A foundation $12m$ long $3m$ wide is to be constructed in a coffer dam at a depth of $1\mathrm{.}8m$ below the dredge line. The soil has the following properties:

$c^{\text{'}}=0,{}^{\text{'}}=32,{}_{sa1.}=20k\frac{N}{m^3}$

Calculate the gross ultimate bearing capacity for a condition where the water level is $1\mathrm{.}5m$ above the dredge line and there is a vertical upwards flow of water with a hydraulic gradient of $0\mathrm{.}25.$