EXAMPLE $6\mathrm{.}9.$ Interpretation of Wellpoint Data

A wellpoint of $0\mathrm{.}1$ m radius in a permeable soil layer $7$ m thick has a constant discharge of $0\mathrm{.}05$ m$3/$s in a $24-$hour operation. The soil parameters are k $=0\mathrm{.}004$ m$/$s and e $=0\mathrm{.}5.$ Determine the radius of influence and the maximum drawdown.

Strategy Use Kozeny$$s $(1933)$ equation for R and then use Equation $(6\mathrm{.}29)$ to calculate dmax.