Since ancient times, humans have piled garbage away from living areas and have used various methods to avoid the unpleasant aspects of their rubbish heaps.
A Brief History
Early in 20th century North America, most MSW was burned either at home, at work, or at an open burning dump. The waste collector was known as “the ash man.” Schools and businesses had incinerators in the basement to dispose of the day’s waste, and periodically the ashes were hauled out to uncontrolled junk yards at the edge of town to be dumped with the rest of society’s discards. This seemed to work satisfactorily, except for the noxious smoke. For much of North America, this system prevailed well into the 1960s.
There were some pioneers however. In 1929, the first reference to “sanitary fill” is found in public works literature, and by 1937, the first “sanitary landfill” was constructed and operated in Fresno, CA. This site has now been designated as a National Historic Landmark. Two key features that distinguished this new innovation were prohibition of open burning and daily soil cover of the trash. The military industrial boom of WWII brought greater use of this new technique, and by 1960, nearly 1,400 cities were using sanitary landfills.
Regulations in the early days were scanty, mainly in the form of guidelines produced during the 50s by the US Public Health Service and APWA. Congress passed the Solid Waste Disposal Act in 1965 and the EPA was created in 1970. The regulatory pace quickened with the advent of the Love Canal debacle and subsequent passage of the 1976 Resource Conservation and Recovery Act (RCRA), which imposed criteria for ground water protection and landfill gas migration control. In 1984, the RCRA Hazardous and Solid Waste Amendments were passed granting the EPA regulatory authority over landfills and directing the preparation of landfill operating criteria. In an effort to isolate waste piles from groundwater, and to limit air pollution, the “dry tomb” concept was born. This philosophy of physically encapsulating waste piles remains the dominant landfill practice in North America today.
Forces for Change
As we begin the 21st century, there are large social forces dictating future changes, and new technologies for residual waste management. To understand these forces, and the likely effect they will have on landfills over the next 20 years, we must first look at the remaining capacity of existing landfills in the US.
According to a recent Smith Barney Report, citing Chartwell data, remaining US landfill capacity as of 2003 was 21.3 years. Table 1 expresses this data on a regional basis.
Although a few new greenfield landfills are planned—and a few have recently been constructed—most industry professionals report severe and increasing public and political resistance to new landfill construction, even to major expansions of existing airspace. This finite landfill life is the first force for change in the landfill industry. Increasingly, it appears that landfill capacity within feasible transport distance is not an expandable commodity and that eventually tipping fees will rise, creating incentive for disposal volume reduction. This will take the form of increased waste reduction, recycling, conversion, and production of higher effective density at existing landfills.
Independent of rising tipping fees resulting from airspace limitations, there is a second force for change: growing public sentiment for greater reliance on other elements of the integrated waste management system.
As this graph illustrates, landfilling remains the dominant disposal method; however, its share of the total has dropped from 93.6% in 1960 to 54.3% in 2005. At the same time recycling has risen from 6.4% to 23.8% of the total and composting and waste to energy have risen from negligible to 8.4% and 13.6%, respectively.
Although these percentage levels have held almost steady over the last five years, we can expect further advances in the diversion of materials from landfills during the next 20 years due to the forces mentioned earlier. However, the actual tonnage to landfills may not decline proportionally, due to increases in population and per-capita generation rates, as has been seen over the last 45 years.
|Figure 1. Waste generation and management methods|
Landfilling is typically considered the lowest level of the waste management hierarchy. Zero-waste groups have become more vocal and politically active with their agenda of curtailing landfill disposal in favor of recycling, composting, and other waste diversion and reduction strategies. A related force discouraging high US reliance on landfilling is peer pressure from societies such as the European Union (EU), which have promulgated more stringent restrictions on landfilling than those currently embodied in US regulation. The EU landfill regulations essentially ban burial of carbon-bearing materials, and when enforced, as they now are in Germany, result in a drastically different waste stream and drastically different landfill operation scenario. Needless to say, neither bioreactor landfills (defined later) and landfill gas recovery are of interest when organic material isn’t present; nor are traditional landfill compactors required for these inert materials. Tipping fees in Germany, which range from about $200 to $300 per ton, are about 10 times higher than in the US.
Finally, the recent prominence of concern over climate change and global warming will engender increasing evaluations of the carbon emission impacts of various waste management practices. Although it is not yet clear how landfilling actually stacks up against alternatives, it is certain that public scrutiny and air pollution control requirements will further increase.
In spite of these three forces (finite disposal capacity, public sentiment to decrease landfill use, and climate change concerns), landfilling remains the cheapest disposal choice at present, and it will always be necessary to some degree.
Response to these three forces will most likely take the form of efforts to achieve the following two goals:
- Extend existing landfill service life, while expanding use of the full MSW integrated management system.
- Further reduce negative environmental impacts of landfilling.
Methods available to advance these goals are of great interest to forward thinking landfill owners.
Extending Service Life
Extension of landfill service life is accomplished in three main ways: diversion of waste away from the landfill, production of higher effective density through modified operating practices, and landfill reclamation involving material recovery. Recent EPA data indicates that American MSW, prior to recycling, is composed of the following materials:
Waste diversion—In the broadest sense, waste diversion can include strategies to reuse materials rather than discard them, recycle materials for remanufacture, compost to produce useful products, or employ other waste conversion techniques such as waste-to-energy in its various formats. Details of these strategies will be presented in other articles of this series.
Density improvement—Another promising approach to increasing the service life of landfills is to increase the effective density (defined as tons received divided by volume filled) in order to allow more tons of waste in the same permitted airspace. This is one of the primary benefits of activities that accelerate the biostabilization of organic waste in the landfill cell. A term commonly used in the US for this activity is “bioreactor landfill.”
Rapid waste mass biostabilization can be either aerobic (with oxygen) or anaerobic (without oxygen). Most US projects are anaerobic, and generally require the addition of water to optimize microbial activity. A great deal of research has been performed over the last 20 years in this area, and recent projects have reported airspace conservation of 20–30%. This technology is quite well understood at the lab scale, but is still developing with respect to field scale practice. We can expect further development is this area, especially due to the synergy of higher density and potentially shortened post closure monitoring periods.
|Figure 1. Waste generation and management methods|
The use of alternate daily cover materials, such as spray applied coatings, tarps, and approved waste products has been shown to increase the airspace utilization efficiency by 10–20% in many cases, and this is clearly a practical method to increase landfill life.
Other waste preconditioning methods include baling to pre-compact the waste and reduce litter during placement, and newer European concepts such as “mechanical biological treatment” to presort and often to precompost organics prior to landfilling of restricted residuals.
Purely physical methods to increase waste density include use of heavier compactors on traditional landfill operations, and the addition of computer-aided GPS compactor tracking and evaluation systems. These new GPS-based systems are gaining in field acceptance and according to many operators they deliver much more efficient compaction. For larger commercial landfills these methods will certainly become more predominant.
Landfill reclamation—A final and sometimes dramatic way to extend landfill life is to mine the in-place waste, then sort and separate various materials for diversion. Process steps such as screening to remove soil, composting to reduce the volume of organics, and using an electromagnet for steel recovery have been employed. Landfill mining has been performed in several locations throughout the US over the last 30 years. Some projects were simply done to move small waste dumps out of the way for construction projects, such as for the Public Works Facility in Albany, NY, in 1991. Other landfill mining and reclamation projects have been performed for the express purpose of reclaiming landfill airspace for reuse, such as the Clovis, CA, project started in 1998. In the 1980s, Robert Fahey of Collier County, FL, performed a widely publicized program to develop a sustainable landfill-mining model involving waste placement in specially constructed cells, accelerated biostabilization and subsequent mining with material recovery to reuse the cell once again. Further studies on these concepts were later funded in New York. Although the landfill reclamation concept for complete sustainable landfill operation has not yet been successful in commercial practice, the idea is still attractive to many planners and operators.
A successful full-scale landfill reclamation project was performed in Lancaster County, PA, during 1990 to 1996 involving the excavation and screening of over 300,000 cubic yards of waste. The non-soil fraction was burned in a waste-to-energy plant while the soil was saved for future landfill cover. Excellent data is available to planners on this project.
Further Reduction of Environmental Impacts
The second major landfill management goal in response to the forces for change is further reduction of negative environmental impacts associated with landfill operation. These impacts generally include air emissions (mostly landfill gas), climate change impacts, ground water impacts (related to leachate discharges), and public health and nuisance impacts (odor, litter, vectors, dust).
Since the mid-1960s when it was first recognized that refuse had the potential to generate gas, and the 1970s, when the first landfill gas collection systems were developed, government agencies began to develop guidelines and regulations to manage landfill operations and minimize negative impacts. Early regulations focused more on the nuisance aspects of landfill gas, such as odors, but it was quickly realized that the potential negative health and safety aspects of landfill gas, and its contribution to ambient pollutant levels, required rigorous performance standards based upon landfill gas collection, management, and monitoring.
Almost concurrent with the realization that refuse-generated landfill gas was rich in methane, were attempts to use this gas to generate energy. Gas-to-energy developed rapidly in the 1980s and 1990s, and quickly was recognized as a valuable renewable energy.
In the area of landfill gas, RCRA Subtitle D had specific requirements for landfill gas monitoring and control including:
- Landfill gas migration subsurface offsite
- Landfill gas migration into onsite structures
- Landfill gas odors at or beyond the landfill boundary
Subtitle D brought much needed national uniformity to landfill gas control, however, in this regulation landfill gas was still treated only as a safety hazard and a nuisance. Landfill gas first started being viewed as a pollutant in 1985 with the advent of the South Coast Air Quality District (SCAQMD) Rule 1150.1, Control of Gaseous Emissions from Municipal Solid Waste Landfills. This regulation was not only promulgated to prevent public nuisance and possible detriment to public health caused by exposure to landfill gas emissions, but was designed to control emissions of nonmethane organic compounds, which can contribute to ozone formation.
In 1988, the EPA announced the decision to regulate landfills under the authority of the Federal Clean Air Act (FCAA). The New Source Performance Standard (NSPS) for municipal solid waste (MSW) landfills (Emission Guidelines, EG, for existing landfills) was first proposed in 1991. The final rule was promulgated in March 1996.
Finally, the use of landfill gas as a valuable source of renewable energy increased significantly through the past few decades. This increase can be attributed to several factors. Developers that had the expertise to finance and build energy projects recognized that producing energy from a renewable fuel could be profitable prompting new gas-to-energy projects. Tax incentives also fueled an increase in landfill gas-to-energy projects by developers. The EPA became a major factor in promoting landfill gas-to-energy by forming the Landfill Methane Outreach Program (LMOP) to work with landfill owners to match energy projects and technologies with developers. All these efforts can once again be described as a success in confirming that landfill gas is a valuable renewable energy as the number of projects throughout the country has dramatically increased.
Climate change impacts landfills through anaerobic decomposition of organic matter, and produces methane gas, a potent greenhouse gas (GHG) that is 21 to 23 times more potent than carbon dioxide. As outlined earlier, regulations to date focused on control of criteria pollutant emissions and toxic constituents, not methane, even though control of these contaminants, indirectly controlled methane emissions. While not a major contributor to overall GHG emissions, landfills are one of the leading emitters of anthropogenic methane making them a target in efforts to reduce GHG.
Concerns over global warming have led to international efforts to address reductions in GHG emissions. Of note is the Kyoto Protocol that came into force in February 2005. The Protocol was ratified by 163 countries, but not the United States. However, individual states, perceiving more inaction than action from the federal government have moved independently to develop programs that would more formally reduce GHG emissions. The most notable regulatory activity in this area is now underway in California. It is likely that the GHG emissions reduction programs developed in California will become a model for other states and perhaps the nation.
In June 2005, California governor Arnold Schwarzenegger signed Executive Order S-3-05, which called for aggressive GHG emission reductions: 1990 levels by 2020; and 80% below 1990 levels by 2050. Other regulatory programs have also been developed to tackle GHG emissions. Most notable is the requirement that utilities include in their energy portfolios at least 20% of the energy from renewable fuels and the Low Carbon Fuel standard that will, in part, drive the use of biofuels, such as landfill gas. The governor’s goals for GHG emission reductions are being enacted through the California Global Warming Solutions Act of 2006 (AB32) with the California Air Resources Board (CARB) as the designated lead agency.
Climate Change Drives Future Regulations
Throughout the climate change regulatory process that has occurred in California, landfills have been a target of regulation, and often misinformation. This is despite the fact that after several iterations of the state, GHG emissions inventory developed by CARB, landfills are now less than 1% of the state’s GHG emissions and the industry believes this number is actually lower. This goes back to the earlier historical discussion of how landfill regulatory efforts promulgated over the past couple of decades have been extremely effective in requiring the collection and management landfill gas. Also, the same CARB inventory showed that the landfill industry actually reduced GHG emissions by about 11% from 1990 levels, the only industry in the state that can show this level of progress; once again, a testament to the success story of modern sanitary landfill. Finally, the industry has successfully argued that landfills sequester carbon, by some estimates up to 50% of the carbon that enters the landfill, making landfills carbon neutral.
Despite this positive assessment by CARB, landfills continue to be targeted for further regulation. In the California program, active and inactive landfills have been brought under AB32’s Early Action measures targeting further methane reduction. Much of this action is based upon misinformation that landfills only capture about 75% of the gas generated in a landfill with the remaining gas venting out of the landfill cover. Using this estimate, the potential would exist for additional capture of landfill gas, and thus methane reduction. However, the industry has data to the contrary that landfills capture over 90% of the gas generated, and in many cases over 95%. By earlier discussion, it is clear that the efforts to regulate landfills over the past decades have achieved most of what these newer regulations are now trying to achieve.
The landfill industry has also recently learned that the EPA will be studying the possibility of further regulations on landfills, starting with the same premise that California has started with; further methane capture is possible. With California leading the way, it is likely other states may follow the same path.
This level of regulatory focus on landfills will continue for the next decade. The landfill industry will likely face new regulations that focus on a greater level of monitoring, perhaps earlier and more extensive landfill gas collection systems and compliance triggers that impact smaller and older landfills in addition to the larger landfills that are already heavily regulated.
While landfills and landfill gas will continue to be a target for further regulation, landfill gas will continue to be a target for energy recovery because it is a valuable renewable fuel.
As electric utilities throughout the country look more and more to increase their portfolio of renewable energy, landfill gas will become a more valuable commodity. This will likely lead to more landfill gas-to-energy projects as a result of tax credits and other incentives to landfill owners and developers. Likewise, Low Carbon Fuel standards will also encourage the use of landfill gas as a biofuel in vehicles. Other financial opportunities may potentially arise through the sale of carbon or offset credits. These opportunities may continue to grow as “cap and trade” market systems are developed throughout the nation. As with the regulatory process, the landfill industry will need to be a part of the debate and growth of the market industry.
The landfill industry will also face challenges that will likely be shared equally by all industries. A recent Supreme Court decision found that the EPA has the authority under the Federal Clean Air Act to regulate carbon dioxide. It’s unclear how the EPA will move to regulate carbon dioxide, but one result can be treating carbon dioxide like other criteria pollutants (e.g., oxides of nitrogen and sulfur dioxide). Concurrent with this outcome could be the development of a carbon-dioxide national ambient air standard leading to increased permitting and compliance burdens that landfills would face at the local level. The implications here are enormous, driving industry, such as the landfill industry, into new rounds of complex regulatory activities.
This issue and all the issues described here have the real potential to consume the landfill industry for at least the next decade as this all plays out.
Groundwater impacts first became publicized in the 1970s by a leakage of chemical contaminants from the Love Canal Site in upstate New York resulting in severe impacts on nearby homeowners. As a result, regulations and subsequent engineering decisions developed over the next two decades culminating the current composite and double composite liners, which are very successful in containing contamination. Also, standards are in place regarding the hydrogeological setting for landfills, which provide further protection. Over the next 20 years, technical evolution in materials will continue, but the groundwater protection standard is quite high now in the US for lined landfills, so the only major changes are likely to be that expansions to new areas in old landfills will have to meet these stringent liner standards.
Other public health and nuisance impacts such as odor, litter, vectors, and dust will require continued focus to improve standards and performance of measures such as improved alternate daily covers to control these problems at the working face and additional manpower and resources directed toward litter pickup, road wetting for dust control, and use of odor neutralizers.
A new concept to address many working face problems, and allow for increased recycling and pretreatment of waste, involves construction of a landfill waste receiving building. Collection trucks dump all MSW in a large enclosed building similar to a MRF or transfer station.
Recyclable materials are pulled from the waste, such as ferrous metal by electromagnets, bulk cardboard with grapples, etc., and then the waste is preconditioned by crushing on the floor with a vehicle with transfer station wheels.
The residual waste is then transported to a much smaller, more controlled working face to minimize open area, blowing litter, and cover requirements. In this scenario, the entire placement operation is much more controlled and less random than the current traditional method of open dumping at the working face, thus allowing for greater reduction of nuisance impacts.
Landfilling is currently the most common MSW disposal method in the US where landfills receive about 54% of all MSW. Existing landfills have a combined total of about 20 years of capacity at present generation rates. Various forces are driving the goals of seeking alternatives to landfill, while extending the service life of existing facilities.
The forces to reduce environmental impacts from landfills are greater than ever, and new regulatory programs, such as GHG emission controls, are redefining how landfills are being regulated. Renewable energies, such as landfill gas and waste-to-energy, have increased in interest.
Numerous technologies exist and are being developed to achieve the goals of landfill life extension and impact reduction. As a more robust integrated solid waste management system is being developed across the country, successful landfill operators of the future will increasingly use these methods
By Bob Wallace, Principal and Vice President of Client Solutions, WIH Resource Group, Inc. (WIH) and Waste Savings, Inc. (WSI), former Boardmember SWANA ~ State of Arizona Chapter (Solid Waste Association of North America), APWA (American Public Works) ~ National Solid Waste Rate Setting Advisory Committee and Member of WASTEC (Waste Equipment Technology Association) NSWMA ~ Phoenix, Arizona USA. (firstname.lastname@example.org).
Source: MSW Management Magazine (Reprint) & WIH Resource Group
Should you have any questions about this news or general questions about our diversified services, please contact Bob Wallace, Principal & VP of Client Solutions at WIH Resource Group and Waste Savings, Inc. at email@example.com
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