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Engineers need to find the porosity and permeability of a soil to know where to place a well for bringing up groundwater from an aquifer for drinking water. They also need to develop technologies for drinking water systems to filter harmful germs and chemical spills. Even though a harmful spill may not occur right over a drinking water source, porosity and permeability allows the contaminants to travel through various soils into an aquifer. Today, we are going to find the porosity and permeability of different soil samples and use this information to understand groundwater flow.
Purpose • To study the characteristics of different kinds of soil by measuring pore space and permeability
Warm-up 10/11 • How do you think porosity and permeability are related? • How would you set up an experiment to test the soil porosity?
Prediction • Which soil do you think will have the greatest porosity? • How about Permeability? • Then Form a hypothesis
Procedures • Pour 40 mL of water into your cup and draw a line where the water stops. • Write 40 mL in the total volume column in your Data Table on the Porosity and Permeability Worksheet. • Pour water back into cylinder. • Fill the cup to the line with soil. • Using your graduated cylinder, SLOWLY and carefully pour the water into the cup until the water reaches the top of your soil. • Write the volume of water remaining in the graduated cylinder in your Data Table. • Subtract the volume remaining from the total (original) volume of water in the cup. Write the volume of water added to the sample in your Data Table - this is the pore space. • To determine the porosity of the sample, divide the pore space volume by the total volume and multiply the result by 100. Write the porosity in your Data Table. (Note: % pore space = pore space / total volume x 100)
Which soil sample had the greatest porosity? • Which sample did the water pass through most quickly? (that tells which had the highest permeability)