A stormwater bioinfiltration system ( 1 m deep, 2 m wide and 2 m length ) contains filter layer as a mixture of sand and soil with the following properties: porosity 0 . 3 9 , bulk density 2 . 1 g / cm 3 , and foc 0 . 1 % . The hydraulic conductivity of the media layer is 1 . 5 cm / min . During a rainfall, the filter media becomes quickly saturated and develop a head equal to its depth; that is hydraulic gradient is 1