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2) An airport drainage area has concrete pavements having the average run off characteristic with 1.8% slope and weakly pervious soils with turf 0.4%. Determine the size, capacity, and slope of centrifugally spun concrete pipe and the invert clevation at the inlet end for handling the worst rain fall. The invert elevation at the outer end is 520.360. The length of the pipe is 928 feet. 12% of the drainage area is paved. The distances to the most remote point from the inlet to the pavement and turfed areas are 180 feet and 1320 feet respectively, (1.25 weight)