Before RCRA Subtitle D regulations mandated composite liner systems in 1991, the standard practice for solid waste disposal was straightforward: find a low spot, fill it with garbage, and move on. No liner. No leachate collection. No gas management. An estimated 10,000 of these pre-regulation landfills exist across the United States — and many are actively contaminating the aquifers beneath them.
But here's the good news: we know how to fix it. And communities across the country are starting to do exactly that.
The Problem We're Solving
Every landfill produces leachate — the liquid that forms when rainwater percolates through decomposing waste, dissolving contaminants along the way. In a modern Subtitle D landfill, composite liner systems and leachate collection networks capture that liquid for treatment. The system isn't perfect, but it dramatically reduces groundwater exposure.
Unlined landfills have no such protection. Leachate migrates directly into the subsurface, carrying heavy metals, volatile organic compounds, ammonia, chlorides, and — increasingly recognized — per- and polyfluoroalkyl substances (PFAS). These contaminant plumes follow groundwater flow paths that can extend for miles, potentially threatening drinking water supplies far from the original disposal site.
The conventional response has been "closure in place" — capping the waste with an engineered cover to reduce rainwater infiltration. Caps are useful, but they don't solve the fundamental problem: the waste is still sitting in direct contact with subsurface moisture and, in many cases, the water table itself. Caps degrade over 30-50 years. Post-closure funding runs out. And the contamination continues.
There's a better answer.
Landfill Mining: Remove the Source
Landfill mining — the systematic excavation, processing, and removal of buried waste — takes a fundamentally different approach. Instead of managing the problem in perpetuity, you eliminate the contamination source. The groundwater recovery timeline accelerates from centuries to decades. The land is restored to productive use. And the community gets closure — literally.
Modern landfill mining has evolved into a sophisticated, multi-step process:
Screening and sorting. Excavated material passes through trommels and screens to separate soil-like fines (typically 50-70% of total volume) from plastics, metals, and other recognizable waste. The fines, after testing, often serve as daily cover at active landfills or as engineered fill — immediately useful material recovered from what was treated as permanent waste.
Metals recovery. Ferrous and non-ferrous metals — aluminum, copper, steel — are separated using magnets and eddy current separators. Depending on the age and composition of the waste, metals recovery can meaningfully offset mining costs. Pre-recycling-era landfills are particularly rich in recoverable metals.
Critical minerals. Research by the Department of Energy's National Energy Technology Laboratory has shown that municipal solid waste — and particularly coal ash co-disposed in older landfills — contains recoverable quantities of rare earth elements. We're sitting on domestic critical mineral resources that have already been "mined" and concentrated. It's a national security opportunity disguised as an environmental liability.
Soil reclamation. The soil fraction, which constitutes the majority of material in older landfills, can be treated and returned to beneficial use. What went in as waste comes out as a resource.
Land restoration. Perhaps the most exciting outcome: fully remediated sites become usable again. Parks, solar farms, commercial development, community green space. Closed unlined landfills often occupy surprisingly valuable real estate — low-lying land near town centers that was considered worthless when the landfill was sited but is now surrounded by development. Mining turns a permanent liability into a community asset.
The Economics Are Better Than You Think
Landfill mining costs $30-75 per ton of material, depending on site conditions. For a 500,000-ton site, that's $15-37 million. That sounds expensive until you compare it to the alternative.
Perpetual cap maintenance, groundwater monitoring, pump-and-treat systems, and emergency remediation when those systems eventually fail can easily exceed $50 million over a 100-year timeframe in net present value. And that assumes the obligations are actually funded — which, for many legacy sites, they aren't.
Factor in the recovered land value, metals revenue, avoided long-term liability, and the economic benefit of removing deed restrictions and institutional controls from prime real estate, and the math tips decisively toward mining at many sites.
European countries, where land scarcity drives different economics, have been leading the way. The EU's Enhanced Landfill Mining research program has funded successful pilots in Belgium, Sweden, and the Netherlands. In the U.S., projects in Florida, Maine, and New York have demonstrated the approach works. The barrier isn't technology — it's policy momentum.
The PFAS Accelerator
The rise of PFAS awareness is adding urgency to the conversation. Pre-Subtitle D landfills accepted consumer products, packaging, textiles, and industrial waste containing PFAS — chemicals that don't degrade in landfill conditions. These sites are now functioning as permanent PFAS sources, generating contaminated leachate with no containment barrier.
EPA's PFAS Maximum Contaminant Levels for drinking water — 4 parts per trillion for PFOA and PFOS — mean even trace concentrations in leachate can push aquifers past safe limits. Capping helps but doesn't eliminate the problem. Removing the source does.
This isn't a theoretical concern. Communities across the country are discovering PFAS in drinking water wells downgradient of old landfills. The connection is becoming impossible to ignore, and landfill mining may be the only permanent solution for the highest-priority sites.
A Vision Worth Investing In
Imagine a federal program that identifies the highest-risk unlined landfills — those within one mile of public water supply wells, in aquifer recharge zones, or with documented PFAS contamination — and funds feasibility studies for mining. Imagine updating RCRA's financial assurance framework to account for the true long-term costs of perpetual care, making the mining alternative comparatively attractive. Imagine communities that spent decades living with a capped waste pile transforming that land into solar arrays, parks, or economic development.
This isn't fantasy. Every piece of the technology exists today. The projects that have been completed demonstrate it works. What's needed is the policy framework to scale it — and the political will to invest in permanent solutions rather than perpetual maintenance.
Where We Stand
EPR Foundation supports federal investment in landfill mining feasibility studies at priority sites, updated financial assurance rules that reflect true perpetual care costs, and research funding for economic recovery of critical minerals from mined landfills.
We buried the problem because we didn't know better. Now we do — and we have the tools to fix it. Every unlined landfill that gets mined is an aquifer protected, a community restored, and a liability erased.
It's time to dig in.