Changes

|''n''||n/a||Porosity of the aggregate or other fill material (e.g. 0.4 for clear stone).<br> *Note: For systems that have significant storage in clear open chambers or other void producing structures, an effective porosity value (''n<nowiki>'</nowiki>'') may be estimated for the whole installation and used in the calculations below. Effective porosity will vary according to the geometry of the storage chambers, so advice should be sought from product manufacturers. Permit applications should include the basis for ''n<nowiki>'</nowiki>'' estimates.

|''n''||n/a||Porosity of the aggregate or other fill material (e.g. 0.4 for clear stone).<br> *Note: For systems that have significant storage in clear open chambers or other void producing structures, an effective porosity value (''n<nowiki>'</nowiki>'') may be estimated for the whole installation and used in the calculations below. Effective porosity will vary according to the geometry of the storage chambers, so advice should be sought from product manufacturers. Permit applications should include the basis for ''n<nowiki>'</nowiki>'' estimates.

|-

|-

|''I''||m²||Impermeable area i.e. catchment

|''I''||m²||Impermeable area within the catchment

|-

|-

|''d''||m||depth of infiltration facility or BMP

|''d''||m||Depth of infiltration BMP

|-

|-

|''P''||m²||Permeable area i.e. footprint area of the facility or BMP

|''P''||m²||Permeable area (i.e. footprint area of the infiltration BMP)

|-

|-

|''x''||m²||Catchment area i.e. area contributing drainage to the BMP

|''x''||m||Perimeter of the infiltration BMP

|-

|-

|''K''||mm/hr||Infiltration coefficient of the filter media or fill used in the infiltration facility  

|''K''||mm/hr||Saturated hydraulic conductivity of the filter media or granular fill (i.e. aggregate) used in the infiltration BMP  

|}

|}

==To calculate the required depth, where the area of the facility is constrained (1D)==

==To calculate the required depth, where the area of the facility is constrained (1D)==

In some very constrained sites, the surface area of the BMP may be limited, in this case the required depth of cell or trench can be calculated.

In some very constrained sites, the surface area of the BMP may be limited, in this case the required depth of the cell or trench can be calculated.

Note that in most cases the results of this calculation will be very similar to those of the above equation using 3D infiltration.  

Note that in most cases the results of this calculation will be very similar to those of the above equation using 3D infiltration.  

:<math>d=\frac{D\left[\left( \frac{I}{P} \right )i-q \right]}{n}</math>

:<math>d=\frac{D\left[\left( \frac{I}{P} \right )i-q \right]}{n}</math>