Disposal of Municipal Solid Wastes: Can the current convenience of landfills be worth it in the long run?
In 1996, New Source Performance Standards and Emission Guidelines required landfills, which produce more than 2.5 million tons of wastes, to control landfill gas and collect it. However, some landfills, such as Freshkills Park in Staten Island, flair the collected methane if it is not needed. Other smaller landfills do not capture the methane at all. What is a little flaring going to do to the environment every once in a while? Much more than what we anticipate. According to Dr. Arlene Fiore, Ocean and Climate Physics Scientist, “gases like methane are long-lived, which means that the amount in the atmosphere is determined by the cumulative sum of many emission sources. So I do think ‘every little bit counts’.”
Production and control of landfill gases is influenced by a number of factors such as moisture, temperature, and enzymes. Additionally, managing these gases does not simply mean implementing an engineered system in a landfill, there are actually a set of requirements that need be met in order for that process to take place.
In Landfill gas: Asset or liability? (1987), E. R. Bogardaus studied the economics of gas production and summarized the requirements that determine the feasibility for a landfill to have this system. These include a minimum of one million tons of refuse in place, an average depth of twelve meters, an active fill area of about sixteen hectares (approximately thirty football fields [thirty-nine acers]), a receipt rate during the sites operational life of about 365 tons per day, and finally guarantee that there are nearby willing users of the gas.
According to Croke and Zimmerman, “newer landfills will expectedly be much larger and then therefore more amenable to economically feasible gas production”. Since smaller landfills are not able to fulfill the requirements, the gas produced would is released on to the environment. However, these requirements promote larger landfills, which would exacerbate the harms of landfills.
Landfill gases are rich in methane and carbon dioxide. Methane is particularly dangerous due to flammability and tendency to migrate and its ability to form explosive mixtures with air. Methane is also capable of moving horizontally and vertically making it easily diffused. Therefore constructing a building above landfills put the occupants of the building or even residents adjacent to the landfill’s health in risk. The possibility of explosions is also a risk since explosions can take place with percentages of methane as low as 5 percent.
Methane contributes to global warming because it has twenty to twenty-five times the effect of carbon dioxide. Methane also persists longer in the atmosphere, making it much more effective at trapping infrared radiation. According to Church and Shepard, in Gas Engineering and Management (1989), around eighteen percent of total global warming is contributed by methane. As a result of the continuous increase in population and urbanization, landfills have become a major contributor to atmospheric methane. Dr. Fiore noted, “when methane is chemically destroyed in the atmosphere, can lead to production of smog (in surface air) and greenhouse gas (in the upper troposphere).”
In addition to Methane and Carbon dioxide, potentially, volatile organic compounds (VOCs) can be emitted as well. VOCs are made of organic chemicals that have a high vapor pressure at ordinary room temperature, at high concentrations VOCs can be extremely toxic. According to T.T. Shen, the exposure of VOCs increases the risk of cancer in local communities and contributes to ambient ozone formation. They are also capable of inhibit the making of methane and corrode the gas recovery equipment.
Since a number of landfills are converted into developments such as parks and golf courses, vegetation damage of the site is often a concern. The displacement of oxygen by landfills gases resulting in oxygen deficiency in the root zone. It is particularly the methane oxidation that takes place near the surface by the methane-consuming bacteria, which contributed to the oxygen difference. The heat and carbon dioxide release during the methane oxidation also affects the growth of plants.
Landfills contribute to the accumulation of greenhouse gases in the atmosphere. According to the U.S. Department of Energy, the Intergovernmental Panel on Climate Change estimates around 20 million metric ton to 70 million metric ton of methane to be emitted annually by the anaerobic decomposition of organic matter taking place at landfills worldwide. That is approximately 6 percent of the estimated global annual methane emissions. Developing countries in particular contribute a little to global methane emissions, however that could be even less if more sanitary landfill practices were implemented.
Over the years, solutions for certain environmental problems associated with landfills led to the rise of other issues. In order to avoid surface water contamination, landfills were sited away from surface waters in the 1960s. Groundwater contamination in the early 1970, led to landfills to be located in area with low waster tables and tight soil. Experts then realized that these changes led to leachate to accumulate within landfills and leak into surrounding areas; mandating leachate collection and treatment systems. As an alternative to these costly systems, landfills operators tired to limit the entry of water into landfills by using membrane caps. However this prevented the venting of methane, leading to the possibility of an explosion. By 1980 methane was collected for flaring or use, yet there was a need for constant monitoring, even after landfills is closed, as completely excluding water from landfills were near to impossible.
Landfills might be easy, fast and convenient, however it requires more effort and more money in the long run. Currently, siting has also been an issue for new landfills due to local resistance, resulting in municipal solid wastes to be hauled farther out, which further increases the costs. Dr. Peter Bower, former mayor of Teaneck, New Jersey, response to our actions is that “we took some usable land, that could be used for farming for used to be as a forest and you have simply destroyed it. Laid it a waste and filled it with garbage. So you take into account that value of productive land that you have destroyed.”
Do you think it’s worth it?
