Testing the water flow in the parking area seems small and insignificant, however the small things sometimes make the biggest difference long term – no ponding, correct flow and getting into the piped system inlets and out of the low point overland flow points means the surface drains and vehicles are not parked in puddles and people can walk without stepping in deep ponds when it is raining.
The water is supposed to flow 45 degrees across the parking to the centre island, through the centre island (which is ultimately to be planted/landscaped, then out through the lower parking area to the grid inlet in the low point of the parking. The small portions of water that can’t make the grid inlet are to flow to the edge beam outlet at the low point of the parking forming the overland flow outlet point.
The photos and video show the constructed product performing as designed . . .