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|   | Before you begin you will need to know the following;<br>  |   | Before you begin you will need to know the following;<br>  | 
| − | * Catchment area (i.e. contributing drainage area), A<sub>c</sub> (m<sup>2)  | + | * Catchment area (i.e. contributing drainage area), A<sub>c</sub> (m<sup>2</sup>)  | 
|   | * Catchment runoff coefficient, C  |   | * Catchment runoff coefficient, C  | 
|   | * Catchment impervious area, A<sub>i</sub> (m<sup>2)  |   | * Catchment impervious area, A<sub>i</sub> (m<sup>2)  | 
|   | * Design storm intensity, i (mm/h)  |   | * Design storm intensity, i (mm/h)  | 
|   | * Design storm duration, D (h)  |   | * Design storm duration, D (h)  | 
| − | * Infiltration target for design storm event, I<sub>d</sub> (mm)  | + | * Infiltration volume target for the design storm event, V<sub>i</sub> (m<sup>3</sup>), based on average annual water budgets for the catchment for pre- and post-development scenarios and the infiltration volume deficit (pre-development minus post-development infiltration)  | 
|   | * Drainage time t (h) to fully drain the active storage of the practice, based on provincial or municipal criteria or average inter-event period for the location  |   | * Drainage time t (h) to fully drain the active storage of the practice, based on provincial or municipal criteria or average inter-event period for the location  | 
|   | * Field infiltration rate of the underlying native soil f<sub>f</sub> (mm/h), median of field measurements or based on interpolation from median grain-size distribution results  |   | * Field infiltration rate of the underlying native soil f<sub>f</sub> (mm/h), median of field measurements or based on interpolation from median grain-size distribution results  |