act 6 groundwater lab 1

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HWR 201 Groundwater Lab PART 1 Oct. 18, 2007

Groundwater Model L ab Name:_____________________Group _________

Objective: After a short introduction to groundwater concepts, students will conductexperiments, observe and interpret results through drawing and explanation to conceptualizegroundwater flow, surface water/groundwater interactions and groundwater contamination.

Introduction:This is a 2-D cross-section model of an aquifer. Anaquifer is a water-bearinggeologic formation that can store and yield usable amounts of water. The water stored in anaquifer is known asgroundwater. Working cooperatively in groups, follow the directions andindividually answer the questions for each part of the lab. It will be useful to read all thequestions in a section before completing theitalicizedaction item.

Part 1 to 5 must be completed in class and turned in (October 18th).Part 6 and 7 must be turned in Tuesday, October 23rd.

Part 1. Aquifer Basics

Action: First read carefully the questions for this part 1. Secondly, to begin, fill the leftrecharge column of the model. As the column is filling, pay attention to which layers allowthe water to move fastest and slowest. Use almost one full bottle.

1. Which layer did the groundwater move fastest through (describe and/or name the material)?Why do you think the water moved fastest through this layer?

2. Which layer did the groundwater move slowest through? Why do you think the water movedslowest through this layer?

3. Based on your answers from 1 and 2, which layer makes the most productive aquifer andwhy? Think about what characteristics would make an aquifer productive.

4. Describe what you observe in the artesian well. Could you explain what you observe?

Action: Saturate the lower 4/5 ofthe model (~2 inches below the top edge) and establish alevel water table. Observe the water table level in the model.

5. List two ways you can identify where the water table is:

7. Oncopy 1 of the groundwater flow model please draw and/or label:1. Water level in each well

The University of Arizona


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2. The water table line for the entire model3. Potentiometric surface (if any)4. The saturated zone5. The unsaturated zone

Part 2. ContaminationAction: Read the questions for Part 2 before starting. Inject dye into the 2 deeper injectionwells until you can see a quarter-sized amount in each location. Observe what happens to thedye for one minute.

1. Oncopy 1 of the groundwater flow model, draw the initial dye locations (label #1) and thearea filled by dye after one minute (label #2). Why does the contamination spread over time?

Action: Add more water to the left recharge column (4/5 full) while using the pump to keepthe right column 1/4 full.

2. On copy 1 of the groundwater flow model, draw the flow paths of the dye after doing this forseveral minutes (label #3). Now what is causing the contamination to move?

Action: Empty the vacuum flask. Place a full bottle of water over the left recharge. Beginpumping water from the deep pumping well. Observe the movement of the dye for 1 minute.

3. Oncopy 2, draw the flow paths of the dye (label #4). Has the dye entered this well afterpumping? How can you tell?

Action: Empty the vacuum flask. Keeping most of the model saturated, begin pumping waterfrom the shallow pumping well. Observe the movement of the dye for 2-3 minutes.

4. On copy 2, draw the flow paths of the dye (label #5). Has the dye entered this well afterpumping? How can you tell?

5. Which well was contaminated more quickly from pumping? Why?



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6. Contamination can come from multiple sources. Looking at the model, can you see any otherrealistic sources of contamination? How would the effects differ from those just observed?

Action: Using dye, contaminate this new source and observe flow paths as you continuepumping from the shallow well draw the flow paths on copy 2.

Part 3. Pumping WellsAction: Read the questions for Part 3 before starting. Saturate the lower 4/5 ofthe model andestablish a level water table. Put a water bottle on both sides.Create a cone of depression bycontinued pumping from the shallow well. Carefully observe the water level in all themonitoring wells as it falls to the level of pumping.

1. Oncopy 3 of the groundwater model, mark the water level or water table in all the wells

before and after pumping from the shallow well. Draw also the water table in the river/lakebefore and after. Label the saturated and unsaturated zones. From these water levels, explain thechange in the water table.

2. Is there any sand being pumped up through the wells? Why not? Why is this important?

Action: Return the water bottle to the left recharge column.

3. Calculate rate of extraction or flow from the shallow well in ml/min and gal/min. (hint: startby emptying the flask; you will need to measure the volume of water extracted over a giveninterval of time; The small beaker may help to accurately measure your volume; 1 gal ~3.8 L)

Part 4. Surface water groundwater interactions.Action: Saturate the lower 4/5 ofthe model and establish a level water table

1. On copy 4 of the groundwater model, draw the water table (label #1), paying particularattention to its level in the lake/river structure.

2. Explain the interaction between the water table and the body of water (lake, stream, etc.).



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How is the surface water body being filled? How does groundwater interact with surface water?

Action: Remove the water bottle. Pump water out of the right column of the model. Observethe effects on the water table and stream.

3. On copy 4, draw the new water table (label #2).

4. Using this demonstration, explain what has happened to the Santa Cruz River and why it nolonger flows perennially.

Part 5. Contamination Clean-upAction:You must now clean up your contaminated groundwater model before you can turn inyour lab. By the end of class, you should have removed all the dye and nearly all the waterfrom the model.

1. How did you clean up the contaminated groundwater? What might be a problem with yourmethod of cleanup?

2. What does this process indicate about potential cleanup in real aquifers?



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Part 6: Other questions

1. What is the difference between a piezometer and a production well?

2. When thinking about the water level in wells, what is the difference between thegroundwater elevation and the static water level?

3. What is the name of the level that water rises to in a piezometer in the unconfined

aquifer?

4. What is the name of the level that water rises to in a piezometer that penetrates theconfined aquifer?

5. Where is the level in the confined (deeper) aquifer, relative to the level in the unconfinedaquifer (shallower) aquifer?

6. When dye enters the aquifer, it is concentrated, occurring in only a small spot. Whathappens to it as it moves down gradient?

7. What do the dye traces indicate about the direction(s) from which water is pumped froma pumping well? How can a pumping well be contaminated by a lagoon down gradient?



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Part 7: Feedback on the Lab excercise

1. What aspects of this exercise helped you understand groundwater the most?

2. What aspects of this exercise are still unclear?



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Copy 1

Copy 2


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Copy 3

Copy 4

act 6 groundwater lab 1

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