A coal slurry pipeline is to be built to transport 45 million tons/year of slurry over a distance of 1500 miles. The slurry can be approximately described as Newtonian with a viscosity of $35 \mathrm{cP}$ and $\mathrm{SG}$ of 1.25. The pipeline is to be built from ANSI 600\# commercial steel pipe, the pumps are $50 %$ efficient, energy costs $\$ 0.06 / \mathrm{kWh}$, and the economic lifetime of the pipeline is 25 years. What would be the most economical diameter for the pipeline, and what would be the corresponding velocity in the pipe?