Question

Hazardous chemicals are disposed of by _____.

placing them in a landfill
burying them deep in the ground in special containers
being poured down a drain

Answer 1

I would say "Burying them deep in the ground in special containers". You don't put hazardous chemicals in landfills, they could seep into the ground, and I somehow doubt it's ethical, let alone legal to pour them down a drain.