I don’t think it’s highly realistic to leakproof something as large as a landfill - we can’t even consistently leakproof house foundations, and those are smalle

I don’t think it’s highly realistic to leakproof something as large as a landfill - we can’t even consistently leakproof house foundations, and those are smaller, easier to inspect, and higher budget. And that’s for new landfills, I don’t think there’s any way to retrofit every existing landfill to prevent leaks.