LANDFILLSSolid waste is the term that civil engineers use to refer to what most of us call garbage.
Municipal solid waste is most familiar to us. It comes from households, institutions, and small businesess. These solid wastes enter the solid-waste stream, and the flow never ceases. While many normal activities are suspended during weekends and holidays, the flow of garbage is non-stop.
Some holidays, such as Christmas, create an enormous wave of solid waste.There are essentially four ways to deal with garbage: 1) recycle it into something that can be used again, 2) dump it, 3) burn it, or 4) reduce the source of material products (such as packaging) in order to eliminate future garbage.Throughout history, dumping has been the preferred means of disposal. Today, landfills are Americas primary method for the disposal of garbage.Approximately 40 to 50 percent of everything we throw away is paper.
Newspapers account for as much as 18 percent of the volume in a landfill. Grass clippings and raked-up leaves account for nearly 20 percent of our waste.Much of the notion that biodegradation takes place within a landfill is a myth. Some food and yard debris degrade at a very slow rate, but the remainder of the garbage in landfills seems to retain its original form, weight, and volume. Even after being buried in a landfill for several years, the print on newspapers remains legible.Landfills also contain a considerable amount of hazardous waste. Today, pesticides, cleansers, and motor oil are commonly found in most households. Many of these find their way to the trash.
Therefore, landfills must be designed for the safe disposal of hazardous household waste.Currently, there is a critical shortage of landfills, expecially in the northeastern United States. It is estimated that 40 percent of the landfills now in use will close down within five years. The reason the percentage is so high is that most landfills are designed to be in use for only about ten years.Many landfills now closing are open dumps. Rain and groundwater trickle through the trash and dissolve metals and other chemicals. This toxic liquid, called leachate, can ooze into the ground and contaminate nearby wells and streams.
In sanitary landfills, daily deposits of fresh garbage are covered with a layer of dirt or plastic or both. However, sanitary landfills can still exude leachate into the water table. In new sanitary landfills, the basin is often lined with clays and impermeable plastic sheets to keep the leachate in.While so many of the countrys landfills are closing down in the next several years, solid-waste engineers face tremendous challenges to properly seal, salvage, and monitor some of the nations most contaminated dumps.
The use of sanitary landfills presents several additional challenges beyond safety and efficiency. One major problem is cost. It is often necessary to transport garbage several hundred miles to an available landfill. The cost for transporting garbage to a landfill can be excessive.An even bigger problem is location. Even if the landfill does not leak pollutants or foul the air, no one wants a landfill for a neighbor.
Consequently, the old landfills are not being replaced.Due to the critical shortage of landfills and the concerns about their safety, environmental consciousness has been raised. There is a growing awareness of the need to improve the environment and become less dependent on landfills.
We must finds ways to reduce waste, and we must find ways to convert waste into something that can be used again.Source reduction offers a real and lasting contribution toward solving our nations solid waste problem and conserving landfill space. Talk to your legislators, both federal and state, about this genuine method of reducing the volume of garbage.