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Adrian Armstrong
Media planner
Asked a question last year

How long does it take recycled and non-recycled materials to decompose?

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Gordon Willis
Ecological Field Technician

This is what I know. I spent a few years working on landfill sites, supervising construction of clay landfill liners and landfill gas collection infrastructure. Yes, it was a smelly job, but not very demanding, at times a little more like watching paint dry when we needed to wait for the rain to stop, so we could get on with the job of moisture control during the placement and compaction of successive layers of the clay foundation or capping. Landfill materials domestic waste decomposes at fairly predictable rates and produces characteristic gases during the landfill decomposition cycle. For the first 2–3 years, expect mainly Ammonia, hydrogen and Carbon dioxide to be produced. Those are the smelliest years. After that, methane becomes the dominant gas for a few years, and the landfill gas produced can be piped from the constructed infrastructure into the gas plant. I am not sure how long it takes before the gas is all used up but I think something like five years was the economically efficient time for operating most landfill cells. Meanwhile, above the capped landfill, there could have been productive farmers fields, golf courses or any number of uses for the land above. Many of the landfill materials will have completely decomposed during the first ten years of domestic refuse burial.