Detention Pond Design

For the given inflow hydrograph, design a detention basin that will reduce the peak flow out of the basin to $10$ cfs$.$

$\backslash$table$[[\backslash$table$[[$Time$],[($minutes$)]],\backslash$table$[[$Inflow$],[($cfs$)]]],[0,0],[20,3\mathrm{.}5],[40,5\mathrm{.}5],[60,8\mathrm{.}5],[80,11],[100,14\mathrm{.}5],[120,17\mathrm{.}5],[140,17],[160,15\mathrm{.}5],[180,13\mathrm{.}5],[200,11\mathrm{.}5],[220,10],[240,8\mathrm{.}5],[260,7\mathrm{.}5],[280,6\mathrm{.}5],[300,5\mathrm{.}5],[320,4\mathrm{.}5],[340,3\mathrm{.}5],[360,2\mathrm{.}5],[380,1\mathrm{.}5],[400,0\mathrm{.}5],[420,0]]$

Your basin should be twice as long as it is wide. The side$-$slopes should be $3$ horizontal to $1$ vertical $(3$:$1).$ I recommend that you have a round orifice on the bottom of your outlet structure $($so that the basin will go completely dry after the storm. You are required to provide me with a design that shows the:

Length, width and water depth $($during peak flow$)$

The configuration of your outlet structure $($basic dimensions $-$ don't worry about thickness of concrete and pipes, etc..$)$

A graph the shows both the inflow hydrograph and the outflow hydrograph

The spreadsheet that you developed to solve this problem. AND, NO$,$ you cannot use any software other than a spreadsheet.

Hints: remember to watch the units $($especially the units of time$).$ Keep it simple, don't try to optimize the design. Develop and use your spreadsheet to route the storm through your basin.