A seepage pit is to be used to fully retain the runoff from a 1500 square foot roof of a residential dwelling during the 10-year, 60-minute storm. This storm has a 2 in./h intensity and amounts to 2 in. of rainfall. Calculate the required storage volume of the seepage pit.

A 6.5 ft O.D., 6 ft I.D., 4 ft high seepage pit, enveloped in a 2 ft thick stone and a 1 ft thick stone base is proposed for this dwelling. Is this pit adequate? Use a void ratio of 40%.