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Containment is a way commonly used at toxic waste storage sites and also at many municipal waste sites to prevent the further spread of toxic chemicals. Essentially, a barrier is put under or around an area where poisonous materials are found. At municipal waste sites (what we would call a dump), a hole is dug in the ground. Often clay, which allows very little water movement through it, is laid down in the hole, and then compacted to make the holes between the clay particles even smaller. Typically, several layers of thick ply plastic tarp are laid down on top of this clay layer, and then another layer of clay is placed atop the plastic tarp to protect it from machinery.

In an area where the aquifer is polluted, the best way to prevent spread of the toxic liquid is to first dig a ditch around the perimeter of the spill, digging down to bedrock (aquitard). It's vital that the bedrock layer isn't too deep, or this isn't economically feasable. After the ditch is laid, various materials are deposited in the ditch which will hopefully retard the movement of pollution out of the area. Such materials are concrete (only useful in small areas), thick plastic tarps, or compacted clay.

In addition, a thick layer of clay, and perhaps plastic tarps are placed over the surface of the ground, so that the poison can't move out of the ground into surface waters or into the air.

Cost: about $11 million/ or about $210 extra per year on the tax bill over a period of 10 years.


1. Relatively inexpensive.

2. Buildings may not need to be dug up and removed if the toxic chemicals are deep underground.

2. Prevents spread of the pollution.

3. This method is quick.

4. This method has been used effectively at municipal waste areas.

5. Little danger to public during the digging and placing of containing materials.


1. Must monitor water for years. Some of the toxic chemicals may leak!

2. Worker safety during installation may be an issue (if the ditch is deep---possible cave ins).

3. If the clay is not compacted correctly, or a rip in plastic tarps develops, the toxic chemical may leak.

4. The pollution hasn't been moved. If public records are lost over the years, people may build over the polluted site and later become poisoned (Research "Love Canal").


Erosion is nibbling away at St Johns Landfill

Love Canal Collection: A town in New York state built on a "contained" toxic waste site.

Online Ethics Center: Love Canal

Love Canal Today

Information about containing toxic waste

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Paul Slichter