Changes

|''q''||mm/hr||Infiltration coefficient, calculated from measured [[Infiltration: Testing| infiltration rate]] and applied [[Infiltration|safety factor]]

|''q''||mm/hr||Infiltration coefficient, calculated from measured [[Infiltration: Testing| infiltration rate]] and applied [[Infiltration|safety factor]]

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|''n''||-||Porosity, as measured (or default to 0.35 for all aggregates).<br> *Note: For systems that have significant storage in clear open chambers, 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.

|''V_R''||-||Porosity (void ratio), as measured (or default to 0.35 for all aggregates).<br> *Note: For systems that have significant storage in clear open chambers, 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.

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

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