helps students understand how Superfund sites are created.
They discuss what activities produce hazardous waste, and
how contaminants are released and spread into the air, water,
soil, and groundwater. Students learn what types of pollution
can be cleaned up using Superfund authority and what types
are addressed through other laws. Students construct a model
to observe how contaminants move in groundwater.
The U.S. Congress passed
the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) in response to growing concern about health and environmental
threats from hazardous waste sites. This law is commonly called Superfund.
Working with states and Indian Tribal governments, Superfund requires
the U.S. Environmental Protection Agency (EPA) to deal with abandoned,
accidentally spilled, or illegally dumped hazardous wastes from
the past, primarily from businesses and industry. Other types of pollution
are handled by other environmental laws.
The Superfund program has
a process for reporting and keeping track of potentially contaminated
sites. Since the early 1980s when the law took effect, more than 37,000
hazardous waste sites have been reported. EPA must investigate each
of the sites to determine the seriousness of the contamination.
Only the most serious sites are cleaned up using Superfund authority;
approximately four percent of reported sites are being cleaned up under
Superfund. Sites not handled by the Superfund Program will be cleaned
up by state governments or under other laws, or will require no cleanup
because they pose no danger to people or the environment.
It is important to keep
in mind that the Superfund Program deals only with abandoned, accidentally
spilled, or illegally dumped hazardous substances. A number of other
major environmental laws-such as the Resource Conservation and Recovery
Act (RCRA), the Clean Water Act, the Clean Air Act, the Toxic Substances
Control Act, and the Safe Drinking Water Act-were enacted to deal with
other types of pollution.
To help prepare your students
for this activity, use Warm-Up 6: What
is an Aquifer? You can perform the entire Warm-Up or simply review
the major points covered in it.
For more information on hazardous
waste sites and cleanups, see the Suggested
Reading list found at the end of the Haz-Ed materials.
Other Haz-Ed materials that are related to the topic include Warm-Up
2: EPA's Superfund Program-Overview.
Gather the following materials
(NOTE: You can split the class into 4 groups if desired and have
each group do the experiment.)
- bottom part of a
clear, plastic two-liter soda bottle
- pump mechanism from
a liquid soap dispenser
- small piece of nylon
fabric to cover the end of the pump tube
- resealable plastic
sandwich bag with 2 cups of small pebbles or aquarium gravel (white
- resealable bag with
2 cups of clean sand (white sand is best)
- large coffee filter
(round with a flat bottom, not cone-shaped)
- clean spray bottle,
the type spray window cleaner comes in
- bottle of red food
- clear measuring cup
copies for each student
Fact Flash 1: Hazardous Substances
and Hazardous Wastes
Fact Flash 2: The Superfund Cleanup
Fact Flash 5: Groundwater
- copies for each student
of the following maps from Fact Flash 3:
Flowing Railroad Hazardous Waste Site
Map 1, Flowing Railroad
Map 2, Flowing Railroad Site Area
Map 3, Diked Sludge Pond, Cross-Section
Read Fact Flashes 1, 2,
3 and 5 to prepare your lecture.
- Distribute Fact Flashes
1 and 2 and assign students to read them as homework.
- Review the main ideas
from Fact Flashes 1 and 2.
- Distribute Map 1, Flowing
Railroad Site (from Fact Flash 3: Flowing
Railroad Hazardous Waste Site). This is an overhead view of a
fictional site showing where past industrial activities are thought
to have taken place. Describe past site activities to the students,
using the information in Fact Flash 3.
- Distribute Map 2, Flowing
Railroad Site Area (from Fact Flash 3). This is an overhead view of
the towns, rivers, and some activities in the surrounding area. Describe
the area to students using information from Fact Flash 3.
Ask students how they
think contaminants might spread from the site. Possible answers include:
- The wind can blow
- The wind can blow
small soil particles to which contaminants are attached.
- Contaminants can be
washed into the Flowing River by rainfall running off the site.
- Liquid contaminants
can flow down through the soil to the groundwater due to gravity.
- Contaminants can be
washed down through the soil to the groundwater by rainfall soaking
into the soil.
- Groundwater moving
underground can spread contaminants in the aquifer.
- Contaminated groundwater
can move that uses the Flowing River.
- Excavation or other
activities that disturb the soil on the site can move contaminants.
Ask students how animals
or plants may be exposed to contaminants from the site. Possible answers
- The wind can blow
- Animals can eat contaminated
- Fish and aquatic plants
can be exposed to contaminants washed into the Flowing River.
- Farmland crops could
be exposed to contaminants through the irrigation system that
uses water from the Flowing River.
Ask students how people
in Ruralville and Utopia may be exposed to contaminants from the site.
Possible answers include:
- Eating contaminated
- Eating contaminated
fish from the Flowing River
- Utopia residents drinking
contaminated water from their municipal wells
- Ruralville residents
drinking contaminated water from the Flowing River
- Children playing on
- Fishermen crossing
the site to get to the Flowing River
- Ruralville residents
breathing air containing contaminated dust blown off the site
- Ruralville and Utopia
residents taking showers with contaminated water.
Ask students what factors
would affect the amount of exposure from site contamination. Possible
- Amount of contamination
originally released at the site
- Amount of dispersion
of the contaminants
- Amount of physical,
chemical, and biological transformation of the contaminants into
- Frequency of contact
with contaminated water, soil, plants, and animals.
- Explain to students that
in a follow-up class, they will look more closely at how groundwater
at the Flowing Railroad hazardous waste site may have been contaminated.
- Distribute Fact
Flash 5: Groundwater and assign students to read it prior
to the next class.
- Distribute Map 3, Diked
Sludge Pond, Cross-Section (from Fact Flash 3).
Briefly review with students the main points in Fact
Flash 5: Groundwater, assigned for reading after the first class.
- Explain that groundwater
contamination is a major concern in the Superfund Program, and it is
difficult to visualize how contaminants move underground. Therefore,
the class is going to construct a small groundwater model to explore
how groundwater and contaminants move in an aquifer.
Construct a miniature model
of a groundwater environment. Choose 2 or 3 students to build the groundwater
model at the front of the class. (If you have enough supplies, divide
the class into 4 groups and have each group construct its own model.)
Use the illustration shown on the next page as a guide.
Your groundwater model is now ready for conducting experiments. Have
students perform the following steps.
- Spray water on the sand
with the spray bottle, until the sand is saturated. The water will filter
down through the sand and into the gravel. Keep spraying until the water
table (the top of the portion of the ground that is completely saturated
with water) is in the sand. Keep track of the amount of water that the
container can hold at your selected water table level.
- Push down on the pump mechanism
and slowly draw a little water from the gravel through the tube and
out of the pump. Make sure the pump empties into the measuring cup.
Explain that the pump mechanism creates a vacuum to draw out the water.
This is essentially the same method used to pump groundwater from aquifers
(underground rock materials that are capable of storing and transmitting
water in useful amounts).
- Spray more water on the
sand until you reach your original water level. Then add a few drops
of red food coloring on top of the sand. Place one of the drops near
the edge of the sand, near the wall of the container. Explain to the
students that the food coloring represents a hazardous waste, such as
gasoline, that dissolves in water.
- Make it rain on your aquifer
model by pumping the spray bottle 5 times.
- Continue pumping water from
the container into the measuring cup. The water in the cup will eventually
have a reddish hue. Keep track of how much water you have to pump from
your groundwater model. Discuss with the students how the pollutant
at the surface level has contaminated the groundwater. This is similar
to rainwater carrying contaminants underground and into an aquifer.
Can the students make any observations about how the pollutant moves
downward through the sand from the drop placed by the wall of the container?
Ask students to guess how
much clean water will have to be sprayed onto the sand to remove all
of the food coloring. Continue adding water to the sand and removing
water with the pump until the students believe your groundwater has
been cleaned up. How much water did it take to clean the aquifer? Was
this close to what the students guessed?
Another way to illustrate this is to build your model using only
gravel. Attach the pump mechanism the same way as for the other
model. Roll a paper towel into a ball and saturate it with red coloring.
Bury it beneath
the surface (in the gravel). The buried paper towel represents an
abandoned waste site. Add water until 1/4 of the pump is submerged.
Then spray more water on the surface until 1/2 the pump is under
water. Press the pump 20 to 30 times, catching the water in another
container. Have students discuss what they observe .
To simulate the addition
and removal of other types of contaminants, you can put other additives
into the water. For example, use molasses or maple syrup to represent
a dense non-aqueous phase liquid (DNAPL)-a substance that is
heavier than water and will not mix with water. Contaminants like
TCE and PCB are DNAPLs. Use vegetable oil to represent a light
non-aqueous phase liquid (LNAPL)-a substance that is lighter than
water and will not mix with water. Jet fuel is an LNAPL. The amount
of water that will have to be flushed through the groundwater; model
should be significantly greater to remove these contaminants than
what was needed to remove the red food coloring.
Ask students how your
small groundwater model represents contamination at a Superfund site.
Answers could include:
- Contamininants on
the ground surface can be washed into groundwater by rainwater.
- Contaminants in groundwater
can be removed by pumping out contaminated groundwater; however,
the amount of water needed to clean contaminants from groundwater
is far greater than the amount of contamination added.
Ask students what is different
between your experimental groundwater model and a real Superfund site.
The following points could be made:
- A Superfund site can
have thousands of gallons of contaminants in the groundwater as
opposed to a few ounces.
- The subsurface at
a Superfund site is far more complex than your groundwater model.
- The water in your
model is contained, but at a real Superfund site it almost always
is flowing slowly in one direction. Flowing groundwater at a Superfund
site can carry contaminants miles from where the contaminants
were spilled on the surface. This can make it very difficult to
locate a contaminant source once contaminated groundwater is detected.
Ask students to consider
the situation at the fictional Flowing Railroad site. Would the residents
of Utopia be in greater danger from contaminated groundwater if the
groundwater beneath the Flowing Railroad site was flowing north toward
Utopia or south away from Utopia? (The answer is that residents
would be in greater danger if the groundwater was flowing away from
Utopia. This may sound surprising, but the reason is that, if the
groundwater is flowing away from Utopia, it is flowing towards their
drinking water wells located 3 miles south of the Flowing Railroad
- Separate the class into
3 groups. Have each group make a different model: (1) use red food
coloring to simulate a water-soluble contaminant; (2) use the buried
paper towel described in the note and illustration on previous page;
and (3) use maple syrup to simulate a DNAPL and/or vegetable oil to
simulate an LNAPL. Have students observe a demonstration of each model
and discuss the differences.
- Consider inviting an EPA
or state Superfund employee involved in overseeing hazardous waste
cleanup projects to discuss a real Superfund site in your state and
what made it a Superfund site.
- As an extra credit project,
advanced students could use a computer model to predict the movement
of contaminants in groundwater under various conditions. Check your
local telephone directory for the nearest EPA or United States Geological
Survey (USGS) office and contact them about obtaining a copy of the
groundwater models they use on a personal computer disk.