Lesson Who's Down the Well?

Learning Objectives

After this lesson, students should be able to:

• Identify several sources of contaminants to groundwater.
• Discuss the movement of possible contaminants through that groundwater from outside sources.
• Describe how environmental engineers analyze contaminants to identify placement of drinking water wells.
• Understand that environmental engineers work to clean areas of contamination around drinking water sources.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

Pre-Req Knowledge

An understanding of groundwater and how it flows, as presented in Lesson 3, An Underground River.

Introduction/Motivation

(In advance, prepare an overhead transparency that shows the major water aquifers in the US; obtain this information from the US Geological Survey website at water.usgs.gov/ogw/karst/aquifers )

Where does your water come from? What is its source? (As necessary, review the concepts learned in Lesson 3, An Underground River, about groundwater flow. Draw a picture on the board of the Earth's water table.)

How can this aquifer be affected by outside sources, such as industries and communities? If people dump something on the ground, where does it go? How can we retrieve the groundwater to use as drinking water? Would we want to drink it straight from the aquifer (saturated zone) or alter it first?

It is a complex process to create a good glass of drinking water. Drinking water directly from a well or surface source (such as a lake, river or stream) may contain harmful contaminants that can cause illness or even death or the organisms that consume the water. Can you think of some examples of contaminants? Some contaminants can occur naturally, such as metals from rock erosion or microorganisms; some contaminants come from human activity, such as fertilizer or roadway run-off or chemical discharge from industrial plants and factories. When these contaminants are present in drinking water, they can become dangerous to plants and animals.

Civil, environmental and chemical engineers work together to design drinking water treatment facilities to prepare safe drinking water that is distributed to our homes. To do this, they find existing sources of water, design safe pathways to reach those sources, and decide how to clean any contamination. Today, we will look at the movement of possible contaminants through that groundwater from outside sources. We will also follow the procedures of engineers as they identify and analyze existing contamination of water sources in order to produce high-quality drinking water.

Lesson Background and Concepts for Teachers

Where is the Earth's water located?

Water is found everywhere on the Earth and in the atmosphere in the form of ice, liquid and vapor. Some interesting water facts:

• 97.24% of the Earth's water is found in the salty oceans.
• 2.14% is found in icecaps and glaciers.
• 0.02% of water is found in inland seas and lakes.
• 0.61% of the Earth's water is found underground in aquifers and soils.

Of all the water on Earth, 99.7% of that water is unusable by humans. Only 0.3% of Earth's water is utilized by humans for drinking, washing, cooking and other daily routines (ga.water.usgs.gov/edu/earthwherewater.html ).

What is drinking water?

Drinking water is generally clean in the US because of strict drinking water quality standards. Although drinking water standards regulate the water that comes from our tap, these standards may vary due to the water source and treatment methods. It is important to regulate drinking water because many contaminants occur naturally in waterways. There is no such thing as completely "pure water."

Drinking water comes from many different sources. One large source is surface water, such as lakes, rivers and reservoirs. If no surface water source exists near your community, then your water may comes from an underground water source such as an aquifer. Wells often tap into the natural aquifers that exist below the surface and run all over the Earth. Aquifers can be very small or many miles long. It is important to consider how your source of drinking water is affected by acts of nature and humans. It is not just what happens in the lake, reservoir or well, but what happens over the whole watershed (as was discussed in Lesson 3, An Underground River).

Drinking water directly from a well or surface source can be risky because that source may already have contaminants present. Refer to the associated activity What's Down the Well? for students to learn by creating models how wells are common water sources that can be contaminated via groundwater. Some compounds in water may be harmful to the organisms that use that water source. These compounds can be naturally occurring — such as metals or minerals from rock erosion, or human-induced — such as fertilizer run-off, factory discharges or dissolved pharmaceuticals. Water dissolves or absorbs whatever it comes in contact with, and this can be dangerous if the substances are harmful.

Water contamination can negatively affect the organisms that come in contact with it. The affects can be acute or cause illness and death. Microbial organisms and large chemical spills in drinking water can cause acute affects. Contaminants can also cause chronic effects in humans, which occur over time after drinking water with dangerous levels of contaminants. Some examples of chronic effects are: cancer, liver and kidney problems. These are most often due to chemical spills, high levels of minerals and other toxins.

Why do engineers care about drinking water?

Environmental engineers are concerned about making drinking water safe for citizens. They determine what contaminants are in the water that may harm people, other species or the environment. They determine the contaminant levels, sources and effects. They monitor industrial and commercial inputs to watersheds as well as natural changes in the watershed from temperatures and time. If industrial inputs are present, engineers track the sources upstream and hold the company responsible for what they are dumping. Engineers use this information to create municipal water treatment plants that remove harmful contaminants from the water. They also take into consideration the water taste. Engineers must be able to design and create a safe water product that tastes and smells acceptable so people will use it. All of these factors are considered when designing a drinking water treatment or remediation system.

What is a water table?

A water table is the surface that divides the vadose zone and the saturated zone of the Earth's crust. The vadose zone is the zone that is exposed to the atmosphere with pore spaces between the individual grains of soil filled mostly with air. The saturated zone is the zone below the water table where the pore spaces of the soil are filled mostly with water. The water table moves up and down with variations in weather, temperature, and precipitation. Because the topography of the Earth's surface is variable, the water table can produce features such as rivers, wetlands, and lakes in low valleys. These water features then change directly with the changing level of the water table.

What is groundwater?

Groundwater is the water source that comes from aquifers below the Earth's surface. These are underground water-bearing sections of permeable rock, sand or gravel. (For more on aquifers, visit the US Geological Survey's Water Science for Schools website at ga.water.usgs.gov/edu/earthgwaquifer.html). About 20% of water used by people comes from groundwater. Mostly, groundwater sources are used in areas that have few fresh lakes and streams.

The amount of groundwater being used in the US for personal and commercial uses has increased since the 1950s. For the 43 million Americans who supply their own water at home, 99% of them use groundwater well sources. The groundwater supply is tapped into by digging or drilling water wells.

Why do engineers care about groundwater?

Environmental engineers spend much time studying groundwater. They make models of groundwater flow to determine which communities can use different aquifers for their water supply. They demonstrate how groundwater moves so they can determine how contaminants spread underground from industrial spills and landfill leaching. They analyze the physical properties of the groundwater to determine how safe it is and how it can be used. Engineers dig wells and tap into this water resource. Water levels in the well do not always remain constant, but change due to seasonal temperatures and precipitation. Engineers design pumps that accommodate changes in water levels to move water out of wells at constant rates, yet not completely deplete the sources; otherwise, if a water level falls below the pump, the well will only pump air, and it will go dry. Only 20% of our water supply comes from groundwater; however, more groundwater exists on the Earth than the amount of water in lakes and streams. It is important for engineers to be able to utilize groundwater sources in places of increasing temperatures due to global climate change and decreasing surface fresh water supplies. Learn more about digging water wells and well types at this US Geological Survey website: ga.water.usgs.gov/edu/earthgwwells.html .

How can you help?

It is important for citizens to understand just how easily (even if accidently) they can contribute to the contaminants in drinking water and what treatment can be done to counteract these harmful effects. People can learn how to help engineers protect our natural water sources by being aware of everything they place or pour on the Earth's surface because it may end up in our drinking water. Students can conduct their own investigation with the associated activity Groundwater Detectives where they are challenged to find a contaminant plume from a spill that occurred many years ago. They test soil samples to find a contaminant plume. 

Associated Activities

• What's Down the Well? - Students create models of groundwater wells. They learn how wells are common water sources that can be contaminated via groundwater.
• Groundwater Detectives - Students are challenged to find a contaminant plume from a spill that occurred many years ago. They test soil samples to find a contaminant plume.

Lesson Closure

What is the source of our drinking water? (Listen to student descriptions.) What outside influences can affect our drinking water? (Answer: Influences can be naturally occurring, such as metals or minerals from rock erosion; or human-induced, such as fertilizer run-off, factory discharges or dissolved pharmaceuticals.)

What roles do engineer play in the drinking water process? (Answer: Environmental engineers find locations of water to use for drinking water, design pathways to reach those locations, and decide how to clean areas of contamination around the drinking water source. Civil engineers design water treatment plants to monitor and modify water quality before human consumption.)

What can we do to help keep our drinking water resources clean of contaminants? (Answer: We can make an effort to not spill harmful compounds on the ground, such as oil or chemicals; we can keep informed of the waste disposal policies of local businesses and industries; and we can also help inform other citizens of what is going on in our communities and how they can help.)

Vocabulary/Definitions

acute: Characterized by sharpness or severity.

aquifer: A water-bearing area of permeable rock, sand or gravel, often underground.

chronic: Marked by long duration or frequent recurrence.

contaminant: Something that soils, stains, corrupts or infects by contact or association.

pores: The spaces between grains of soil that can be filled with air, water or contaminants.

saturated zone: The zone of soil below the vadose zone where the pore spaces are filled with water.

vadose zone: The layer of soil exposed to the atmosphere that has pore spaces filled with air and minimal water.

water table: The surface separating the vadose zone and the saturated zone.

Assessment

Pre-Lesson Assessment

Know/Want to Know/Learn (KWL) Chart: Before the lesson, ask students to write down in the top left corner of a piece of paper (or as a group on the board) under the title, Know, all the things they know about groundwater. Next, in the top right corner under the title, Want to Know, ask students to write down anything they want to know about groundwater. After the lesson, ask students to list in the bottom half of the page under the title, Learned, all of the things that they have learned about groundwater. Ask students to name a few items and write them on the board.

Question/Answer: Ask students the following questions to review their pre-lesson knowledge of groundwater flow:

• What is an aquifer? (Answer: An aquifer is water under the ground that technically provides a useable amount of water when pumped.)
• Why do engineers and many people care about groundwater? (Answer: because many people get their drinking water from the groundwater.)
• If a can of oil was spilled on the ground by the school, could it end up in the town well 5 miles south of the school? (Answer: Yes, the oil infiltrates through the ground and then travels with the groundwater in the direction of groundwater flow. The oil would not end up in the town well, however if the groundwater does not flow south.)

Post-Introduction Assessment

Brainstorming: Have students work in pairs to brainstorm five ways groundwater could become polluted. Write ideas on paper and then, as a class, get one answer from each team and record it on the board. (Examples: not properly disposing of oil after an automobile oil change, a factory dumping chemicals and waste on the ground or into streams, herbicides used on crops moved from fields to ditches by rain and irrigation, pouring paint into a storm drain, using pesticides on a lawn, etc.) Point out that these are examples of how citizens can alter their behavior to keep water sources clean.

Lesson Summary Assessment

Engineering Design: Working in groups of 3 or 4, have students design systems to stop a known polluted aquifer from migrating further and reaching a town well. Require that teams create posters of their designs and present the posters to the class. Do this as a creative activity and do not stress the technical viability of the treatment. If students have trouble thinking of ideas, conduct some Internet research by searching on "groundwater treatment." (Possible ideas: pump all the pollution out, build a wall to stop the pollution from migrating, add something to the water that treats the pollutant, or implement bioremediation.)

Is It Clean?: After students have completed the two associated drinking water activities, ask them to brainstorm with a partner on what other tests might need to be performed on water to determine if it is clean and safe to drink. Have the student pairs make lists of possible water quality tests, including ones they have used in this unit thus far. Ask students to create a preliminary flow chart of how to collect and treat drinking water from a groundwater aquifer all the way to the faucets in their houses.

Lesson Extension Activities

Have students write and perform short plays about drinking water and aquifers. Setting: Atown meeting about a commercial release of pollution. People present: An environmental engineer, a manager of the industrial plant, a local politician, and various citizens. Scenarios include:

• A train wreck with toxic chemicals released into the watershed.
• A break in a wastewater main pipeline causing contamination into the watershed.
• An oil spill from a truck that released chemicals into the watershed.

Visit a local municipal wastewater treatment plant and have students talk about water treatment with engineers on site. Have students write paragraphs about what they saw at the plant to share with the class.

References

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.