As an alternative to traditional impervious pavements like concrete and asphalt, the runoff volumes generated by the Gravelpave2 surface will be greatly reduced. Indeed, as much as 35% of the compacted porous base course and porous wearing course pavement section is air (void), which will be the first area for stormwater to occupy as it falls upon the surface. Assuming a native soil of clay (not true in your case), with a depth of pavement 12” thick, then 35% of void would absorb a 4.2” rainfall before becoming saturated and beginning to create runoff. Variables: runoff from roofs and other hard surfaces directed to the porous pavement would diminish the rainfall capacity, but porous surfaces below the pavement would increase rainfall capacity.
Gravelpave2 is designed to support 220 psi when empty, and when filled with fine gravel will support in excess of 5700 psi. These numbers relate directly to vehicular tire pressures, and are nearly twice as strong as standard site concrete materials. It must be remembered however, that the base course must receive the load transferred by the rings and grid, and must be designed accordingly to match design loads with capabilities of native soils below to avoid rutting (standard pavement design). Poor soils such as clay and silt should always use a geotextile filter fabric between the subsoil and the base course to prevent pot holes from developing.
Gravelpave2 vs Concrete Pavements