|''d<sub>r</sub>''||m||Water storage reservoir depth. For practices without an underdrain (i.e. full infiltration design), d<sub>r</sub> is the total depth of the practice (i.e. includes surface ponding and filter media depths). For practices with an underdrain (i.e. partial infiltration design), d<sub>r</sub> is the depth below the invert of the underdrain perforated pipe or riser pipe upturn. | |''d<sub>r</sub>''||m||Water storage reservoir depth. For practices without an underdrain (i.e. full infiltration design), d<sub>r</sub> is the total depth of the practice (i.e. includes surface ponding and filter media depths). For practices with an underdrain (i.e. partial infiltration design), d<sub>r</sub> is the depth below the invert of the underdrain perforated pipe or riser pipe upturn. |