As the comment you were responding to noted, new landfills protect the groundwater by completely lining the dumping area and then capture this methane and use i

As the comment you were responding to noted, new landfills protect the groundwater by completely lining the dumping area and then capture this methane and use it to produce energy. Cleaner burning and less CO2 than simply burning the waste stream because anaerobic bacteria capture a lot of the carbon and the parts of the waste stream that would produce nasty combustion byproducts are contained underground.