Day: March 14, 2020

The theory behind landfills is that once waste is buried, the contamination remains inert in landfill “cells.” To keep the waste dry and contained, landfill cells today are required to have two plastic liners, each backed with synthetic clay, putting a few inches between decomposing trash and the soil beneath it. Once the landfill cell is full, gravel, a flexible plastic cap, and some sod are then built on top of the cell.

This should be a nice, tidy end to that waste, but in reality, it is impossible to keep landfill cells dry. Rain and snow get into them while they’re open and accepting waste (which can be for years). And even after the cell is sealed, the plastic caps develop holes over time, letting in more rain and snow.

The water that gets into landfill cells picks up contaminants from the waste and becomes “leachate.” What’s in the leachate depends on what’s in the landfill, but some chemicals can be counted on, such as volatile organic compounds, chloride, nitrogen, solvents, phenols, and heavy metals.