Then increase A<sub>r</sub> accordingly to keep R, the ratio of impervious contributing drainage area to water storage reservoir area, between 0 and 2 to reduce hydraulic loading and avoid premature clogging, assuming that water storage reservoir area and permeable pavement area are the same (A<sub>r</sub> = A<sub>p</sub>).
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Then increase A<sub>r</sub> accordingly to keep R, the ratio of impervious contributing drainage area to water storage reservoir area, between 0 and 2 to reduce hydraulic loading and avoid premature clogging. This assumes that the water storage reservoir area and permeable pavement area are the same (A<sub>r</sub> = A<sub>p</sub>).