Example $10$: Well pumping test

A well pumping test was carried out in an unconfined layer of clean sand

$15m$ thick and overlying an impermeable stratum. The water table was $2m$

below the ground surface. The discharge after achieving equilibrium was

measured as $1\mathrm{.}1\frac{m^3}{m}in$ while the drawdown in two observation wells at

$20m$ and $40m$ from the pumping well were measured at $0\mathrm{.}80m$ and $0\mathrm{.}55m$

respectively.

Produce a sketch of the problem and calculate the average permeability of

the sand.

A particle size distribution indicated that $D_{10}$ for the sand was $0\mathrm{.}25mm.$ Is

this consistent with the permeability determined from the pumping data?