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WHERE DOES DRINKING WATER COME FROM

By Phillip Hicks,2014-06-23 11:45
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WHERE DOES DRINKING WATER COME FROM

    HOW CONTAMINANTS MOVE IN GROUNDWATER

Description

    Students learn about monitoring groundwater movement. They perform an investigation of a

    small-scale groundwater contamination problem.

Student Outcomes

    Student will:

    ; Learn basic well construction.

    ; Understand importance of monitoring wells in studying groundwater. ; Calculate groundwater elevation to determine gradient and direction of groundwater flow.

    ; Map groundwater flow.

    ; Perform an investigation of a groundwater contamination problem.

Student Products

    ; Reading for Understanding Questions

    ; Smithville Activity

Prerequisites

    ; Background Activity 2: Topographic Maps and Models

    ; Background Activity 8: Groundwater Basics

     National Standards

    Subject Area Standards Covered: Geography, Language Arts, Math, Science, and Social Studies. See Appendix D for the complete list of national education standards.

     Teamwork Skill

    Stay on task with your group: everyone contributes and helps.

    Activity Timing

    Time Estimate Two 50-minute Class Periods

    60 min Prep Time: photocopying and preparing for demonstration

    Homework Background Reading and Reading for Understanding Questions

    Day 1 Smithville Activity

    Day 2 Optional: Complete Smithville Activity

    Hydroville Curriculum Project ?2007, Oregon State University 9-1

Water Quality

    BA 9: How Contaminants Move in Groundwater

    Materials

    ; Hydroville Journal

Preparing Acid Solutions (per class):

    ; pH buffer capsules for pH 4, 5, 6 and 7 (available through Carolina or Flinn Scientific ,

    “Buffer, Hydrion pH”)

    ; Distilled water

    ; Lab tape

    ; Permanent marker

    ; 100 mL graduated cylinder

    ; pH meter or narrow range pH paper for pH 1-7 (better than pH 1-14 scale) ; Four screw-top, acid-safe glass bottles, about 250mL capacity ; 15 small beakers or cups

    ; 15 eye droppers or disposable pipettes

    ; Goggles, gloves and lab coat

For Smithville Activity (per pair of students):

    ; Fifteen 50 or 100 mL beakers or small cups

    ; Fifteen eyedroppers or disposable pipettes

    ; Fifteen strips of narrow range (pH 1-7) of pH paper or pH meter ; Paper towel

    ; Goggles, gloves and lab coat

Teacher Information

    See Background Reading: Understanding Groundwater Movement.

     Terminology

    Ground surface elevation Water well

    Groundwater elevation Well casing

    Monitoring well Well field

    Stick-up

     Suggested Lesson Plan

Getting Started

    1. Contact your local public water system to learn about the location of well fields and

    monitoring wells in your community. If possible, show students a map of the well field with

    monitoring wells.

2. Prepare the Smithville water samples using buffer capsules.

    a. Use buffer capsules to create solutions of pH 4-7 Hydroville Curriculum Project ?2007, Oregon State University 9-2

Water Quality

    BA 9: How Contaminants Move in Groundwater

    b. The amounts calculated in the table below are for one class set of water samples. You may

    wish to set up multiple sets of water samples. In this case, you will need to double or triple

    the amounts of each pH solution that you create and also gather more small beakers or

    cups and eye droppers.

    pH Amount needed

    4 100 mL

    5 100 mL

    6 100 mL

    7 200 mL

    c. Safety precautions: Wear safety goggles, gloves, and lab coat to protect against acid

    burns and damage. Keep a solution of sodium bicarbonate handy in case you spill

    concentrated acid on your skin.

    d. Store the solutions in screw-top, acid-safe glass bottles.

3. Smithville Activity Set-up:

    a. Label fifteen 25 or 50 mL beakers (or small cups) 1-15. Each of these beakers represents a

    water sample that was collected from a different monitoring well. Students will measure

    the pH of each water sample.

    b. Pour about 20 mL of the appropriate solution into each sample beaker. (See Table 1 in

    Teacher Key for pH of each sample.)

    c. Place an eyedropper or disposable pipette into each beaker. It may be helpful to also label

    each dropper or pipette to prevent mix-ups.

    d. Set up a station or stations with water samples so students can place a drop of each water

    sample on their pH paper.

    e. To save time and conserve pH paper, tear 25-30 inch pieces of pH paper. Keep dry.

4. Homework: Assign Background Reading: Understanding Groundwater Movement and

    Worksheet 1: Reading for Understanding Questions.

Day 1. Smithville Activity

1. Assign Journal Prompt-11 (TM-1):

    a. What information do hydrogeologists need to know to determine the gradient and direction

    that groundwater flows in an aquifer?

     Depth of groundwater (from ground surface elevation), ground surface elevation, and

    groundwater elevation.

    b. How do they get this information?

     They get this information by taking measurements from monitoring, municipal, and

    private wells.

    c. Where might you find monitoring wells in your community?

     Answers will vary, but could include areas near landfills, municipal well fields,

    contaminated sites, or underground storage tanks.

Hydroville Curriculum Project ?2007, Oregon State University 9-3

Water Quality

    BA 9: How Contaminants Move in Groundwater

2. Review calculations for finding groundwater elevation on homework, Reading for

    Understand Questions (WS-1).

    3. Hand out Smithville Activity (WS-2). Read introduction and divide students into pairs. There are two parts to this activity.

4. Part I. Testing pH of Water Samples:

    a. Students test the pH of 15 water samples from monitoring wells in Smithville. b. Review lab safety since the pH of these solutions range from pH 2-6. Provide goggles and

    other safety equipment.

    SAFETY: Students should avoid getting any of the water samples on their skin or eyes.

    If exposed, flush with water for 2-3 minutes.

    c. Students plot pH of each sample on Smithville Site Map.

5. Part II. Determining Direction of Groundwater Flow

    a. Students calculate groundwater elevation of each well and label on Smithville Site Map.

    b. Review how to draw contour lines. In this activity, the contour lines represent

    groundwater elevation, not ground surface elevation.

    c. Students estimate direction of groundwater flow and source of contaminant.

    6. Students work individually to complete the Conclusion Questions on WS-2.

Wrap-up

    Students can complete their worksheet as homework if they did not finish it during the class period.

Assessment

    The following student products can be used for assessment

    Individual

    ; Journal Prompt-11

    ; Reading for Understanding Questions (WS-1)

    ; Smithville Activity (WS-2)

    Resources

    For more information about drinking water reports, see the water quality resources on the Hydroville Curriculum website at: www.hydroville.org/links/wq_resources.aspx

    Hydroville Curriculum Project ?2007, Oregon State University 9-4

Water Quality

    BA 9: How Contaminants Move in Groundwater

    Teacher Keys

Reading for Understanding Questions (WS-1)

    1. Why would it be important to know the direction that groundwater is flowing?

     This information can help them determine if the groundwater will become contaminated if there is a pollutant source nearby.

2. Describe two differences between water wells and monitoring wells.

     Water wells are used for water production and monitoring wells are primarily for sampling. Monitoring wells are installed in areas to monitor water quality. Water wells are drilled in locations where groundwater supply is adequate.

    3. Practice calculating groundwater elevation. Measure the groundwater measurements in the steps below using the well in Figure 4. Measure to the nearest ?”, ?”, ?”, or whole number. Convert number to a decimal point: 0.25, 0.50, or 0.75.

    Note: 1 inch = 1 vertical foot

a. Depth to Groundwater (c = b a)

    i. Measure (a) stick-up height 0.75 feet

    ii. Measure (b) depth to groundwater (from top of casing) 4.50 feet

    iii. Subtract the stick-up height (a) from depth to groundwater (b).

    iv. What is (c) depth to groundwater (from the ground surface)? 3.75 feet

b. Groundwater Elevation (e = d c)

    i. What is the (d) ground surface elevation? 400 feet

    ii. What is the (c) depth to groundwater (from the ground surface)? 3.75 feet

    iii. Subtract depth to groundwater (c) from ground surface elevation (d). What is (e)

    groundwater elevation? (Round to the nearest whole number) 396.25 feet

4. In your own words, explain what is meant by “groundwater elevation”.

     Groundwater elevation is the height of the groundwater from mean sea level. Hydroville Curriculum Project ?2007, Oregon State University 9-5

Water Quality

    BA 9: How Contaminants Move in Groundwater

Smithville Activity (WS-2)

    Table 1. Monitoring well measurements

     A B C = B - A D E = D - C

    Ground Depth to Depth to Groundwater Stick-up Surface Well Groundwater Groundwater Elevation pH Height Elevation No. (from top of (from ground (ft above (ft) (ft above casing) (ft) surface) (ft) MSL) MSL)

    1 7 2 45.0 43.0 81.0 38.0

    2 7 2 29.5 27.5 64.0 36.5

    3 7 2 27.5 25.5 63.0 37.5

    4 7 2 34.0 32.0 67.0 35.0

    5 7 2 22.5 20.5 56.0 35.5

    6 7 2 25.0 23.0 60.0 37.0

    7 7 2 31.0 29.0 66.0 37.0

    8 7 2 28.0 26.0 60.0 34.0

    9 7 2 19.5 17.5 52.0 34.5

    10 6 2 20.0 18.0 54.0 36.0

    11 6 2 36.0 34.0 70.0 36.0

    12 5 2 16.0 14.0 49.0 35.0

    13 4 2 22.5 20.5 56.0 35.5

    14 5 2 14.5 12.5 47.0 34.5

    15 4 2 17.5 15.5 50.0 34.5

Conclusion Questions

    1. What is the direction of groundwater flow? South or southwest

    2. Where is the area of highest contamination? Down gradient of the town landfill

    3. Who is the potentially responsible party or parties (PRPs)? The town landfill

4. After the site has been cleaned up, the Smithville City Council requests that you develop a

    monitoring plan. Why?

     The site needs to be monitored to ensure that the remediation was complete and the

    groundwater is no longer affected.

5. One water sample costs $200 to collect and process the sample in an analytical lab. In your

    opinion, how often should Smithville monitor the site? (circle your answer below)

    c. once a month

    6. Explain why you chose your answer in # 5.

     Monitoring once a month will be frequent enough to determine if the contamination is gone,

    but not so frequent that it becomes too expensive. Hydroville Curriculum Project ?2007, Oregon State University 9-6

Water Quality

    BA 9: How Contaminants Move in Groundwater

Smithville Site Map (WS-2)

    pH 6

    pH 6

    pH 6

    pH 6

    pH 6 pH 6

    pH 5

    pH 5

    pH 6 pH 6 pH 5

    pH 3 pH 2

    pH 4

    pH 2

    KEY

    ; Monitoring Well

    (35.5) Groundwater Elevation

    feet above mean sea level (MSL)

    Groundwater Elevation Contours

     Contour interval = 1 foot

Hydroville Curriculum Project ?2007, Oregon State University 9-7

Water Quality

    BA 9: How Contaminants Move in Groundwater

     Pages to Photocopy

Note: Unless indicated, make one copy per student of all Handouts. For ease of photocopying,

    Transparency Masters appear first in the student pages.

Handouts and Transparency Masters

    *Day What is Needed Type

    Understanding Groundwater Movement BR

    HW

    Reading for Understanding Questions WS-1

    Journal Prompt-11 TM-1

    1-2

    Smithville Activity WS-2

    * Type = Transparency Master (TM), Background Reading (BR), Worksheet (WS), Map (M)

    Hydroville Curriculum Project ?2007, Oregon State University 9-8

Water Quality TM-1

    BA 9: How Contaminants Move in Groundwater

    JOURNAL PROMPT - 11

    1. What information do hydrogeologists

    need to know to determine the

    gradient and direction that

    groundwater flows in an aquifer?

    2. How do they get this information?

    3. Where might you find monitoring wells

    in your community?

    Hydroville Curriculum Project ?2007, Oregon State University 9-9

Water Quality

    BA 9: How Contaminants Move in Groundwater

    Blank Page

    Hydroville Curriculum Project ?2007, Oregon State University 9-10

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