Okay kiddo, have you heard of coal? It's a black rock that we use to make electricity. When we dig coal out of the ground, it's often mixed with water and turns into a messy mixture called a slurry.
Now, sometimes people want to store this slurry so they can use it later. So they dig a big hole in the ground and line it with special materials to keep the slurry from leaking out. This big hole is called an impoundment.
The problem is, if the impoundment gets too full, it can burst and all that slurry can spill out. This can be really dangerous for people and the environment, because the slurry can pollute rivers and streams and harm animals and plants.
So, we have to be very careful and make sure that the impoundment is built and maintained correctly to prevent any spills. That's why people are always talking about coal slurry impoundments, because they want to make sure they are safe and don't cause any harm.