When it comes to sustainability, the role of the landfill is most often portrayed in unflattering terms. Over the past 30 years the drive to divert material from the landfill has changed the template of recycling. From dual stream bin collection to commingled carts, more and more materials have been incorporated as acceptable items as more municipalities push for increased sustainability. Although the goal to recycle more and landfill less continues to be a desirable goal, landfills are a necessary component.
With recycling in the current state of recycling markets (see New Economics of Recycling) the landfill deserves recognition as still one of the key components of the waste management pyramid, especially when economics are included in the evaluation.
Western Disposal uses the Front Range Landfill in Erie, CO for non-recyclable and non-compostable wastes. This landfill is a modern, municipal solid waste landfill (MSWLF). Not unlike the nearly 2,000 MSW landfills in the United States, Front Range adheres to both federal and state regulations. The Colorado Department of Public Health & Environment alone outlines an extensive list of regulations in a 500-page document covering all solid waste disposal sites and facilities in the state.
Key requirements specific to landfills include location restrictions, liner requirements, operating practices, groundwater monitoring, and closure and post-closure rules.
How does a landfill work?
The simple answer is the process involves layering waste into a hole.
A MSW landfill places a synthetic or plastic liner at the base to prohibit trash as it decomposes from entering the environment and groundwater. After the base liner is in place, trash is dumped into designated areas called cells. To decrease air space trash is compacted. Compaction is done with heavy equipment such as bulldozers and graders, which roll over the mounds several times. As each cell is completed, it is covered with soil and compacted. Multiple cells are arranged in rows and layers.
When multiple cells, or a section is finished it is covered with a polyethylene layer or cap. The cap is covered with several feet of compacted soil and planted with erosion reducing vegetation such as grass. Root penetrating plants are avoided to eliminate contact with the trash.
Plastic drainage pipes and storm liners collect water from areas of the landfill and channel it to drainage ditches. Similar systems are included for water that encounters the compacted trash. Leachate is the term for this water with any dissolved contaminants. Collection ponds separate any leachate where it is tested and treated as required, often similar to sewage and wastewater.
Among the most commonly asked questions are what items are not acceptable at the landfill. The following items are not allowed at Front Range:
- Batteries, lead-acid automotive
- Biohazardous Waste
- Electronic Waste
- Hazardous/Toxic Waste
- Hot Ashes
- Liquids: paint, oil, septage, chemicals
- Propane gas containers
Modern Landfills are increasingly developing and implementing renewable energy programs. Methane, a byproduct at MSW landfills, is a potent greenhouse gas. Landfills are the 3rd largest source of man-made methane, representing about 17% nationally. Landfill gas is typically 50% methane and 50% carbon dioxide.
Front Range Landfill operates a Green Energy system that captures landfill gas and converts it to electricity. The environmental benefits include a reduction in the use of more polluting forms of energy and cleaner air. The Environmental Protection Agency estimates capture rates of methane average between 60 to 90%.
Economically, landfill gas conversion is cost-effective and a reliable source of local energy. Front Range generates 3 megawatts of electricity annually (on average, a megawatt will power 650 homes). Unlike solar and wind, landfill energy is 24/7 reliant, and not subject to variability.
While Landfills are positioned at the bottom of the Waste Management Hierarchy, it is worth noting the regional option for non-recyclable and non-compostable waste is tightly regulated and includes a gas capture and conversion system.