720 square feet of my roof drain into a gutter. The water flows out of a drain pipe that is 4 feet in length. During a heavy rain, JPart of the flow goes into my neighbor's yard. Possibly, if I direct the flow into a dry well, I can avoid this. (Thus far, my neighbor is still friendly.)
A heavy rain might be 3-4 inches in 24 hours although it is more likely to be 1-2 inches. For 3 inches in 24 hours, I calculate that the dry well will have to handle 180 cubic feet over 24 hours. Water will come in and, presumably, leach out. The soil is not sandy. It is just plain dirt. For 2 inches, it will have to handle 120 cubic feet over 24 hours.
There is no pond to drain into and the town will not be happy if I connect to the storm drain in the street.