The Mystery of Fruitvale s Water

Transcription

1 GROUNDWATER CONTAMINATION: INVESTIGATION 1 The Mystery of Fruitvale s Water CHALLENGE Is something wrong with the water in Fruitvale? READING For the next few weeks, you will be investigating the water in an imaginary town. You will be playing the role of a concerned visitor to the town of Fruitvale, a favorite place of yours to visit. To become familiar with the town and water problem, read the following story and think carefully about what information you know and what information you need to gather. Summer vacation has arrived at last, and you are on a bus that has just pulled into Fruitvale. You are going to spend a few weeks with your cousins, and you can t wait to get there. They have a big back yard big enough for playing baseball and tag and best of all, at the far end of their yard there is Strawberry Creek where you have always enjoyed cooling off on hot afternoons. Your cousins meet you at the bus stop and take you to their house. When you get there you are hot and thirsty from the long bus ride, so you go straight to the sink to get a drink of cold water. Your Aunt Marge says, Don t drink the tap water! Here, have some bottled 7

2 8 GROUNDWATER CONTAMINATION water. This surprises you because you always drink water from a tap, especially in Fruitvale. Aunt Marge tells you that for the past couple of months, the water in Strawberry Creek has had an odd smell. People in town are worried that the water may be contaminated. Your aunt goes on to explain that this is why the refrigerator is stocked with bottled water and why no one should play in Strawberry Creek. This is really disappointing. You had looked forward to spending many hours playing with your cousins in and around the creek. You are not too happy that the water might be contaminated, and because you can t spend your time having fun by the creek, you decide to investigate the mystery of Fruitvale s water. You first find out that Fruitvale s tap water comes from the Fruitvale Municipal Water Well. Any water that comes from a water well is groundwater water that has collected in cracks and other spaces underground. Groundwater also helps keep creeks running during the dry summer months. You remember from science class that if water has a smell, something must have gotten into it. You set out to find out what that something could possibly be and how it could have gotten into the water. You decide to record all of the evidence you find out about Fruitvale and its water in your journal. First, you check Strawberry Creek. It does smell funny but it has always smelled funny to you. The question is, does the creek smell different from the last time you smelled it? Next, you ask the neighbors, the Washingtons, whether they ve noticed anything wrong with their water. Mrs. Washington tells you that she hasn t noticed anything unusual, but she mentions that their dog, JoJo, who often plays in the creek, has been sick. She wonders if JoJo got sick from drinking creek water. You begin to make notes on a map to record what you find out. As you walk through the neighborhood, you notice that it has changed a lot since your first visit four summers ago. There has been a great deal of building recently. Areas that were once farms or woods are now stores, parking lots, homes, playing fields, and a park. The two-lane road is being expanded to a new highway. The old chemical factory appears to be shut down. Somebody has been throwing trash down the banks of the river at the north end of town. After an afternoon out walking in the sun, you stop at The Honest Diner to have a cold drink.the diner s owner, Lamar, sees you looking at the map and

3 GROUNDWATER CONTAMINATION: ACTIVITY 1 / THE FRUITVALE STORY, PART ONE 9 asks you about it. You explain your concern about the water, and he tells you that he heard that the water from a well in Fruitvale Estates is contaminated. Fruitvale Estates, he tells you, is one of the new housing complexes, and it was built on land that used to be an orchard. ANALYSIS Group 1. What information did you learn? What do you still need to know? What steps could help solve the mystery? Make a table with three columns. In the first column, list any information that you learned about Fruitvale and its water. In the second column, list any questions you want to ask about water, water contamination, or the town of Fruitvale. In the third column, list your next steps to find the answers to your questions. Share your ideas with your group or class. Individual 2. Write a paragraph or two explaining the situation in Fruitvale. Include evidence, questions, and concerns that were raised in the reading and discussions. Include any ideas or inferences you might have that could help explain the mystery. Suggest the next steps you might take to solve the mystery and to obtain any other information you might need.

4 Fruitvale Vocabulary Name: Directions: Use this sheet to record any word that is new to you during your investigation of Fruitvale. If the meaning of the word is not found within the text of the provided readings, look the word up in a dictionary. Vocab Word Definition Picture or Linking Word contaminant; contamination municipal orchard

5 Name:

6 NAME DATE STUDENT SHEET 1.1 Street Map of Fruitvale Lots of trash Country Road Strawberry Creek Hillside Drive + Blueberry Hill Eden Agricultural Chemical Company Berry Lane Eat Em Up Berry Farm Creekside Homes Highway 15 Honest Diner Strawberry Creek Fruitvale School Randy s Gas Station City Park Aunt Marge s House Washington s House Fruitvale Municipal Water Well Orchard Lane Fruitvale Estates I Fruitvale Road Orchard Orchard Lane Fruitvale Estates II (under construction) KEY Scale meters GROUNDWATER CONTAMINATION 11 N

7 GROUNDWATER CONTAMINATION: INVESTIGATION 2 The Original Super Soaker CHALLENGE How does water disappear into the earth and how can we get it back? MATERIALS For each group of four students 1 supply of gravel 1 supply of sand 1 supply of clay (optional) For each team of two students 1 plastic cup of water 1 syringe 1 30-mL graduated cup 1 hand lens The residents of Fruitvale, both humans and other living organisms, use water that is found on and below the surface of the earth. How and where water flows on the surface may not be a big mystery to you, but do you know how water gets below the earth s surface and how we get it back? In this Investigation, you will explore how water enters and flows through earth materials. The results of your exploration will help you better understand how water is stored and moves beneath Fruitvale. This information might be helpful in understanding and solving the town s water problem. The ground beneath your feet looks solid, and it certainly feels solid when you jump up and down on it. But what happens when you pour water on the ground? Depending on what the ground is like, it might make a puddle or a little stream, or it might soak right in. Materials that liquids can flow through are called permeable, and permeable earth materials that collect water are called aquifers. Materials through which liquids cannot soak or flow are called impermeable, and impermeable earth materials are called aquitards. 23

8 24 GROUNDWATER CONTAMINATION PROCEDURE 1. Use your hand lens to help you examine the samples of gravel, sand, and clay. In your notebook, describe and sketch the size and shape of the particles of each earth material as best you can. 2. In your notebook, make a table similar to the one below. Comparing Earth Materials Water Gravel Sand Clay Predicted volume (ml) Measured volume (ml) Volume recovered 3. Fill your graduated cup to the 30-smL mark with gravel. Use the syringe handle to gently tap down the gravel. 4. Predict the maximum volume of water you think the gravel-filled cup will be able to hold. Record your prediction. 5. Fill the syringe with 20 ml water. 6. Slowly add water to the gravel-filled cup until the water level is even with the top of the gravel. It is all right if a little pools on the surface. 7. Record the volume of water you added. 8. Put any remaining water in your syringe back into the cup of water. 9. Poke the whole syringe tip into the gravel and slowly pull the plunger up to the top. Describe what happens in your notebook. Include any important measurements. 10. Carefully pour the gravel back into the gravel supply cup. 11. Repeat Steps 4 9 using sand instead of gravel. 12. Repeat Steps 4 9 using clay instead of gravel.

9 GROUNDWATER CONTAMINATION: ACTIVITY 2 / UNDERSTANDING GROUNDWATER 25 ANALYSIS Group 1. Look at your data table and compare your predicted volumes of water with your measured volumes. Were you surprised by any of your results? Why or why not? 2. What properties of sand, gravel, and clay do you think affect the ability of each material to hold water? What properties affect the ability of water to move through them? 3. How do you think this activity modeled both natural processes and human activities? What natural process did the syringe represent? Could it represent a human activity? Explain. Individual 4. Of the three earth materials you explored gravel, sand, and clay which makes the best aquifer? Which makes the worst aquifer? Support your choices with evidence. 5. Explain how permeability can be a useful property of earth materials. 6. Explain how impermeable earth materials can also be useful.

10 GROUNDWATER CONTAMINATION: ACTIVITY 2 / UNDERSTANDING GROUNDWATER 27 Thinking More About Investigation 2 Earth s Groundwater Supply CHALLENGE What is groundwater? READING Since you learned about the problem in Fruitvale you have decided that you need to know more about groundwater. To help you learn more, read the following information about the earth s groundwater supply. Try to imagine all of Earth s water sources. How many come to mind? There are oceans, seas, lakes, reservoirs, ponds, polar ice caps, glaciers, icebergs, snow fields, rivers, streams, creeks, and groundwater. If the contents of a 2-liter bottle represented all the water on Earth, what fraction of the bottle do you think would represent the salt water found in the oceans and seas? How much of the water in the bottle would represent the supply of fresh water found at the surface of the earth? How much would represent the groundwater, the underground supply of fresh water? Believe it or not, 1,948 ml out of the total 2,000 ml, or about 97.5%, would be salt water! All the earth s fresh water would be only 52 ml barely enough to make a popsicle. If you took away all of the groundwater, including all the water frozen into ice caps and glaciers, you would be left with 0.28 ml of water less than 5 drops to represent every bit of the fresh water found on the Earth s surface in all of its lakes and rivers. The amount of fresh water on the surface of the Earth depends on your location, landscape, and climate. About 50% of the fresh water used in homes throughout the U.S. comes from surface water sources. The other 50% of the homes in the U.S. obtain their water from underground aquifers, which are layers of rock through which water can flow and be stored. Some of these people get the water from their own private wells, while others obtain it from wells operated by municipal (city or town) water departments. Although they are different, groundwater and surface water supplies are related and interconnected. Surface water is continually soaking into the ground and becoming groundwater. At the same time, groundwater is continually being removed by humans or by natural processes such as seeps and

11 28 GROUNDWATER CONTAMINATION springs, which keep water flowing into lakes, streams, and rivers even when there is a drought. The amount of water in the ground depends on climate, the amount of water seeping into the ground, and the type of soil and rock. The depth below the Earth s surface at which groundwater can be found often changes. This depth defines the upper boundary of saturated ground and is called the water table. The water table rises closer to the surface during times of wet weather and sinks farther from the surface during times of drought or heavy pumping from water wells. A well that has dried up often indicates a lowered water table. seasonal stream water well position of wet season water table groundwater flow permeable rock layers position of dry season water table aquitard Although groundwater is an excellent source of drinking water, by its very nature it is never pure water. As water from various sources, such as precipitation (rain, snow, etc.) and agricultural irrigation, soaks into and through the earth s layers, it collects and carries dissolved and suspended materials with it. Although soil does act as a natural filter and often helps remove some dangerous substances from water, it can also be a source of natural contaminants such as radioactive minerals (radium) and gases (radon), toxic substances given off by organisms, and disease-causing microbes such as giardia and amoebas. The human population adds to this natural contamination through the use of pesticides, fertilizers, and other chemicals that can soak into the earth. Humans also add to contamination by accidental chemical spills and undetected leaks in storage tanks, sewage pipes, and landfills. Chemical pollutants released into the air can be transported back to the earth, and into the groundwater, by rain and snow.

12 GROUNDWATER CONTAMINATION: ACTIVITY 2 / UNDERSTANDING GROUNDWATER 29 ANALYSIS Group 1. What is groundwater? Why is it important? 2. Where does the water that you drink come from? 3. What concerns do you have about the water supply in your region? 4. What concerns do you have about the quality of the water in your region? 5. Did you learn any new information or read anything that will affect how you think or act? Individual 6. How can surface water become contaminated? How can groundwater become contaminated? 7. Describe some advantages and disadvantages associated with using water from an aquifer.

13 GROUNDWATER CONTAMINATION: INVESTIGATION 4 Maps and More Maps CHALLENGE What information do different types of maps provide that will help solve the mystery of Fruitvale s water? MATERIALS For each team of two students 1 ruler 1 piece of string 1 index card For each student Now that you have a clearer understanding of how water moves and changes in the environment, you decide to learn more about the land and places in Fruitvale that could affect 1 Student Sheet 1.1, Street Map of Fruitvale 1 Student Sheet 4.1, Topographic Map of Fruitvale 1 Student Sheet 4.2, Geologic Cross Section of Fruitvale 1 Student Sheet 4.3, Fruitvale Features 1 Student Sheet 4.4, Comparing Different Types of Maps the water or be affected by contaminated water. You know that people have been making and using maps for centuries, and you decide to check the library and the Internet to see if there are any maps that might help solve the mystery of Fruitvale s water. The librarian helps you find several different types of maps, each showing different kinds of information. You explain the groundwater problem, and he recommends that you consult the topographic map and the geologic cross section map of Fruitvale. 53

14 54 GROUNDWATER CONTAMINATION Topographic maps show you where elevation changes occur and the shape of the land the hills, valleys, ridges, and flat areas. Geologic cross sections show you what is below the surface. All maps have a key that contains important information to help you use the map properly. Keys often contain a north arrow, that points toward the north pole, and a scale, which lets you calculate the actual size of a map feature or the distance from one point to another. PROCEDURE 1. Look at Student Sheet 1.1, Street Map of Fruitvale. List three major features shown on the map. 2. Look at Student Sheet 4.1, Topographic Map of Fruitvale. List three prominent features shown of the map. 3. Look at Student Sheet 4.2, Geologic Cross Section of Fruitvale. List three obvious features shown on the map. 4. Use the maps to fill in the missing information (including the blanks in Column 1) in the table on Student Sheet 4.3, Fruitvale Features. ANALYSIS Group Use the table on Student Sheet 4.4, Comparing Different Types of Maps, to complete Questions 1 and What information can be found on all three maps? 2. What information is found only on, or is easier to find on: a. a street map? b. a topographic map? c. a geologic cross section? Individual 3. Which of the three maps provides the most useful information for solving the mystery of Fruitvale s water? Explain your choice.

15 NAME DATE STUDENT SHEET 4.1 Topographic Map of Fruitvale 1, ,080 1,060 Blueberry Hill 1,040 Strawberry Creek 1,020 KEY 1,000 1,000 contour interval N = creek = contour line = 10 m. Scale meters GROUNDWATER CONTAMINATION 55

16 NAME DATE STUDENT SHEET 4.2 Geologic Cross Section of Fruitvale Highway 15 Strawberry Creek X Fruitvale Estates Fruitvale Municipal Water Well KEY N 0 Horizontal scale 200 X soil sand gravel clay water well private water well meters Vertical scale 0 20 meters meters Vertical exaggeration = 10x 56 GROUNDWATER CONTAMINATION

17 NAME DATE STUDENT SHEET 4.3 Fruitvale Features Information Map Type(s) That Map Feature That Allows Contain This Feature You to Determine This The berry farm is in the corner of the map. The highest point in the area has an elevation of about. The depth of Strawberry Creek is about. The creek is about long. The depth of the Fruitvale Municipal Water Well is about. The Fruitvale Municipal Water Well pumps water from a layer of. The distance between the gas station and the Fruitvale Municipal Water Well is about. The distance around the park is about. The elevation of the Honest Diner is about. GROUNDWATER CONTAMINATION 57

18 NAME DATE STUDENT SHEET 4.4 Comparing Different Types of Maps Street Type of Map Information Specific Information Common to Each Type Map to All Three Types of Maps Topographic Geologic Cross Section 58 GROUNDWATER CONTAMINATION

19 GROUNDWATER CONTAMINATION: INVESTIGATION 5 Points and Plumes CHALLENGE What are the similarities and differences between point and non-point source contamination? MATERIALS For each group of four students 1 30-mL dropper bottle of groundwater contaminant access to sink or tub for wastewater For each team of two students 1 Chemplate 1 plastic cup of water 1 syringe 1 contaminant plume tray 2 moistened paper layers The geologic cross section of Fruitvale showed that a contaminant in water or another liquid could easily percolate down and spread out into an aquifer. The part of the aquifer that becomes contaminated is called a plume. Knowing this, you decide to find out more about how contaminants move once they have been released onto the earth s surface. You discover that substances released into the environment, whether they are harmful or not, can be classified into two categories, depending on their source. If there is a single source of the chemical, such as a leaky fuel storage tank or an overturned tractor-trailer, the contamination is called a point source. If there are a number of sources, such as millions of automobile exhaust pipes, or acres of fertilized farmland, the contamination is called a non-point source. Point source and non-point sources can produce very different plumes. Safety Note: Food coloring can stain clothes, and work surfaces. Immediately rinse any spills with water. 65

20 66 GROUNDWATER CONTAMINATION PROCEDURE Part A: Point and non-point source plumes in horizontal layers Before modeling a contaminant plume, draw a prediction in your science notebook. After modeling a contaminant plume, draw the actual shape that appears on both the top paper layer and the bottom paper layer. 1. Fill the syringe with 5 ml of water. 5 drops here 2. Place the contaminant plume tray on the tabletop and place the two paper layers, stacked on top of one another, inside the tray. 3. Squeeze 5 drops of groundwater contaminant, one on top of the other, onto the center of the filter papers as shown to the left. Sketch what you observe. 4. Gently drop 5 ml of the water in the syringe over the entire area of the filter papers as evenly as possible. 5. Wait 30 seconds, and while waiting, describe any changes you observe in the food coloring. 6. Carefully peel both layers off the plastic tray and separate them. Describe, sketch, and compare the appearance of the top paper layer and the bottom one. 7. Empty the water out of the tray into a sink or washtub. 8. Carefully and thoroughly rinse the color out of the paper layers Note: Do not squeeze the paper layers. Repeat Steps 1 8, except this time place each of the 5 drops of groundwater contaminant adjacent to, not on top of each other, in the center of the paper, as shown below.

21 GROUNDWATER CONTAMINATION: ACTIVITY 5 / MODELING GROUNDWATER CONTAMINATION 67 Part B: Point and non-point source plumes in tilted layers 13. Repeat Part A, except this time prop one end of the contaminant plume tray on your Chemplate as shown below. ANALYSIS Individual 1. Compare and contrast point source and non-point source groundwater contamination. Which type of contaminant plume do you think might be easier to clean up?

22 GROUNDWATER CONTAMINATION: ACTIVITY 5 / MODELING GROUNDWATER CONTAMINATION 69 Thinking More About Investigation 5 Predicting the Spread of Groundwater Contaminants CHALLENGE How might a contaminant spread under different circumstances in Fruitvale? MATERIALS For each group of four students 4 colored pencils The colored areas that you observed on the paper layers represented a groundwater contaminant plume. The shape and size of a contaminant plume is affected by a number of factors related to the contaminant and to the local environment. These factors include the amount of contaminant released, whether it was a point or non-point source, the For each student 1 Student Sheet 5.1, Predicting Plumes Using Geologic Cross Sections type of earth material through which the contaminant is spreading, the amount of time the contaminant has been spreading, the amount of precipitation or irrigation that has occurred during that time, and the amount and direction of groundwater flow. PROCEDURE Draw your plumes for the following scenarios on the geologic cross sections. 1. Choose a colored pencil and draw the contaminant plume you predict would occur if a 200-liter barrel of pesticide spilled at the Eat Em Up Berry Farm. 2. Choose a different colored pencil and draw the contaminant plume you predict would occur if 200 liters of pesticide had been evenly spread over the Eat Em Up Berry Farm. 3. Choose a different colored pencil and draw the contaminant plume you predict would occur if a 200-liter barrel of pesticide spilled at the orchard. 4. Choose a different colored pencil and draw the contaminant plume you predict would occur if 200 liters of pesticide had been evenly spread over the orchard.

23 70 GROUNDWATER CONTAMINATION ANALYSIS Group 1. Which of the scenarios described in Procedure Steps 1 4 are point sources and which are non-point sources? Explain. Individual 2. For each of the scenarios, explain why it is likely or unlikely to produce a contaminant plume that would include a. the water well marked X on the map. b. the Fruitvale Municipal Water Well. Note: If you like, you may provide your response in the form of a data table.

24 NAME DATE STUDENT SHEET 5.1 Predicting Plumes Using Geologic Cross Sections 1. Eat Em Up Berry Farm, 200 liter barrel spill Highway 15 Strawberry Creek X 2. Eat Em Up Berry Farm, 200 liters of sprayed pesticide Highway 15 Fruitvale Municipal Water Well Strawberry Creek X Fruitvale Municipal Water Well Highway Orchard, 200 liter barrel spill Strawberry Creek X 4. Orchard, 200 liters of sprayed pesticide Highway 15 Key soil sand Fruitvale Municipal Water Well gravel clay site of spill area of sprayed pesticide Strawberry Creek Fruitvale Municipal Water Well GROUNDWATER CONTAMINATION 71 X

25 source source Flat Tilted Flat Tilted Prediction (underground) Top (surface) Bottom (underground) source source Flat Tilted Flat Tilted Prediction (underground) Top (surface) Bottom (underground)

26 GROUNDWATER CONTAMINATION: INVESTIGATION 6 Disappearing Dye CHALLENGE What is a serial dilution and how do we measure contaminants in water? MATERIALS For each group of four students 1 30-mL dropper bottle of groundwater contaminant 1 plastic cup of rinse water 1 plastic cup of clean water supply of paper towels For each team of two students 1 Chemplate 1 dropper 1 sheet of white paper Now that you have a better understanding of how contaminants and contaminated water behave beneath the surface of the earth, you need to understand how to determine if water is contaminated and how you can measure contamination levels. When groundwater is tested for purity, the level of the dissolved substances can be measured as a percent, or part per hundred, of the weight of the water. Because many of the substances health officials are interested in discovering make up only a small fraction of a percent, it is easier to report the concentration of these substances in parts per million (ppm), parts per billion (ppb), and even parts per trillion (ppt). Ppm, ppb, and ppt are very small amounts, but very small amounts of very toxic substances can be extremely dangerous. Safety Note: Food coloring can stain clothes and work surfaces. Immediately rinse any spills with water. 81

27 82 GROUNDWATER CONTAMINATION PROCEDURE ANALYSIS Group 1. Place a piece of white paper under your Chemplate. 2. Place 10 drops of groundwater contaminant into the larger, oval cup in your Chemplate. 3. Use your dropper to transfer 1 drop of the groundwater contaminant into Cup Rinse your dropper thoroughly, and then add 9 drops of clean water to Cup 4. Use the dropper to mix the solution thoroughly. 5. Use your dropper to transfer 1 drop of the liquid from Cup 4 to Cup Rinse your dropper thoroughly and then add 9 drops of clean water to Cup 3. Use the dropper to mix the solution thoroughly. 7. Use your dropper to transfer 1 drop of the liquid from Cup 3 to Cup Rinse your dropper thoroughly and then add 9 drops of clean water to Cup 2. Use the dropper to mix the solution thoroughly. 9. Use your dropper to transfer 1 drop of the liquid from Cup 2 to Cup Rinse your dropper thoroughly and then add 9 drops of clean water to Cup 1. Use the dropper to mix the solution thoroughly. 11. Record the color of the liquid in all five cups in a data table. 1. Which cup(s), if any, contain(s) a colorless liquid? 2. The liquid in the oval cup has a contaminant concentration of 500 ppm. Determine the contaminant concentration of the liquids in Cups 4 1, and record this information in your data table. Individual 3. If a clear liquid, such as water, is colorless, does that mean that it is not contaminated? Explain, using evidence from this activity. 4. Describe an experiment you could do with your local tap water to determine if it contains anything other than water. Check your idea with your teacher, try it out, and record your results.

28 GROUNDWATER CONTAMINATION: INVESTIGATION 7 Pesky Pesticide CHALLENGE What are the most likely locations for the pesticide to have entered the groundwater? As it turns out, a few days after you and your cousin were enjoying milkshakes at the Honest Diner and talking about your investigations, some Fruitvale Water Department workers stopped in for lunch. Lamar, the owner, told them about the talk you had with him, and since they were interested, he gave them your phone number. They called and ask you to come down to the Water Department to meet with them. Read the following story about what you learned at the Water Department and think about what your next steps might be. READING When you get to the meeting at the Water Department, you find out that the rumor Lamar heard about the water in Fruitvale Estates is true. A routine laboratory test of the well water used on the lawns at the Fruitvale Estates detected 4.9 ppb of No-Bug pesticide. This is important, Water Department workers tell you, because for drinking water, 5 ppb is the maximum legally allowed level for the active ingredient in No-Bug pesticide. You ask them to draw an X on your map to show you where the contaminated well is located. The water workers explain that in the days before the city drilled its municipal well, each house had its own private well. Although these private wells no longer supply homes with drinking water, many of them still exist, and a few continue to supply water for irrigating farms, orchards, and lawns. The Water Department workers also tell you that the Fruitvale Municipal Water Well has been tested, and it is not contaminated. You also learn that No-Bug pesticide is no longer produced. Although it was always known that the toxic chemical in No-Bug could cause painful skin rashes and intestinal bleeding, initial testing showed that after a few weeks under normal soil and groundwater conditions, the toxic chemical breaks down into non-toxic chemicals. As a result of these tests, No-Bug was approved as safe for use and sold for several years. The pesticide was manufactured at the Eden Agricultural 91

29 92 GROUNDWATER CONTAMINATION Company on the outskirts of Fruitvale, and many of the local farmers used it on their fields. Then, eight years ago, it was discovered that the toxic chemical in No-Bug does not decompose as expected in certain soil and water conditions. These soil and water conditions are not widespread, but they do exist in the Fruitvale area. Soon after this discovery No-Bug pesticide was banned in the United States. Because a significant amount of No-Bug was used locally, the discovery of the contaminated well water has made city officials worried that much of Fruitvale s groundwater may already be contaminated or is in danger of becoming contaminated in the very near future. In an emergency session, the city council voted to approve the expenditure of $6,000 to determine where the No-Bug pesticide is getting into the groundwater and the size and shape of the plume area containing contaminated groundwater. This is enough money to collect and test water samples from 12 wells. The problem that now faces the Fruitvale Water Department is how to choose which 12 of the 40 private wells to test. Impressed with your careful investigations, the water workers ask for your help in deciding which wells should be tested. They give you a map that shows the location of the contaminated well, the location of the Fruitvale Municipal Water Well, and the location of each of the 40 other water wells that can be tested.

30 GROUNDWATER CONTAMINATION: ACTIVITY 7 / THE FRUITVALE STORY, PART TWO 93 ANALYSIS Group 1. What information and evidence do we have that is relevant in solving the mystery of Fruitvale s water? Individual 2. What three locations in and around Fruitvale do you think are the most likely possible sources of the pesticide? Explain why you picked each location and how it may have contributed to the water contamination. 3. What additional information about Fruitvale and its water supply would you like to know?

31 NAME DATE STUDENT SHEET 7.1 Map of Fruitvale s Wells 2 5 Lots of trash Eden Agricultural Chemical Company ( ) Country Road Strawberry Creek Hillside Drive Eat Em Up Berry Farm (since 1973) Creekside Homes (vineyard before 1996) Strawberry Creek 26 Fruitvale School (new building in 1995) Highway 15 Randy s Gas Station X City Park (since 1996) Fruitvale Municipal Water Well 28 Orchard Lane Fruitvale Estates I (orchard before 1999) Fruitvale Road Orchard (since 1975) Orchard Lane Site of Fruitvale Estates II (orchard before 2001) 0 34 X KEY Scale 200 GROUNDWATER CONTAMINATION 95 N untested well with location no. Fruitvale Municipal Water Well well with 4.9 ppb No-Bug meters

32 GROUNDWATER CONTAMINATION: INVESTIGATION 8 Testing the Waters CHALLENGE What is the extent and source of Fruitvale s contaminated groundwater? MATERIALS For the class 40 dropper bottles labeled: Fruitvale Water Sample (Wells 1 40) For each group of four students 1 Chemplate 1 30-mL dropper bottle of universal indicator 1 set of colored pencils supply of paper towels or sponges For each student 1 Student Sheet 7.1, Map of Fruitvale s Wells 1 Student Sheet 8.1, Well Testing Results and Pesticide Testing Key You have agreed to help the Fruitvale Water Department test and analyze some well data. In this Investigation, you will test well water samples to try to determine the source of the pesticide contamination and to measure how far it has spread. Because Fruitvale s funds are limited, you can test water samples from only 12 of the possible 40 wells. This means you must use the evidence you obtain from every well you test and carefully and thoughtfully decide which well to test next. Safety Note:Although this activity is a simulation and there are no toxic chemicals in any of the samples, it is necessary to wear safety eyewear and avoid skin contact with the chemicals. PROCEDURE 1. The Pesticide Testing Key on Student Sheet 8.1 tells you how to interpret the test results. Pick a different colored pencil to represent Hazard Levels 0 4, and use the appropriate pencil to color in the circles representing the two wells that have already been tested: Well Number Pesticide Concentration Hazard Level X 4.9 ppb 2 Fruitvale Municipal Not Detected 0 Water Well (<0.1 ppb) 101

33 102 GROUNDWATER CONTAMINATION 2. Recall the three locations you thought would be most likely to be the source of the pesticide and then decide as a group which well to test first. If you can t agree you may test two or three wells at the same time. 3. Record the number of the well you chose to test and explain your reasons for choosing it in your science notebook. 4. To test your well, take your Chemplate to the well area, find the bottle with the well number you chose, and add 5 drops of the well water to an empty cup in the Chemplate. Carefully bring your Chemplate back to your table. Note: Do not remove bottles of well water from the well area! 5. Add one drop of universal indicator to the 5 drops of well water and record the results of your test on Student Sheet On the map of Fruitvale, draw a circle around the well you just tested using the colored pencil you chose to represent the hazard level your test has detected. 7. Look at the map, and consider the results of each of your tested wells before you decide upon which well to test next. 8. Repeat Steps 3 7 until you have tested a total of 12 wells. Record all results on Student Sheet 8.1. ANALYSIS 1. Where do you think the source of the pesticide is located? Explain. 2. Do you think it is a point source or non-point source? Explain.

34 NAME DATE STUDENT SHEET 8.1 Well Testing Results and Pesticide Testing Key Well Number Test Color Pesticide Concentration Hazard Level Pesticide Testing Key Test Color Pesticide Concentration Hazard Level Map Color Red-orange Not Detected (< 0.1 ppb) 0 Yellow ppb 1 Yellow-green ppb 2 Green ppb 3 Blue-green > 10 ppb 4 GROUNDWATER CONTAMINATION 103