There has been plenty of open cut mining in the salt lake out at...

There has been plenty of open cut mining in the salt lake out at Lake Lefroy near Kambalda.
No problems at all.
Build a bund wall around the perimeter to hold back surface water.
Pump out any groundwater inflows (which are generally not necessarily high)
From a mining perspective unit mining costs of the clay pan muds are very low as no blasting is required, however the batter angles have to laid back extremely flat as the clays have no strength.

Cheers
Gosouth