by: Leslie Jones
A landfill is a large area of land or an excavated site that is specifically designed and built to receive wastes. The volume of waste consumers and businesses throw out increases when the economy is doing well. When the economy is stagnant, volume decreases. Garbage volumes rose sharply in 2013 indicating that the economy is improving.
In the past, garbage was collected in open dumps. These uncovered and unlined sites allowed leachate , a liquid formed by decomposing waste, to soak into the soil and groundwater. As referenced in the previous article Open Dumps...A Thing of the Past Landfills vs Open Dumps, part 1, Open dumps also attracted rodents and insects, emitted odors, and created fire hazards. Most of these small and unsanitary dumps have been replaced by large, modern facilities that are designed, operated, and monitored according to strict federal and state regulations. Today’s landfills eliminate the harmful and undesirable characteristics of dumps to help protect public health and the environment. Their larger size is necessary to accommodate the increasing amounts of Municipal Solid Waste (MSW).
Federal landfill regulations have eliminated the open dumps of the past. Today’s modern landfills must meet stringent design, operation, and closure requirements. A typical modern landfill is lined with a layer of clay and protective plastic to prevent the waste and leachate from leaking into the ground or groundwater. The lined unit is then divided into disposal cells. Only one cell is open at a time to receive waste. After a day’s activity, the garbage is compacted and covered with a layer of soil to minimize odor, pests, and wind disturbances. A network of drains at the bottom of the landfill collects the leachate that flows through the decomposing waste. The leachate is sent to a leachate recovery facility to be treated. Methane gas, carbon dioxide, and other gases produced by the decomposing waste are monitored and collected to reduce their effects on air quality.
Landfills are regulated by both federal and state laws. The federal laws dictate where landfills can be located, such as away from unstable land prone to earthquakes or flooding, and require them to be lined and have a leachate collection system. In addition, landfill owners must monitor and collect explosive gases, regularly test nearby groundwater, and compact and cover waste with a layer of soil on a daily basis.
State guidelines may be even a little more stringent. Many states require landfill operators to obtain a license and present a plan for how the site will be safely closed, or capped, even though the closing date might be estimated at 50 years in the future.
Once a landfill is capped, the operator must monitor the site for gas and leachate for a minimum of 30 years after the closing date. A landfill that has been capped, may later be used for recreation sites such as parks, golf courses, and ski slopes. Some housing developments or commercial businesses have also been built on former landfill sites.
Methane gas, a byproduct of decomposing waste, can be collected and used as fuel to generate electricity. This energy is commonly used to power the landfill itself, or sold to local utility companies or companies. This process allows landfills to reduce their dependence on fossil fuels and save money and, therefore, pass fewer costs on to the consumer.
New trends evolving in the landfill industry include landfill reclamation and ways to speed the rate of decomposition. Landfill reclamation is where old cells are excavated to recover recyclable items. This process, in which recovered recyclables, soil, and waste can be sold, reused, or burned as fuel, is a new approach used to expand landfill capacity and avoid the cost of acquiring additional land.
One strategy to speed the rate of decomposition of landfill waste is to recirculate the collected
leachate by pouring it over the cells and allowing it to filter through the rotting garbage. Since modern landfills are almost too efficient, if left to decompose naturally, the process would take considerably longer.
Increased waste generation requires landfill operators and managers to constantly evaluate
and improve current disposal methods. For more information on waste disposal and recycling methods, visit us at www.wasteawaygroup.com.