constructed wetland

[Jacky Foo]

Source: http://www.iobbnet.org/drupal/node/view/970/3270#comment-3270
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constructed wetland
Submitted by Jacky Foo on Wed, 11/07/2007 - 05:42.

Liaqat Hayat wrote:
>After this e-workshop, I intend to construct a suitable CWL
>with local materials. The site is clay and sand mixed type
>and hence I feel that excavated surface has to be given a mud
>plaster membrane to avoid seepage to the underground.

Dear Liaqat

Q: Do you intend to have a canal-CWL system or a pond-CWL system ?

Q: How wide and deep do you intend to build your CWL canals or pond(s) ?

In Western Samoa (and earlier - 40 years ago - in Bangkok), there is/was a natural system where people would dig a trench or drain (at least 1 m wide) along the road between their houses and the road (or in the process of building roads, trenches were created as soil was needed to make the foundation of the roads). These trenches fill up with water due to frequent rains. Wash water from the houses (and all other liquid wastewater) would also flow into these trenches. Because of dilution from rainfall, these trenches become basically CWLs. Plants grow at the edges and float on the waters. There is always fishes that eat up the mosquito larvae.

These "sustainable systems" are lost now due to space limitations and as paper and plastic scraps are blown into them and accumulate in such trenches, people avoid building them. Also in some countries you are not allowed to have stagnant water (mosquito control strategy). Actually the "modern" concrete underground and covered drain systems are more hazardous as they are breeding grounds for mosquitoes, cockroaches and rats.

Liaqat:
If a narrow strip of land is available (e.g. along a road), then a long canal would be your option. You will not be able to maintain a mud plaster bottom since you need to grow plants in them. If you are in a residential area (with no farming activities), then beautification with flowering plants is essential.

..... more comments when we have more information on the landscape of your site.

regards
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Jacky Foo
http://www.iobbnet.org


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