Leachate is water that travels through trash and picks up nasty stuff along the way. I used to build landfill at the end of the last century. Landfill regulat

Leachate is water that travels through trash and picks up nasty stuff along the way. I used to build landfill at the end of the last century. Landfill regulations vary from place to place, but in essence new landfills are some of the worlds largest plastic bags. NY used a double liner system (a bag within a big). It was 1 foot of clay (water moves slowly through clay) at the bottom, bentomat and 60mil hdpe liner "welded" together into a big waterproof mat. They put corregated pipes along the bottom to funnel leachate out for treatment. sand and fill with trash. The top with 40 mil Hdpe. They do that even for old landfills without bottom liners. The have to vent because landfills produce flamable gasses. I hope these systems work well.