<p>An internal water storage zone/reservoir (IWS or IWSZ) is created by including an upturned 90 deg on the outflow pipe to force an elevated outlet. For practical reasons, this is commonly applied within a manhole or other nearby piece of infrastructure, rather than being buried directly adjacent. The effect is to create longer term, water-logged, low-oxygen environment within the bottom of the bioretention cell. <br>
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<p>An internal water storage (IWS) reservoir or zone is created by including an upturned 90 deg on the outflow pipe to force an elevated outlet. For practical reasons, this is commonly applied within a manhole or other nearby piece of infrastructure, rather than being buried directly adjacent. The effect is to create longer term, water-logged, low-oxygen environment within the bottom of the bioretention cell. <br>