Tuesday, March 10, 2020

Homeschool Science: Make a Model Landfill, Fill it with Municipal Solid Waste, and Try Not to Poison Your Community

AP Environmental Science has SO MANY fabulous possibilities for labs and other hands-on activities. I am absolutely loving mentoring this study for Will, and hauling Syd along for the ride!

This particular hands-on activity comes from AP Environmental Science Unit 8: Aquatic and Terrestrial Pollution. For Syd, it also works for Honors Biology, using CK-12 Biology Chapter 12: Communities and Populations as a spine. Will read Living in the Environment Chapter 21: Solid and Hazardous Waste as her spine.

The main idea is that currently, there is no way to completely rid ourselves of solid waste, and therefore, it's important to find the most efficient, least environmentally impactful method to store municipal solid waste.

For that, you need a landfill! But what kind of landfill should you make? Ideally, your landfill should hold all of the municipal solid waste that your community produces, should have a barrier in place to keep all leachate from contaminating the ground or water, and should be capped to prevent scavengers and wind from spreading waste and rainfall from entering the landfill and therefore becoming contaminated, as well.

Here's a good diagram of a landfill.

Designing your dream landfill, building a model of it, and then testing that model is a fun STEM activity and hands-on science enrichment. I planned out a more casual version of this lesson, and the kids loved it!

The basic idea is that the kids each get a plastic bin, to which they add a 1"-2" sand layer and a 1"-2" soil layer. I provided the following supplies:

  • Monopoly houses
  • more sand and soil
  • popsicle sticks (these are a trap!)
  • homemade play dough (already portioned, and definitely not enough to solely use to make a landfill
  • paper
  • plastic grocery bags
I filled a pint Mason jar with cotton balls, then added green food coloring and water to the 2-cup line. This is our municipal solid waste!

The kids' challenge was the following:
  1. Using the provided supplies, create a community that includes a landfill. The community should have at least a dozen houses.
  2. The landfill should be impervious to rain and scavengers entering it, and impervious to solids and liquids leaving it. 
  3. The landfill should hold at least one cup of municipal solid waste, which includes both solids and liquids.
  4. The landfill should be able to survive a rainstorm and high winds without destruction or leakage.
Will had already read her AP Environmental Science chapter and watched most of the relevant videos in our AP Environmental Science playlist, so she had an advantage over Syd, who had only looked at the landfill anatomy diagram and read about solid waste storage more generally in her CK-12 Biology chapter. Regardless of background knowledge, though, this is still a fun engineering challenge, and I think you can see on the kids' faces how much fun they had with it!

Syd prepares the liner for her landfill.
Will falls into the trap by using popsicle sticks. They're a terrible choice for building a leak-free landfill!

At times, I felt more like a preschool teacher mediating children's work with sensory bins. After a long winter, the kids seemed to adore getting their hands dirty!

All those popsicle sticks! 
Syd's landfill is far larger than she needs for this challenge. I appreciate the room for growth, but it's going to suck trying to keep that whole landfill leak-free.

We add one cup of sopping wet cotton balls and green water.

Next, Will has to cover it and build a cap.

Popsicle sticks AGAIN!!!

Alas! The landfill has sprung a leak!

The engineer observes the problem and starts troubleshooting.

Meanwhile, in the next town over, the world's largest landfill receives its first cup of municipal solid waste.

Oh, dear! This community has just experienced a terrible rainstorm, and the cap on their landfill has taken a LOT of damage!

Syd adds the last dregs of municipal solid waste to her community's landfill.

Will the landfill hold?!?

It... will not. See that leakage? Syd has apparently foregone a liner entirely and instead relied just on the sand to hold the leachate.

This is a disaster! She's delighted.

If the landfill is this leaky already, what on earth is going to happen when it rains?

Wow. That's an environmental disaster, all right!

There seems to be a LOT of leakage. I wonder what the underlying ground looks like?

Oh, no! The soil of the entire community has been contaminated!
Chaos ensues, as the goddess of this little community seemingly decides to just give up and turn evil:

Will, her own landfill safely recapped with plastic, thought that Syd's crash-and-burn trainwreck of a landfill was HILARIOUS.
That plastic cap, though? Worked perfectly! Perhaps her community can take in the survivors from the other plastic bin.
Lessons were definitely learned about the importance of a leak-free landfill!

At the conclusion of this challenge, the kids washed the Monopoly houses and returned them to the game, threw away the play dough and plastic bags, and then dumped the rest of their landfill community--sand, soil, popsicle sticks, and cotton balls--into our compost. 

If you wanted to extend this activity, you could try to design and test landfills that deal with a variety of environmental challenges: a tornado or hurricane using a fan, a flood using more water, an earthquake using a shaker table, a population growth using more cups of municipal solid waste, etc. For us, though, this was a super fun way to always remember the importance of good design in a landfill, and what can happen when that design fails.

And the next day, we took a field trip to a REAL landfill!!!

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