Design horizontal$-$flow rectangular sedimenation basins for a water treatment plant that must treat a flow of $200$ million liters per day $(52\mathrm{.}8$ MGD$).$ Since alum is used as a coagulant, an overflow rate of $1\mathrm{.}5$ m$/$h is appropriate. The minimum water temperature is $10$oC$.$

Your principal engineer recommends using $4$ basins. Justify this assumption and complete the problem assuming there will be $4$ basins.

Determine the basin plan area for each basin.

Using a hydraulic retention time of $3$ hours, find the depth of the basins.