Thursday, July 14, 2011

Landfills a History

Historically trash had just been “tossed” out of our living areas. In cities trash and human waste was simply thrown into the streets or outside the gates. As cities became more populated and disease spread mankind came to the realization that throwing waste into the streets was contributing to the spread of devastating disease outbreaks and making cities centers of filth and disease. Bubonic Plague, Cholera, and Typhoid fever were just a few of the diseases spread by filth that harbored rats, and contaminated water supplies. It was not uncommon for European city dwellers to throw their trash and human wastes out of the window to decompose in the street. During the 1800’s the connection between disease, sewage, trash and filth was discovered. Though there was tremendous resistance most famously in France, by the late 1800’s cities created garbage collection and disposal systems using horse-drawn carts to collect garbage and dispose of it in open dumps, incinerators, or at sea. In New York City in 1916 the garbage collection took in 4.6 pounds of garbage per person per day.

During the first half of the 20th century when garbage was routinely collected incineration was a common method of disposal. Many apartment buildings were constructed with garbage incinerators in the basements and trash shoot systems. In the 1920’s it was common for garbage, incinerator ash, and dirt to be used to fill in swamps near cities which allowed the contamination of groundwater. The precursor to the modern landfill was first tried in California in 1935. Trash was thrown into a hole in the ground that was periodically covered with dirt. In 1959 the American Society of Civil Engineers first published guidelines for a “sanitary landfill” that suggested compacting waste and covering it with a layer of soil each day to reduce odors and control rodents. Even at this point landfills were designed by excavating a hole or trench, filling the excavation with trash, and covering the trash with soil. In most instances, the waste was placed directly on the underlying soils without a barrier or containment layer (liner) that prevented water percolating through the waste and picking up contaminants know as leachate from moving out of the landfill and contaminating groundwater.

The first federal legislation addressing trash or more properly solid waste management was the Solid Waste Disposal Act of 1965 (SWDA) that created a national office of solid waste. In 1976, the Resource Conservation and Recovery Act (RCRA) expanded the federal government’s role in managing waste disposal. RCRA divided wastes into hazardous and solid waste categories, and began the process of developing standards for sanitary landfills and closing or upgrading existing dumps to meet the sanitary landfill standards. (The Office of Solid Waste was transferred to the US EPA in 1974. I met my husband when the Office of Hazardous Waste was combined with the Office of Solid Waste where I worked in shortly thereafter.)

In 1979, EPA developed the first set of criteria for sanitary landfills that included standards for locating new landfills and operational standards for existing landfills to reduce disease vectors and increase protection of surface and groundwater. RCRA was amended in 1984 to require EPA to assess and revise the sanitary landfill requirements. Finally, in 1991, EPA established new federal standards for municipal solid waste (MSW) landfills that updated location and operation standards and added design standards, groundwater monitoring requirements, corrective action requirements for known environmental releases, closure and post-closure care requirements, and financial assurance requirements to ensure that there would always be adequate funding to maintain closed landfills. During my environmental career, landfills changed from little more than holes in the ground to highly engineered, state-of the-art containment systems requiring large capital expenditures.

Modern landfills are specifically designed to protect human health and the environment by controlling water and air emissions. Modern landfills are built as a series of cells. The cells include liners of plastic membranes and watertight clay on the bottom and the leachate collection systems to prevent groundwater contamination. Liners prevent leachate and methane and CO2 gas migration out of the landfill while directing liquids to the leachate collection system. Liner systems are typically constructed with layers of low permeability, natural materials (compacted clay) and/or synthetic materials (high-density polyethylene). The leachate collection system removes the liquid contained in the liner. A typical leachate collection system may consist of (from bottom to top) a perforated leachate collection pipe placed in a drainage layer (gravel). The leachate is collected, filtered, typically tested and sent on to waste water treatment either on or off site. At the end of each day, the waste is covered with six inches of soil or an alternative daily cover (foam, tarps, ground tires, incinerator ash, compost) to control the spread of disease through birds and rodents, odors, fires, and blowing litter.

Virginia has roughly 60 solid waste landfills still in operation there are closed landfills required to be monitored and maintained according to regulation. There are 134 counties and cities in Virginia, so solid waste management has become a regional operation. In 1993, the General Assembly mandated in a law known as "HB 1205" that existing landfills that did not meet the new regulations must be closed and could not maintain their grandfathered status. Old landfills would be permitted to continue accepting waste until their existing facilities were filled, but no horizontal expansion of old landfills would be permitted and the older landfills must then be caped and monitored. All new cells, at old or new landfills, would have to meet stricter requirements for liners, clay caps, leachate collection systems, gas release/collection systems, and monitoring. Older landfills would have to be stabilized to prevent contamination of groundwater.

1 comment:

  1. Drinking contaminated groundwater can have serious health effects. Diseases such as hepatitis and dysentery may be caused by contamination from septic tank waste.
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