Clogging of landfill tyre and aggregate drainage layers by methanogenic leachate and implications for practice

This paper reports the results of pilot scale tests carried out to investigate the clogging of shredded and baled tyres in comparison with aggregates when percolated by leachates representative of those generated by methanogenic stage landfills. Realistic lifetime loading rates of methanogenic leachate were applied, and clogging was not generally apparent in any of the drainage media studied. This is in apparent contrast to many other studies that have demonstrated the susceptibility of all forms of drainage media to biological and chemical clogging when percolated with high strength organic and calcium rich leachates. The reasons for this difference are identified, the implications for landfill drainage system design are discussed and some suggestions for operational practice are presented for discussion.

► Field scale clogging tests on a variety of landfill drainage media are reported.
► Methanogenic leachate obtained directly from a landfill was used in the tests.
► No clogging occurred even when a landfill’s lifetime leachate load was applied.
► Our results contrast to the clogging that occurs with high strength organic and calcium rich leachates.
► We propose changes to landfill practice to protect drainage layers from clogging.