Changes

|Thickness (mm)||Entire trench

|Thickness (mm)||Entire trench

|-

|-

|Void ratio||Suggest value 0.4 (unless otherwise tested) for designs using just clear stone [[reservoir aggregate]] for storage. For any design using preformed [[infiltration chambers]], the overall ‘effective void ratio’ will vary according to product geometry. Contact manufacturer(s) for recommended value. 

|Void ratio||Suggest value 0.4 (unless otherwise tested) for designs using just clear stone [[reservoir aggregate]] for storage. For any design using preformed [[infiltration chambers]], the overall ‘effective void ratio’ will vary between 0.67 and 1.0 according to product geometry.  

|-

|-

|Seepage rate (mm/hr)||Infiltration rate of native soil. See [[design infiltration rate]]

|Seepage rate (mm/hr)||Infiltration rate of native soil. See [[design infiltration rate]]

|Clogging factor||Typical value of 0.5 for aged structures.  

|Clogging factor||Typical value of 0.5 for aged structures.  

|-

|-

|Design drawdown time (hrs)||Suggested value 72 - 96 hours, see [[drainage time]]

|Design drawdown time (hrs)||Suggest that this be the time within which there's a 50 % chance of recurrent rainfall? [[drainage time]]

|-

|-

!colspan = "2" style="background: darkcyan; color: white; align = center"|Drain (underdrain)

!colspan = "2" style="background: darkcyan; color: white; align = center"|Drain (underdrain)

|Flow exponent||Suggested value 1

|Flow exponent||Suggested value 1

|-

|-

|Offset height||This is the height from the base of the cell to the height at which the drain discharges. In some designs this may be the height of the perforated pipe within the storage layer. In other designs this height is adjusted by creating an upturn in the discharge pipe.  

|Offset height||This is the height from the base of the cell to the height at which the drain discharges. In some designs this may be the height of the perforated [[pipe]] within the storage layer. In other designs this height is adjusted by creating an upturn in the discharge pipe.  

|}

|}

[[category: modelling]]

[[category: modelling]]