Also, I would check consolidation settlements of the saturated clay. Settlements may be large assuming that the loaded area is large (large size SOG since it is an industrial building) and if the clay layer is thick. Also, check if you will have new fill to match the proposed grades. New fill loads may be larger than the SOG loads and therefore contribute to more consolidation settlement. The differential settlement of the SOG and the foundation may be critical for deciding betweeen a floating slab vs. a fix slab. I would also consider some capillary break (some engineers also use vapor barriers) under the slab since groundwater is high. Anyway, I know that you will get more comments from the senior guys here in this forum...
