Design infiltration rate

The design infiltration rate (f') is used in all sizing calculations for bioretention and bioswales, dry ponds, infiltration trenches and chambers, and exfiltration trenches. It is related to, but not synonymous with 'permeability', 'field hydraulic conductivity' (K_fc), or 'saturated hydraulic conductivity' (K_sat). Before application a safety correction factor (SCF) is incorporated into the figure, depending upon the source of the raw data, and the risk of failure of the finished practice.

It is highly recommended that data are collected on site.

Sources of data

Caption: Acceptable sources of data

Procedure	Suitability
Guelph Permeameter

The rate at which stormwater percolates into the subsoil measured in inches per hour.

A parameter that describes the capability of a medium to transmit water.