Dig out a pit to take the size of grid. Dig to a depth of 2'6", backfill with hardcore 16" depth, consolidate down. Place grid unit on hardcore base. Backfill around edges and drive over in 3 hours. Put perforated pipe under hardcore for drainage purposes. You can also install on a 150mm concrete pad if you wish. GENERALLY 3 - 4 HOURS FROM THE START OF DIGGING IT IS READY FOR USE!