impervious vs imperviable

impervious and imperviable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
impervious	No	Yes	No	No
imperviable	No	Yes	No	No

As adjectives, impervious and imperviable are synonyms defined as:

impervious and imperviable: not admitting of passage or capable of being affected

impervious (adjective)	imperviable (adjective)
not admitting of passage or capable of being affected	not admitting of passage or capable of being affected