The water level in a water tower is $110 \mathrm{ft}$ above ground level. The tower supplies water to a subdivision, 3 miles away, through an 8 in. sch 40 steel water main. If the minimum water pressure entering the residential water lines at the houses must be $15 \mathrm{psig}$, what is the capacity of the water main (in gpm)? If there are 100 houses in the subdivision and each consumes water at a peak rate of $20 \mathrm{gpm}$, how big should the water main be?