$12\mathrm{.}3$ For the hydrograph presented in Table $12\mathrm{.}14,$ estimate the volume of storage required to control the post$-$development peak flow using runoff difference. The watershed drainage area is $165$ acres and is in a NRCS Type II rainfall region. Express the storage estimate in acre$-$ft$.$ Keep in mind that runoff volume in $f{t}^3$ can be calculated by summing the hydrograph ordinates and multiplying that sum by the time step in seconds. Use of a spreadsheet is encouraged.