$1.$ The areas shown below are to be drained by a storm sewer system. The size of each area, the inlet times, and the runoff coefficient are as shown in the table. The lengths between major maintenance holes and the surface grades are also given. Assume Manning's $\backslash ($ n$=0\mathrm{.}015\backslash )$ for the concrete sewer pipes. The design rainfall IDF curve is given by $\backslash ($ i$=705/($t$+10)^\{0\mathrm{.}85\}\backslash )$ where $\backslash ($ i $\backslash )$ is the rainfall intensity $(\backslash (\backslash$mathrm$\{$mm$\}/\backslash$mathrm$\{$hr$\}\backslash ))$ and $\backslash ($ t $\backslash )$ is time $($minutes$).$ Calculate the design flows and the actual pipe flow velocities; and size the sewer with commercially available pipe sizes.

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