If a $50-cm$ long field sample with an estimated hydraulic conductivity of $40m$ day is to be

tested in the laboratory using water at $20$C$,$ what would be maximum allowable head

difference across the column? The sample has a median grain diameter of $1\mathrm{.}5$ mm $.$

Note: Darcy's Law is valid for Reynold's Number $<mtext></mtext><mn>1</mn>$

Darcy's velocity, $V$

Head difference, $dh$