Download Groundwater - Sturgeon City

7th Grade: It’s Our Water
Station 1: Groundwater
- What is groundwater
- Ways that contaminants enter the groundwater
- Ways to prevent groundwater contamination
- Use groundwater simulator to show how contaminants enter the groundwater and flow
through
Timing outline of Station
1. Groundwater Lecture ( 10 mins)
a. What is ground water
b. Ways that contaminants enter the groundwater
c. Ways to prevent contamination
2. Groundwater Simulation demonstration ( 15 mins)
3. Wrap-up (5 mins)
Materials
Groundwater Simulator
Dye
Injectors
Water
Groundwater
Groundwater is the water that is contained in saturated soil and rock materials below the earth’s
surface. The source of groundwater is precipitation. When rain falls on the surface of the ground, some
of it runs off the land into lakes and streams (runoff), and some soaks into the ground (infiltration).
Groundwater moves slowly between the grains of soil or in cracks in rock until it reaches a point where
it can discharge at the surface, such as a lake, stream or wetland, or until it is withdrawn from a well. It
then becomes surface water again.
Groundwater is stored underground in the pore spaces of saturated soil and rock materials. An
underground unit of soul or rock which can yield a significant quantity of groundwater is an aquifer.
Aquifers are not always uniform because of differences in composition or in properties. Aquifers may be
separated by layers which do not transmit much water. These layers are called confining layers. If the
confining layer exists above an aquifer which is fully saturated, this aquifer is called a confined or
artesian aquifer. Aquifers without a confining layer above them are called unconfined aquifers.
Groundwater gets polluted in many different ways. Rainwater and runoff may contact contaminated soil
while filtering down into groundwater. Waste water from septic systems that are not working properly
can leak into the groundwater. Improper disposal of used oil, gasoline, or other chemicals can also soak
into the groundwater. There are also ways to help prevent this from happening. Disposal facilities are
places that you can take your used oil and chemicals to be disposed of properly. Do not dump anything
onto the ground. Also make sure that the septic systems are installed and functioning properly.
Demonstration
Explain to students that this is a groundwater simulation system. This is used to show how groundwater
moves underneath the surface. This model shows both the confined and unconfined aquifers (layer).
There is also a leaky lagoon and a underground tank (septic).
1. Charge the groundwater simulator. Do this by placing both water bottles on either end of the
model and allow the model to fill until the water stops draining out into the model. Refill the
bottles and place back on the system.
2. Once full ask students to notice where the water table is (they should look in the piezometers).
3. Draw a line across the simulator with the chalk pencil to mark the water table. Open the bottom
outlet and let the water flow through the system. Ask the students what happens to the water
table as water is being used up out of the ground? (the water table will drop)
4. Tell students to watch throughout the demonstration what happens to the water table.
5. Explain to the students that you are going to be injecting dye in certain parts of the system. The
dye is going to represent different types of pollutants.
6. Inject blue die into piezometers B, F, and G. Add dye until it reaches the bottom of the
piezometer.
7. Fill the remaining piezometers with green dye.
8. Inject red dye into the underground tank and the leaky lagoon.
9. With all the dye in place, put the tube extending from the lake/stream outlet into a bucket.
Slowly open the tube so that only a small amount of water flows out. Refill the water bottles as
needed. (Ask students where the dye is moving. The dye should be moving towards a discharge
area such as the lake.)
10. As the dye reaches the bottom of the lake/stream, close the outlet. Water should begin to fill
the lake/stream. With it, dye will also enter. Explain to students why pollutants from the lagoon
are the first to arrive. Ask the students what they dyes are doing in the confined versus
unconfined layers. Pollutants in the confined layers are remaining within that layer and not
moving rapidly. Pollutants in the unconfined layer are moving rapidly towards the discharge
areas.
11. When finished, to get the remaining dye out of the sand, close the lake outlet and open the
bottom outlet. Continuously run water through the model using the bottles until all of the dye is
out. To get the dye out of the piezometers and wells, carefully inject clean water in them until
the dye is pushed out of the bottom. As you are doing this have a wrap-up discussion with the
students.
Wrap-up
After the demonstration is done lead the students in a discussion of what they noticed. Did they notice
that the dye in the confining layer (aquifer) never left that layer? The black layer of clay did not allow the
dye, or pollutants, to escape from the confining layer. What about the unconfined layer (aquifer)? The
dye, or pollutants, were able to flow through the layer and into a discharge area. This allows the
students to better understand what they saw during the demonstration.