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Line 70: − |- − |style="text-align:left;"|'''Cons''' − *Requires larger land area − *Sludge removal may be more difficult − *Open water may generate more health and safety concerns. − |} − *Sub surface flow systems provide generally lower health and safety risks and are sometimes employed to handle stormwater in combination with another wastewater stream. In horizontal sub-surface flow wetlands, water flows horizontally through a media bed, while in vertical sub-surface flow wetlands, water is introduced at the surface and percolates vertically through the media. − − {|class="wikitable" − |- − !Horizontal sub-surface flow − !Vertical sub-surface flow − |- − |[[File:Tilley et al 2014 Schematic of the Horizontal Subsurface Flow Constructed Wetland.jpg|frameless|upright=1.5]] − |[[File:Tilley et al 2014 Schematic of the Vertical Flow Constructed Wetland.jpg|frameless|upright=1.5]] − |- Line 98:
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→Planning considerations
Constructed wetlands differ based on how water travels through the system<ref>Grant, N., M. Moodie, and C. Weedon. 2000. Sewage Treatment Solutions. p. 35–67. In Sewage Solutions: Answering the Call of Nature. Centre for Alternative Technology Publications.</ref><ref name="EPA">United States Environmental Protection Agency. 1995. A handbook of constructed wetlands: A guide to creating wetlands for agricultural wastewater, domestic wastewater, coal mine drainage and stormwater.</ref><ref name="JW">Jacques Whitford Consultants, 2008. Constructed and engineered wetlands. p. 1-21</ref>:
Constructed wetlands differ based on how water travels through the system<ref>Grant, N., M. Moodie, and C. Weedon. 2000. Sewage Treatment Solutions. p. 35–67. In Sewage Solutions: Answering the Call of Nature. Centre for Alternative Technology Publications.</ref><ref name="EPA">United States Environmental Protection Agency. 1995. A handbook of constructed wetlands: A guide to creating wetlands for agricultural wastewater, domestic wastewater, coal mine drainage and stormwater.</ref><ref name="JW">Jacques Whitford Consultants, 2008. Constructed and engineered wetlands. p. 1-21</ref>:
*Free-water surface flow wetlands have water exposed on the surface, which provides excellent water quality treatment but may pose health and safety risks. Free-water surface flow wetlands are most commonly employed for stormwater treatment and are similar to [[SWM ponds]] in function and design. However, ponds and wetlands differ by the extent to which shallow zones for wetland [[plants]] are incorporated. A facility is normally characterized as a wet pond if shallow zones (<0.5 m deep) comprise less than 20% of its surface area, while a facility is normally characterized as a wetland if shallow zones (<0.5 m deep) make up more than 70 % of its volume. Unlike SWM ponds and constructed wetlands, [[Dry ponds|dry ponds]] are designed to temporarily store stormwater runoff and completely drain out between storm events and focus more on flood attenuation than treatment.
*Free-water surface flow wetlands have water exposed on the surface, which provides excellent water quality treatment but may pose health and safety risks. Free-water surface flow wetlands are most commonly employed for stormwater treatment and are similar to [[SWM ponds]] in function and design. However, ponds and wetlands differ by the extent to which shallow zones for wetland [[plants]] are incorporated. A facility is normally characterized as a wet pond if shallow zones (<0.5 m deep) comprise less than 20% of its surface area, while a facility is normally characterized as a wetland if shallow zones (<0.5 m deep) make up more than 70 % of its volume. Unlike SWM ponds and constructed wetlands, [[Dry ponds|dry ponds]] are designed to temporarily store stormwater runoff and completely drain out between storm events and focus more on flood attenuation than treatment.
*Sub surface flow systems provide generally lower health and safety risks and are sometimes employed to handle stormwater in combination with another wastewater stream. In horizontal sub-surface flow wetlands, water flows horizontally through a media bed, while in vertical sub-surface flow wetlands, water is introduced at the surface and percolates vertically through the media.
{|class="wikitable"
{|class="wikitable"
|+ Types of Constructed Wetland<ref>Grant, N., M. Moodie, and C. Weedon. 2000. Sewage Treatment Solutions. p. 35–67. In Sewage Solutions: Answering the Call of Nature. Centre for Alternative Technology Publications.</ref><ref name="EPA">United States Environmental Protection Agency. 1995. A handbook of constructed wetlands: A guide to creating wetlands for agricultural wastewater, domestic wastewater, coal mine drainage and stormwater.</ref><ref name="JW">Jacques Whitford Consultants, 2008. Constructed and engineered wetlands. p. 1-21</ref>
|-
|-
!Free-water surface flow
!Free-water surface flow
!Horizontal sub-surface flow
!Vertical sub-surface flow
|-
|-
|[[File:Schematic of the Free Water Surface Constructed Wetland.jpg|frameless|upright=1.5]]
|[[File:Schematic of the Free Water Surface Constructed Wetland.jpg|frameless|upright=1.5]]
|[[File:Tilley et al 2014 Schematic of the Horizontal Subsurface Flow Constructed Wetland.jpg|frameless|upright=1.5]]
|[[File:Tilley et al 2014 Schematic of the Vertical Flow Constructed Wetland.jpg|frameless|upright=1.5]]
|-
|-
|style="text-align:left;"|'''Pros'''
|style="text-align:left;"|'''Pros'''
*Can be beautiful
*Can be beautiful
*Sludge removal infrequent
*Sludge removal infrequent
|style="text-align:left;"|'''Pros'''
|style="text-align:left;"|'''Pros'''
*Well established technology
*Well established technology
*Will function prior to establishment of vegetation
*Will function prior to establishment of vegetation
|-
|-
|style="text-align:left;"|'''Cons'''
*Requires larger land area
*Sludge removal may be more difficult
*Open water may generate more health and safety concerns.
|style="text-align:left;"|'''Cons'''
|style="text-align:left;"|'''Cons'''
*Requires more land
*Requires more land