Grit chamber is designed to remove particle of $0\mathrm{.}25$ mm dia Terminal velocity Vs $2\mathrm{.}5$ cm$/$sec $0\mathrm{.}025$ m$/$sec Width of chamber $0\mathrm{.}50$ m$.$ Depth of flow H $0\mathrm{.}75$ m Flow through velocity V$=0\mathrm{.}3$ m$/$sec$.$ L$=?$ As it is asked to remove $0\mathrm{.}25$ mm particle completely efficiency is $100\%$