Aging Landfills - An Ongoing Environmental Issue

by Curt Kerns, M.S., R.P.Bio., C.F.S                

An issue common for many communities across North America is an aging landfill, located on a site that may not be selected today due to its hydrogeology. Ground and surface water too often finds its way into the solid wastes dissolving a veritable devil’s brew of contaminants. A water sample taken today speaks not to what may be in the leachate tomorrow, or next year, or 20 years from now. Identifying new landfill sites is often a very lengthy exercise as first it must be geologically suitable, and not have neighbors close by. While we all generate solid wastes, few of us want a landfill located near us. When a new site is located, the former landfill must be closed in according to strict environmental regulations in a manner that does not cause it to be a source of contamination for decades to come. The community must bear the costs with the landfill no longer generating tipping fees for decades to come. 

3  .. Landfill leachate is a complex and ever-changing wastewater stream. It can be comprised of some of the most ecologically troublesome substances known, such as heavy metals, petroleum products, pesticides, herbicides, household, commercial, and industrial wastes that contain virtually any chemical used in modern life. And leachate can leak from landfills for many decades. Consequently physio-mechanical treatment is very expensive and, relatively speaking, very energy intensive. Fortunately there is an excellent solution to treating landfill leachate that is well proven over much of the world - free water surface constructed wetlands.
Knockholt Land Fill Constructed Wetland, located near Huston, BC    

Wetlands have an unparalleled ability to remove virtually any contaminant found in leachate. They are essentially a series of shallow ponds powered by sunlight. They are a largely passive biotechnology that employs biomimicry, that is they duplicate the many treatment and removal pathways found in natural wetlands to remove virtually all inimical substances even persistent organic pollutants such as DDT. They produce water that is biochemically indistinguishable from that emanating from a natural wetland.

This eco-technology is often an ideal choice for communities on a budget as the potential for long-term sustainability and significant cost savings are inherent. Initial capital costs are usually less, and operational costs are often a small fraction of physio-mechanical treatment. Once established, free water surface constructed wetlands can operate passively for many decades. Their functional life span can exceed a century. Constructed wetlands are an excellent choice especially for communities with a limited tax base.

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“The significant problems we face cannot be solved at the same level of thinking we were at when we created them.” Albert Einstein

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