Although individuals and corporations alike are making strides to reduce the amount of waste that goes into nationwide landfills, trash and by-products are still populating landfills. After reuse, recycling, and composting efforts, 54% of America’s municipal solid waste meets its final destination in a landfill.
While landfill disposal is the least desirable option in the waste management hierarchy, it’s important to know how landfills work and that modern landfills shouldn’t carry the same negative connotations of older versions.
The Modern Landfill vs. the Old Dump
So, what is a modern landfill? You may have heard them called municipal solid waste landfills, and they are highly regulated and advanced. They are very different than the old-fashioned “dumps” you probably picture when thinking about waste disposal.
In the past, dumps were created very simply, digging a hole in the ground and filling it with trash. Once the trash reached a certain limit, it was burned and then the entire opening was covered with new soil.
These old dumps were located in areas thought to have little value, including swaps, ravines, gravel pits or other lands. The practice of dumping waste in these areas often led to environmental and health concerns. While some former dumps created fire hazards from leaking landfill gases, other sites contaminated groundwater used for drinking.
Dump waste can be a chemical or physical hazard. Often, the soil covering over old dumps was not maintained, leading to the exposure of broken glass and other sharp objects that could cause injury. Exposure increases when visible waste such as wet soils, stained soils or liquid is observed.
Initiated by The Resource Conservation and Recovery Act (RCRA), passed by Congress in 1976, these dumps were overhauled and have become more efficient and environmentally conscious. The RCRA expanded the federal government’s role in managing waste disposal, divided waste into non-hazardous and hazardous categories, and developed design and operational standards for sanitary landfills.
In today’s municipal solid waste landfills, we see evidence of advanced regulation and sustainability efforts in the following improvements:
- Locations & Operations
- Better Designs
- Environmental Protection
- Reclamation & Reuse
Types of Landfills Today
The RCRA classifies three main categories of waste landfill under Subtitle C for hazardous waste and Subtitle D for solid waste. They include:
- Hazardous waste landfills: Categorized as Subtitle C landfills, hazardous waste facilities are used explicitly to dispose of hazardous waste, meaning they are not intended for solid waste. The Subtitle C program ensures that hazardous waste is handled properly from cradle to grave to protect the environment and human health. Subtitle C regulations encompass the treatment and transportation, generation, storage or disposal of hazardous wastes.
- Industrial waste landfills: These types of landfills are designed to collect institutional and commercial waste, which often represent a significant portion of solid waste, even in suburbs and small cities. Industrial waste landfills are categorized as Subtitle D landfill sites. They focus on local and state governments as the primary implementing, regulating and planning entities for non-hazardous solid waste management. Examples include Coal Combustion Residual (CCR) Landfills and Construction and Demolition (C&D) Debris Landfills.
- Municipal solid waste landfills (MSWLFs): Another Subtitle D landfill site, an MSWLF is designed to receive non-hazardous wastes such as household waste. A bioreactor landfill is an MSWLF that operates to degrade and transform organic waste rapidly.
Problems Addressed by This New Landfill Design
Many of the environmental concerns attributed to landfills of the past have been addressed and eliminated as modern landfill techniques began to be used.
1. Unsafe and Inappropriate Locations
Prior to RCRA regulation, dumps were potentially created on any large, unused space with little concern for its impact on the surrounding areas. Waste was compacted each day and covered with soil to reduce odor and contamination. New landfills, however, take into consideration the health of individuals and the environment. Today’s landfills cannot be constructed near floodplains, wetlands or fault areas/unstable areas.
2. Groundwater Contamination
Another problem with older landfill design was that waste was deposited directly onto the soil with no barrier or liner. This allowed leachate, liquid produced by the natural decomposition of waste and rainfall that accumulates in all types of landfills, to percolate through the waste, pick up harmful contaminants, and then enter into the soil. In some landfills, leachate can be highly toxic to aquatic life if it discharges without being diluted or treated appropriately beforehand. If it reaches below-landfill ground level, leachate can seep into nearby wells, ditches, streams, rivers or lakes. In addition to groundwater contamination, leachate can also cause explosions and fires, unpleasant odors, vegetation damage, air pollution and landfill settling.
Improved landfill design requires a leachate collection system, including protective liners made of clay or plastic, to provide a barrier between the disposed waste and the ground below. Now any liquid that develops among the waste is collected and treated to prevent contamination. The leachate collection system maintains compliance with state requirements by automatically pumping leachate to collection sumps to be treated and removed from the landfill properly.
3. Release of Methane Gases
Methane gas and carbon dioxide, also known as greenhouse gases, are natural by-products of any landfill, whether old or new. They are created as organic waste matter decomposes. These gases are known to trap and hold heat in the atmosphere, known as the greenhouse effect, and are recognized as being a leading contributor to global warming.
Modern advances in landfill technology have made it possible to minimize the number of greenhouse gases released from landfill waste. Under the Clean Air Act, larger facilities where gas emissions reach 55 tons per year are required to install a gas collection and destruction system. Additionally, many smaller facilities have voluntarily installed similar systems. When greenhouse gases are captured, they can be destroyed or treated to generate energy sources such as electricity and fuel.
4. Reuse of Space
In the past, when dumps were no longer usable, a final layer of soil was added to the top and, in some instances, vegetation was planted. But often, vegetation couldn’t even grow due to the methane gas and contaminated soil found below, and the space was never useable again.
But limited land and growing interest in cultivating community and green space have changed the way that closing landfills are used. Modern landfills are designed from the start for reuse once the landfill closes. Almost indistinguishable from other land, you can now find parks, sports fields, parking lots, commercial space, and even agricultural land thriving over landfill land.
The Future of Modern Landfills
Always looking for a way to implement more sustainable and green practices, the waste industry is developing further enhancements for the future of landfills.
One solution is turning waste into energy via biological technologies. Future enhancements for modern landfills also include ratcheting up the recyclability of materials, introducing consumers to smart measuring technology and providing grants for sorting-facility upgrades to make collecting gable and aseptic top cartons easier.
Sustainable and green practices for modern landfills also include the use of bioreactors and biocovers.
Bioreactor landfills add liquid and air to the disposed waste, which in turn accelerates the degradation of the waste. When waste breaks down faster, there is a shortened period of time that greenhouse gases are produced and a quicker turnaround of the land for reuse in the community.
A biocover is created when a facility uses composted yard waste as the final cover for a landfill. Biocovers go even further in reducing the number of greenhouse gases released by waste facilities, as the gases are oxidized and stabilized by the compost.