Investigating Porosity and Permeability Aquifer Study Porosity and permeability are related terms used to describe any rock or loose sediment. Both of these properties are essential to the formation of an aquifer. Specifically, porosity of a rock is a measure of its ability to hold a fluid. Permeability is a measure of the amount of fluid able to flow through a rock. An aquifer is a geologic formation that will yield water to a well in sufficient quantities to make the production of water from this formation feasible for beneficial use. It contains permeable layers of underground rock or sand that hold or transmit groundwater below the water table. Artesian aquifers are confined on the top and bottom by non-permeable rock layers, sometimes called aquitards, which put the aquifer under pressure and allow springs and wells to flow without being pumped. PURPOSE Students will be able to describe porosity and permeability in sand, gravel, and clay. MATERIALS fine sand clay gravel course sand 100 mL graduated cylinder
rubber bands ring stand stop watch 1 or .5 liter carbonated beverage bottle with cap pantyhose
PROCEDURE 1. In the space marked HYPOTHESIS on your student answer sheet, write a hypothesis addressing which of the four materials (fine sand, course sand, gravel, and clay) will be the most porous and which will be the most permeable. 2. Cut a 20 cm square of pantyhose and fold it in half. Remove the cap from the bottle, place the pantyhose over the opening of the bottle, and secure with a rubber band. 3. Replace the cap and firmly attach it so that water will not leak out of the bottle. See the picture. Pre-test your bottle with some water to ensure that it does not leak. 4. Empty the water from the bottle, and proceed to the next step. 5. Fill the bottle to the black line with the sample material that will be tested. Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
613
32
Investigating Porosity and Permeability
6. To measure the porosity we will determine the volume of water it takes to just saturate the test material. Fill the graduated cylinder to 100 mL. Slowly add water to the sample material until water begins to pool at the surface of the sample. If you have added too much water, carefully pour off the excess back into the graduated cylinder. 7. Record the volume of water in mL that was added to the sample in the data table in the Porosity column on your student answer page. Then, record this value for your class data as your teacher instructs. 8. To measure the permeability we will determine the amount of time in takes for 200 mL of water to flow through the sample material. Add the remaining water in your graduated cylinder to the sample container. Add any additional water to the sample so that the TOTAL VOLUME of the water added is 200 milliliters. For example, if you added 60 milliliters to the sample in the porosity test, you will have to add 140 milliliters more to the container. 9. Position a 250 mL beaker under the neck of the bottle to catch the run-off water. Simultaneously, start the stopwatch and remove the cap from the bottle. Stop the timer when the dripping water from the bottle has a frequency of one drop every 10 seconds. 10. Record the time in the data table on your student answer page in the Flow time column. Then, record this value for your class data as your teacher instructs. 11. Using the run-off water in your beaker, measure the amount of water that passed through your sample with a graduated cylinder. Record this value in the data table on your student answer page in the Recovered water column. Then record this value for your class data as your teacher instructs. 12. Using the volume of recovered water and the elapsed time, calculate the porosity in mL/min for each sample. Record these values in your data table in the Permeability column and with the class data as your teacher instructs.
614
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
Investigating Porosity and Permeability
32
Name _____________________________________ Period _____________________________________
Investigating Porosity and Permeability Aquifer Study HYPOTHESIS
DATA AND OBSERVATIONS Sample Gravel Coarse Sand Fine Sand Clay
Porosity (mL) Flow time (min) Recovered water (mL) Permeability (mL/min)
ANALYSIS Make one graph that shows both porosity and permeability using the two y-axes to show the data.
CONCLUSION QUESTIONS 1. Which sample held the most water? Which held the least?
2. What can you assume about the material that held more water?
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
615
32
Investigating Porosity and Permeability
3. Which sample was the most permeable? Which was the least/not permeable?
4. Why would gravel be a poor filter for water? Which material might make a good filter?
5. Why would clay act as a confining layer for an aquifer?
6. Aquifers must be permeable. List the samples which would be good aquifers.
7. Discuss the truth of statement “What goes in, must come out.” How does your data support or refute this statement.
616
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
Investigating Porosity and Permeability
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
32
617
Investigating Porosity and Permeability
Investigating Porosity and Permeability Aquifer Study OBJECTIVE Students will test the porosity and permeability of several different substances and from the results draw conclusions about which substances make good aquifers and which make good confining beds, or aquitards. LEVEL Middle Grades: Earth Science
T E A C H E R
P A G E S
NATIONAL STANDARDS UPC.2, UPC.3, A.1, A.2, D.2, F.3 TEKS 6.2(B), 6.2(C), 6.2(D), 6.2(E), 6.14(B) 7.2(A), 7.2(B), 7.2(C), 7.2(D), 8.2(A) 8.2(B), 8.2(C), 8.2(D), 8.14(A) IPC 1(A), 2(A), 2(B), 2(C), 2(D), 3(A) CONNECTIONS TO AP AP Environmental Science: I. Interdependence of Earth’s Systems: Fundamental Principles and Concepts B. The Cycling of Matter 1. water II. Renewable and Nonrenewable Resources: Distribution, Ownership, Use, Degradation A. Water 1. fresh TIME FRAME 50 minutes MATERIALS (For a class of 28 working in groups of 4) 1 10 lb bag of sand 1 10 lb bag of clay 1 10 lb bag of gravel 1 10 lb bag course sand 7 100 mL graduated cylinders
7 rubber bands 7 ring stands 7 stop watches 1 or 0.5 liter carbonated beverage bottles with cap several pairs of old nylon stockings
TEACHER NOTES The sand and gravel can be purchased at a garden store. Regular art clay can be used for the clay sample. The pantyhose tend to break easily so have extra on hand and replace as needed. All of the empty bottles need to be the same size, but either 1 liter or 0.5 liter bottles will work, depending on the size of the rings you have for your ring stands. 610
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
Investigating Porosity and Permeability
32
After getting 7 same sized bottles the teacher should cut the bottom of the bottles off so they are open and easy to fill. The cap end of the bottom stays untouched so that the lid can be taken off and put back on during the lab. Use a permanent marker to draw a line around each bottle 10 centimeters from the cap end. The teacher needs to measure and draw a black line to the same level on each of the bottles so that each bottle will contain the exact same amount of material to be tested. For a 0.5 liter bottle measure from the bottom of the neck POSSIBLE ANSWERS TO THE CONCLUSION QUESTIONS AND SAMPLE DATA Answers will vary widely with the provided materials. A range of answers is given below. Porosity (mL) Flow time (min) Recovered water (mL) Permeability (mL/min) 45 - 65 2-5 190 - 200 100 - 40 40 - 60 2 - 10 150 - 190 95 - 15 30 - 55 8 - 11 145 - 185 23 - 13 0 0 0 0 porosity permeability
120
40
100 80
30
60 20
40
10
20
0
0
gravel
coarse sand
fine sand
millileters per second
50
P A G E S
millileters
Porosity and Permeability
clay
1. Which sample held the most water? Which held the least? • The gravel held the most water, clay held very little or no water. 2. Describe the amount of available pore space in the material that held more water? • The material that held the most water has the most porosity, or rather has the most space between particles to hold water. 3. Which sample was the most permeable? Which was the least permeable? • Gravel was the most permeable. Clay was the least permeable. 4. Why would gravel be a poor filter for water? Which material might make a good filter? • Gravel allowed the water to pass through too quickly to filter the water. Sand would be a much better filter. Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
T E A C H E R
Sample Gravel Coarse Sand Fine Sand Clay
611
32
Investigating Porosity and Permeability
5. Why would clay act as a confining layer (aquitard) for an aquifer? • Clay does not allow water to pass through and therefore is an excellent confining layer. 6. Aquifers must be permeable. List the samples which would be good aquifers. • Gravel and both types of sand would be good aquifers because they are both porous and permeable.
T E A C H E R
P A G E S
7. Discuss the truth of statement “What goes in, must come out.” How does your data support or refute this statement. • The volume of water that was recovered was less than the volume of water that was added. Some of the water remained in the material clinging to the particles. Therefore, only some of what goes in comes out!
612
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
Investigating Porosity and Permeability
32
Investigating Porosity and Permeability Aquifer Study Porosity and permeability are related terms used to describe any rock or loose sediment. Both of these properties are essential to the formation of an aquifer. Specifically, porosity of a rock is a measure of its ability to hold a fluid. Permeability is a measure of the amount of fluid able to flow through a rock. An aquifer is a geologic formation that will yield water to a well in sufficient quantities to make the production of water from this formation feasible for beneficial use. It contains permeable layers of underground rock or sand that hold or transmit groundwater below the water table. Artesian aquifers are confined on the top and bottom by non-permeable rock layers, sometimes called aquitards, which put the aquifer under pressure and allow springs and wells to flow without being pumped. PURPOSE Students will be able to describe porosity and permeability in sand, gravel, and clay. MATERIALS fine sand clay gravel course sand 100 mL graduated cylinder
rubber bands ring stand stop watch 1 or .5 liter carbonated beverage bottle with cap pantyhose
PROCEDURE 1. In the space marked HYPOTHESIS on your student answer sheet, write a hypothesis addressing which of the four materials (fine sand, course sand, gravel, and clay) will be the most porous and which will be the most permeable. 2. Cut a 20 cm square of pantyhose and fold it in half. Remove the cap from the bottle, place the pantyhose over the opening of the bottle, and secure with a rubber band. 3. Replace the cap and firmly attach it so that water will not leak out of the bottle. See the picture. Pre-test your bottle with some water to ensure that it does not leak. 4. Empty the water from the bottle, and proceed to the next step. 5. Fill the bottle to the black line with the sample material that will be tested. Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
613
32
Investigating Porosity and Permeability
6. To measure the porosity we will determine the volume of water it takes to just saturate the test material. Fill the graduated cylinder to 100 mL. Slowly add water to the sample material until water begins to pool at the surface of the sample. If you have added too much water, carefully pour off the excess back into the graduated cylinder. 7. Record the volume of water in mL that was added to the sample in the data table in the Porosity column on your student answer page. Then, record this value for your class data as your teacher instructs. 8. To measure the permeability we will determine the amount of time in takes for 200 mL of water to flow through the sample material. Add the remaining water in your graduated cylinder to the sample container. Add any additional water to the sample so that the TOTAL VOLUME of the water added is 200 milliliters. For example, if you added 60 milliliters to the sample in the porosity test, you will have to add 140 milliliters more to the container. 9. Position a 250 mL beaker under the neck of the bottle to catch the run-off water. Simultaneously, start the stopwatch and remove the cap from the bottle. Stop the timer when the dripping water from the bottle has a frequency of one drop every 10 seconds. 10. Record the time in the data table on your student answer page in the Flow time column. Then, record this value for your class data as your teacher instructs. 11. Using the run-off water in your beaker, measure the amount of water that passed through your sample with a graduated cylinder. Record this value in the data table on your student answer page in the Recovered water column. Then record this value for your class data as your teacher instructs. 12. Using the volume of recovered water and the elapsed time, calculate the porosity in mL/min for each sample. Record these values in your data table in the Permeability column and with the class data as your teacher instructs.
614
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
Investigating Porosity and Permeability
32
Name _____________________________________ Period _____________________________________
Investigating Porosity and Permeability Aquifer Study HYPOTHESIS
DATA AND OBSERVATIONS Sample Gravel Coarse Sand Fine Sand Clay
Porosity (mL) Flow time (min) Recovered water (mL) Permeability (mL/min)
ANALYSIS Make one graph that shows both porosity and permeability using the two y-axes to show the data.
CONCLUSION QUESTIONS 1. Which sample held the most water? Which held the least?
2. What can you assume about the material that held more water?
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
615
32
Investigating Porosity and Permeability
3. Which sample was the most permeable? Which was the least/not permeable?
4. Why would gravel be a poor filter for water? Which material might make a good filter?
5. Why would clay act as a confining layer for an aquifer?
6. Aquifers must be permeable. List the samples which would be good aquifers.
7. Discuss the truth of statement “What goes in, must come out.” How does your data support or refute this statement.
616
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
Investigating Porosity and Permeability
Laying the Foundation in Middle Grades Life and Earth Science ©2004 Laying the Foundation, Inc. All rights reserved. Visit: www.layingthefoundation.org
32
617
