$5.$ An stormwater analysis utilizing the SCS method, revealed the following information.

Existing Site

Drainage Area$-7\mathrm{.}00$ Ac

CN$-79$

Tc$-0\mathrm{.}50$ hours

Run$-$off $0\mathrm{.}7$ inches

Proposed Site

Drainage Area$-7\mathrm{.}00$ Ac

CN$-88$

Tc$-0\mathrm{.}392$ Hours

Run$-$off $1\mathrm{.}2$ inches

$\backslash$begin$\{$tabular$\}\{|$c$|$c$|$c$|\}$

$\backslash$hline $\backslash$begin$\{$tabular$\}\{$l$\}$

If the $\backslash \%$ increase in runoff $\backslash \backslash$

volume is:

$\backslash$end$\{$tabular$\}$ & & $\backslash \backslash$

$\backslash$hline Equal to or greater than & And less than & $\backslash$begin$\{$tabular$\}\{$l$\}$

The critical storm event to $\backslash \backslash$

be used for onsite detention $\backslash \backslash$

is:

$\backslash$end$\{$tabular$\}\backslash \backslash$

$\backslash$hline $0$ & $10$ & $1-$year storm event $\backslash \backslash$

$\backslash$hline $10$ & $20$ & $2-$year storm event $\backslash \backslash$

$\backslash$hline $20$ & $50$ & $5-$year storm event $\backslash \backslash$

$\backslash$hline $50$ & $100$ & $10-$year storm event $\backslash \backslash$

$\backslash$hline $100$ & $250$ & $25-$year storm event $\backslash \backslash$

$\backslash$hline $250$ & $500$ & $50-$year storm event $\backslash \backslash$

$\backslash$hline $500$ & $\backslash (\backslash$cdots$-\backslash$cdots $\backslash )$ & $100-$year storm event $\backslash \backslash$

$\backslash$hline

$\backslash$end$\{$tabular$\}$

Utilizing the chart above determine the Critical storm for the detention, show calculations