a Calculate the runoff as a volume from a building 446 ft by

a.) Calculate the runoff (as a volume) from a building 446 ft by 280 ft during a massive storm that rained 2.2 inches per hour for 3.75 hours.

b.) Convert this amount to something people can understand. For example, how many swimming pools would it fill up?

Solution

(a). The area of the top of the building is 446 ft.* 280 ft. = 124880 sq. ft. A storm rained 2.2 inches per hour for 3.75 hours or, 2.2*3.75 = 8.25 inches or, 8.25/12 ft. = 0.6875 ft. Then, the total volume of the runoff is 124880*0.6875 = 85855 cu. ft.

(b). In USA, the dimensions of an Olympic size swimming pool are length- 50 meters/164.04 ft., width- 25 meter/82.02 ft. and depth- 2 meters/6.5616 ft. The volume of such a swimming pool is 2,500 m³ / 88,283 cu. ft. Thus, the runoff would fill up 85855/88283 = 0.97 swimming pool , or, say 1 swimming pool ( on rounding off to the nearest whole number).