Is there any benefit to using PICPs on low-infiltration soils such as some types of clays?
Yes. If soil infiltration is slow (generally under 0.5 in./hour or 1.3 x 10-2 m/sec), perforated plastic pipe drains at the bottom of the base can remove excess water while still allowing some of the water to infiltrate into the soil. The drainage rate for the water contained in the base is typically no greater than 24 hours. Over practically impervious soils or high bedrock, an impervious pond liner can be used to detain, filter and release the water through drain pipes. Regardless of the rate of soil infiltration, the filtering action of the open-graded base can reduce water pollutants. All permeable pavements require periodic surface cleaning.
