Constructed Wetlands as Wildlife Habitats
Constructed wetlands are typically built to achieve a balance between high effluent quality while limiting the land-take in the project. Generally, the bigger the wetland the cleaner the effluent - so although taking up all of the site would give best water quality results, it isn't usually practical approach.
However for some projects, considerable over-sizing can yield beneficial results in terms of both water quality and habitat enhancement or creation. This can be particularly effective where there is a large site size, exceptional water quality requirements and/or an impermeable clay subsoil.
It is not advisable to use existing wetland habitats for sewage treatment, but where a new sewage treatment wetland can double as a new wetland habitat, so much the better. This approach is to some extent dealt with in the 2010 Department of the Environment's Integrated Constructed Wetlands Guidance Document, however for best results, really focus in on the habitat enhancement aspect of the project and achieve a mix of water purification, wildlife benefit and amenity value.
This can be done for the effluent treatment wetland, the stormwater control wetland and to improve natural streams and drains on the site.
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