MSW (Subtitle D) Landfills

What is a municipal solid waste landfill?

A modern, Subtitle D landfill is a scientifically engineered structure built into or on the ground that is designed to isolate waste from the environment. Landfills operate in accordance with EPA’s Subtitle D regulations. Waste is isolated by a liner that is placed on the bottom of the landfill to collect and remove any water that might pass through the waste and by a cover system over the waste to control water infiltration. In addition, gas collection systems are installed to collect any gas generated by the decomposition of the waste and groundwater-monitoring wells are installed around the landfill to monitor the performance of the liner systems.

How many Subtitle D landfills are operating in America?

In the early 1970s, about 20,000 landfills, most of which were actually unlined dumps, were being used. Today, as a result of the regulations imposed by the Resource Conservation and Recovery Act, the dumps are closed and about 1654 Subtitle D landfills are operating in the 48 contiguous states. Figure 4 shows the decline in the number of MSW landfills over time.

Who owns these landfills?

According to a report by the Environmental Research and Education Foundation, the public sector owns two-thirds of U.S. landfills and the private sector owns one-third.

How much garbage is landfilled?

Landfilling is the most common way to handle our garbage. Of the 250 million tons of municipal solid waste (MSW) generated in 2008, 135.1 million tons (54.4%) were landfilled.

Are we running out of landfill disposal capacity?

No. On a national level, the United States has 20 years of disposal capacity. However, on a state level, Alaska, Connecticut, Delaware, North Carolina, New Hampshire, and Rhode Island have less than five years of available capacity. The Western and Pacific states have the greatest capacity while the Northeast states have the least capacity.

How much waste can be put in a landfill?

A landfill’s design capacity is measured in volume (cubic yards), not in tons, because landfills fill up by volume, not by weight. When it is placed in a landfill, solid waste has a density of 1,200 to 1,400 pounds per cubic yard. After the waste has settled and degraded, the waste can have a density of 1,700 to 1,900 pounds per cubic yard.

Where is America’s largest landfill?

The largest operational landfills in the U.S. (by tonnage, according to Waste & Recycing News, as of November 2010) were the Apex Regional Landfill (receiving 3,199,653 tons in 2008) in Las Vegas, Nevada, and the Puente Hills Landfill (receiving 3,149,906 tons in 2008) in Whittier, California. However, if the criteria is remaining capacity for garbage, the Pontiac Landfill in Pontiac, Illinois, is largest with a remaining capacity of almost 233 million tons. For decades, America's largest landfill had been the Fresh Kills Landfill in New York City. It was closed in 2002. The New York City Department of Parks and Recreation currently is converting that former landfill into one of the the nation's largest city parks. And although some people believe the old Fresh Kills landfill was large enough to be seen from outer space, it was far too small to be seen from that far away.

How much does it cost to landfill a ton of garbage?

The average landfill tip fee in 2004 was $34.29 per ton. A “tip fee” is the price paid, usually on a per ton basis, to dispose of trash at a landfill. The “average” tip fee is the “gate rate” for a ton of garbage. A gate rate is similar to the published prices for airline tickets or hotels, before discounts or contract prices (which could be higher or lower) are considered. The gate rate is the true daily market value of the tip fee. The average tipping fee in the United States has risen consistently since 1985 when it was $8.20 per ton. In 2004, the Northeast (CT, ME, MA, NH, NY, RI, and VT) had the highest tipping fees at $70.53 per ton, while the South Central (AZ, AR, LA, NM, OK, and TX) and West Central (CO, KS, MT, NE, ND, SD, UT, and WY) states had the lowest tipping fees at $24.06 and $24.13 per ton, respectively.

Which costs more, landfilling or combustion?

Average tipping fees are lower at landfills than at combustion facilities, largely because of the high capital costs at those facilities. In 1982, the average landfill tip fee was $8.02 per ton while the average combustion tip fee was $12.91 per ton. In 2004, the average landfill tip fee had risen to $34.29 per ton while the average combustion tip fee rose to $61.64 per ton.

Are landfills a safe way to dispose of trash?

Yes. Modern landfills are well-engineered facilities subject to strict federal and state regulations for location, design, operating conditions, monitoring, closure, post-closure care, clean-up (if necessary) and financial assurance. These regulations were established to protect human health and the environment. The federal regulations were mandated by the Resource Conservation and Recovery Act and are called the Subtitle D standards. They contain:

• Location restrictions that restrict the placement of landfills in unstable geological areas (near faults or seismic zones), in wetlands or floodplains, or near airports;
  
  
• Liner requirements that can include clay, geotextiles, and/or plastics on the bottom and sides of the landfill to prevent liquids from leaving the landfill and impacting groundwater resources;
  
  
• Leachate collection systems that collect and remove water (rainwater or liquids contained in the waste) draining out of the waste (typically referred to as leachate);
  
  
• Operating practices that require covering the waste daily, controlling explosive gases, restricting access, excluding hazardous wastes and liquids, and controlling surface water;
  
  
• Groundwater monitoring standards that require groundwater well testing to ensure that leachate and gas has not escaped the landfill;
  
  
• Corrective action requirements to ensure that if something escapes the landfill and migrates to the groundwater the problem is corrected and cleaned up;
  
  
• Closure and post-closure care requirements that ensure the landfill is properly covered at the end of its useful life and the landfill is monitored and cared for after closure; and
  
  
• Financial assurance requirements that ensure monies are available to properly close and care for the landfill after closure.

States can impose additional requirements that exceed the federal requirements or contain additional features that ensure protection of human health and the environment.

Do landfills cause air pollution?

Not if properly managed. The organic portion of municipal solid waste will biodegrade over time when placed in a landfill because of naturally occurring microorganisms. Biodegradation initially proceeds under aerobic conditions (with oxygen) and produces carbon dioxide (CO2) and water (H2O). After the oxygen is completely used, the biodegradation process continues under anaerobic conditions (without oxygen), which produce methane (CH4) and CO2 in about equal proportions. During biodegradation, small quantities (less than one percent) of organic gases are produced or released from the waste. Because methane and trace organic gases can affect human heath and the environment, landfills install gas collection systems to extract the gases from the landfill and combust them with a 98 percent destruction efficiency. The energy from combustion can be used as an alternative energy source. The installation of gas collection systems and the destruction of these gases are regulated by federal rules under the Clean Air Act as well as state requirements.

Do landfills smell?

Decaying trash produces an odor that is offensive to some people. The smell associated with MSW can start prior to collection and can continue at the landfill during disposal and after burial. At the landfill, these odors can be minimized and controlled through a number of methods such as covering the waste every day, minimizing the working face (the area were the waste is actively deposited) of the landfill, installing and operating a gas collection system, and masking the smell with deodorizers. These methods will minimize and control the odor of the landfill.

Managing Solid Waste Facilities to Prevent Odors is an NSWMA research paper on odors management.

What is a bioreactor landfill?

A bioreactor landfill promotes the rapid decomposition of the organic portions of trash by maintaining optimal moisture conditions for the decomposing bacteria at or near field capacity (35 to 65 percent). Leachate is injected into the landfill as are other liquids, if necessary. The liquids are added to the landfill through vertical wells, horizontal pipes, or trenches. The primary purpose of a bioreactor is to accelerate decomposition so that the post–closure care period can be shortened to less than 10 years.

Can a landfill be used after it is closed?

Yes. Closed landfills and their buffer areas can be converted into recreational facilities (golf courses, ski resorts, parks, ball fields); building sites for commercial, industrial, and residential development; and nature and forest preserves. Most landfills have a post-closure plan that includes a strategy for final use of the property after closure.

Modern Landfills - A Far Cry from the Past is an NSWMA White Paper that examines the many techonological changes that have made landfills even more protective of the environment.