Method of reinforcing smectite shale in opencast mines embankment

The stabilizing smectite slate may include treating smectite shale in a subsurface formation with a dehydrating fluid in order to obtain stabilized smectite slate, wherein the dewatering fluid comprises an aqueous base fluid and a dehydrating additive. In some cases, a portion of a slope may be at least formed in an open pit mine at a slope Boschungsbaustandort comprising the stabilized smectite slate.