b$)$ A $5,000m^2$ wastewater lagoon with minimum operating depth $0\mathrm{.}6m$ and maximum operating depth $1\mathrm{.}5m$ receives $9000\frac{m^3}{d}$ of wastewater having an average BODs of $122m\frac{g}{L}.$ Calculate the BOD s loading $($in $k\frac{g}{m^2}.$day$)$ and detention time of the pond $($in hours$).$

$(6$ marks$)$