A water main is to be laid from the present pumping station in a small community to a new subdivision. The estimated future population of the subdivision is 1500 persons, each of whom will use an average of 40 gal of water per day, with the maximum rate of 4 gph. The pipe is to be cast iron. The subdivision lies on the crest of a low hill whose summit is 75 ft above the pumping station, and the route of the pipe is 13500 ft long to the summit. The pump delivers the maximum capacity at a head of 145 ft. If the pressure at the summit must be 25 psig under the maximum flowrate, what pipe size (inches) is required?​