Analytical Equations for Estimating the Total Runoff Reduction Efficiency of Infiltration Trenches

The total runoff reduction efficiency of infiltration trenches can be used as the primary indicator of their stormwater management performance. In this technical note, analytical equations are derived for estimating the runoff reduction rates of infiltration trenches. These equations take as input variables the contributing area, the storage space provided by a trench’s stone reservoir, the groundwater recharge rate facilitated by a trench’s underlying soils, and parameters representing local climate conditions. For a wide range of possible design cases, results of the analytical equations were found to be comparable to those from computer simulations. Example applications of the equations are made for two locations representative of humid and dry climate conditions.