Changes

==Planning considerations==

==Planning considerations==

===Infiltration===

===Infiltration===

Permeable pavements can be constructed over any soil type, but hydrologic soil group (HSG) A and B are best for achieving water balance objectives.  Native soil infiltration rate at the proposed facility location and depth should be confirmed through in-situ measurements of hydraulic conductivity under field saturated conditions.  A liner will be required if native soils are contaminated.

For information about constraints to infiltration practices, and approaches and tools for identifying and designing within them see [[Infiltration]].

Systems located in low permeability soils with an infiltration rate of less than 15 mm/hr (i.e., hydraulic conductivity of less than 1x10^-6 cm/s), require incorporation of a perforated pipe underdrain. Pavements require an impermeable geomembrane where the underlying soils are contaminated or the pavement is within two year time-of-travel wellhead protection area (see local drinking water source protection plan).

 

Permeable pavements can be constructed over any soil type, but hydrologic soil group (HSG) A or B soils are best for achieving water balance and erosion control objectives. Facilities should be located on portions of the site with the highest infiltration rates. Native soil infiltration rate at the proposed facility location and depth should be confirmed through in-situ measurements of hydraulic conductivity under field saturated conditions. For guidance on infiltration testing and selecting a design infiltration rate see [[Design infiltration rate]]. Systems located on low permeability soils with an infiltration rate of less than 15 mm/hr (i.e., hydraulic conductivity of less than 1x10^-6 cm/s), should include a perforated pipe underdrain. A liner will be required if native soils are contaminated.

For guidance on infiltration testing and selecting a design infiltration rate see [[Design infiltration rate]].

===Space===

===Space===