Excavation for the tank is complete and now we have begun setting the tank in to the hole.  As you can see this is a large 3500 gallon tank.

To give you an idea of how much water that is, an average garden hose without a nozzle can pour out 530 gallons of water in an hour.  It would take almost seven hours to fill this tank with a hose, but filling this underground water retention tank with rain from a 3600 square foot roof  can happen quickly in a big rain.