Designing a section of pervious concrete is a multi task analysis.
Step 1: The subgrade must be analyized for water percolation. This is the amount of water that can be absorbed into the ground over a 24 hour period.
Step 2: The thickness of the stone or gravel subbase is determined by the amount of water that needs to be stored. The amount of water that needs to be stored is determined by the percolation rate of the subgrade and the storm events that produce rainfall during a length of time. Usually this is from 1-3 days.
Step 3: The section of pervious concrete is determined by the traffic index (TI) that the pavement will be used for. The rule of thumb is 0-20 trucks is 6 inches thick, 20-100 trucks is 8 inches thick, 100+ trucks is 10-15 inches thick.