challenge is something wrong with the water in...

• • • • © CHALLENGE

Is something wrong with the water in Fruitvale?

For the next few weeks, you will be investigating the water in an imag-inary town. You will be playing the role of a concerned visitor to thetown of Fruitvale, a favorite place of yours to visit. To become famil-iar with the town and water problem, read the following story andthink carefully about what information you know and what informa-tion you need to gather.

• • • • © READINGSummer vacation has arrived at last, and you are on a bus that hasjust pulled into Fruitvale. You are going to spend a few weeks withyour cousins, and you can’t wait to get there. They have a big backyard—big enough for playing baseball and tag—and best of all, at thefar end of their yard there is Strawberry Creek where you have alwaysenjoyed 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 AuntMarge says, “Don’t drink the tap water! Here, have some bottled

G R O U N D W A T E R C O N T A M I N A T I O N : I N V E S T I G A T I O N 1

The Mystery of Fruitvale’s Water

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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 inStrawberry Creek has had an odd smell. People in town are worriedthat the water may be contaminated. Your aunt goes on to explainthat this is why the refrigerator is stocked with bottled water and whyno one should play in Strawberry Creek. This is really disappointing.You had looked forward to spending many hours playing with yourcousins in and around the creek. You are not too happy that the watermight be contaminated, and because you can’t spend your time hav-ing fun by the creek, you decide to investigate the mystery ofFruitvale’s water.

You first find out that Fruitvale’s tap water comes from the FruitvaleMunicipal Water Well. Any water that comes from a water well isgroundwater—water that has collected in cracks and other spacesunderground. Groundwater also helps keep creeks running duringthe dry summer months. You remember from science class that ifwater has a smell, something must have gotten into it. You set out tofind out what that something could possibly be and how it could havegotten into the water. You decide to record all of the evidence you findout about Fruitvale and its water in your journal.

First, you check Strawberry Creek. It does smell funny—but it hasalways smelled funny to you. The question is, does the creek smelldifferent from the last time you smelled it? Next, you ask the neigh-bors, the Washingtons, whether they’ve noticed anything wrong withtheir water. Mrs. Washington tells you that she hasn’t noticed any-thing unusual, but she mentions that their dog, JoJo, who often playsin the creek, has been sick. She wonders if JoJo got sick from drink-ing creek water.

You begin to make notes on a map to record what you find out. Asyou walk through the neighborhood, you notice that it has changed alot since your first visit four summers ago. There has been a great dealof building recently. Areas that were once farms or woods are nowstores, parking lots, homes, playing fields, and a park. The two-laneroad is being expanded to a new highway. The old chemical factoryappears to be shut down. Somebody has been throwing trash downthe banks of the river at the north end of town. After an afternoonout walking in the sun, you stop at The Honest Diner to have a colddrink.The diner’s owner, Lamar, sees you looking at the map and

8 G R O U N D W A T E R C O N T A M I N A T I O N

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asks you about it. You explain your concern about the water, and hetells you that he heard that the water from a well in Fruitvale Estates iscontaminated. Fruitvale Estates, he tells you, is one of the new hous-ing complexes, and it was built on land that used to be an orchard.

• • • • © ANALYSISGroup

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 learnedabout Fruitvale and its water.

• In the second column, list any questions you want to ask aboutwater, water contamination, or the town of Fruitvale.

• In the third column, list your next steps to find the answers toyour 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 inthe reading and discussions.

• Include any ideas or inferences you might have that couldhelp explain the mystery.

• Suggest the next steps you might take to solve the mystery andto obtain any other information you might need.

G R O U N D W A T E R C O N T A M I N A T I O N : A C T I V I T Y 1 / T H E F R U I T V A L E S T O R Y , P A R T O N E 9

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Name: ________________________ Fruitvale Vocabulary 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

Name: ________________________

N A M E DAT E S T U D E N T S H E E T 1.1

Street Map of Fruitvale

G R O U N D W A T E R C O N T A M I N A T I O N 11

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0 200

meters

Scale

N

Highway 15

Hill

side

Dri

ve

Cou

ntry

Roa

d

Berry Lane

Orchard Lane

Frui

tval

eR

oad

Blueberry Hill

Eat ’Em Up Berry Farm

Orchard

Fruitvale Estates II(under construction)

Lots of trash

Randy’s GasStation

Fruitvale Estates I

FruitvaleSchool

Aunt Marge’s House

Washington’s House

Fruitvale Municipal

Water Well

Eden Agricultural Chemical Company

+

City Park

Creekside Homes

Orchard Lane

Honest Diner

Stra

wbe

rry

Cre

ek

N

Stra

wbe

rry Cre

ek

KEY


How does water disappear into the earth and howcan we get it back?

The residents of Fruitvale, both humans and other living organisms,use water that is found on and below the surface of the earth. Howand where water flows on the surface may not be a big mystery toyou, but do you know how water gets below the earth’s surface andhow we get it back?

In this Investigation, you will explore how water enters and flowsthrough earth materials. The results of your exploration will help youbetter understand how water is stored and moves beneath Fruitvale.This information might be helpful in understanding and solving thetown’s water problem.

The ground beneath your feet looks solid, and it certainly feels solidwhen you jump up and down on it. But what happens when you pour

water on the ground? Dependingon what the ground is like, it mightmake a puddle or a little stream, orit might soak right in. Materials thatliquids can flow through are calledpermeable, and permeable earthmaterials that collect water arecalled aquifers. Materials throughwhich liquids cannot soak or floware called impermeable, andimpermeable earth materials arecalled aquitards.


The Original Super Soaker

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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

• • • • © 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 andshape of the particles of each earth material as best you can.

2. In your notebook, make a table similar to the one below.

3. Fill your graduated cup to the 30-smL mark with gravel. Use thesyringe handle to gently tap down the gravel.

4. Predict the maximum volume of water you think the gravel-filledcup 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 iseven with the top of the gravel. It is all right if a little pools on thesurface.

7. Record the volume of water you added.

8. Put any remaining water in your syringe back into the cup ofwater.

9. Poke the whole syringe tip into the gravel and slowly pull theplunger 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.


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Water Gravel Sand Clay Predicted volume (mL)Measured volume (mL)Volume recovered

Comparing Earth Materials


1. Look at your data table and compare your predicted volumes ofwater with your measured volumes. Were you surprised by any ofyour results? Why or why not?

2. What properties of sand, gravel, and clay do you think affect theability of each material to hold water? What properties affect theability of water to move through them?

3. How do you think this activity modeled both natural processesand human activities? What natural process did the syringe repre-sent? Could it represent a human activity? Explain.

Individual

4. Of the three earth materials you explored—gravel, sand, andclay—which makes the best aquifer? Which makes the worstaquifer? Support your choices with evidence.

5. Explain how permeability can be a useful property of earthmaterials.

6. Explain how impermeable earth materials can also be useful.

G R O U N D W A T E R C O N T A M I N A T I O N : A C T I V I T Y 2 / U N D E R S T A N D I N G G R O U N D W A T E R 25

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Thinking More About Investigation 2

Earth’s Groundwater Supply• • • • © CHALLENGE

What is groundwater?

Since you learned about the problem in Fruitvale you have decidedthat you need to know more about groundwater. To help you learnmore, read the following information about the earth’s groundwatersupply.

• • • • © READINGTry 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 saltwater found in the oceans and seas? How much of the water in thebottle would represent the supply of fresh water found at the surfaceof the earth? How much would represent the groundwater, the under-ground 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 ground-water, including all the water frozen into ice caps and glaciers, youwould be left with 0.28 mL of water—less than 5 drops—to representevery bit of the fresh water found on the Earth’s surface in all of itslakes and rivers.

The amount of fresh water on the surface of the Earth depends onyour location, landscape, and climate. About 50% of the fresh waterused in homes throughout the U.S. comes from surface water sources.The other 50% of the homes in the U.S. obtain their water fromunderground aquifers, which are layers of rock through which watercan flow and be stored. Some of these people get the water from theirown private wells, while others obtain it from wells operated bymunicipal (city or town) water departments. Although they are dif-ferent, groundwater and surface water supplies are related and inter-connected. Surface water is continually soaking into the ground andbecoming groundwater. At the same time, groundwater is continuallybeing removed by humans or by natural processes such as seeps and


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springs, which keep water flowing into lakes, streams, and rivers evenwhen there is a drought.

The amount of water in the ground depends on climate, the amountof water seeping into the ground, and the type of soil and rock. Thedepth below the Earth’s surface at which groundwater can be foundoften changes. This depth defines the upper boundary of saturatedground and is called the water table. The water table rises closer tothe surface during times of wet weather and sinks farther from thesurface during times of drought or heavy pumping from water wells.A well that has dried up often indicates a lowered water table.

Although groundwater is an excellent source of drinking water, by itsvery 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 dis-solved and suspended materials with it. Although soil does act as anatural filter and often helps remove some dangerous substances fromwater, it can also be a source of natural contaminants such as radioac-tive minerals (radium) and gases (radon), toxic substances given offby organisms, and disease-causing microbes such as giardia and amoebas. The human population adds to this natural contaminationthrough the use of pesticides, fertilizers, and other chemicals that cansoak into the earth. Humans also add to contamination by accidentalchemical spills and undetected leaks in storage tanks, sewage pipes,and landfills. Chemical pollutants released into the air can be trans-ported back to the earth, and into the groundwater, by rain and snow.


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seasonal stream

position of dry season water table

position of wet season water table

aquitard

permeable rock layers

water well

groundwater flow


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 yourregion?

4. What concerns do you have about the quality of the water in yourregion?

5. Did you learn any new information or read anything that willaffect how you think or act?

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6. How can surface water become contaminated? How can ground-water become contaminated?

7. Describe some advantages and disadvantages associated withusing water from an aquifer.


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Maps and More Maps©

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What information do different types of maps pro-vide that will help solve the mystery of Fruitvale’swater?

Now that you have a clearer understanding of how water moves andchanges in the environment, you decide to learn more about the land

and places in Fruitvale that could affectthe water or be affected by contaminatedwater. You know that people have beenmaking and using maps for centuries,and you decide to check the library andthe Internet to see if there are any mapsthat might help solve the mystery ofFruitvale’s water. The librarian helps youfind several different types of maps, eachshowing different kinds of information.You explain the groundwater problem,and he recommends that you consult thetopographic map and the geologic crosssection map of Fruitvale.

53

MATERIALS


1 ruler

1 piece of string

1 index card

For each student

1 Student Sheet 1.1,“Street Map of Fruitvale”

1 Student Sheet 4.1,“Topographic Map ofFruitvale”

1 Student Sheet 4.2,“Geologic Cross Section ofFruitvale”

1 Student Sheet 4.3,“Fruitvale Features”

1 Student Sheet 4.4,“Comparing Different Typesof Maps”


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Topographic maps show you where elevation changes occur and theshape of the land—the hills, valleys, ridges, and flat areas. Geologiccross sections show you what is below the surface. All maps have akey that contains important information to help you use the mapproperly. Keys often contain a north arrow, that points toward thenorth pole, and a scale, which lets you calculate the actual size of amap feature or the distance from one point to another.


1. Look at Student Sheet 1.1, “Street Map of Fruitvale.” List threemajor features shown on the map.

2. Look at Student Sheet 4.1, “Topographic Map of Fruitvale.” Listthree 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 theblanks in Column 1) in the table on Student Sheet 4.3, “FruitvaleFeatures.”

• • • • © ANALYSISGroupUse the table on Student Sheet 4.4, “Comparing Different Types ofMaps,” to complete Questions 1 and 2.

1. 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?

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3. Which of the three maps provides the most useful information for solving the mystery of Fruitvale’s water? Explain your choice.


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Topographic Map of Fruitvale

+

= creek

= contour line

1,000

1,020

1,040

1,060

1,080

1,060

1,000

contour interval = 10 m.

Blueberry Hill

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meters

Scale

KEY

N

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Geologic Cross Section of Fruitvale

Highway 15

Strawberry

Creek

Fruitvale Estates

Fruitvale Municipal

Water Well

X

KEY

N

soil

sand

gravel

clay

water well

private water well

X

200

meters

Horizontal scale

0

20meters

Vertical scale

0

Verticalexaggeration = 10x

meters


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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 _________________.

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Comparing Different Types of Maps

Type of Map Information Specific Information Commonto Each Type Map to All Three Types of Maps

Street

Topographic

Geologic Cross Section


What are the similarities and differences betweenpoint and non-point source contamination?

The geologic cross section of Fruitvale showed that a contaminant inwater or another liquid could easily percolate down and spread outinto an aquifer. The part of the aquifer that becomes contaminated is

called a plume. Knowing this, youdecide to find out more about how con-taminants move once they have beenreleased onto the earth’s surface.

You discover that substances releasedinto the environment, whether they areharmful or not, can be classified intotwo categories, depending on theirsource. If there is a single source of thechemical, such as a leaky fuel storagetank or an overturned tractor-trailer,the contamination is called a pointsource. If there are a number of sources,

such as millions of automobile exhaust pipes, or acres of fertilizedfarmland, the contamination is called a non-point source. Pointsource 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.


Points and Plumes

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MATERIALS


1 30-mL dropper bottle of groundwater contaminant

access to sink or tub for wastewater


1 Chemplate

1 plastic cup of water

1 syringe

1 contaminant plume tray

2 moistened paper layers


Part A:Point and non-point source plumes in horizontal layers

Before modeling a contaminant plume, draw a prediction in your sci-ence notebook. After modeling a contaminant plume, draw the actualshape that appears on both the top paper layer and the bottom paperlayer.

1. Fill the syringe with 5 mL of water.

2. Place the contaminant plume tray on the tabletop and place thetwo paper layers, stacked on top of one another, inside the tray.

3. Squeeze 5 drops of groundwater contaminant, one on top of theother, 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 areaof the filter papers as evenly as possible.

5. Wait 30 seconds, and while waiting, describe any changes youobserve 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 paperlayer 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 ofgroundwater contaminant adjacent to, not on top of each other, inthe center of the paper, as shown below.


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5 drops here

Part B:Point and non-point source plumes in tilted layers

13. Repeat Part A, except this time prop one end of the contaminantplume tray on your Chemplate as shown below.

• • • • © ANALYSISIndividual

1. Compare and contrast point source and non-point sourcegroundwater contamination. Which type of contaminant plumedo you think might be easier to clean up?

G R O U N D W A T E R C O N T A M I N A T I O N : A C T I V I T Y 5 / M O D E L I N G G R O U N D W A T E R C O N T A M I N A T I O N 67

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Thinking More About Investigation 5

Predicting the Spread ofGroundwater Contaminants


How might a contaminant spread under differentcircumstances in Fruitvale?

The colored areas that you observed on the paper layers represented agroundwater contaminant plume. The shape and size of a contami-nant plume is affected by a number of factors related to the contami-nant and to the local environment. These factors include the amount

of contaminant released, whether itwas a point or non-point source, thetype of earth material through whichthe contaminant is spreading, theamount of time the contaminant hasbeen spreading, the amount of precipi-tation or irrigation that has occurredduring that time, and the amount anddirection of groundwater flow.

• • • • © PROCEDUREDraw your plumes for the following scenarios on the geologic crosssections.

1. Choose a colored pencil and draw the contaminant plume youpredict would occur if a 200-liter barrel of pesticide spilled at theEat ‘Em Up Berry Farm.

2. Choose a different colored pencil and draw the contaminantplume you predict would occur if 200 liters of pesticide had beenevenly spread over the Eat ‘Em Up Berry Farm.

3. Choose a different colored pencil and draw the contaminantplume you predict would occur if a 200-liter barrel of pesticidespilled at the orchard.

4. Choose a different colored pencil and draw the contaminantplume you predict would occur if 200 liters of pesticide had beenevenly spread over the orchard.

G R O U N D W A T E R C O N T A M I N A T I O N : A C T I V I T Y 5 / M O D E L I N G G R O U N D W A T E R C O N T A M I N A T I O N 69

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MATERIALS


4 colored pencils

For each student

1 Student Sheet 5.1,“Predicting Plumes UsingGeologic Cross Sections”


1. Which of the scenarios described in Procedure Steps 1–4 are pointsources and which are non-point sources? Explain.

Individual

2. For each of the scenarios, explain why it is likely or unlikely toproduce 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 adata table.


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Predicting Plumes Using Geologic Cross Sections©

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X

Fruitvale MunicipalWater Well

Highway 15

Straw

berry Cree

k

X


Highway 15

Straw

berry Cree

k

soil

sand

gravel

clay

Key

1. Eat ’Em Up Berry Farm, 200 liter barrel spill

2. Eat ’Em Up Berry Farm,200 liters of sprayed pesticide

3. Orchard, 200 liter barrel spill

4. Orchard, 200 liters of sprayed pesticide

site of spill

area of sprayed pesticide

X


Highway 15

Straw

berry Cree

k

X


Highway 15

Straw

berry Cree

k


__________________ source ___________________ source

Flat Tilted Flat Tilted

Prediction

(underground)

Top

(surface)

Bottom

(underground)

__________________ source ___________________ source

Flat Tilted Flat Tilted

Prediction

(underground)

Top

(surface)

Bottom

(underground)


What is a serial dilution and how do we measurecontaminants in water?

Now that you have a better understanding of how contaminants andcontaminated water behave beneath the surface of the earth, you need

to understand how to determine if wateris contaminated and how you can meas-ure contamination levels.

When groundwater is tested for purity,the level of the dissolved substances canbe measured as a percent, or part perhundred, of the weight of the water.Because many of the substances healthofficials are interested in discoveringmake up only a small fraction of a per-cent, it is easier to report the concentra-tion of these substances in parts per mil-lion (ppm), parts per billion (ppb), and

even parts per trillion (ppt). Ppm, ppb, and ppt are very smallamounts, but very small amounts of very toxic substances can beextremely dangerous.

Safety Note: Food coloring can stain clothes and work surfaces. Immediately rinse any spills with water.


Disappearing Dye

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MATERIALS


1 30-mL dropper bottle of groundwater contaminant

1 plastic cup of rinse water

1 plastic cup of clean water

supply of paper towels


1 Chemplate

1 dropper

1 sheet of white paper


1. Place a piece of white paper under your Chemplate.

2. Place 10 drops of groundwater contaminant into the larger, ovalcup in your Chemplate.

3. Use your dropper to transfer 1 drop of the groundwater contami-nant into Cup 4.

4. Rinse your dropper thoroughly, and then add 9 drops of cleanwater 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 toCup 3.

6. Rinse your dropper thoroughly and then add 9 drops of cleanwater to Cup 3. 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 of500 ppm. Determine the contaminant concentration of the liq-uids 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 youridea with your teacher, try it out, and record your results.


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What are the most likely locations for the pesticideto have entered the groundwater?

As it turns out, a few days after you and your cousin were enjoyingmilkshakes 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, andsince they were interested, he gave them your phone number. Theycalled and ask you to come down to the Water Department to meetwith them. Read the following story about what you learned at theWater Department and think about what your next steps might be.

• • • • © READINGWhen you get to the meeting at the Water Department, you find outthat the rumor Lamar heard about the water in Fruitvale Estates istrue. A routine laboratory test of the well water used on the lawns atthe Fruitvale Estates detected 4.9 ppb of No-Bug pesticide. This isimportant, Water Department workers tell you, because for drinkingwater, 5 ppb is the maximum legally allowed level for the active ingre-dient in No-Bug pesticide. You ask them to draw an X on your map toshow you where the contaminated well is located. The water workersexplain that in the days before the city drilled its municipal well, eachhouse had its own private well. Although these private wells no longersupply homes with drinking water, many of them still exist, and a fewcontinue to supply water for irrigating farms, orchards, and lawns.The Water Department workers also tell you that the FruitvaleMunicipal Water Well has been tested, and it is not contaminated.

You also learn that No-Bug pesticide is no longer produced. Althoughit was always known that the toxic chemical in No-Bug could causepainful skin rashes and intestinal bleeding, initial testing showed thatafter a few weeks under normal soil and groundwater conditions, thetoxic chemical breaks down into non-toxic chemicals. As a result ofthese tests, No-Bug was approved as safe for use and sold for severalyears. The pesticide was manufactured at the Eden Agricultural


Pesky Pesticide

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Company on the outskirts of Fruitvale, and many of the local farmersused it on their fields. Then, eight years ago, it was discovered that thetoxic chemical in No-Bug does not decompose as expected in certainsoil and water conditions. These soil and water conditions are notwidespread, but they do exist in the Fruitvale area. Soon after this dis-covery No-Bug pesticide was banned in the United States.

Because a significant amount of No-Bug was used locally, the discov-ery of the contaminated well water has made city officials worried

that much of Fruitvale’sgroundwater may already becontaminated or is in danger ofbecoming contaminated in thevery near future. In an emer-gency session, the city councilvoted to approve the expendi-ture of $6,000 to determinewhere the No-Bug pesticide isgetting into the groundwaterand the size and shape of theplume area containing contam-inated groundwater. This isenough money to collect andtest water samples from 12wells. The problem that nowfaces the Fruitvale WaterDepartment is how to choosewhich 12 of the 40 private wellsto test.

Impressed with your careful investigations, the water workers ask foryour help in deciding which wells should be tested. They give you amap that shows the location of the contaminated well, the location ofthe Fruitvale Municipal Water Well, and the location of each of the 40other water wells that can be tested.


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1. What information and evidence do we have that is relevant insolving the mystery of Fruitvale’s water?

Individual

2. What three locations in and around Fruitvale do you think are themost likely possible sources of the pesticide? Explain why youpicked each location and how it may have contributed to thewater contamination.

3. What additional information about Fruitvale and its water supplywould you like to know?

G R O U N D W A T E R C O N T A M I N A T I O N : A C T I V I T Y 7 / T H E F R U I T V A L E S T O R Y , P A R T T W O 93

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Map of Fruitvale’s Wells


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34

1

2

3 4

6

9

5

7

810

11

12

13

14

15

16

17 18

19

20

21

23

22

25

26

2728

32

33

34

35

36

37

38

2429

30

31

39

40

200

Scale

N

meters

0

X

X

City Park(since 1996)

Creekside Homes(vineyard before 1996)

FruitvaleSchool

(new building in 1995)

Site of Fruitvale Estates II(orchard before 2001)

Orchard(since 1975)

Eden Agricultural Chemical Company

(1965–1990)

well with 4.9 ppb No-Bug

untested well with location no.

Fruitvale Municipal Water Well

Eat ’Em Up Berry Farm(since 1973)

Lots of trash

Stra

wbe

rry

Cre

ek

Stra

wbe

rry Cre

ek

KEY

Highway 15

Hill

side

Dri

ve

Cou

ntry

R

oad

Frui

tval

eR

oad

Randy’s GasStation

Fruitvale Estates I(orchard before

1999)

Fruitvale Municipal

Water Well

Orchard Lane

Orchard Lane


What is the extent and source of Fruitvale’s con-taminated groundwater?

You have agreed to help the Fruitvale Water Department test and ana-lyze some well data. In this Investigation, you will test well water sam-

ples to try to determine thesource of the pesticide con-tamination and to measurehow far it has spread. BecauseFruitvale’s funds are limited,you can test water samplesfrom only 12 of the possible40 wells. This means youmust use the evidence youobtain from every well youtest and carefully andthoughtfully decide whichwell 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.


1. The Pesticide Testing Key on Student Sheet 8.1 tells you how tointerpret the test results. Pick a different colored pencil to repre-sent Hazard Levels 0–4, and use the appropriate pencil to color inthe circles representing the two wells that have already been tested:


Testing the Waters

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MATERIALS

For the class

40 dropper bottles labeled: Fruitvale Water Sample(Wells 1–40)


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 andPesticide Testing Key”

Well Number Pesticide Concentration Hazard Level

X 4.9 ppb 2

Fruitvale Municipal Not Detected 0Water Well (<0.1 ppb)

2. Recall the three locations you thought would be most likely to bethe source of the pesticide and then decide as a group which wellto test first. If you can’t agree you may test two or three wells atthe same time.

3. Record the number of the well you chose to test and explain yourreasons for choosing it in your science notebook.

4. To test your well, take your Chemplate to the well area, find thebottle with the well number you chose, and add 5 drops of thewell water to an empty cup in the Chemplate. Carefully bringyour 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 waterand record the results of your test on Student Sheet 8.1.

6. On the map of Fruitvale, draw a circle around the well you justtested using the colored pencil you chose to represent the hazardlevel your test has detected.

7. Look at the map, and consider the results of each of your testedwells before you decide upon which well to test next.

8. Repeat Steps 3–7 until you have tested a total of 12 wells. Recordall 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.


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Well Testing Results and Pesticide Testing Key


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Well Number Test Color Pesticide Concentration Hazard Level

Test Color Pesticide Concentration Hazard Level Map Color

Red-orange Not Detected (< 0.1 ppb) 0

Yellow 0.1–0.9 ppb 1

Yellow-green 1.0–4.9 ppb 2

Green 5.0–9.9 ppb 3

Blue-green > 10 ppb 4

Pesticide Testing Key

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