Is there any way to do an Ufer (concrete-encased) ground with a monolithic slab that has a vapor barrier?
Front Porch Grounding Electrode

An Ufer ground (concrete-encased electrode) can be made from any reinforced foundation or footing that is in direct contact with the earth, whether it is supporting a structure or not.  This means that not only is the house foundation eligible provided it is in direct contact with the earth, but a front or back porch or stoop can be used in addition or instead provided it has a sufficient length of suitable rebar or wire inside and has a footing that is in direct contact with the earth.  Since there's no need for a vapor barrier on a porch or stoop where the concrete's wearing surface is exposed to the elements anyway, this means that with perhaps a bit of trickery, you can get the benefits of an Ufer ground without having to give up a sub-slab vapor barrier for the main foundation and footings.